Hi-Rez Highway

You know what I have to say, right?.......:-).........nt

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Alex Peychev

(M)

In Reply to: Re: Burr Brown DACS posted by Ric Schultz on October 09, 2003 at 20:40:08:

:-)

Follow Ups:

These guys agree with Alex for their new CD player . . . - J North 11:30:58 10/10/03 (7)
http://www.avihifi.co.uk/LabSeries CD/LabCD.html
Quote:
"There are several DACs competing for top spot, all sound slightly different and after careful consideration, we have chosen the Cirrus Crystal 24 bit Delta Sigma, 192kHz D/A Converter. In our opinion it is the most musically rewarding and gives the best results with the widest range of program material."
FYI only.
- Thank you very much!.....:-)......... - Alex Peychev 00:48:21 10/11/03 (0)
  ....Even if Burr-Brown comes up with -150db Dynamic range and THD+N, it will still sound as BB. They have changed a lot, but Crystal does not stay still during that time....:-)
  Regards,
  Alex
- Re: These guys agree with Alex for their new CD player . . . - Ric Schultz 11:54:23 10/10/03 (5)
  What puzzles me is that a lot of these commercial companies do not tell you much of anything about their equipment except they choose a particular DAC chip or are using 50mhz Bipolars (this company as an example). They don't show pictures of the insides, they don't talk seriously about their design philosophy, just a bunch of fluffy words. Where's the beef? Its no wonder we are all confused. So many products, so many fluffy words and so few ways to tell if this amp or CD player is any good. It is what makes high end so interesting and so darn confusing/frustrating at the same time. At least with video and computers it is pretty darn straight forward. In audio, for every company that chooses one DAC chip you have another that chooses another. Which company has better ears?
  Hey, we will all have fully digital signal paths soon(player directly into the amp)and we won't have to worry about DAC chips any more! he he.
  - Re: These guys agree with Alex for their new CD player . . . - J North 12:03:46 10/10/03 (4)
    Full digital systems (with digital amplification) create all kinds of new problems that need new solutions. High RF noise is one.
    There has to be some kind of conversion from redbook sampling frequencies in the 40Khz range and digital switching amplification frequencies in the 200 to 800Mhz range. It does not always work out the best. It is better for SACD though.
    The Solar Hifi forum on audiocircle addresses this real well.
    Why do most digital amps (BC, PSA, etc) only accept an analog signal?
    - There is no such thing as Digital Amps : - Marconi 14:10:43 10/11/03 (1)
      all class D (or "switching") amplifiers are Analog. "D" stands not for digital!
      They may feature a digital input that accepts PCM, but this is always converted to analog ( yes... a dac inside) before being converted to PWM. And PWM is Not a digital signal.
      The overruling feature for a signal to be digital is that it contains BITS at a certain Sample Rate, and those Bits form a Word with a specific length; and this word contains specific data, stored as such into this word according to some complex mathematical structure. PWM is just a square wave that is modulated in the time domain by the analog signal that comes out of the (internal) DAC, with the help of a comparator (kind of fast opamp in open loop configuration).
      For DSD this is different, this is directly converted to PWM because their composition schemes are somewhat similar. Still: after this conversion the signal is essentially Analog.
      This all, however, does not disqualify class D in the least: the big bang of Class D is imminent and beware: it sounds better than anybody is willing to admit - if applied properly, which nobody has done so far (commercially - at least).
      A note about HF noise: No such thing affects data in the all-digital audio chain, until the signal reaches the final amp stage. Here the signal amplitudes are so large and the HF is so far out of audible territory that it don't reach your ears.
      Kevin of Solar is deceptive...talking about digital amps that are immune to jitter but can be too accurate. Are you kidding?
      No digital: No jitter? Wrong! Jitter is just "timing errors".
      The 350 kHz to 600kHz square wave that is the carrier for the audio signal must not be allowed to vary beyond what is dictated by the audio signal, because variations in time will automatically translate into a lower frequency that is put on top of the audio signal; and from this point on (if it will pass the output filter) it has become an undistinguishable PART of the audio signal.
      Who is going to separate these two? There is as of yet no system capable of determining which part of an analog audio signal is distortion and which is the undistorted music part. Would be fancy, just taking the distortion out of your music, at the end of the chain! Would take a hell of a library to store all possible sounds, number them all, and have them available for comparison at lightspeed...
      Class D has its own set of distortions, and it will take time to iron them out. But they are fewer, and they are easier to understand.
      No more hassle with thermal compression, negative feedback that is always too late, output transistors that loose all their current gain when emitter currents reach over just a couple of amp�res, or open loop bandwidths of just a couple of kHz introducing horrible phase distortions.
      As Ric sez: the revolution has begun.
      I say: Beware of "poyama people" that want to block progress because they just can't handle it. Or don't understand it.
      - Good post - thanks (nt) - Metralla 19:04:17 10/11/03 (0)
        
