Peter Qvortrup On Digital

Peter Qvortrup On Digital

یکشنبه 25 آوریل 2010
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این مطلب از سایت dagogo برداشته شده که نگاه طراح Audio Note UK رو در مورد Digital شرح میده:

Peter Qvortrup On Digital

Jack: Peter, please share with us your opinion on the basic differences between CD and vinyl sound.

Peter: My view is that digital cannot resemble the original because of the inaccuracies introduced at the point of entry in the digital domain. The errors and omissions introduced by all current and past methods of conversion are so great that, at best, all we get is a card board copy of the original and it is clearly audible, as a quick comparison between a decent turntable and even the most expensive CD replay set up will quickly reveal.

This is because much like the flawed assumptions used by mathematicians to create the financial “innovations” which lie at the heart of the current financial crisis, the fundamental assumptions that created the way we digitize the analogue signal also fail to describe the content of dynamic wide band signals and the way they flow. The end result is a set of mathematical formulas that are sadly lacking in their ability to model the full range of variables in a music signal, and as a result when we come to make the analogue to digital conversion process, the bar is set at a level which is lower than it needs to be, resulting in conversion technology which does not do justice to the analogue signal it is being presented with, resulting in an anemic digital version of the analogue original.

It is therefore no major surprise that the digital medium, as we know it, lacks authority, authenticity, immediacy, instrumental medium and density, dimensionality, and overall presence when compared to its analogue version, to the point where even some digital recordings sound better on LP than the CD (the reverse is of course also occasionally true, but for sake of a proper comparison, we should always compare early all-analogue recordings on LP with their CD counterparts from the early to mid 1980s, my experience has always been that AAD recordings generally sound better than ADD, and ADD generally sounds better than DDD), which leads me to believe that the signal damage goes beyond merely the digital conversion process itself, as it would appear that the longer the signal stays in the digital domain the more damage it suffers, which may also explain some aspect of what I hear in music servers.

The high “resolution” formats like SACD and DVD-A are no better, just different versions of the same problems that beset Redbook, but unlike standard Redbook, the SACD/DVD-A converters are virtually impossible to improve upon as the 1Bit system they use do not allow removing the oversampling and digital filtering, for example, so we are reduced to playing with component choices and power supply configurations, which is like putting lipstick on a bulldog, to use a currently popular phrase!

Jack: Then Peter, how did you come to build some of the most musical sounding CD players, DACs, and Transports?

Peter: Well, from the onset I disliked CD with a vengeance, but over some years I was increasingly faced with the opposing choices or dilemma if you like, of preferring the quality of the purely analogue source but also a great need to be able to hear a lot of the music I liked that only came out on CD. So, I had no real choice but to try to work out how one makes a digital-analogue converter that does not completely sucks the life out of any musician’s best efforts, including when the recording engineers have also not done their greatest job, which of course many LPs also suffer under, but which to me at least manifests itself as far worse when it is on CD than LP.

I always felt that the main improvements were available in the DAC, so that is where our main efforts have been concentrated. However, recent development work has shown that the CD transport has equally great potential for improvement, so considerable efforts are now given to find out how far the CD transport can be taken: We now employ a valve power supply in our best CD transport for part of the circuit!

Perhaps a little history?

In 1991, I set about with my engineer at the time, Guy Adams (of Voyd Turntables fame!) to develop a digital-to-analogue converter which has a less digital signature. This work led to the use of a transformer as the I/V interface, a practice we patented across the world, and the DAC3 was born in 1993. I have always been doubtful about techniques that purport to improve the signal, so sometime in 1994 I asked Guy whether it was possible to remove the oversampling and digital filters from the converter. Guy felt it was not feasible after speaking to various people at Burr Brown, so in late 1995 I mentioned it to Andy Grove, and Andy said he would look at it, a prototype was made a week later and the sound was a revelation, although it needed some fine tuning to get rid of the out of band interference.

We released the first non-oversampling (we call it 1xoversampling) design as the DAC5 Special in July 1997, and the rest is really history. We have spent the years since then refining the circuit, I/V interfaces and power supplies.

