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جمع بندي من از كامپيوتر آوديو COMPUTER AUDIO

شنبه 18 آگوست 2018
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ما سه چالش داريم در گرفتن صداي خوب از كامپيوتر :
اول اينكه فايل هاي دانلودي فعلا كيفيتاشون نامشخصه و تو بهترين حالت كه كسي بياد از روي CD ريپ كنه كيفيت فايل يه چيز متغيير هست بسته به خط و خش نداشتن دیسک ، سرعت خوندن ، كيفيت نرم افزار rip و CDRom اي كه اون سي دي رو ريپ ميكنه.
اين ادعا هست كه فايل ريپ شده همه اطلاعات روي سي دي رو در ممکنه در خودش نداشته باشه بخاطر عواملي چون ضعيف بودن فرمت ديتا روي سي دي و ضعف CDRom ها در تشخيص C2 Error و سالم نبودن دیسک.
نظر گوردون اينه اين فايل ريپ شده (اگر دیسک سالم باشه) میتونه کاملا اوكي باشه یعنی Ripped File = CD Data

(Not that I am going to read this because it’s total BS, but they probably don’t mention that they are using the same drives that are in computers and therefore have the worse problems reading on the fly compared to reading it more than ounce.)

تو سايت رومي (http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=3&postID=25039) من نظرات دیگری ديدم . در هر حال اين حقيقت هست كه چون فرمت ساختاري اطلاعات روي Audio CD با ديتا فرق داره خوندن دقيق اون اطلاعات هم توسط Firmware هر CDRom اي با دقت بالا ممكن نيست ولی ناممکن هم نیست و شرایط خاصی میطلبه.

دومين مشكل اينه كه وقتي فايل خونده ميشه و از خروجي USB اين اطلاعات مياد بيرون كيفيت سيگنال بسته به انتخاب ما متفاوته ، مثلا نوت بوك هاي اپل خيلي بهتر از بقيه هستند و اونهمه كامپيوترهايي كه بر مبناي آئوديو هم جمع ميشوند صداهاشون متفاوته.
مجموعا من مك بوك پرو ١٥ اينچ ٤ هسته مدل ٢٠١٥ رو پيشنهاد ميكنم ولي هيچكدوم اينها براي آئوديو بهينه نشده .
سوم اينكه اون دك يا مبدلي كه ديتاي USB رو به I2S يا SPDIF تبديل ميكنه هم كيفيتش مهمه و من كدهاي آسنكرون Gordon Rankin رو پيشنهاد ميدم مثل بركلي و ارت لگاتو يا دك هاي خود wavelength و یا Ayre.
مجموعا با چالش هايي كه هست بهترين كار خريدن CEC TL0X 3.0 هست .
اگر پول اون ترنسپورت رو نداشتيد و حتما نظرتون روي خريد كامپيوتر ائوديو هست اينو پيشنهاد ميدم :

Macbook Pro quad core 15” Display model 2015  MJLQ2LL/A  ,  MJLT2LL/A

Music AIFF Files play on External SSD Hard Drive (thunderbolt)

Ripping Audio CD by dbpoweramp + Apple Superdrive

Wavelength USB DAC

Purist Audio USB Cable 30 Anniversary

اون Wavelength سه مدل دك داره و اگر خودتون دك داشتيد ميتونيد بجاش مبدل usb to spdif رو از Berkeley بگيريد ولی بهتره همون دک Wavelength بگیرید.
بازم توصيه مي كنم CEC (البته فقط مدل TL0X) بگيريد .

اگر هم خيلي كم ميخواهيد هزينه كنيد يه نتورك پلير مثل Sonore microRendu بگيريد.
من خيلي خيلي خيلي وقت و انرژي گذاشتم به هيچ وجه پيشنهاد نميكنم براي كامپيوتر ائوديو خرج كنيد و راه هاي متفاوت رو امتحان كنيد. همينايي كه پيشنهاد دادم رو بگيريد.

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Telegram Channel

دوشنبه 6 آگوست 2018
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سلام
نوع صدایی که من دوست دارم تو هاي فاي ایناست -> صداي آنالوگ ، صداي آئوديونت (تو سیستم match خودش) ، صداي بلندگوي تنوي red قديمي ، صداي هورن ليوينگ وويس ، من این تيپ صدا ها رو دوست دارم.

اگر شما نوع صداي دیگری دوست داريد مثل بلنگوی ۸۶ دی بی با وضوح بالا (۹۰٪ بلندگو های گران تو ایران اینطور هستند) و يا آمپلي فايرهای توان بالا يا صداي ديجيتال high Rez و … با کمال احترام این کانال برای شما حرفي برای گفتن نداره دليلش اينه همه پيشنهادات و نوشته ها و قضاوت ها تو كانال من بر مبناي رسيدن به اون تيپ صدايي است كه من دوست دارم .

