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SHARC DSPs and Digital Clock
Old 14th November 2002
  #1
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e-cue's Avatar
 
🎧 15 years
SHARC DSPs and Digital Clock

Can someone explain why the SHARC DSPs have a more solid clock for digital audio that any other run of the mill dsp in an A/D D/A type peice of gear? Some tech told me they run about $90 a pop which is expensive for 1 chip.
Old 15th November 2002
  #2
Registered User
 
🎧 15 years
Hi

The Sharc DSP chip by itself has little or no relation to typical clock issues discussed on these boards. It is just a processor running software. The software should run the same with or without jitter fortunately.

We might know where some of the question arises though. We (Manley) use a pair of Sharcs in the digital converter option for the SLAM!. This software is very effective at removing jitter. Most converters use Phase Lock Loops which is usually a hardware solution, typically a little chip. We were concerned that most converters sound better with a good word clock inserted, which sez to us, "that phase lock loop isn't doing a good job, it isn't attenuating jitter enough and requires the help of a cleaner clock signal". Great Phase Lock Loops seem to be very rare in converters if most benefit from a word clock BNC cable and we wanted a better solution.

Enter a new Swiss company called Anagram Technologies. They came very highly recommended by a few of our audiophile contacts. These guys were building converters for companies like Audio Aero and Nagra that were shaking up the high end hi-fi industry. They had developed an Asychronous Sample Rate Converter based on the fastest Sharc available that eliminated the need for a PLL. They supplied us with an evaluation DAC and we began the process of listening, comparing and sending it out to trusted golden ears. We were somewhat skeptical because ASRCs have generally been a bad idea in practice. We were very pleasantly surprised.

It immediately sounded better than anything we had to compare it to and by a large margin. It sounded faster, drums sounded like real acoustic drums, stereo imaging improved dramatically, everything became clearer and more life-like. It really reminded us more of analog than digital and was real fun to listen to. The other converters we had around sounded compressed, blurry and strained. We couldn't make the Anagram mis-behave no matter how we tortured it with jitter and closely related clocks and repeated patching. This thing rocked and brought the groove and feel back into many CDs that were collecting dust. We had a winner.

The Anagram DAC upsamples to 192K, which allows the linear phase FIR filter to be gentler and have fewer time-domain ripples. Why we hear these ripples as time-smear has yet to be proven, but in my opinion the time-smear or pre-echo as some call it is not subtle. To our ears, Anagram's process results in less audible time-smear than other 192K converters, yet one can get that performance with 44.1 data.

The software anticipates jitter both in the data stream and crystal clock. In Quantum physics one can know the mass or velocity (energy) of an atomic particle, but never both values at the same time. Anagram uses a similar idea for digital audio. If jitter is assumed, then the data can be be assumed to be slightly vague, and more of an 2 dimensional area than an absolute point. So they treat both the data and time in parallel and run similar algorithms on both 'dimensions'. They do this from the the other side as well and treat the 192K clock as yet more data, which reduces its phase noise (jitter) by a large factor. Clever lads indeed.

Is all this worth it? Sharc chips (we need 2 good 'uns) are not cheap, engineering time to develop bullet proof software adds up, more power supply and space is needed - so its not going to compete with $1000 8 channel sound cards. For those whose careers rely on providing great sound, we think it was well worth doing for them. When they spend so much effort capturing and creating the groove and feel, maybe some will appreciate a converter that retains that magic.

3D Audio recently ran a huge A to D converter shootout with 30 different units plus some variations. It will be released soon on a 2 CD set and we encourage you to get it. It could save you a bundle or cost you a bundle. There is no declared winner, that is up to you to decide. If you are working in digital, you owe it to yourself to hear and evaluate all these converters, and learn a tiny bit more. For those not shopping, it could be considered ear-training or gear-slut conversation fodder.

The analog side of converters is another story for another day.
hutch




Chief Designer, Manley Labs
Old 15th November 2002
  #3
Founder
 
Jules's Avatar
How can any-one get any sleep when there are posts like that coming in!

heh

Old 15th November 2002
  #4
Lives for gear
 
Wiggy Neve Slut's Avatar
 
🎧 15 years
Ditto...

Cant wait for the next installment on AD/DA..

PEACE
Wiggy
Old 15th November 2002
  #5
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groundcontrol's Avatar
 
🎧 15 years
Hi Hutch, thanks for a great post and for those great sounding pieces that have come out of your lab!
This place is really groovin'!
Old 15th November 2002
  #6
Jax
Lives for gear
 
🎧 15 years
Quote:
Originally posted by hutch
Is all this worth it? [/URL]
Send me a SLAM! with A/D and D/A and I'll let you know!

heh



I feel like I'm in a good place when EveAnna, George M, and Hutch all show up in the same day.
Old 15th November 2002
  #7
Lives for gear
 
e-cue's Avatar
 
🎧 15 years
Ok Jules... Hutch gets some kind of "Best First Post Ever Award" for that one...
Old 15th November 2002
  #8
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StoneinaPond's Avatar
 
1 Review written
🎧 15 years
Thank goodness for the people who care!

Peace
Old 15th November 2002
  #9
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Ol' Betsey's Avatar
 
1 Review written
🎧 15 years
But...

"In Quantum physics one can know the mass or velocity (energy) of an atomic particle, but never both values at the same time."

Doesn't that beg the question:

If a clock jitters but Britney's fan's can't hear it...

SORRY SORRY SORRY

Excellent post!

My respect for Manley has just increased 10-fold and now I rue the day that the 3D Audio CD pops through my post box.

R.
Old 16th November 2002
  #10
Founder
 
Jules's Avatar
"Ok Jules... Hutch gets some kind of "Best First Post Ever Award" for that one"

First prize!
Old 17th November 2002
  #11
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Steve Smith's Avatar
 
🎧 15 years
Quote:
Originally posted by Jules
"Ok Jules... Hutch gets some kind of "Best First Post Ever Award" for that one"

First prize!
perhaps that should be his " rating"?

Hutch
Best First Post Ever Award Winner
Old 10th June 2003
  #12
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Johnny B's Avatar
 
🎧 15 years
bump
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