We added dedicated 1xoversampled CD players in 1998 and started work on CD transports in 1997, the first one being the CDT Two, unfortunately the Korean manufacturers who were building all the CD products for us went under in 2000, and it took us another 4 – 5 years to develop a replacement for the CDT Two. The CDT Two/II was released in late 2004.

Jack: One last question Peter, what are Audio Note’s future plans for digital playback?

Peter: We continue to refine the circuitry and power supplies and we keep discovering incremental improvements to add to the circuits, components and materials. As an ultimate statement, Andy has been working on two major projects, the first is an all discrete 20 – 24 bit converter, and the second, which is more interesting, is a completely new conversion system which we originally designed as an out-of-house project for a company that does investigations into molecular resonance in materials; initial experiments look promising, so we shall see.

On the CD transport side, we are finishing development of the CDT Five, where a couple of valve in part of the power supply has shown that even here, valves are superior to semiconductors.

I think that covers it!

فکرش رو بکنید آیا ممکنه روزی استودیوها به سمت آنالوگ برگردند؟ من که فکر نمیکنم. بازار یک مشکل اساسی با کیفیت داره و من فکر نمیکنم دیگه آنالوگ برگرده، البته مد شدن دوباره آنالوگ هم چیز مسخره ایست مثل مد شدن لامپ که هر دوی اینها بیشتر برای ایجاد بازار هست. وقتی آنالوگ مد میشه معنی اش این نیست که همه استودیوها دارند آنالوگ ضبط میکنند و با بهترین کیفیت به شما Vinyl ارائه میدهند بلکه تمام پردازشها دیجیتال انجام میشه و بعد اینکه تو Digital Domain همه بلاها سر رکوردآورده شد میارنش روی Vinyl تا یه شعاری مثل Analog Back یه بازار جدیدی ایجاد کنه. مد شدن لامپ هم در نوع خودش یک پدیده ایست که بازار ازش استفاده میکنه و بقول Steve (که خودش آمپلی فایر لامپی طراحی میکنه) تعداد آمپلی فایرهای بدصدا لامپی خیلی بیشتر از خوباشون هست.

There are TONS of CRAPPIE sounding tube amps out there.  I would say way more than good ones.

به هر حال ما منتظر میمونیم بازار یک شعار مشتری پسند بده تا بریم پولهلمون رو دور بریزیم، رسم بازار همینه و بدتر از اون تحلیل گرانی هستند که دانسته و ندانسته چنین موجی رو پیش میبرند.

یک مطلب دیگه اینجاست که میتونید بخونید :

The problem with CDs was not the discs themselves but the hunk of metal you were playing them on. Which is why the name Peter Qvortrup should be music to your ears.
John MLaren has the full story.

A funny thing happened to the CD on the way to the loudspeaker: some of the sound went missing. “Perfect sound forever”, its inventors called it, and that slogan helped sell players by the tanker-load. But many listeners remained unconvinced, finding the sound chromium-plated, artificial and tiring, and resolutely stuck with their vinyl. Over time the inventors, Philips and Sony, came close to recognizing the shortcomings of their system, though they only became enthusiastic about this admission when they’d developed a replacement – the recently introduced Super Audio CD (SACD) – and were raring to persuade us to replace our hardware and software yet again. But Audio Note, a mighty mouse of a company, may turn out to have rained on the giants’ parade. The boffins in Audio Note’s modest Hove HQ scratched their capacious craniums about what was wrong with CD, and concluded that conventional CD players were losing up to four-fifths of the data. Now they’re building machines that unearth those lost chords. The discovery is startling – it may mean we can all upgrade our music collection dramatically, without having to buy a single new disc.

Peter QvortrupIt’s not the first time that Audio Note’s visionary Danish boss, Peter Qvotrup, has stood conventional wisdom on its head. Among Europeans, he was the main man who insisted that old-fangled valves actually sounded much better than the transistors which replaced them. He endured great tidal waves of scoffing from ‘experts’ who gleefully demonstrated that transistors’ laboratory performance was superior, never thinking that the tests themselves might be suspect. Since then, humble pie has been consumed on an industrial scale, and the majority of expensive equipment now uses valves.

