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CEC DA 0 3.0

چهار شنبه 20 جولای 2016
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این برند CEC آمده ایران و رومی از CEC استفاده میکنه به عنوان ترنسپورت. تو انگلیس هم Living Voice محصولاتش رو با این CEC دمو میکنه با Audio Note ژاپن.

ما هم این ترنسپورت رو شنیدیم و تفاوتش رو دیدیم چقدر زیاد بوده با ترنسپورت های دیگه.

حالا این CEC اومده یه Dac زده که روی کاغذ خیلی وسوسه کننده است. مالتی بیت ، R2R بدون هیچ چیپ تبدیل ، بدون فیلتر خروجی و …

نگاهی بهش بندازید جالبه :

http://www.cec-international.com/PAGES/s25.html

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iFi Audio AMR Audio by thorsten loesch

دوشنبه 25 آوریل 2016
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Retro-Stereo50-01

 

LS35_Main

این آقای thorsten loesch یه طراح باهوش حساب میشه تو این های اند و تو سایت رومی هم ای دی داره و بحث میکنه.

این آدم تو حوزه دیجیتال خیلی کار کرده و مقالاتی داره که خیلی ها از جمله طراح Lampizator هم اونارو خونده و از تجربیات تورستن استفاده کرده.

این طراح تو کلاس قیمتی پایین سیستم های زیر رو ارايه داده که من  iDSD و 3.0 iUSB رو خریدم. یه ست جالب خونگی هم داره که با بلندگوی BBC فروخته میشه. هر کدوم از این کامپوننت ها یه کاری انجام میده.

توضیحات بیشتر تو سایت http://ifi-audio.com/ هست. نماینده این برند هم آرمن هست 09121198262 . قیمت ها بین 300 تا 500 دلار هست.

 

http://ifi-audio.com/wp-content/uploads/2016/02/banner-iCAN-SE.jpg miCAN SE_EN_11 idac204 http://ifi-audio.com/wp-content/uploads/2015/07/miusb3.001.jpg iPhono2-1 Micro-iDSD-02 MicroiCANPic01 MicroiLinkPic03 MicroiTubePic01 Read More

Wilson Audio Modular Monitor (WAMM) loudpeaker system

پنجشنبه 25 سپتامبر 2014
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اینم از خاطرات ویلسون و همسرش:

http://www.stereophile.com/content/wilson-audio-modular-monitor-wamm-loudpeaker-system

No, we made no typos in the specifications sidebar. The weight of the Wilson Audio Modular Monitor (WAMM) speaker system is enough to make you consult a structural engineer before dropping it on your living room floor—fragile, 300-year old New England frame houses are probably out. And the recent price increase from $32,000 to $35,000 is enough by itself to buy a pair of Quad ESL-63s—which is not a bad speaker system. The WAMM represents an all-out assault on both the state of the art in speaker systems and on the limits to which wealthy audiophiles will go in order to have the best (footnote 1).

Actually, it’s pretty easy to poke fun at a $35,000 speaker system—kind of like making tall-man jokes about Kareem Abdul Jabbar. The question is, is this the best speaker system you can buy? I’ve only spent a portion of two days with the WAMM, but I would have to say it’s the best speaker system I’ve ever heard, and I’d love to have a pair in my house. (I’ve even got the floor and walls to withstand the weight and low frequencies.) I’m not an authority on the Infinity IRS or the Levinson HQD (which at $29,000 and $24,000 respectively are the only speakers competing in this price category), so I can’t really make a valid comparison with the competition, though I have heard both of those systems. (An A/B comparison would require a forklift!)

Compared to the experience of live music, the WAMM does some things well that I have not heard reproduced music do before, and that’s certainly one of the main criteria. In addition to that, the WAMM proved useful in making evaluations of other equipment to a degree I’ve not experienced before. To say that every equipment reviewer should own one of these systems (what would the folks at The Sensible Sound magazine say to that?) is both fatuous and not strictly to the point. It is not, after all, through WAMMs that a clear majority of readers will be listening to their amplifiers and cartridges. I can only reiterate that I would love to have them in my home (perhaps a utility cabinet could drop the price a few $k), both for listening to music and for evaluating equipment.

Description
First, a description. The complete WAMM system consists of six pieces: two 6½’ subwoofers (also available in a low, fatter version); two 6½’ “full-range array towers” containing the mid-bass, midrange, and high-frequency drivers; one modified Crown equalizer (!!); and an electronic crossover. As implied by the term Modular in the name, the pieces are available separately: two full-range arrays with equalizer and personal calibration ($28,000), one or two subwoofers with electronic crossover by themselves ($4500 for one, $8000 for two), and the modified equalizer by itself ($1500). Other than the arrays, these are not unheard-of prices in high-end audio. The subwoofer modules are large, quite attractive boxes, heavily reinforced, which are simply enclosures for the extraordinary Magnat woofers that were mentioned last year in Stereophile (Vol.5 No.5). I have never seen a woofer as well-constructed as the Magnat. As a machine for moving air under control they seem without peer—although I’m sure the people at Hartley and Yamaha (who make a 24″ and a 36″ woofer, respectively) would differ with me on that point.

For some time now I’ve been leaning towards the opinion that smaller, highly-controlled woofers are the way to go in low- frequency reproduction. Considering that the Magnats in the WAMM system respond flat (or a little up, depending on your sitting position) down to 20Hz at sound pressure levels up to 120dB (10% harmonic distortion), they could be considered a small woofer.

The full-array towers themselves each consist of 15 separate drivers: two KEF B139 woofers mounted in an extremely well-sealed, well-baffled box which serves as a base for the remainder of the array; one modified Braun satellite speaker mounted on a handsome cast-aluminum “beanpole” immediately above the midbass enclosure; the electrostatic array (9 panels) mounted further up the array; and finally an additional Braun satellite speaker at the top of the beanpole (up where the Giant lives, so to speak). The satellites and electrostatic array are extended out in front of the vertical beanpole on aluminum rods which are themselves adjustable forward and back. The whole thing is not unattractively reminiscent of a schematic for ET, or maybe ET with a little ET riding on his (her?) shoulders.

Although ungainly, it is not unattractive, and I found the WAMMs less oppressive than the Acoustat 2+2s, which visually dominate a room in an inescapable fashion. Definitely not for small rooms (although Wilson Audio says rooms as small as 2000 cubic feet are suitable from a sonic standpoint) or audiophiles dedicated to disguising their fanatical interest in reproduced sound.

The electronic crossover is packaged in a separate chassis which can be stacked above the equalizer. The equalizer has been modified significantly by Wilson Audio, primarily by installing integrated circuit chips (with a much higher slew rate) and precision film capacitors. The original Crown costs $1200 and allows ±15dB of equalization in 11 octaves, with the centerpoint of each octave widely adjustable. At the Wilson’s house the largest variation from flat was 2dB, with most octaves equalized less than that. For those of you horrified by an equalizer, Dave Wilson pointed out that this equalizer causes 3° of phase shift for each dB of equalization; in the Wilson home there was from the equalizer a total phase shift of 6° from 0. I would be astonished to read evidence of someone detecting this amount of phase shift (though obviously the equalization itself would be detectible—that’s why it’s in there).

Sound Quality
How do they sound? There’s been much discussion in the press of the WAMM’s abilities to reproduce low frequencies at high volume levels. The shaking of several floors of the Riviera Hotel at the 1983 Las Vegas CES comes immediately to mind. These reports are not unfounded. The amount of press attention to low frequencies also reflects the interests of the WAMM’s designer, David Wilson.

Just before I left the Wilson house in Novato I was “treated” to a fairly high-level audition of one of Dave’s master tapes (Wilson Audio also makes records, which are not infrequently reviewed in these pages) wherein the organ used in one of Dave’s records plays a 16Hz note for some time. Dave had me sit in his favorite spot for that cut where he confessed, with a twinkle in his eye, the 16Hz tone was reproduced about 2dB above reference level. In other words, he’s a bass freak.

For those of you not used to hearing 16Hz at high volume (that should include almost every¬ one), it ain’t fun if you’re not a bass freak. Although clearly audible, a primary mode of sensing 16Hz is through your organs: stomach, kidney, liver, etc. which are not accustomed to being shaken around that way. Although I didn’t like it, I must confess the organ sounded very realistic and the sound was reproduced without apparent effort, distortion, or strain. That’s a real accomplishment for any sound reproduction system.

Focusing on the extraordinary low-frequency capabilities of the WAMMs misses the point, though. Their true value to the music-lover lies elsewhere. There are three character¬ istics that I found remarkable: a “bloom” in the mid and upper bass region, which allows the power of an orchestra to almost overwhelm you in live performances; seamless presentation of the entire frequency range, so that one thinks only of instruments and voices, not individual drivers; and uncanny imaging—so specific that it’s almost unrealistic.

The demonstration at the Riviera Hotel used a record with which I’m intimately familiar (Hot Stix on the M&K label). At one point in the record, the drummer beats the rim of a drum with his sticks, producing an unusual, very woody sound. On the WAMMs it was possible to hear the drum stick move from one point on the rim of the drum to a point only 2″ away, both points clearly defined (aurally) in the air. Fantastic! I’m sure this effect would not have been so dramatic in a live performance, just as I’m sure it’s information the microphones (which are frequently much closer to the performer than any listener) captured and which I was hearing reproduced accurately for the first time.