معتقدم نوشته هاي من كمكي به شما كه سليقه متفاوتي داريد نميكنه و حتي ممكنه شما رو از اون صداي مطلوبي كه دوست داريد دور كنه چراكه اين نظرات كاملا در تضاد با نگرش شما خواهد بود.

اكثر صداهايي كه مورد توجه اين صنعت هست و در نمايشگاه ها شنيده ميشه و در مجلات ريويو ميشه چيزي نيست كه من بدنبالش باشم. بحثم فقط انتخاب دستگاه ها نيست بلكه اون رويكرد غالب در دنيا چه در ميكس و مسترينگ استوديوها چه در ساخت دستگاه ها و چه در قضاوت صداها همه و همه به دور از اون چيزي هست كه من بدنبالش هستم.
اين مساله باعث ميشه شما هميشه تفاوت هايي ببينيد در قضاوت هاي من در مقايسه با نظرات ريويوئرهاي معروف و اين مساله طبيعيه چون اونا صدايي رو تبليغ ميكنند كه صداي ماركت هست و با سليقه ٩٠٪؜ مخاطبان سازگاري داره اما من صداي ديگري رو دوست دارم.

کانال تلگرامی من برای نوشتن در مورد های فای :

https://t.me/hificlub

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Loudspeaker Sensitivity and Amplifier Power

سه شنبه 31 جولای 2018
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A 7.5w       101db
B 15w        98db
C 30w        95db
D 60w        92db
E 120w      89db
F 240w      86db
G 480w      83db

عدداي بالا كه نوشتم تقريبا تناسب بين توان امپلي فاير با حساسيت بلندگو هست

يك لامپ خوش صدا 300b تو مد سينگل اندد بيشتر از ٧/٥ وات نميتونه بده

لامپ ٢١١ يا ٨٤٥ گرچه ميتونن بيشتر از 300b توان بدن اما هم كار كردن باهاشون سخت تره و هم ممكنه اون ظرافت 300b رو تو صدا به شنونده ندن.

اگر ايده ال بخواهيم فكر كنيم براي سينگل اندد لامپي راهي جز انتخاب بلندگوي بالاي 100db نداريم و عملا از درايوري خارج ميشيم ميرسيم به هورن

حالا طراحا چكار كردن كه ما از غير هورن هم صدا بشنويم . اومدن دوتا لامپ رو موازي كردن مثل كوندو جكو ps . اومدن از لامپهاي قوي تر استفاده كردن مثل ٢١١ . اومدن بجاي ترايود از مد پنتود لامپ كه غيرخطي تره استفاده كردند. اومدند از پوش پول بجاي سينگل اندد استفاده كردند.

ولي مساله اينجاست كه وقتي خطي ترين حالت رفتار يك لامپ مد ترايود سينگل اندد هست با ولتاژ كمتر كاري هر كاري كنيد كه توان بيشتر بشه ديگه مثل قبل خطي نيست و چه با فيدبك اينو تغيير بديد چه نديد در حالت توان بيشتر شما يه چيزايي رو ممكنه از دست بديد و راه حل ايده ال اينه خود بلندگو حساسيتش بالا باشه.

 

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=1&postID=11455#11455

The problem is that it is completely impossible, even theoretically impossible to be able to hear anything audio-valuable when one uses 200-400 watts SS push-pull and dead tonally and contrast disabled loudspeaker. Why? Connect this 300W SS amp to a PROPERLY BUILT AND PERFORMING 110dB sensitive system and listen what this realy amp does. Sound too revolting? Now connect it back to your 90dB sensitive speakers (even a god one) and see if your SS amp can REALLY discriminate tonal and dynamic charisma of notes? It is it! The game is over and the high power SS amp after this self-education should be sent to hell, or more precisely to the Audiogon to benefits a next idiot out there….

It is 21 century and still there is no good, tonally and contrast capable high sensitively loudspeaker. If all those people who waste themselves by infinite search of high power SS push-pull Messiah would spend the same amount of time and money to discover the potentials of properly done multi-channel (no single driver idiocy please!) high sensitively speaker then ALL those high power, SS, push-pull, gray-sounding amplifiers will die off and will not be applicable for a high demanding home sound reproduction…

Romy The Cat …

تنها راه برای صدای خوب بلندگوی حساسیت بالاست

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Original vs Fake Audio CD

سه شنبه 31 جولای 2018
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تفاوت سي دي اصل رو با چاپ هاي متفرقه توضيح ميدم.

كيفيت چاپ روي ديسك و كيفيت چاپ كاغذ آلبوم موسيقي كاملا متفاوته وقتي تقلبي ميخريد.
چاپ آلبوم هاي تقلبي رنگ هاش يه كم تيره تر و حالت كم انرژي تر هست

اكثر البوم هاي اصل خارجي بجاي اين پلاستيك سياه كه زير ديسك قرار مي گيره استفاده نمي كننده و از پلاستيك كاملا شفاف كه مثل شيشه هست استفاده مي كنند اما البوم هاي تقلبي از اين پلاستيك مشكي ممكنه استفاده كنند.