        In Reply to: There is no such thing as Digital Amps : posted by Marconi on October 11, 2003 at 14:10:43:
        
        .
        
        Regards,
        Metralla
    - Fully Digital playback including some with SACD - Ric Schultz 13:47:25 10/10/03 (1)
      There are several companies that are doing this (usually with many patents). Sony, TI (they bought Tocatta Tech) and Apogee all have pure digital input modules. Sharp also.
      PCM can be upsampled to DSD or to higher sample rates before conversion to PWM (class D). It is much easier to design an analog input class D amp then it is to make one with pure digital input. That is why there are so many analog input amps. But with the TI, Apogee chips, (I don't know if Sony will license its technology to others), and others coming, the pure digital path is coming to roost. Tact was the first (using Toccata Tech, now ownded by TI) but look at the progress. Tact's first two channel amp was $10,000 and now you can buy the Panasonic with 6 channels for $300!!!!!
      Sony is releasing some very interesting pure digital products. One you mentioned was the XA9000ES with the top of the line new digital receiver. This receiver does 200 watts a channel for 7 channels. It can accept the digital SACD or CD info from the XA9000ES and goes directly to the amp with no conversion to analog. Another even more interesting (to me, at this point) product is the new Sony AVD-S500ES DVD receiver. This 6 channel-80 watts a channel(8 ohms)receiver is pure digital and has a built in DVD/SACD player. So the DSD and PCM info go directly to the built in digital amps......Now we are talking...no cables even. This machine lists for $800 and will naturally be discounted. This, I want to mod!!!
      The Panasonic recevier has 100 watts a channel of pure digital in but can only take up to 24/96...no DSD. It uses the TI main chip and supposedly sounds quite remarkable.
      This is just the beginning. I predict that within 5 years all commercial lower cost gear will be digital (analog and/or digital in) and that more and more high end companies will have digital amps (both digital and analog in). The revolution has begun.
      As far as RF, this has ever been a problem with digital, so a digital amp is just the same. Some people who have these amps (both digital and analog in) think they sound quite remarkable. Of course, they will get better, just as SACD players, etc. have all gotten better.
      So far, only the Sony and Sharp can do DSD and PCM direct into the amp, but I am sure, more will follow.
      No, these digital amps will never sound like tubes (notice the Solar Hifi guy putting a tube in front of the digital module for "increased" musicality). But hopefully, they will be transparent to the source. We shall see. Ever the optimist.
      - Re: Fully Digital playback including some with SACD - J North 14:20:44 10/10/03 (0)
        
        In Reply to: Fully Digital playback including some with SACD posted by Ric Schultz on October 10, 2003 at 13:47:25:
        
        Yes, digital technology has certainly moved along fast. It also has a ways to go.
        If you care about measurements, a lot of the digital gear does not test very well.
        It is not entirely transparent either, as various implemmentations have differing sonic signatures, call it "coloration" or not.
        There are also various complaints of noise and hiss out of the new Sony ES digital receivers
        I am not saying that analog is any better, just that digital is not the end-all be-all (yet?).
        In the end, it comes down to system synergies, budgets, priorities, source material quality, long vs short term listening etc etc - and each persons situation is obviously different. Just like a Ford Tauras stationwagon is not the best car for all of us.
        And that is why this hobby is so much fun (or not)!

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