Seamless presentation of the frequency range is a characteristic shared by other speakers, even some that are not all that expensive. The Quad ESL-63, the Thiel 03a, and the new Spica TC-50 come to mind. What is unusual, and truly an achievement, is that the WAMMs do this with a complex, hybrid system over a very wide range of frequencies, much wider than the other speakers mentioned and at much higher sound pressure levels. Hybrid systems have a strong tendency to remind you of their different driver characteristics, and of the struggle the designer had in getting them to blend together. The Plasmatronics and HQD, to mention two otherwise excellent systems, are good examples. I would say that Dave Wilson has overcome this problem, certainly to a large degree. Whether he has completely overcome it would require much more extended listening; probably he has not. His technique for coming as close as he does will be described below.

I’ve saved the best for last. To say the mid and upper bass “bloom” referred to above is unusual would be a dramatic understatement. In my experience virtually all systems fail down when it comes to portraying the dynamics of live music, particularly orchestral music. Along with the upper midrange stress that always seems to accompany disc reproduction, there is an unwillingness of the system to increase its volume level as the orchestra reaches a crescendo, particularly at lower frequencies. Speakers that reproduce mid and upper bass dramatically are boomy; non-boomy speakers sound too lean. The absence of this difficulty is a hallmark of live music. The little drivers in their boxes just can’t match the 80 players with their celli, trombones, french horns, and fiddles up on that stage.
It is this acceleration of aural intensity which produces a kind of rapture in the music-lover—Do I wax too poetic? Are you checking the cover of your magazine to see if it’s really Stereophile?—that the WAMMs do uniquely well. As you can see, I was bowled over. As an equipment reviewer I would like the WAMMs for their cleanness of presentation, their tonal neutrality; as a sensual human being I would like the WAMMs for their ability to present realistic orchestral dynamics.

It’s hard to assign one specific cause to above effect. I suspect that the key decision was to use $8000 worth of cabinetry and driver to cover at most three octaves. This not only reproduces those octaves well—it frees up the rest of the system to perform in a dynamically satisfying way. Then again, the use of two KEF B139s per side, mounted in extremely well-braced boxes, to cover a frequency range that begins at 50Hz, is the kind of overkill that effects the freedom referred to above. And not to be dismissed is the all-out commitment of the designer together with his resourcefulness, the willingness to make a product that obviously will not sell in the hundreds of units and might have a hard time selling at all.

That he was willing to use modified Braun satellites and a Crown equalizer, two products that won’t win him status points amongst high-end aficionados, in his quest for aural realism is to Dave Wilson’s credit. And you shouldn’t think that his is a commercial path lined with easy money. It’s probably harder to make money producing a state-of-the-art speaker system than any way you could choose. Just ask Infinity how much they’ve made producing IRSes.

Not as much as they make selling $77 speakers, I’ll wager.

Set-Up
With the WAMM system, however, you don’t just get a bunch of boxes with a nail-puller and start unpacking. If you buy the system through a dealer the dealer ensures that you have adequate associated equipment (a word about that, later) and does the basic unpacking of the WAMMs. When all this has been done, Dave Wilson flies in and spends two days doing the final setup and calibration of the WAMM system.

There are basically five steps: (1) physical location in the listening room; (2) time-alignment of the individual driver units with respect to the listener’s specific location in the listening room; (3) basic adjustment of the equalizer to compensate for room anomalies and particular associated equipment; (4) fine adjustment of the centerpoint of each equalizer band using a unique Wilson Audio method; (5) and final adjustment of the equalizer for user preference. The two most interesting steps are (2) and (4).

One of the unusual design aspects of the WAMM system concerns physical adjustability of the drivers. Time-Alignment of drivers is a name copyrighted by E.M. Long, but the basic procedure (under some other name) can be used by any speaker manufacturer. The goal is to ensure that the successive wavefronts of a complex musical waveform produced by more than one driver will arrive at the listener’s ear at the same time.

In a rudimentary example, one can see that the so-called acoustical center of a 15″ woofer and a 1″ dome tweeter mounted on a flat speaker baffle will arrive at the speaker’s ear differentially in time simply because the woofer’s voice-coil, from which the basic signal emanates, is a significant distance further away from the listener than the tweeter’s voice-coil. In fact, calculating the arrival time of an acoustic wavefront from a particular driver is a complex process wherein minor changes in crossover and driver design become important.

Dave Wilson is able to solve this problem in a fairly straightforward fashion due to the fact that his drivers, each in their individual enclosures, can be moved from front to back, and because his listener chooses one ideal seat and speaker location, to which Dave can customize the speaker orientation. Other designers must assume a specific listener distance from the speaker and height off the floor—probably most listeners are not actually located where they “should” be, and so the time-alignment for those listeners is inaccurate. Specifically, Dave mounts a microphone at the height and location of his listener’s ear and aligns each driver starting with the midbass unit so that a test pulse arrives at identical times from the different drivers (both midrange units, at different heights, and the tweeter panel). Since the ear is insensitive to low-frequency arrival times, the placement of the subwoofers is made so as to excite room resonances as little as possible, or following aesthetic considerations.

The other fascinating adjustment by Dave Wilson concerns the adjustment of the centerpoint of the equalizer passbands, a process he calls “vowelization” or “vowelling”. With the equalizer set for approximate amplitude correction, Dave puts on a master tape of Sheryl Lee Wilson, his wife (see the cover of Vol.6 No.2), singing. He then adjusts the centerpoint of the midrange bands on the equalizer, creating an “oooh–aaah” effect until he arrives at the point which to his ear most accurately reproduces his wife’s voice—a source with which he is quite familiar.

Great idea! Dave has promised to write an article for us on this technique, which should be usable by the general audio public (provided they own a Crown equalizer with its adjustable centerpoints)—unless of course the wife’s voice is not a source of delight. In that unlikely instance, the equalizer might be used to eliminate a certain stridency in the offending wife’s voice—which stridency would no longer be available in your favorite Shostakovitch violin sonata!

An Analysis Tool
An interesting aspect of my visit to Wilson Audio was the use the WAMM system can be put to for analyzing differences between associated components. First, the components we used: (1) source material was Wilson Audio master tapes played on a modified Revox A77 and analog records, primarily from Wilson Audio, as played by an EMT/van den Hul cartridge mounted in a Technics tonearm on an Oracle turntable; (2) pre-preamplification through a Sig Modes-modified “Powerlight 3” head-amp; preamplification through the Spectral DMC-10 (Beta); amplification through two Krell KMA-200 amplifiers and the BEL 2002 amplifier.

As a test of the system’s resolving capabilities, as well as two highly rated cartridges, we compared the van den Hul EMT to the original master tapes as well as to the Accuphase AC-2, which would also be compared to the master tapes. A switching device was rigged up so that the two cartridges could be played through the same preamplifying device. Methodological problems lay in the use of two different turntables and tonearms, as well as a switching device whose changes were noticeable through a fairly loud click.

Most profoundly noticeable was the system’s ability to resolve small differences. We were fortunate to have on hand master tapes of the discs we were listening to. Outside of PCM-F1 copies of master tapes (to which I imagine Dave would object) I don’t know of a way to compare a disc to its master tape in a home situation.

The results? Well, the van den Hul EMT produced a very faithful recreation of the master tape. I’m astonished that it’s possible to amplify the signal from a tape, operate a cutting stylus to create a lacquer, make a mother and then a stamper, stamp a vinyl disc, turn it on a turntable, play it with an electro-mechanical generator interacting with the semi-fluid vinyl, and run it through an RIAA correction circuit with so little degradation. The test was neither single- nor double-blind but I could easily have become confused between the cartridge and the master tape. There were small differences in the amount of detail available, but only repeated playings of the comparison would reveal this. Spectral balance was virtually identical with the exception of the lowest bass, where the van den Hul EMT was slightly deficient.

How did the Accuphase AC-2 do? By comparison to either the EMT or the master tape, there was a constant amount of mid- to high-frequency distortion added to the music, as an overlay. To describe it as an extra amount of sibilance gives an accurate idea of the sound. This distortion was readily evident comparing to either the master tape or the van Den Hul.

Summing Up
So, what do we have with the WAMMs? For me it’s the most enjoyable speaker system I’ve listened to, and significantly valuable as a diagnostic tool. This is particularly true when evaluating cartridges, preamplifiers, turntables and other source material. I urge caution in using the WAMM system, or any particular speaker system, for evaluation of amplifiers. Time and time again we at Stereophile have seen an extremely good amplifier fall down with some particular system, and conversely have found combinations where an otherwise ordinary amplifier mates very well with a particular speaker.

In this respect the WAMM is not different from other speaker systems. In matters of clarity and revelation of detail the system may be unsurpassed; with respect to tonal balance the WAMM is a special load for an amplifier, and results obtained with it may well not be universally applicable. Moreover, the WAMM’s use of an equalizer, which is presumably adjusted to accommodate the varieties of amplifier used, should put on an equal basis many otherwise different amplifiers. Nevertheless, I lust after this speaker system for use in evaluating related components.