 

اختلاف ديگه سي دي اصل و تقلبي در قسمت نوشته ديسك هست ، ببينيد 👇

ديسك پاييني 👆كه تقلبي هست در قسمتي كه ميبينيد عبارت disc نوشته نشده

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ASR Emitter Review

یکشنبه 22 جولای 2018
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من قبلا هرچي نوشتم در مورد اميتر نظرم همونه (زماني كه من اميتر و ويتوس رو پيشنهاد دادم بياد هيچكدومشون رو نشنيده بودم 😉) و فكر ميكنم براي بالاي ١٠٠ وات گزينه خوبي هست اميتر ، البته الان با اطلاعاتي كه دوستان دادن ظاهرا براي بالاي ١٠٠ وات گزينه هاي خوب ديگري هم مثل اپسيلون يونان هست و برند Ayre . اپسيلون فيدبك منفي خيلي كمي داره و صداش متفاوته اما آمپ بسيار خوبيه از نظر دوستاني كه مونيخ شنيدند.
چيزي كه در صداي اميتر جذابه اينه شما اونو با يه بلندگوي بزرگ از نظر حجم بيس بشنويد مثلا 4way يا 3way اكستندد مثل JBL DD66000 و معتقدم از سه سطح صدا كه قبلا تعريف كردم اميتر از سطح دو پايين تر نمياد و شنونده ميتونه ساعت ها بدون مشكل به موسيقي گوش بده.
لذت سطح سوم رو فقط از لامپي هاي سينگل خوب ميشه انتظار داشت كه نميشه از اونها بالاي ٢٠ وات گرفت اما در سطح دوم اميتر هم به قيمت صداي خوبي ميده هم اجازه ميده شنونده به موسيقي گوش كنه.
حقيقتا تنها امپلي فايري كه تو Manual به گراند لوپ و خيلي نكات ديگه توجه دقيق داشت همين اميتر بود و واقعا آمپ خوبي از نظر كيفيت ساخته .
از نظر من اگر شما اميتر داشتيد و خواستيد عوض كنيد با توجه به شناختي كه من از علاقه مندان دارم فكر ميكنم بهتره قبل از عوض كردن اميتر به مسائل ديگه برسيد چون احتمالش كمه مشكل از صداي اميتر باشه مگر اينكه شما نوع صدايي مثل Audionote رو با بلندگوي حساسيت بالا دوست داشته باشيد که دنیای دیگه ای هست.

قبل از خرید حتما ASR رو بشنوید.

اميتر رو روي كمترين فيدبك و بایاس بالا تنظيم كنيد و هر ٧ سال باتري هاشو عوض كنيد و من ١٠٠٪؜ توصيه ميكنم براي اميتر و بقيه دستگاه ها از پيور پاور ٣٠٠٠ استفاده كنيد.

يكبار ديگه تاكيد مي كنم صدايي كه من خودم دوست دارم سينگل اندد آئوديونت هست بدون فيدبك اونم با بلندگو هاي حساسيت بالا مثل ليوينگ وويس يا تنوي قديمي Red و اين ASR يا Vitus رو به علاقه منداني پيشنهاد ميكنم كه صداهاي ماکرو دوست دارند و حساسيت بلندگوي آنها زير ٩٥ دي بي هست.

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Less Negative Feedback -> Higher Output Impedance -> Better Sound

پنجشنبه 21 ژوئن 2018
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بين آمپلي فايرهاي ترانزيستوري و هيبريد (خروجي SS) كمترين فيدبك رو برندهاي زير دارند :

Ayre , Ypsilon , Dartzeel , Firstwatt J2 , Dan Dagostino , Hovland, Naim

بين آمپلي فايرهاي Tube كمترين فيدبك رو برندهاي زير دارند :

PrimaLuna , Air Tight , Sophia Electric , Wavac , Wavelength Audio , Antique Sound Lab , Audiopax , Audio Note , Leben , Manley Laboratories

بین مدلهای Lamm فقط مدل Lamm ML3 فیدبک نداره.

من نظرم اينه نداشتن فيدبك منفي شرط لازم براي صداي خوب هست و نه كافي و با ديدن اين ليست اول اونايي كه تو ليست فيدبك منفي بالايي دارند رو حذف ميكنم و بعد اونايي كه فيدبك منفي كمي دارند رو سعي ميكنم بشنوم ببينم صداشون چطوره.
لازم به توضيح هست توپولوژي هاي مختلف رو نبايد با هم مقايسه كنيد واسه همين من لامپي رو از ساليد استيت جدا كردم و بين ساليد استيت ها هم اونايي كه ترانس خروجي دارن وضعيتشون متفاوته.

A Future Without Feedback?
When Black proposed negative feedback in 1927, he was trying to solve a specific problem: the deep cascading of imperfect, transformer-coupled tube amplifiers. But has anyone explored the implications of negative feedback for reproduced sound quality in the absolute sense?

