John Curl's Blowtorch preamplifier part II

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I find that most CD's in general, just don't have enough original info to sound as good as SACD (good, honest ones), DVD (made by serious recording companies), or good records (most of them). Sometimes I hear a really good CD, but not usually.
The server that we used, recopied the CD, then worked it over until it was virtually error free, and then put it into fixed memory, to be played back with a separate clock. As far as I can determine, the company did a great job, trying to get as much as possible from a CD. It still was disappointing, but sort of good enough for a show. I would not hesitate to use the same server again, but I would bring my own CD's (the few that sound good to me) and 24-96K DVD discs.
 
I would like to again talk about servos, specifically the 2 servos in the JC-80 line amp stage. One servo is to reduce the DC outputs, (there are 2 outputs) as close to ground as possible. The other is to reduce the actual DC difference between the two outputs.
The servo at the bottom of the page looks at the 2 outputs and tries to minimize their difference by adding DC gain.
The servo at the top right compares both DC outputs to ground and tries to average the 2 outputs as close to ground as possible.
The combination of the 2 servos gives the circuit the ability to be direct coupled to a power amp and to change polarity by selecting one output or the other, without a pop when switching.
 
i have not heard a server that i liked better then my CD player - DA combination.
I see too many compromises in the analog section and the powersupply. Bit perfect is really not a problem. At Audio Physic we build the first server with bit perfect memory player over 10 years ago. the category had not even been invented yet. I invented the word "Solid State Player" and tried to patent it without succes. I think dynamic range of a CD can be good enough with noise shaping but the 44kHz is quite a bottleneck. Bob Stuart compared the human ear to a 96KHz 21.5Bit system i think. What can help is a spline reconstruction filter but that is a long story.
 
I would like to again talk about servos, specifically the 2 servos in the JC-80 line amp stage. One servo is to reduce the DC outputs, (there are 2 outputs) as close to ground as possible. The other is to reduce the actual DC difference between the two outputs.
The servo at the bottom of the page looks at the 2 outputs and tries to minimize their difference by adding DC gain.
The servo at the top right compares both DC outputs to ground and tries to average the 2 outputs as close to ground as possible.
The combination of the 2 servos gives the circuit the ability to be direct coupled to a power amp and to change polarity by selecting one output or the other, without a pop when switching.

John, sorry to barge in.. As I have always been interested in your implementation of servos, you have my attention. Of course there are numerous ways to skin a cat, but some approaches work better than others in certain topologys. As shown in this case with the JC-80 this was probably the best and most effective approach. Referring to the BT there were many approaches possible of which most seem to work well... I assume you took a somewhat similar approach as the JC-80 and maybe the BT servos are closer to the Halo JC-2? Nomatter which approach was taken, I'm all ears... so please carry on with your tutorial and thanks for sharing.
 
i What can help is a spline reconstruction filter but that is a long story.

High order splines make pretty pictures, but mathematically they are inherently flawed.

My intent was that the computer side of a music server need not cost more than a couple of hundred. YMMV on external DAC, I find an M-audio sufficient for my needs but no need to discuss that here.
 
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High order splines make pretty pictures, but mathematically they are inherently flawed.

My intent was that the computer side of a music server need not cost more than a couple of hundred. YMMV on external DAC, I find an M-audio sufficient for my needs but no need to discuss that here.

Yes. If someone wants to impress you with 'my server cost $20k' he is either -
talking out of his rear end, or
gambling you don't know these things and will be suitably impressed.

In both cases, the target is most probably your wallet ;)

jd
 
Yes. If someone wants to impress you with 'my server cost $20k' he is either -
talking out of his rear end, or
gambling you don't know these things and will be suitably impressed.

In both cases, the target is most probably your wallet ;)

jd

Maybe the server was only $500 but the rest was for the power cord?

On a more serious note, in the early days of CDs the A/D converters were 16 bits but only 9 bits linear and a 7 bit filler. That was the way T. Stockham did it at first and was widely copied. This information was buried nicely because all of the first A/D chips used for CD recording were made by Sony. You had to dig a bit to see how it worked. 1 9 bit converter worked first then a 7 bit on the remnant. 9 & 7 sounded better than 8 & 8 because of the zero crossing. Today you will see 24 bit converters that are really 18 & 6 or similar.
 
I do know what is wrong here, and it is not just me. However, I had never before used a $20,000 server that had an open loop vacuum tube analog stage, and just about everything else that I could think of to make a world class CD player-server. Looking at the unit and reading the specifications and design of the server, I would personally not know what to do better. BUT this is the problem. IF a playback system of such effort, and complexity cannot easily find and play CD's to the quality that we had hoped for, then the vast majority of CD's are most likely fundamentally flawed, as expected, with just too little to make them sound virtually perfect, sonically. Still, there are a few, even by my listening experience, that are OK, but unfortunately we did not bring them to the show. They are the exceptions, not the typical.
It has been shown to my satisfaction that more SACD's and 24-96K DVD's sound better to my ears, percentage wise, than CD's. This does not surprise me, as they also offer better rise-time, less phase-shift at high frequencies, and even more potential bits of resolution. Now, just because a performance is made with SACD, does this make it great? Well, of course not, in fact, Teresa, my SACD fanatic, and music reviewer condemned a certain offering from Water Lily, as lacking in bass to such an extent, that it ruined the recording. Of course this was strongly contested by Kavi.
I happen to have the recording here, so I must now listen to it , and decide. However, this shows that not all SACD recordings are greeted equally by enthusiasts, as it well should be.
 
I don't know, but this SACD has CD built into the same disc. It is the recording of the performance that is the alleged problem here, not the ultimate technology. This MUST be taken into account when someone listens casually and randomly to an SACD and who bases all opinion on it. Please read earlier criticisms of my advocacy of SACD over CD, before commenting in a critical way. By the way, talked to Dick Sequerra lately?
 
I think SACDs have some sort of a problem with the treble and aliasing. An engineer who masters and authors DVD-As first pointed this out to me and I can't ignore it ever since. It's this weird artifact in the hi end that makes everything sort of go hard on your ears. I have seen some other golden ears also point it out since then as being a big problem.

My SACD player is cheap though so I guess it's kind of expected to not be good for me. But the engineers that reported it and made it obvious to me were supposedly using hi end reference systems.

In general from ripping and comparing DVD-As to CDs the main glaring difference is in the mastering. And just a more conservative approach to compression on the end release. Really I have yet to encounter a hi res and CD example that have been mastered equally. Probably the closest would be to compare Classic 200gram Kind of Blue with the SACD Kind of Blue as they both use remarkable the same type of signal chain - all tube mastering. And of course one is a record (way too many variables) and one is digital so that comparison wont work.
 
It has been shown to my satisfaction that more SACD's and 24-96K DVD's sound better to my ears, percentage wise, than CD's.

But is that because of the SACD process or because they're mastered with audiophiles in mind, and the same mastering could result in CDs that sounded just as good? Excessive EQ and compression are far too common- they're not inherent in the CD technology, they're inherent in the commercial mind-set. As Scott notes, if there is even only ONE superb-sounding CD, we know that the technology is capable.
 
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