Is it worth the money? Surely not, for any person whose income or net worth is less than stratospheric—and certainly not for one who has to be concerned with mundane subjects like mortgage payments and mere cost-of-living salary increases. But my dealings in the expensive automobile business have revealed to me that there is a significant number of Americans (and non-Americans) to whom large amounts of money are merely digits to be entered in their checkbook—they don’t worry about the balance, which apparently takes care of itself. To such people, or possibly to an absolutely fanatic though financially more normal audiophile, I would certainly recommend an audition of the WAMM speaker system.

Aiming for such heights in audio componentry is a bold first move for David and Sheryl Lee Wilson, and I wish them all the luck in the world. I have my reservations about their most recent $7000 price increase (footnote 1), though it may not put off any truly potential buyers. About one thing I have no reservations: I can think of no person or company I would prefer to have supporting and warrantying such a substantial investment.

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Western Electric

شنبه 12 نوامبر 2011
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برگردیم به گذشته و ببینیم چه کمپانی هایی دست اندر کار آئودیو بودند. وسترن الکتریک (با نام مخفف WE) یکی از همین قدیمی هاست مثل Altec و JBL و Quad و … که کارهای زیادی انجام داده.

از ساخت لامپ گرفته تا درایور بلندگو و بلندگوی هورن و …

یه تاریخچه از بلندگو اینجاست http://en.wikipedia.org/wiki/Loudspeaker و اینجا هم چند تا دیگه هست که حتما بخونید ببینید وسترن و بقیه چه نقشی در تاریخچه ساخت بلندگو داشتند:

http://homepage.mac.com/oldtownman/recording/loudspeaker.html

http://www.altecpro.com/about/timeline.htm

http://www.nutshellhifi.com/library/tinyhistory1.html

http://homepage.mac.com/oldtownman/recording/notes.html

دلیل توجه من به این شرکت این بود که الان فکر میکنم جای بلندگوی هورن تو ایران خیلی خالیه. قبلا هم نوشتم برای لامپ خصوصا صدای فول رنج (برای غیر فول رنج از همین 2way های آئودیو نت که هورن نیستند هم میشه استفاده کرد) باید به سمت هورن رفت و بهترین آمپ لامپی مثل آئودیونت زمانی همه قابلیت هاش مشخص میشه که با بلندگوی مناسبش Match بشه. منظورم از Match بودن هم امپدانس هست و هم حساسیت و مهمتر از این دو Match بودن شاخص صدا در میکرو.

طبیعتا درایورهایی که پاسخ میکرو بهتری مثل paper ها دارند با آئودیونت جواب بهتری میدهند.

وسترن الکتریک مثل Altec قبل ها هورن میساخته و درایورهایی داره که میشه باهاشون هورن ساخت. عکس زیر هورن وسترن الکتریک تو نمایشگاه مونیخ امسال 2011 هست که شرکت Silbatone دمو کرده بود :

جالبه ببینم چه کسی تو ایران اولین برند هورن رو وارد میکنه یا چه کسی اولین بلندگوی هورن رو بر اساس همین قدیمی ها از جمله وسترن الکتریک یا التک تو ایران میسازه.

اگر مساله بلندگو برای لامپ تو ایران حل بشه (در قیمت های متوسط و پایین) مطمئن باشید تو رنج قیمت های معقول این تلفیق رقیبی نخواهد داشت و ما مجبور نیستیم اگر میکرو صدا برامون مهم باشه پول زیادی برای آمپ و بلندگو بدیم.

http://www.westernelectric.com/

http://www.westernelectric.com/history/tour01.html

http://www.porticus.org/bell/westernelectric_history.html

http://www.porticus.org/bell/westernelectric_history.html#Western%20Electric%20-%20A%20Brief%20History

http://vintagetubeservices.com/we.htm

http://www.audioheritage.org/html/profiles/lmco/shearer.htm

http://www.roger-russell.com/sonopg/sonos.htm

http://vintagehifiexperience.blogspot.com/

http://www.vintage-hifi.2itb.com/

http://itishifi.blogspot.com/

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برند EAR Yoshino با طراحی Tim de Paravicini

سه شنبه 30 آگوست 2011
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آقای فاطمی نمایندگی محصولات یکی از بهترین طراحان دنیا رو گرفتند، برند EAR Yoshino با طراحی آقای Tim de Paravincini هم اکنون در ایران قابل دسترس هست و علاقه مندان میتونند برای خرید کامپوننت های این برند با آقای علی فاطمی تماس بگیرند.

برند EAR هم محصولات استودیویی میسازه و هم محصولات های فای خانگی و بیشتر آمپلی فایر هاش لامپی بین 30 تا 70 وات هست ، البته 100 وات هم داره و یک مدل ترانزیستوری هم داره که 100 وات رو تو مد سینگل اندد میده که خیلی جالبه.

You use vacuum tubes in many of your designs. Some people have said that tubes have euphonic even-order harmonic distortion. Do you rely on this tube nonlinearity to achieve the sound of your mods, or do you always run the tubes in their linear region?

I do not rely on tube nonlinearity. I don’t want a sound in my machines. What comes out must sound the same as what went in.

The “warmth” in a lot of tube electronics is due to their dismal top end, the bad transformers they use, and the loading down of their high-impedance outputs. Because of the output transformer and the feedback used, many tube circuits have a partial bass instability that gives a bloated bass. Any warmth in the tube sound is a defect, but listeners don’t want to know that.

I don’t have to use tubes in my designs; I only do it for marketing reasons. I’ve got an exact equivalent in solid state. I can make either type do the same job, and I have no preference. People can’t pick which is which. And electrons have no memory of where they’ve been! The end result is what counts.

Most transistor-circuit architecture was different from tube-circuit architecture, and that’s what people were hearing, more than the device itself. The main advantage of tubes is that an average tube has more gain than an average transistor. Second, tubes don’t have the enormous storage times of transistors, so they are very fast. Tubes go to 100 MHz without trying.

متن پایین در مورد آقای تیم نوشته :

There are very few modern designers in the audio field who can claim as much as de Paravicini. No aspect of the recording and reproduction chain has been left untouched, no aspect of circuit design not further researched and developed.

As early as 1965 Tim was involved in custom design work for rock and roll bands; manufacturing his own public address equipment, and modifying existing studio equipment to realise even greater potential. A move to South Africa from England saw a further development of his own unique design genius, and the launch of his own professional amplifier product, sold simply as “de Paravicini”.

While working in South Africa, Tim had a chance meeting with representatives of the Lux Corporation, and in 1972 was invited back to Osaka, Japan, and offered a job as audio designer. Tim soon put together some very interesting designs for Lux, including the remarkable C1000/M6000 pre/power amplifier combination. One of his own favourite designs from this period was the Luxman 3045 tube mono block. At the time, this was the only mono block design available in the audio field, and backed up de Paravicini’s preference for locating the power amplifiers close to the loudspeakers. Tim also designed the actual output tube for this amplifier, the 8045 power tube. As always with his designs, the output transformer was a custom de Paravicini design.

In 1976 de Paravicini returned to England, and very quickly made an impact as a design consultant, initially working with the ALBA Radio Corporation, and Tangent Loudspeakers. Tim was also responsible for the later ranges of Michealson and Austin tube amplifiers, including the TVA10 and M200 mono blocks.

Within a year, he had set up Esoteric Audio Research Ltd., and was marketing the remarkable EAR 509 100 watt professional tube mono block power amplifiers. He developed a unique output transformer/tube interface circuit called “balanced bridge mode”, in which all the electrodes (except the control grids) have their own separate windings on the thirteen-section, biflar wound, output transformer. In addition, the amplifier has no overall feedback, something of a de Paravicini trade mark. Technically this amplifier proved that tubes are capable of performing equally as well as transistors in a laboratory, with a specification that included a power bandwidth of 9-85,000 Hz, -3dB, and also proved that tubes are capable of better things than the “retro” sound some manufacturers look for. Subjectively the 509 amplifiers were a big hit. Although aimed at the professional market, several Hi-Fi magazines picked up on the 509’ss, and compared them to the then State of the Art domestic High End equipment. The fact the 509 beat all of the competition at the time helps explain why the 509 is still in production today. the 509 was designed by de Paravicini to have no sound; trying to sum up the 509 is hard, it does not offer the warm ‘comfortable’ tonal quality which so often mark most tube amplifiers out. They are remarkably clear, transparent, with firm realistic bass, effortless top end, detailed and very alive.

In the twenty years since 1976, Tim has designed a mammoth catalogue of Hi-Fi and Studio components, both for Esoteric Audio Research and for other domestic audio companies. Currently the ‘E.A.R.@ professional product range includes a tube capacitor microphone, built with a rectangular gold spluttered capsule. A design which easily betters the classic European designs. Tube microphone preamplifiers, tube equalisers, record cutting systems, analogue to digital converters (for CD mastering) plus custom components and servicing for some of the Worlds most famous recording artists. His is most famous in the studio industry for the stunning analogue tube master tape recorders. These units have very special custom designed heads, and are capable of digital levels of signal to noise ratio, with a bandwidth in excess of 8Hz to 80,000Hz!