Based on my experience of the pairing of a zero-loop-feedback preamplifier and amplifier, and supported by the evidence that amplifier designers consciously or unconsciously attempt to reduce negative feedback to improve subjective quality—even if this means worsening the measured performance—we need to reconsider the subject.

It is possible that engineers need to rethink how audio systems should be designed. Before the introduction of transistors limited to low voltages, which forced the speaker industry down to 8 and 4 ohm impedances, speakers were typically 8 to 16 ohms, did not need thick cable to wire them up, achieved maximum electromagnetic utilization at good efficiency, and were well matched to tube amplifiers. Higher efficiency spells better dynamics, reduced thermal compression, and the potential of using smaller, more perfect power amplification. But if speakers were designed to have smooth impedance curves, to be relatively uncritical of amplifier or cable matching, and to offer higher sensitivity, we would have greater freedom to examine the feedback question and the validity of the low-power, short-path, zero-feedback approach.

We still have much to learn about the art of sound reproduction; ultimately, our responsibility is to our ears, not to established precepts.

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Output Impedance , Negative Feedback

چهار شنبه 20 ژوئن 2018
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هرچقدر فیدبک منفی کمتر باشه امپدانس خروجي بيشتر ميشه و صدا بهتره.

https://www.stereophile.com/reference/70/index.html

Ypsilon Electronics Hyperion monoblock power amplifier its output impedance was relatively high for a solid-state design, at 0.35 ohm

Ypsilon Aelius monoblock power amplifier The output impedance was high for a solid-state design, at 0.44 ohm at 20Hz and 1kHz, 0.47 ohm at 20kHz.

AkitikA GT-102 power amplifier 0.2 ohm at 20Hz, 0.11 ohm at 1kHz, and 0.13 ohm at 20kHz

Constellation Inspiration Stereo 1.0 power amplifier The output impedance was low, varying from 0.11 ohm at 20Hz and 1kHz to 0.12 ohm at 20kHz.

Bel Canto Design Black ACI 600 integrated amplifier The output impedance at the speaker terminals was 0.2 ohm at all audio frequencies

Pass Laboratories XA25 power amplifier The output impedance (including 6′ of speaker cable) was low, at 0.08 ohm at 20Hz and 1kHz, rising very slightly to 0.1 ohm at 20kHz.

PS Audio Stellar M700 monoblock power amplifier The output impedance (including 6′ of speaker cable) was low, at 0.1 ohm at 20Hz and 1kHz.

Pass Laboratories XA60.8 monoblock power amplifier The XA60.8’s output impedance, including 6′ of speaker cable, was 0.07 ohm at 20Hz and 1kHz, rising to 0.1 ohm at 20kHz.

Dan D’Agostino Progression Mono monoblock power amplifier The output impedance was high for a solid-state design, at 0.44 ohm at 20Hz and 1kHz, rising slightly to 0.49 ohm at 20kHz.

Siltech SAGA power amplifier output impedance was higher than is usual for a solid-state design, at 0.23 ohm

Krell OLD KST-100 power amplifier output impedance was close at 0.15 ohms, rising to 0.2 ohms by 20kHz.

Emotiva XPA Gen3 two-channel power amplifier The output impedance, including the series resistance of the speaker cables I used, was very low at 20Hz and 1kHz, at 0.09 ohm, and rose only slightly at 20kHz, to 0.125 ohm.

Mark Levinson No.536 monoblock power amplifier The output impedance was low, at 0.1 ohm at 20Hz and 1kHz, rising slightly to 0.13 ohm at 20kHz.

Audionet Max monoblock power amplifier The output impedance was very low, at 0.045 ohm (including the speaker cable) at 20Hz and 1kHz, rising slightly to 0.07 ohm at 20kHz.

AVM Ovation MA8.2 monoblock power amplifier The output impedance (including 6′ of cable) was very low, at 0.08 ohm at 20Hz and 1kHz, rising very slightly to 0.1 ohm at 20kHz

Boulder Amplifiers 2150 monoblock power amplifier Measurements The output impedance, including 6′ of speaker cable, was extremely low, at 0.02 ohm at low and middle frequencies; this rose only slightly, to 0.026 ohm, at the top of the audioband

Bel Canto e.One Ref600M power amplifier output impedance, including 6′ of cable, was low, at 0.1 ohm from 20Hz to 20kHz.

First Watt J2 power amplifier The output impedance was relatively high for a solid-state design, at 0.5 ohm from 20Hz to 20kHz.

PS Audio BHK Signature 300 monoblock The output impedance (including the series resistance of 10′ of speaker cable) was on the high side for a solid-state amplifier, at 0.16 ohm at all audio frequencies

Ayre Acoustics MX-R Twenty monoblock power amplifier the output impedance was higher than usual for a solid-state design: 0.26 ohm at low and middle frequencies, rising to 0.28 ohm at 20kHz

Simaudio Moon Evolution 860A power amplifier The output impedance, including 6′ of speaker cable, was very low, at 0.09 ohm at low and middle frequencies, rising to 0.11 ohm at the top of the audioband.