Qvortrup started his career as a marine broker before getting into hi-fi retailing with a clutch of shops in Copenhagen. His first foray into making the gear came with Audio Innovations, which he set up in 1984 and later sold. Audio Note was formed in 1991, and for the first few years combined manufacture with distributing a line of high-end equipment from Japan. The importing has gone now, and the company can concentrate on its own enormously wide range. It is probably the only small company in the world that makes a full line-up of audio products from cartridges to speakers.

Audio Note gear is probably the best that money can buy, and given the price of its flagship models, it bloody well ought to be. Want to know how much? Is your seatbelt fastened? Audio Note’s range-topping system will set you back a cool 400,000… pounds.

He endured tidal waves of scoffing from’ experts’ who never thought their tests might be suspect. Since then humble pie has been consumed on an industrial scale.

That’s almost as much as it costs to build a Formula One car (minus engine). As it happens, they’re very similar. After all, they’re both at the absolute cutting edge, use mind-blowing expensive materials, and need highly trained staff to design and assemble them. Since so few are made, the expense has to be amortized over a tiny number of units. The performance of this hi-fi is as far removed from a normal system as the race car is from a Hyundai.

And finally, both provide a trickle down of technology to more humble machines. Audio Note’s range starts with a jewel-like mini system at a mere £2,300, that’s like buying a McLaren road car for Rover money, and may be the biggest sound reproduction bargain of all time. In all, there are five separate levels of systems, and many different choices within each level.

Qvortrup believes that the Audio Note philosophy makes it distinct from the herd. “Most hi-fi makers are concerned primarily with packaging and market share. Even most so-called high-end machines use much the same technologies and processes as mass-market products. We prefer to stretch the envelope, to improve and refine constantly. However, doing that isn’t easy. It makes a great deal of time, and requires superb materials. It’s rather like cooking: whether you’re making some thing simple or complicated, you’ll always get caught out if you skimp on ingredients. Audio Note systems may sometimes cost more, but they offer a far higher enjoyment factor, and give our customers a real pride of ownership, like they might get from a Swiss watch or a racing yacht.”

The breakthrough in CD reproduction shows the value of their painstaking research. It took them two years to get to the heart of the matter.

“All normal CD players have error correction circuits which ‘sample’ sound backwards and forwards as the disc is played, and help paper over any cracks in the data. They slice and dice the input as they go, and then reconstitute the whole. The trouble is that this is like mincing a piece of beef: once you’ve done that, you can’t make a fillet steak out of it again. Basically sound is the same, it’s a continuum, and we discovered that these circuits cause the loss of weak signals – subtle things like echoes, harmonics, spatial information, which are vital to natural reproduction. So we came up with our own approach, leaving the data raw, and unadulterated. We found that other conventional components were contributing to data loss, too, and we replaced them with aerospace-grade materials applied in a new patented way”

The result has to be heard. Try your favourite CD – one you think you know in every tiny detail – and be prepared to be astonished. Suddenly a plucked bass appears from nowhere. Hey, who brought that snare drum in here? The sax has somehow acquired a far richer timbre, and the backing singers are no longer a flat wall of sound, but three distinct, mouth-sized humans. The whole thing sounds so alive, so tactile, so real.

The only people who will be crestfallen are the vinyl die-hards. Up till now, they’ve probably been right, that if you can put up with the pops and clicks, and the dreadful Heath Robinson-ness of it all, LP does sounds better. Not any longer. Fish out the same recording on CD and vinyl, and compare them using an Audio Note digital to analogue converter. Within 30 seconds it’s clear that the poor old black record is deep in cocked-hat territory.

I haven’t heard SACD, or any of the other competing new formats, but Peter Qvortrup has and is very, very confident that his machinery will see them all off using normal CDs. (in case his customers want to satisfy their curiosity, his converters can handle all of those formats as well.) As for Peter and his wife Lesley, who helps him run the company, they’re far from ready to stop listening to LPs. Mind you, they do own 35,000, and they will keep making brilliant record players for people like themselves.

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