Work for the recording industry has brought critical acclaim. On the ‘Waterlily’ label, “A Meeting by the River” received a prestigious ‘Grammy’ award for its sound quality. This was a mid/side technique recording using a pair of crossed microphones. Waterlily’s microphones, preamplifiers, analogue master recorder and A/D converter were all built and designed by Tim.

In 1985, de Paravicini introduced his new record cutting system. Now installed at ‘The Exchange’ in the heart of London, (originally Island Records ‘Sound Clinic’ facility). This is phase corrected, and uses in excess of 1,000 watts of tube audio power, based on the classic EAR 509 circuit. The cutter head is again, a custom design, and is capable of cutting deeper, wider grooves than any other system. The result is higher dynamics, with a true signal to noise ratio in excess of 65 dB from records pressed off a master cut on this system. It is truly as close to the original master tape as it is physically possible to get.

Throughout the past twenty years, Tim has worked with many different manufacturers. For London based Musical Fidelity, Tim designed the amazing A1, taking the concept of a cut down ‘High End’ audiophile amplifier, the only compromise being the 10 watts output, albeit pure class ‘A’. Other products designed for ‘M.F.’ include the A470/370, P270, Digilog, CD-T, etc.

More recently in Europe, the ‘Tube Scene’ in domestic audio has really taken off. A lot of European manufacturers have stolen both older European designs, and designs from Japanese magazines and journals. Most of these amplifiers are very poor sounding, and terribly unreliable. These manufacturers neither understand the designs or how to build them. They use the reputation of tubes to sell their poor, none original product. De Paravicini’s answer to these companies, was the award winning EAR 859 amplifier. His all new Enhanced Triode Mode circuit bettering the performance of directly heated triodes designs. It provided the public with a real design, from a professional maker.

The EAR 834P phono stage was also introduced, and similar to the ‘859 has proved very popular, offering un-rivalled performance per dollar. The particular speciality being the stunning Moving Coil stage transformers – transformer design being one of Tim de Paravicini’s fortes – unlike most manufacturers, who just buy in ‘off-the-peg’ transformer designs or just specify the most basic requirement to an outside supplier.

All EAR amplifiers are truly original, including the custom transformer, metal work, circuit printed cicuit board. All the work of Tim de Paravicini.

Tim de Paravicini works by a simple premises: If he designs it, it must be a better design than anything else, or he will not manufacture it. His sole goal is taking audio to the furthest possible point of development. Current research is taking him further along this path than any single competitor.

در ضمن آقای Tim برندهای Jorma Design ، Marten Design و TownShend رو در امریکا دمو میکنند و تو اکثر نمایشگاه ها با همین دو برند جورما و مارتن حاضر میشوند.

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Cessaro Horn Acoustics

چهار شنبه 1 ژوئن 2011
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شرکت آلمانی Cessaro بلندگوی هورن میسازه و بین بلندگوهای تو بازار تا حدی مورد توجه رومی (Romy the cat) هست. از اونجایی که رومی خیلی بد میزنه تو سر برندها (مثلا خیلی زده تو سر همین مارتن و خارما یا آوانگارد البته باید اضافه کنم رومی معتقده استفاده از درایورهای سرامیک تنها با پوش پول ترانزیستوری بدون ترانس خروجی مثل ویتوس یا ASR خوب جواب میده) و خیلی هم کم پیش میاد از برندی تعریف کنه آدم کنجکاو میشه ببینه این برند چه خصوصیاتی داره. رومی در مورد مدل اومگا نوشته خیلی پیاده سازیش شبیه به بلندگوی خودش یعنی Macondo هست و احتمال داده طراح این برند به سایت رومی سر میزنه.

غیر از پیشنهاد رومی (که من معتقدم بدون فهمیدن دقیق دلیل علاقه رومی به یک صدا ، پیشنهاد اون صدا یا برند به دیگران کار معقولی نیست) دو نفر از کسانی که از نمایشگاه مونیخ امسال بازدید کردند (از ایران) هم نظرشون خیلی در مورد صدای Cessaro تو نمایشگاه مثبت بود و در مجموع میشه احتمال داد اومدن این بلندگو به ایران میتونه اتفاق مثبتی باشه.

دلیل علاقه من به پیشنهاد شنیدن صدای Cessaro حساسیت بالاش هست که تازه علاقه مندان میتونند با این بلندگو به ارزش صدای آمپلی فایر های خوب لامپی مثل Audio Note پی ببرند. با اومدن Cessaro تازه میفهمیم Audio Note چه صدایی داره که قبلا تجربه اش نکردیم. بدون بلندگوی مناسب حرف از لامپ زدن نتیجه مثبتی در عمل نخواهد داشت اما با بلندگویی مثل Cessaro و آمپلی فایری مثل Audio Note میتونید ادعا کنید هیچ آمپلی فایری حتی Vitus و ASR هم واقعا نمیتونند صدای Audio Note رو به ما بدهند.

من که برام خیلی خبر خوبیه بشنوم یک بلندگوی با حساسیت بالا مثل Cessaro بیاد و با Audio Note دمو بشه چون یک مسیر جدید کاملا مثبت پیش روی علاقه مندان باز خواهد شد اما باز هم تکرار میکنم من به شخصه در مورد صدای Cessaro نه مطالعه ای کردم و نه صداشو شنیدم پس من تنها شنیدنش رو پیشنهاد می کنم چون ایده ای در مورد صداش ندارم.

http://www.cessaro-horn-acoustics.com/

http://www.cessaro-horn-acoustics.com/index.php?id=39

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برند Abis Shuhgetsu Amplification from Japan

یکشنبه 8 می 2011
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http://www.sibatech.co.jp/abis/index.html

http://www.sibatech.co.jp/abis/Shugetsu%20tech%20for%20web.pdf

Idealized In The Digital Realm, Perfected In The Real World

Before we became acquainted with Tetsuo Kawanishi, former associate professor of the University of Electro-Communications Tokyo, we were unaware of the root cause of high frequency transient distortion in circuits employing negative feedback. Mr. Kawanishi’s work has revealed that this peculiar distortion is the result of modulation of high frequencies in circuits using (or misusing) negative feedback. The result of Mr. Kawanishi’s research is Shuhgetsu NRF (Negative Resistance Free) solid-state amplification technology. After extensive listening sessions using Mr. Kawanishi’s prototype amplifiers, and with numerous speaker types, we engaged him to design a completely new preamplifier and power amplifier. These new designs, the C-120 Stereo Preamplifier, and P-1120 Mono Block Power Amplifier, make use of Mr. Kawanishi’s patented circuits and years of research into the behavior of feedback amplifiers.

Good Sound Starts With a Good Circuit

No amount of expensive parts and careful tweaking can overcome the limitations of a poorly designed circuit. When we fully understood Mr. Kawanishi’s identification of the cause of bad sound from misapplied feedback, and his unique approach to perfecting feedback circuits, we knew that his designs would be an ideal platform for state-of-the-art audiophile components. Before talking about special quality parts, and build techniques, we want to share some technical insights about ‘negative resistance’ in a feedback amplifier.

Transient Distortion as caused by Negative Resistance:

What is ‘negative resistance’ and how harmfully is it to reproduced sounds?

Many solid-state amplifiers employ negative feedback to minimize high-frequency distortion. However, standard feedback does not work perfectly resulting in the erratic behavior of input and output impedance. The result is negative resistance. Such design flaws are present in emitter-follower and cathode-follower (as used in Marantz type equalizer) circuits.

Transient distortion may arise once this behavior occurs. Negative resistance tends to oscillate a circuit which destabilizes an amplifier’s operating point, causing the signal to be improperly amplified with transient distortion, which muddies the reproduced sound. When the circuit containing this negative resistance is exposed to high frequency noise (RFI, or switching power supply noises, for example), its operation is further destabilized, increasing transient distortion. In the old days of vacuum tubes, such high frequency noises seldom existed in audio reproduction. And even when the noise did occur, most tube amp designs employed a high frequency roll-off network at the point where the negative feedback was injected. This kept the amplifier from trying to reproduce frequencies outside the capabilities of the output transformer. The downside was “classic tube sound” and poor high frequency response.

But since the invention of semiconductors, the negative resistance issue is exacerbated by the transistor’s mass application in audio designs, and further compounded by the development of digital audio techniques. High frequency noises generated by electronic equipment has dramatically increased since the advent of switching power supplies, increased use of radio waves (cell phones) and the inclusion of digital circuitry in virtually every household device (ovens, toasters, etc..). Further, in negative feedback type amplifiers, high frequency noise will often be modulated by audio signals, causing further signals to be created as the result of the intermodulation of signal, HF noise, and “normal” distortion products (meaning distortion from active and passive parts; parts which deviate from the theoretically perfect device—all deviate from the idealized perfect part).

Measures taken in the Shuhgetsu circuits to cope with negative resistance:

In order to remove negative-resistance generated at the amplifier’s input stage, the designer has employed a patented circuit with carefully calculated values. Furthermore, in the feedback line which returns to the first stage of the amplifier, another patented circuit is inserted with differently calculated values to remove negative-resistance born in output impedance.