Bricasti Design M28 monoblock power amplifier The output impedance, including 6′ of speaker cable, was very low, at 0.05 ohm at low and middle frequencies, rising to 0.06 ohm at the top of the audioband.

Constellation Audio Performance Centaur Mono monoblock power amplifier The output impedance was low for a bridged design, at 0.07 ohm including the cable at low and middle frequencies, rising slightly to just under 0.1 ohm at the top of the audioband.

Symphonic Line Kraft 400 monoblock power amplifier The output impedance was 0.04 ohms or less at low and mid frequencies, and under 0.07 ohms at 20kHz

Mark Levinson No.53 Reference monoblock power amplifier The output impedance at low frequencies was very low, at 0.06 ohm, including 6′ of speaker cable. This rose to 0.25 ohm at the top of the audioband

darTZeel NHB-458 monoblock amplifier The output impedance was high for a solid-state design, at 0.3 ohm (including 6′ of speaker cable) at all frequencies.

Lamm M1.2 Reference monoblock power amplifier The output impedance at the “1–6 ohms” setting was 0.15 ohm at low and middle frequencies, rising to 0.18 ohm at 20kHz.

MBL Reference 9011 monoblock amplifier The output impedance was very low, at 0.05 ohm at 1kHz and below, rising to 0.1 ohm at 20kHz.

Goldmund Mimesis 8 power amplifier output impedance: assessing this by measuring the voltage drop at a 1W level when an open-circuit load was replaced by an 8 ohm resistor gave a figure of 0.04 ohms at 20Hz and 1kHz. Repeating the measurement using a 4 ohm load, thus demanding twice as much current, gave a figure twice this, at 0.08 ohms. Though this is still inconsequential, it puzzles me, as does the fact that at 20kHz, the discrepancy was smaller, at 0.12 ohms (8 ohm load) vs 0.15 ohms (4 ohm load).

Soulution 710 power amplifier The output impedance, including the series resistance of 6′ of speaker cable, was very low, at 0.06 ohm at 20Hz and 1kHz, rising to 0.075 ohm at 20kHz.

Luxman B-1000F monoblock power amplifier The output impedance was 0.125 ohm at 20Hz and 1kHz, rising slightly to 0.15 ohm at 20kHz.

Electrocompaniet AW400 monoblock power amplifier The output impedance is specified as being below 0.01 ohm, which is very low. However, including 6′ of speaker cable, I measured 0.135 ohm at low and midrange frequencies, rising very slightly to 0.17 ohm at the top of the audioband.

Bryston 7B SST2 monoblock power amplifier The Bryston’s output impedance was low for a balanced design, at 0.11 ohm at low and middle frequencies, rising slightly to 0.17 ohm at 20kHz.

Aesthetix Atlas power amplifier The output impedance was relatively high for a design with a solid-state output stage, at 0.34 ohm at low and middle frequencies, rising very slightly to 0.36 ohm at 20kHz.

EAR/Yoshino M100A monoblock power amplifier Transformer Coupled It was lowest from the 4 ohm output, at 0.55 ohm across most of the audioband—equivalent to a damping factor of just under 8—rising to 1.05 ohms at 20kHz. The 8 ohm figures were 1.1 ohms, rising to 2.3 ohms at 20kHz, while from the 16 ohm transformer I measured 1.9 ohms at 20Hz and 1kHz, and a very high 4 ohms at 20kHz.

Adcom GFA-565 monoblock power amplifier output impedance was uniformly low—ranging from 0.02 ohms from the bass to the upper midrange and increasing slightly to 0.03 ohms at 20kHz.

Musical Fidelity 750K Supercharger monoblock power amplifier The output impedance was a little higher than usual for a solid-state design, at 0.11 ohm at 20Hz and 1kHz, rising to 0.22 ohm at 20kHz

Electrocompaniet Nemo monoblock power amplifier The output impedance measured higher than specified, at between 0.17 and 0.23 ohms

Accuphase M-2000 monoblock power amplifier The output impedance was a extremely low 0.035 ohm at 1kHz, increasing to a measured maximum of 0.038 ohm at 20Hz into an 8 ohm load, and 0.063 ohm at 20kHz into 4 ohms.

Halcro dm88 Reference monoblock power amplifier The dm88’s output impedance was very low across almost all the audioband, at 0.1 ohm including 6′ of multistrand speaker cable. It rose slightly at 20kHz, to 0.14 ohm

McIntosh MC501 monoblock power amplifier output impedance, I was surprised to find it to be lowest from the 8 ohm tap, at 0.08 ohm, and highest from the 2 ohm tap, at 0.13 ohm

Edge NL-12 power amplifier output impedance was 0.1 ohm over most of the audioband, rising to 0.3 ohm at 20kHz

Pass Labs X1000 monoblock power amplifier The output impedance measured between 0.18 and 0.20 ohms (the higher values were at 20kHz)

47 Laboratory 4706 Gaincard power amplifier I measured around 0.15 ohm at 20Hz and 1kHz, this dropping to 0.08 ohm at 20kHz

Hovland Radia power amplifier The output impedance was a low 0.2 ohm across most of the band, this rising inconsequentially to 0.26 ohm at 20kHz.