Herewith, NRF (negative resistance free) circuits are accomplished wherein the operating point is stabilized. Shuhgetsu amplifiers employ NRF circuits in voltage amplification and current amplification. Also, the regulated power supplies used by Shuhgetsu dramatically decreases transient distortion. The combination of carefully applied negative feedback, with low impedance power supplies allow the Shuhgetsu components to realize the potential of feedback, with none of the audible distortions which have given misapplied negative feedback a bad reputation.

Special attention given to power supplies:

Though an oversimplification, amplifiers modulate a power supply. If a power supply has high impedance at some frequencies, and low impedance at other frequencies, an amplifier might display deviations from a flat frequency response. Even worse, the amplifier may be driven to clipping at one frequency and not at others, and these distortions when added to the music can produce gross harmonic and intermodulation distortion.

Shuhgetsu amplifiers use fully regulated power supplies from the front-end voltage gain stages to the current amplifying output stages. The result is an amplifier with excellent damping, frequency response, and low distortion. No matter how good the signal circuit and parts quality, an amplifier must have an adequate power supply, or else the circuits and parts cannot perform their job.

The musical qualities of a regulated power supply:

* Powerful and tight bass in the P-1120 power amplifier. Thanks to use of regulated power supplies placed in all power amplification stages, which prevent voltage drop at significant power output, bass is clean, articulate and tonal. Unlike many tube amplifiers which have unregulated power supplied and limited reserves of power, there is no artificial warmth, no overhang, and no muddiness.

* Whereas power amplifiers generally use regulated power supplies only in the first voltage amplification stages, the Shuhgetsu P-1120 has stabilized power supplies throughout – all the way through to the power stage – unlike others. This fully regulated power supply is costly, but enriches bass reproduction by preventing voltage drops at high output.

* An ideal power supply has zero source impedance to prevent voltage drops, from DC to ultra high frequencies. The source impedance of the Shuhgetsu P-1120 amplifier is in the order of 0.01 ohm up to around 10KHz, and stays within 0.1 ohm above 10KHz due to special filtering and decoupling capacitors used in the power supply.

* An ideal power supply does not have high frequency noise from the AC line input, or generated by rectifiers. Because of carefully chosen transformers, rectifiers, resistors, and filtering capacitors, high frequency noise is shunted to ground before it can be injected into the signal.

* If the source impedance is high in a preamplifier, the sound becomes less powerful and clear. An ideal power supply should be regulated, having low impedance. So, the Shuhgetsu C-120 preamplifier uses the same principals as the P-1120 power amplifier. The supply for the C-120 preamp is the PS-120, which is housed in a separate chassis. By housing the power supply in a separate chassis, the delicate signals present in a preamplifier are fully protected from the various AC line noises and possible EM radiation from the transformer.

* The P-1120 power amplifier is built with a very large capacity EI core transformer, with excellent electromagnetic and electrostatic shielding to prevent this kind of noise from being radiated into the power amplifying circuits.

After a thoroughly engineered design comes careful tuning

After the design was completed to our satisfaction, it was finally time to do final tuning. Many high-end companies spend enormous amounts of time and energy covering up a bad circuit with good parts. With the Shuhgetsu, the parts are just as good, but happen to be in a superior circuit.

* Superior music reproduction is enhanced by the careful selection of circuit components which are chosen based on electrical characteristics. The electrical performance was scrutinized, and parts were chosen based on how close they came to the ideally perfect part.

* Resistors were chosen based on their linearity versus frequency. In other words, some resistors change value with frequency. The Shuhgetsu uses extremely linear resistors, chiefly from Nikkohm.

* Select power supply smoothing capacitors and low value (small capacitance) capacitors were chosen based a number of criteria, including ESR, frequency linearity, and lack of coloration in reproduced sound. This last judgment was based on listening tests, but was given as much importance as the electrical values. The quality of capacitors employed in the power supply has a major impact on the performance of the music amplifying circuits. As it has been said: garbage in, garbage out. The Shuhgetsu power supplies provide premium quality current to the signal stages. The capacitors employed include film types from Rifa and Rifa type 02 electrolytic smoothing caps.

* The Shuhgetsu products employ EMe (epitaxial mesa) power transistors and low noise SiE (SiEP) small signal transistors. These are ultra high performance transistors, carefully chosen for their high performance, are hand matched for minimum channel to channel variation and maximum reduction of distortion.

* TO-3 metal packaged power transistors were chosen for their minimal mechanical vibration and electromagnetic wave generation properties. This reduces intermodulation distortion (IM). Generally speaking, a power transistor generates imperceptible mechanical vibration by music signals, while also generating electromagnetic waves that vary with the music. This often impacts the input stage and causes intermodulation distortion.

Other Features and Considerations

* Differential Input Balanced Transmission Scheme

Balanced operation and connections are featured in both the C-120 preamplifier and P-1120 power amplifier. The benefits of balanced operation far outweigh the extra cost and difficulty in manufacturing. With common mode noise rejection, and low levels of hum, there are drastic improvements in dynamic scaling, localization, airiness, and spatial perspective. Further, the impact of cable quality is much less when using balanced connections. We do encourage purchasing cabling of impeccable build quality, but you will find less audible variation from brand to brand than when compared to single-ended connections. This is due to common mode noise rejection and the more robust nature of balanced operation. However, to make the most of your Shuhgetsu preamp and power amp, please consider the following:

* Because the wavelength of audio frequencies are sufficiently long compared to the length of wiring used in audio equipment, very little scientific investigation has been expended on the influence of cabling on audio signals. When we consider the influence of high frequency noise on an amplifier, it is quite important to emphasize cable matching in high frequency reproduction between an amplifier’s internal wiring and speaker cables. When there is an impedance mismatch, reflections at cable ends will occur, possibly causing an increase in high frequency noise. Shuhgetsu amplifiers are designed with countermeasures that assume a characteristic impedance of 75 ohms for line cables, and 120 ohms for speaker cables. We recommend use of cables specified by the Shuhgetsu designer.

* The cancellation of noise that is a benefit of balanced connection and operation is virtually impossible with single-ended connections. With single-ended connections, any noise induced through EMI or RFI on the connecting cables becomes part of the musical signal because there is no reference with which to compare the original signal. Only balanced connection can delete the problems of EMI and RFI through common-mode noise rejection.

* Further, it was found that balanced amplifiers heat up and stabilize much quicker than single-ended designs. Kawanishi’s unbalanced amplifiers would require at least 15 minutes of heating and stabilization for best sound. But the balanced versions of Kawanishi’s amplifiers sounded good almost immediately after powering up. In comparison to many power-hungry, single-ended designs, which must be left on for hours to stabilize, the Shuhgetsu won’t waste power or shorten your valuable listening time.

Some say that balanced design is a waste. Some say that it doesn’t sound as good. These opinions are based on poorly designed products. Balanced operation produces dramatic improvements, but requires bulkier and more expensive equipment because of the need to process two independent signals in one chassis. Put simply, a balanced design doubles everything of a single-ended design. It takes two duplicate circuits, working in tandem, to produce one balanced circuit. Other manufacturers of balanced amplifiers, with good specifications on paper only, have chosen to use cheap integrated circuit operational amplifiers for cost and space savings. Generally speaking, an IC op-amp is by nature a very high feedback device, and thus generates negative resistance that will muddy the sound. Understandably, this poor sound quality from cheaply built balanced products has lead listeners to conclude that an unbalanced type is actually better in sound. On the other hand, unbalanced amplification fosters listeners’ belief that the sound is better because there is a constant level of even order distortion, clouding the performance, and making the sound less precise. When they hear a poorly built balanced product that has very low noise and even order distortion, it serves to amplify the relative severity of the negative resistance and high order distortion caused by the IC op-amp, mediocre power supply or bad parts quality. Therefore, the Shuhgetsu products, which eschew the use of such IC op-amps is both theoretically and realistically superior in reproduction of natural sound by common mode noise removal.

Sturdy Housing and Provisions for Electromagnetic Wave

* The P-1120 Power Amplifier uses 5.6mm thick steel sheet for the chassis to secure internal components and suppress mechanical vibration at all points.

* Hospital-grade shielding of power transformer winding gaps, as used in medical equipment, guards against electromagnetic waves and noise which would cause common mode noise in the power supply. Without proper shielding, these spurious noises which occur in all transformers would in injected into the musical signal.

* Circuits and components have been carefully arranged to prevent the interaction of power supply circuits and amplification circuits. In very compact designs, there is coupling from one stage to another, causing IM distortion, spurious noise and instability. Components are arranged in the Shuhgetsu in a way that they aren’t being adversely affected by another component.

*The C-120 Preamplifier and PS-120 Power Supply use 3mm thick steel sheet to support the PC boards with a floating anti-vibration rubber mounting system.

* The separate power supply unit suppresses magnetic flux leakage to the preamplifier circuit.

* The same transformer shielding technology used in the power amplifier is used in the preamplifier power supply.