Krell Full Power Balanced 350mc monoblock amplifier the output impedance was 0.18 ohms at 1kHz and 20kHz, 0.15 ohms at 20Hz

Musical Fidelity Nu-Vista 300 power amplifier the output impedance was 0.08 ohms/0.04 ohms, left/right, respectively, across most of the audio band.

Linn Klimax 500 Solo monoblock power amplifier The output impedance measured a minuscule 0.043 ohms at 1kHz, increasing to 0.071 ohms at 20kHz, both assessed by measuring the voltage rise when an 8 ohm load was open-circuited. Using 4 ohm loads, this increased by a maximum of 0.01 ohm at 20kHz, to 0.081 ohm.

Mark Levinson No.33H monoblock power amplifier output impedance was extremely low at 0.02 ohms at 20Hz and 1kHz, rising slightly to 0.026 ohms at 20kHz.

Ayre AX-7 integrated amplifier Its output impedance was moderately high for a solid-state design, at 0.4 ohm across the audioband.

ASR Emitter II Exclusive integrated amplifier The ASR’s output impedance was very low: <0.08 ohm across the audioband (including the series impedance of 6′ of multistrand speaker cable).

Mark Levinson No.383 integrated amplifier The power-amplifier output impedance was very low at approximately 0.055 ohms across most of the audioband, this rising to a still negligible 0.065 ohms at 20kHz

Luxman L-509X integrated amplifier The output impedance at the speaker terminals was a very low 0.075 ohm at low and middle frequencies, rising to 0.11 ohm at the top of the audioband.

NAD C370 integrated amplifier output impedance across most of the audioband a moderate 0.16 ohm, this rising slightly to 0.19 ohm at 20kHz.

Ayre Acoustics AX-5 integrated amplifier The AX-5’s output impedance was a little high for a solid-state design, at 0.27 ohm across the audioband, this due to the circuit’s lack of loop negative feedback.

Roksan Kandy K2 integrated amplifier  output impedance was a very low 0.09 ohm at low and middle frequencies, rising slightly to 0.15 ohm at 20kHz due to the usual series Zobel inductor.

Sugden A21ai The amplifier’s output impedance from the speaker jacks was a low 0.12 ohm at 1kHz, rising to 0.39 ohm at 20Hz and 0.25 ohm at 20kHz.

Krell FBI integrated amplifier The output impedance (including 6′ of speaker cable) was very low, at 0.08 ohm at low and midrange frequencies.

darTZeel CTH-8550 integrated amplifier The CTH-8550’s output impedance was quite high for a solid-state design, at 0.4 ohms in the bass, rising to 0.5 ohms at 20kHz.

Devialet D-Premier D/A integrated amplifier I measured 0.04 ohm at all audio frequencies, but thus includes the impedance of the 6′ of speaker cable I used for the test. But the fact that the D-Premier has an extraordinarily low output impedance

Naim Audio NAIT 5si integrated amplifier The output impedance ranged from 0.34 ohm at 20Hz and 1kHz to 0.36 ohm at 20kHz—a very slight increase.

Creek Evolution 100A integrated amplifier The output impedance at the speaker terminals was less than 0.1 ohm, including 6′ of speaker cable.

GamuT Di150 LE integrated amplifier The Di150’s output impedance was very low, at 0.09 ohm (including 6′ of speaker cable) at low and middle frequencies, and rose only slightly, to 0.11 ohm, at 20kHz.

Cyrus 6vs integrated amplifier impedance of 0.08 ohm at low and midrange frequencies, rising very slightly to 0.1 ohm at 20kHz.

Arcam Alpha 10 integrated amplifier The output impedance is comfortably low—under 0.06 ohms up to 1kHz, rising to a maximum of 0.16 ohms at 20kHz

Chord CPM 3300 integrated amplifier the source impedance was a very low 0.06 ohm, rising slightly to 0.08 ohm at 20kHz.

 


 

Jadis JA200 Mk.II monoblock power amplifier The output impedance (including 6′ of speaker cable) was very low for a transformer-coupled tube amplifier, at 0.18 ohm at 20Hz and 1kHz, and 0.14 ohm at 20kHz.

PrimaLuna ProLogue Premium power amplifier The output impedance from both output taps was significantly higher than that of the ProLogue Premium integrated amplifier. From the 8 ohm tap, I measured 9.2 ohms at 20Hz, 8.75 ohms at 1kHz, and 8.45 ohms at 20kHz; from the 4 ohm tap, the respective impedances were 4.7, 4.5, and 4.35 ohms.