The fruit of our labors, the unique sound of Shuhgetsu

* Extraordinary amounts of detailed information, and low-level signal resolution, enable you to catch subtle point of sounds and to better appreciate and understand the music.

* No colorations assure you that you are experiencing the original sound from the musical instrument, as intended by the artist (not the equipment manufacturer).

* Highly accurate timbre keeps the relative levels of notes in proper placement, so notes do not improperly pop out of focus to impede upon listener engagement.

* No annoying peaks at high output levels from negative resistance. No aggressive sound or distortion at musical climaxes.

* Precise spatiality allows you to hear instrument placement quite clearly, and hear each instrument reproduced independently.

* Accurate phase produces wider listening area so you can better enjoy music off-axis of your speakers.

* Using regulated power supplies for all stages reproduces low frequencies with exceptional stability and clarity, and allows you to appreciate tonal scales of low-pitch instruments.

* The distinct airiness, openness and sound-staging reproduce the atmosphere of a live performance in your listening room.

* From the sound of a gentle stream, to a powerful ocean wave, Shuhgetsu can deliver massive changes in mood, timbre, scale, loudness, and all the other musical attributes that create the musical experience.

* Because of the low levels of noise and distortion, and highly accurate gain stages, the Shuhgetsu amplifier can, as a matter of course, reproduce acoustic instruments with a great degree of fidelity to overtones and detail. At the same time, any category of music can be enjoyed because of the power reserves and truthful character of Shuhgetsu.

* The bottom line is that by using patented circuits that avoid negative-resistance, power supplies that are quiet and low-impedance, parts that are very linear and noise-free, and chassis that rigidly hold components and circuits in an ideal spatial orientation, the sound is amplified with nothing added or taken away.

Abis Shuhgetsu: The genuine sound of musical instruments with no electronic distortion.

————————————————————————————————————–

Model C-120 Stereo Preamplifier (with PS-120 Power Supply Unit)
Model P-1120 Mono Block Power Amplifier
We were unaware of behaviors of modulated high audio frequency that resulted in uncomfortable transient distortion before we became acquainted with Tetsuo Kawanishi, former associate professor of the University of Electro-Communications Tokyo, and the designer of the Shuhgetsu NRF solid-state amplification technology. After exhaustive auditioning and investigation of Prof. Kawanishiʼs prototype amplifiers with different speakers, we asked him to design a combination of commercial equipment, preamplifier and power amplifier, as we were converted by his patented circuit design.
◎ Sonic Characteristics of Shuhgetsu Amplifiers
○ High-level of information density: Enables you to catch subtle point of sounds.
○ No coloration: Assures you an experience of the original sound from musical instrument.
○ Highly accurate timbral portrayal: The piano, horn, or soprano vocalization likely coming “Shuhgetsu” NRF Solid State Stereo System up at specific musical scales that does not irritate ears.
○ No annoying peaks at high output level: No looming aggressive sound and distortions.
○ Precise spatiality: You can see instrument placement quite clearly, and hear each instrument reproduced independently.
○ Accurate phase: Produces wide listening area so you can well enjoy music at any position off the speakerʼs front.
○ Full stages driven by stabilized power supply: Exceptionally stable reproduction of low frequency range that allows you to appreciate tonal scales of low-pitch instruments.
○ Quite distinct airiness and perspective of acoustic field: Reproduces the atmosphere of live performance in your listening room.
○ Sound unworldly like a limpid stream, and powerful like the ocean wave.
○ Depth of character: A Shuhgetsu Amplifier can as a matter of course reproduce acoustic instruments and any category of music.
◎ Genuine sound of musical instrument with no electronic distortions, employing patent applied circuit that deletes Transient Distortion caused by Negative Resistance.
● Transient Distortion caused by Negative Resistance
What is ‘negative resistance’ and how harmfully is it to reproduced sounds?
Solid-state amplifiers generally adopt ‘feedback’ circuitry to minimize high-frequency distortion, but it usually does not work perfectly resulting in possible degradation of real part
(pure resistance excluding inductance and capacitance) of each input and output impedance (usually complex number) into negative behavior, or negative resistance. Such deficit is
present in emitter-follower and cathode-follower (as used in Marantz type equalizer) circuits.
Transient distortion may arise once Negative Resistance is generated.:
Negative resistance tends to oscillate a circuit which destabilizes an amplifier’s operating point, causing music signal to be improperly amplified with transient distortion, which muddies the reproduced sound.
Infections of external noise:
When the circuit containing this negative resistance is exposed to external high frequency noise, its operation is increasingly destabilized with all the more transient distortion. In the
old days of vacuum tube, such high frequency noises seldom existed in audio reproduction.
But since the invention of semiconductors, the negative resistance issue is exacerbated with the transistorʼs mass application in audio designs, and further compounded with digital
technologies development. Infections of high frequency noises generated by electronic equipment has incomparably increased more than ever. (In a feedback type amplifier, high
frequency noise may also be modulated by audio signals.)
● What measures are taken in the Shuhgetsu amplifiers to cope with negative resistance? (2 patents applied)
In order to remove negative resistance generated in input impedance, the designer added a patented circuit with carefully calculated constant value in the input stage. Furthermore, in
the feedback line which returns to the first stage of the amplifier, another patented circuit is inserted with differently calculated constant value to infinitely remove negative resistance
born in output impedance.
Herewith, NRF (negative resistance free) circuit is accomplished wherein the operating point is stabilized. Shuhgetsu amplifiers employ NRF circuit in voltage amplification, power
amplification and stabilized power supply circuits to dramatically decrease transient distortion.
◎ Super High Fidelity music reproduction by use of carefully selected circuit components which are graded as close as possible to ideal elements.
● Theoretical values of high grade resistors and capacitors used in Shuhgetsu are about the same value in high frequency reproduction as in the following:
○ Resistors with minimum value variation regardless of frequency change.
○ Select electrolytic capacitors and low-capacitance capacitors for free of coloration in reproduced sound.
○ Block type electrolytic capacitors and film capacitors strictly selected for smoothing of ripple current and absorption of rectifying pulses in the power rectification circuit.
○ Adoption of EMe (epitaxial mesa) power transistors and low noise type SiE (SiEP) small signal transistors.
○ TO-3 metal package power transistors for their minimal mechanical vibration and electromagnetic wave generation properties, which reduces cross-modulation distortion.
(Generally, a power transistor generates imperceptible mechanical vibration by music signals, while also generating electromagnetic waves in parallel with the signals. This often impacts
input stage and causes cross-modulation distortion.)
◎ Balanced Connection adopted in both preamplifier C-120 and power amplifier P-1120 with positively deleted in-phase common mode noise and hum noise, for stabilized reproduced sound with drastic improvement in dynamic scaling, localization, airiness, and spatial perspective.
● Cable Matching:
Because the wavelength of audio frequency is sufficiently long compared to the length of wiring used in audio equipment, less attention has been paid to wiring affecting sound quality.
However, it is quite important to emphasize cable matching in high frequency reproduction between an amplifierʼs internal wiring and speaker cables when we consider the influence of
high frequency noise to an amplifier. When matching is not properly taken, reflections at cable ends will occur to cause possible increase of a particular bit of high frequency noise.
Shuhgetsu amplifiers are devised with countermeasures that assumed a characteristic impedance of 75 ohms for line cables and 120 ohms for speaker cable respectively. We
recommend use of cables specified by the Shuhgetsu designer.
● Balanced Connection:
In order to clear up these problems once for all, Shuhgetsu amplifiers employed Differential Input Balanced Transmission Scheme, wherein 3-line information transmission (phase
between hot and cold differs by 180 degrees) with a cold line added to ordinary two-line unbalanced transmission (hot and ground). This method enables cancellation of high
frequency noise riding on a signal line as in-phase element and delete to the utmost limit in order to depress transient distortion as much as possible. This is an effect impossible with
unbalanced system. Further merit is in heat-up time of the amplifier. The designer Kawanishi’s unbalanced type amplifiers used to require at least 15 minutes in heating up, but
balanced type enables quick music-listening right after the power is switched on with ideal sound quality.
● Does balanced connection produce bad sound?:
This balanced connection method produces dramatic improvements but may require more space and make the equipment bulky due to the need to process two independent signals in
one chassis. So some other miniature balanced type amplifiers with perfect specifications have adopted IC operational amplifiers for amplification stage to save space. Generally, an IC
operational amplifier is of high feedback nature and generates negative resistance that may muddy the sound, thus leading listeners to conclude that an unbalanced type is actually
better in sound. On the other hand, unbalanced amplification fosters listeners’ delusions that the sound is better because it becomes only partially aggressive when it comes under the
influence of high frequency noise. Therefore, Shuhgetsu balanced system without the use of such IC operational amplifiers is both theoretically and realistically superior in reproduction of
natural sound by common mode noise removal.
◎ Powerful and Sharp Bass in the P-1120 power amplifier, thanks to use of stabilized power supplies placed in all power amplification stages to prevent voltage drop at significant power output
● Whereas a power amplifier generally employs a stabilized power supply only in the front power amplification stage, Shuhgetsu P-1120 has stabilized power supplies throughout – up
to the power stage, unlike others. This full-stage stabilization is costly but enriches bass reproduction by depressing voltage drop at high output.
● An ideal power supply has zero source impedance to prevent voltage drop from DC to high frequency area, and does not have high frequency noise. Source impedance of Shuhgetsu
amplifier P-1120 is in the order of 0.01 ohm up to around 10KHz, and stays within 0.1 ohm even in higher (than 10KHz) frequency area due to special decoupling capacitors circuit in
the power supply.
● If the source impedance is high in a preamplifier, overall sound becomes less powerful and sharp. An ideal power supply should be a stabilized type having low impedance. So, Shuhgetsu preamplifier C-120 is also designed with this type of supply unit PS-120, which is housed in a separate chassis.
● P-1120 is built with a large capacity EI core transformer with excellent electromagnetic and electrostatic shielding to secure stable and clean power supply.
◎ Sturdy Housing and Provisions for Electromagnetic Wave
● Power Amplifier P-1120:
1) 5.6mm thick steel sheet for chassis to secure internal components and suppress mechanical vibration at all points.
2) Hospital-grade shielding for power transformer winding gaps, as used in medical equipment against electromagnetic wave and static electricity to block off common mode noise in the power supply.
3) Appropriately isolated stage placement to prevent interference between flux leaked from the power supply and electromagnetic wave generated in the amplification circuit.
● Preamplifier C-120 and Power Supply PS-120:
1) 3mm thick steel sheet as strong support structure for PC board unit, with vibration absorption rubber float system.
2) Separate power supply unit to suppress magnetic flux leakage to the preamplifier circuit.
3) Hospital-grade shielding for power transformer winding gaps, as used in medical equipment against electromagnetic wave and static electricity to block off common mode noise in the power supply.
Doc.abis20081218
Additional Technical Description
1. Circuit constant of the Shuhgetsu amplifier was determined not through monitoring scound quality, but by numeric calculation using a computer of a condition wherein negative resistance does no exist after having analyzed input and output impedances modelling on a single stage differential amplification with emitter-follower circuit.
Then the circuit constant is as straightly as possible applied in an actual circuit to determine a final circuit design. Thus, the Shuhgetsu circuitry was determined not by cut and try method but by using the values logically calculated as are. On the other hand, the elements chosen and used by monitoring sound are such parts as resistors and capacitors which are of high grade required to realize the determined circuit design as ideally as possible.
2. Key components used for the Shuhgetsu amplifier are as below:
A) EMe power transistors
B) SE capacitors for compensation
C) RIFA film capacitors as used for coupling or bypassing
D) RIFA Type 02 electrolytic capacitors
E) NIKKOHM plate type resistors
NONE of OFC parts including wires are being used.
3. Points taken care through sound monitoring to select required parts:
A) Much care was taken to enable to hear every note of the piano sound in any scale without deforming the sound image as well as the sound of collision occurring when the piano hammer is percussed. For example, there should not occur abnormal sound of a single note that suddenly brings pressure on the eardrums, and each note in tremolos should be clearly recognized.
B) Lift of soprano or alike vocal in a cetain interval should not abnormally give pressure on the eardrums.
C) Sound image of horn(s) should not deform otherwise distance perspective becomes hard to recognize.
D) The violins in a string concert should not be tightened or get clogged so that sound softness peculiar to strings as often heard in a concert house can be sensed.
E) A single note in piccicato part for contrabass should not unusually hollow in a room, and descending intervals can be clearly caught. (Such low pitched tone instruments as contrabass, bassdrum, timpani, or organ when simultaneously played can be cleanly heard.)
F) Finally, the Shuhgetsu should reproduce a concert hall presence in an audio listening room.
4. Shuhgetsu amplifier does not need a special listening room.
Conventional amplifiers had a problem in transient characteristics, so is much affected by a listening room, where listeners have to care much for curtains, rug or carpet, or other sound absorption material, but Shuhgetsu with super transient characteristics sets you free from sound absorption cares. In any type of room, Shuhgetsu sounds in its own way.
You also do not have to worry about the position to place a speaker system. Even if the speakers are roughly placed, more than a certain level of presence can be obtained. Its practical service area is quite wide allowing a listener with less knowledge about the acoustic field to command the Shuhgetsu. Ideally, the best is to place the speakers facing the front and listen at the vertex of an isosceles triangle. Further, it is suggested to give minimum 1 meter gap between the speakers and the wall behind.
Designer Tetsuo Kawanishi
Jan. 19, 2009
His following patents are employed in the Shuhgetsu:
No. 2118015 Collector type 2 stage feedback amplification (Dec. 6, 1996)
No. 2794667 Negative feedback amplification (June 26, 1998)
About the Output Circuit of P-1120 Power Amplifier
P-1120 output stage is ended with Complementary Parallel Push-Pull circuit. Designer Tetsuo Kawanishi explains why he adopted this circuitry as follows.
“As known widely, a transistor amplifier was born with semi-complementary push-pull circuit. Later a complementary circuit designs were developed little by little, and amplifier manufacturers began employing the complementary circuit except for a part of power IC, and majority of the manufacturers have followed one after another up to the present date.
Recently, production of power transistors suitable for audio use tend to be discontinued, so there are some manufacturers who went back to semi-complementary design. I am using complementary circuit for high end and semi- for less expensive products.
Parallel connection is adopted for the Shuhgetsu P-1120 to achieve high power output successfully without sacrificing audio quality as long as maximum two parallel stages.
This is the best choice to satisfy both of power output and sound quality. Many other manufacturers employ more than four parallels knowing that sound suffer demerits such as blur and lack in delicacy. Therefore, P-1120 can outstrip other higher output power amplifiers with 4 parallels. An example of the reports from my client is that Telos-200 sounds generally inferior to P-1120.”
April 4, 2009
Translation: M. Shibazaki, SIBATECH, Inc.