Thöress 300B monoblock power amplifier The output impedance was relatively low for a single-ended design, at 1.9 ohms at 20Hz and 1kHz, rising to 2.4 ohms at 20kHz

Air Tight ATM-1S power amplifier the Air Tight’s output impedance was high, ranging from 3.6 ohms at 20Hz to 3.3 ohms at 20kHz. This suggests that the single output-transformer tap is optimized for a 4 ohm load

VTL Siegfried Series II Reference monoblock power amplifier he lowest impedance was in triode/MDF mode, at 0.88 ohm in the midband and 0.9 ohm at the extremes of the audioband. The output impedance rose a little with each reduction of feedback, reaching 1.36 ohms at 1kHz and 1.4 ohms at the frequency extremes in the LDF condition.

Sophia Electric 91-01 300B monoblock power amplifier output impedance was also high, at 5.6 ohms at 20Hz, 3.7 ohms at 1kHz, and 8–9 ohms at 20kHz

Lamm Industries ML3 Signature monoblock power amplifier Even without any negative feedback, the 4 ohm tap’s output impedance was moderately low for a single-ended design, at 1.55 ohms at low and middle frequencies, rising to 1.9 ohms at the top of the audioband. Without NFB, the output impedance was much higher from the other taps, the 8 ohm tap measuring 2.9–3.9 ohms

Lamm ML2.2 monoblock power amplifier The output impedance also depended on the transformer tap used. From the 4 ohm tap, the impedance was a low 0.38 ohm at low and middle frequencies, rising to 0.5 ohm at 20kHz. As expected it was higher from the 8 ohm tap, at 0.7 ohm at 20Hz and 1kHz, and 0.8 ohm at 20kHz, and higher still from the 16 ohm tap: 1.35 ohms at all audio frequencies.

Octave Audio RE 290 power amplifier The output impedance was fairly high, measuring 2.2 ohms at 20Hz and 1kHz, rising slightly to 2.4 ohms at 20kHz.

Jadis SE300B monoblock amplifier The output impedance was 2.5 ohms at 1kHz, 2.7 ohms at 20kHz, and 0.76 ohms at 20Hz.

Jadis Defy-7 Mk.II power amplifier with solid-state amplifiers it is usually sufficiently low to be considered negligible: 0.1 ohm or under. With a number of tube amplifiers it can be rather higher. For example, the “1000”—a low-feedback triode amplifier made by Audio Innovations in the UK—has an output resistance of several ohms. This is by no means an isolated example. The Defy-7’s output or source resistance was quite constant over the audio band, ranging from 0.45 ohms at 20kHz, to 0.4 ohms, midband, and 0.45 ohms at 20kHz.

Allnic Audio A-5000 DHT monoblock power amplifier output impedance was impressively low for a single-ended tube design even from its 16 ohm tap, where it measured 1.6 ohms at 20Hz, 1.35 ohms at 1kHz, and 1.5 ohms at 20kHz. As expected, the respective impedances were lower from the 8 ohm tap: 1, 0.8, and 0.85 ohm.

Conrad-Johnson LP125M monoblock power amplifier The source impedance from the single pair of output terminals was a high 2 ohms at low and middle frequencies, rising slightly to 2.2 ohms at 20kHz

VTL MB-450 Series III Signature monoblock power The output impedance also depended on the amount of negative feedback and the operating mode. The lowest impedance was in triode mode with the maximum amount of feedback, where it measured 0.87 ohm in the midrange, rising very slightly to 0.89 ohm in the low bass and 0.9 ohm at the top of the audioband. With the lowest amount of feedback, these figures rose to 1.45, 1.5, and 1.53 ohms, respectively. Operating the MB-450 in tetrode mode gave a slightly higher source impedance, ranging from 0.95 ohm at 1kHz with the maximum feedback, to 1.95 ohms at 1kHz with the lowest feedback.

Balanced Audio Technology VK-55SE power amplifier the output impedance from the VK-55SE’s High and Med taps was high, at 2.7 ohms in the midrange, rising to almost 3 ohms at high and low frequencies

AudioValve Baldur 70 monoblock power amplifier The Baldur’s output impedance, from both the 8 and 4 ohm transformer taps, was lower than usual for a tubed amplifier, at 0.66 and 0.42 ohm, respectively.

Yamamoto A-08 power amplifier The right channel measured 3.2 ohms at 20Hz, dropping to 2.85 ohms at 1kHz and 2.16 ohms at 20kHz. The corresponding figures for the right channel were a little lower, at 3 ohms, 2.73 ohms, and 2.05 ohms, respectively, but these are still high in absolute terms.

Bel Canto SET 80 monoblock power amplifier The measured output resistance was 1.7 ohms, corresponding to a low damping factor of 4

Cary Audio Design CAD-805 monoblock power amplifier output impedance is 0.74 ohm

Cary CAD-1610-SE monoblock power amplifier impedance from the 8 ohm output was high at 3.4 ohms across most of the band, rising to 4 ohms at 20kHz.

Graaf GM 200 OTL power amplifier The output impedance was 0.79 ohms at 1kHz, 0.7 ohms at 20Hz, and 0.83 ohms at 20kHz

Audio Research VTM200 monoblock power amplifier output impedance also varied according to which tap was used: a reasonably low 0.35 ohm from the 4 ohm tap, rising to 0.6 ohm from the 8 ohm tap and 1 ohm from the 16 ohm tap

Sonic Frontiers Power 3 monoblock power amplifier output impedance a maximum of 0.17 ohm at 20Hz and 1kHz, increasing to a maximum of 0.22 ohm at 20kHz

Wavac SH-833 monoblock power amplifier The SH-833’s output impedance was on the high side, at 5 ohms from the 8 ohm transformer tap and 2.6 ohms from the 4 ohm tap. These figures were maintained across most of the audioband, with a rise at 20kHz from the 4 ohm tap to 3.6 ohms. Unexpectedly, the 20kHz source impedance from the 8 ohm tap dropped from 5 to 4.3 ohms.

EAR 890 power amplifier the EAR 890’s output impedance was around 1.5 ohms from its 16 ohm tap and 0.5 ohm from the 8 ohm tap

Wavelength Audio Cardinal XS monoblock amplifier output impedance was a very high 3.4 ohms at 1kHz, increasing to 5.9 ohms at 20Hz and 5.3 ohms at 20kHz.

Antique Sound Lab Explorer 805 DT monoblock power amplifier output impedances were high, at 7.2 ohms (16 ohm tap), 3.65 ohms (8 ohm tap), and 2 ohms (4 ohm tap)

Audiopax Model Eighty Eight monoblock power amplifier output impedance also varied with the control settings. It was lowest with them at full clockwise, but was still very high in absolute terms at 3.5 ohms across most of the audioband. Unusually, the source impedance dropped at low frequencies, reaching 1.8 ohms at 20Hz.

Air Tight ATM-211 tube monoblock power amplifier output impedance measured a high 3.7 ohms at 1kHz. Unusually, this decreased slightly to 3.5 ohms at 20Hz and 20kHz.

Hovland Sapphire power amplifier The output impedance from the 16 ohm tap was a very high 3.55 ohms across most of the audioband, rising to 4.3 ohms at 20kHz.

Wavelength Audio Gemini monoblock power amplifier The low-frequency source impedance with the 2A3 was 3.7 ohms (8 ohm tap) or 1.7 ohms (4 ohm tap); the midrange impedance was 3.1 and 1.5 ohms, respectively; while at 20kHz, the impedance rose to 4.6 and 1.8 ohms, respectively. The respective figures with the 45 tube were 3.2 and 1.5 ohms, 5.5 and 2.6 ohms, and 6.8 and 2.9 ohms.

McIntosh Labs MC2000 power amplifier The output impedance measured a maximum of 0.4 ohm—quite high in comparison with solid-state amplifiers but admirably low for a tube amp.

Nagra VPA monoblock power amplifier output impedance was quite high, varying between 2.23 and 2.26 ohms depending on frequency and load impedance (measurements taken at the 8 ohm output).

Manley Laboratories Stingray integrated amplifier The output impedance, however, was also high, ranging from a maximum of 3.87 ohms at 20Hz to a minimum of 2.83 ohms at 20kHz—values guaranteed to affect the amplifier’s frequency response through real loudspeakers.

EAR V20 integrated amplifier The output impedance from the 8 ohm speaker terminals measured a minimum of 0.77 ohms and a maximum of 1.14 ohms, the latter at 20kHz. The corresponding values from the 4 ohm taps were 0.47 ohms and 0.62 ohms—respectably low values for a tube amplifier. The output impedance at the V20’s tape-monitor jacks was 1k ohm with a 25 ohm source impedance, and 1.56k ohms with a 600 ohm output impedance, indicating an unbuffered tape output.

Audio Note Jinro integrated amplifier The output impedance from the single transformer tap was commendably low for a single-ended-triode design, at 2.5 ohms

Leben CS300 integrated amplifier The output impedance at 20Hz was similar from all three outputs at 3–3.5 ohms. It did differ at higher frequencies: at 1kHz, the impedance was 2.65 ohms (8 ohm tap), 2.25 ohms (6 ohm tap), and 1.8 ohms (4 ohm tap); at 20kHz, it was 2.4, 1.6, and 1.1 ohms, respectively.

Quad II Classic Integrated amplifier The output impedance was on the low side for a transformer-coupled tube amplifier, at 0.28 ohm at 20Hz and 1kHz, dropping to 0.2 ohm at 20kHz.

Woo Audio WA5 integrated amplifier The output impedance from the speaker terminals was also high, at 3.2 ohms across the audioband

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