 

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DAC پیشنهادی

چهار شنبه 5 ژانویه 2011
/ / /

لازم شد در مورد انتخاب های سورس دیجیتالم یه توضیحی بدم.

نوشتم بهترین DAC رو Audio Note میدونم که باید اضافه کنم این DAC رو فقط در سیستم مبتنی بر خودش پیشنهاد میکنم یعنی اگر کل سیستم رو Audio Note جمع کردید از این DAC استفاده کنید. البته این یک قانون نیست ولی احتمال گرفتن بهترین پاسخ از این DAC تو سیستم های دیگه و بدون آگاهی از وضعیت اون پایینه.

من قبلا هم نوشتم Audio Note تو میکرو بهترین پاسخ رو داره ولی شرط استفاده اش اینه کل سیستم رو Audio Note بگیرید حتی بلندگوها رو . البته میشه بعدها بلندگو ها رو با تست و تجربه بیشتر تغییر بدید اما من فعلا بلندگویی تو ایران نمیبینم که هم حساسیت بالایی داشته باشه و هم صداش با Audio Note جور دربیاد.

نظر من اینه Audio Note میتونه بهترین صدا رو بهتون بده اما به این شرط که کل سیستم رو Audio Note انتخاب کنید.

نکته دیگری که میخواستم در موردش بنویسم ساختار DAC هاست. ببینید DAC ها از چند بخش تشکیل میشن، یکی بافر ورودی و مدار تصحیح Jitter هست ، یکی بخش پردازش دیجیتال ، دیگری بخش تبدیل دیجیتال به آنالوگ و در انتها هم فیلتر آنالوگ خروجی.

Weiss و Playback Design بین DAC ها تصحیح Jitter خیلی خوبی دارند و مثلا Weiss حتی تو فرکانسهای پایین هم Jitter کمی داره و هر دو تو این شاخص وضعیت خوبی دارند البته بقیه DAC ها هم تونستند تو این شاخص پاسخ خیلی خوبی داشته باشند و کلا بیشتر سورس های دیجیتال مطرح دنیا Jitter خیلی کمی دارند.

تو قسمت پردازش دیجیتال دو تا ایده هست ، یکی NOS ها (Non-Oversampling) مثل Zanden و Audio Note و 47Lab که این DAC ها روی سیگنال دیجیتال هیچ پردازش دیجیتالی انجام نمیدن و هیچ Upsample و یا Oversample ای ندارند و دیگری اونهایی که پردازش دیجیتال دارند. مقاله 47 Labs رو در این مورد بخونید جالبه :

http://www.sakurasystems.com/articles/Kusunoki.html

We can control the “diffusion of sound coherence” only by constructing it with smaller number of taps. From that aspect, Wadia’s decoding computer (13 taps) or Luxman’s former fluency DAC, DA-07 (3 taps) are considered to be excellent machines. They both received (Wadia still does) outstanding appraisals at the time for their sensual representation of the sound. The sound of non-oversampling DAC is on the extension of these machines, and theoretically, it can exceed those achievements.
The difference between the non-oversampling DAC and the conventional DAC with the digital filter lies whether you attach importance on the accuracy in the time domain or in the frequency domain. In other words, whether you choose the musical performance or the quality of a sound. This trade-off line defines the boundary of the current digital audio format .
A natural, stress-free sound that communicates the musicians’ intention directly to you. That is the sound of non-oversampling DAC. The feel of this sound is closer to that of analog reproduction.

بین اونهایی که پردازش دیجیتال دارند عده ای مثل Lavry معتقدند نباید بیشتر از 2X ما ارتقا فرکانسی داشته باشیم و عده ای هم اینطور فکر نمیکنند. Lavry که مورد تایید رومی هست مقاله های جالبی رو اینجا نوشته که میتونید بخونید :

http://www.lavryengineering.com/supportpage.html

http://www.lavryengineering.com/documents/Sampling_Theory.pdf

Dan Lavry توضیح میده بهترین حالت هم برای حذف نویز فرکانسهای بالا و هم فیلتر مناسب خروجی آنالوگ استفاده از Upsampling 2X هست یعنی از 44.1 کیلو هرتز به 88.2 کیلو هرتز. ایشون توضیح میدن ما همیشه یک trade off بین سرعت پاسخ و دقت پاسخ یک سیستم داریم و نمیشه هر دو رو با هم بیشتر کنیم.

There is an inescapable tradeoff between faster sampling on one hand and a loss of accuracy, increased data size and much additional processing requirement on the other hand.
AD converter designers can not generate 20 bits at MHz speeds, yet they often utilize a circuit yielding a few bits at MHz speeds as a step towards making many bits at lower speeds.
The compromise between speed and accuracy is a permanent engineering and scientific reality.
Sampling audio signals at 192KHz is about 3 times faster than the optimal rate.
It compromises the accuracy which ends up as audio distortions.
While there is no up side to operation at excessive speeds, there are further disadvantages:
1. The increased speed causes larger amount of data (impacting data storage and data transmission speed requirements).
2. Operating at 192KHz causes a very significant increase in the required processing power, resulting in very costly gear and/or further compromise in audio quality.
The optimal sample rate should be largely based on the required signal bandwidth. Audio industry salesman have been promoting faster than optimal rates. The promotion of such ideas
is based on the fallacy that faster rates yield more accuracy and/or more detail. Weather motivated by profit or ignorance, the promoters, leading the industry in the wrong direction, are
stating the opposite of what is true.

تو بحث پردازش دیجیتال ایده های دیگری هم هست مثل استفاده از فیلترهای پیچیده FIR و پردازش های زیادتر و خلاصه تو این پردازش ها برندهایی مثل Wadia و Ayre و Emm Labs و Playback Design و Meridian (فکر کنم Spectral هم تو مدل 4000 تو همین گروه قرار بگیره) تو Time Domain پاسخ بهتری دارند که بنظر من بهترینشون Playback Design هست و عده ای هم مثل Esoteric و Krell و Accuphase و dCS و APL و Burmester ، Gryphon و … تو Frequency Domain پاسخ بهتری دارند که بنظر من بهترینشون Weiss Medea هست.

DAC شرکت Abbingdon Music Research (این برند هم تو رنج قیمتیش خیلی عالیه) هم گزینه های متفاوتی رو برای Upsample به کاربر میده که جالبه. برخی هم از ماژول Anagram استفاده میکنند مثل Audio Aero و ویتوس و Orpheus Lab .

بخش دیگه و مهم یک DAC بخش مبدل دیجیتال به آنالوگ هست که تو این بخش روشهای متفاوتی وجود داره. تو این بخش Weiss و Playback خیلی ایده خاص یا متفاوتی از دیگران تو پیاده سازی ندارند اما تو سایت رومی خوندم Lavry بشکلی درست از Multibit استفاده میکنه. APL و Esoteric و Accuphase میان از موازی کردن چند DAC استفاده میکنند تا پاسخ بهتری بگیرند. dCS به گفته خودش از Ring DAC استفاده میکنه و خلاصه تو این بخش هم هر کدوم ایده ای دارند ولی همشون مجبورند از همین چیپ هایی که کمپانی هایی مثل Analog Device میسازند استفاده کنند، البته Emm Labs ادعا میکنه خودش بصورت Discreet اومده مبدل رو پیاده سازی کرده که جالبه اما من برند دیگری رو نمیشناسم که از همین چیپ های تو بازار استفاده نکرده باشه.

برندهای Zanden و AMR از چیپ معروف Philips TDA1541A استفاده میکنند که بنظر میرسه پاسخ خوبی داشته باشه. APL و Gryphon و بعضی مدلهای Esoteric از چیپ های AKM استفاده میکنند.

تو قسمت فیلتر خروجی آنالوگ و بافر خروجی هم Weiss طراحی فوق العاده خوبی داره و البته بقیه هم خیلی خوبند اما این قسمت خیلی بخش حساسی بحساب نمیاد و برخی از لامپ استفاده میکنند مثل APL و برخی هم از Opamp و برخی هم بجای opamp از مدارات Discreet استفاده میکنند.

نکته آخری که هست اینه که ما فراموش میکنیم این سی دی های موسیقی قبلا تو استودیو روشون پردازشهای زیادی شده و ممکنه حتی با یک DAC خوب ما صدای جالبی از اون آلبوم نگیریم و ممکنه با یک DAC غیر ایده ال تر با همون آلبوم پاسخ بهتری بگیریم. کلا دیجیتال بیشتر مایه دردسر های فای شده و من معتقدم اگر امکان رفتن به سمت ریل و LP باشه واقعا حیفه ما روی سورس دیجیتال هزینه کنیم.

غیر از سورس هایی که معرفی کردم پیشنهاد میکنم روی Lavry و Bow Technologies هم تحقیق کنید.

زیباترین DAC ای که دیدم هم Orpheus Labs سوئیسی بود که عکسش رو اون بالا گذاشتم.

تا این لحظه سیستم های پیشنهادی من به شرح زیر بوده :

بلندگو :    Marten Design ، Tidal برای صداهای Live و ESP برای صدای حسی که هر سه بلندگو حساسیتی زیر 94 دی بی دارند

آمپلی فایر :  ASR Emitter برای توان های بالای 100 وات و Vitus برای توان های زیر 100 وات ، هر دو آمپلی فایر مناسب برای بلندگوهای با حساسیت زیر 94 دی بی و Audio Note UK برای زیر 50 وات مناسب با بلندگوهای بالای 94 دی بی حساسیت

مبدل دیجیتال به آنالوگ : Audio Note UK برای صدای حسی و Playback Design و Weiss برای صداهایReal

کابل : برند Jorma Design برای حالت عمومی و Van den Hul تمام کربنی (برای شرایط خاص)

بقیه برندهایی که معرفی شدند مثل Concert Fidelity و یا Decware هم تو گروه بهترین کیفیت با توجه به کمترین قیمت بودند (بقول خارجی ها Best Performance/Price).

باید برای بالای 94 دی بی حساسیت هم بلندگو معرفی کنم و همچنین برای ترنسپورت و سورس آنالوگ.

تا یادم نرفته سایت زیر رو ببینید، اخبار رو مینویسه :

http://cybwiz.blogspot.com/

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DAC پیشنهادی من

دوشنبه 3 ژانویه 2011
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اگه یادتون باشه قرار بود سورس دیجیتال معرفی کنم و من فعلا بدون معرفی Transport میرم سراغ DAC پیشنهادیم.

همونطور که قبلا گفتم من دو دسته رو در نظر میگیرم یکی صدای Real و دیگری صدای Emotional که اولی تو ماکرو پاسخ بهتری داره و دومی تو میکرو.

تو گروه DAC ها اونایی که پردازش دیجیتال ندارند مثل DAC شرکت Audio Note UK و یا DAC شرکت Zanden صداشون بیشتر Emotional هست که با چیزهایی که من دستگیرم شد DAC شرکت Audio Note میتونه بهترین انتخاب باشه البته Zanden هم خیلی خوبه اما من در مجموع فکر میکنم اگر یک Transport خوب رو به Audio Note بزنیم صدایی فوق العاده خواهد داشت.

پس تو پاسخ میکرو انتخاب من Audio Note UK هست که تو ایران هم نمایندگی داره (آقای فاطمی).

اونایی که پردازش دیجیتال دارند صدایی Clean تر و در ماکرو بهتر دارند که بین همه اونها من DAC شرکت Weiss رو پیشنهاد میکنم.

البته ما دو گروه تو پردازش دیجیتال داریم، یکی اونایی که تو Time Domain پاسخ بهتری دارند و یکی اونهایی که تو Frequency Domain پاسخ بهتری دارند. DAC شرکت Weiss بنام Medea تو Frequency Domain بهترین پاسخ رو داره و DAC شرکت Playback Design تو Time Domain .

خب نتیجه اینکه تو صداهای Real من دو گزینه رو پیشنهاد میکنم :

Weiss Medea

Playback Design

خودم به دومی گرایش بیشتری دارم تا به Weiss اما طراحی Weiss هم طوریه که صداش واقعا Impressive هست و انتخاب بین ایندو تا حد زیادی به بقیه اجزای سیستم وابسته هست.

اینم ترتیب اولویت های من تو انتخاب سورس دیجیتال :

1. Audio Note UK DAC5 , DAC4 (عکس بالا)

2. Playback Design MPD-5 , MPS-5

3. Weiss Medea

بد نیست بدونید رومی DAC شرکت bidat و Lavry رو دوست داره.

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