Looking for Better Jitter Reduction in a DAC

It is quite easy to go down the garden path with digital.  There are a lot of variables, even when using a transport, including jitter, digital filtering in the DAC and DAC output stage and power system.  Any of these can make it sound "digital".

The best way I have found to approach this challenge is to focus on one thing at a time and optimize it, eliminating that effect as a cause.

The first thing is to eliminate jitter.  Trying to do this by selecting a particular DAC just confuses things.  Most DACs with resampling in them change the jitter and thereby the sound, but never never eliminate jitter, or even reduce it to inaudible levels.  The source must be optimized in order to do this, whether its a transport, USB converter, server, computer or network renderer.  With most transports, the best solution is a reclocker, unless you are willing to spend $20K for a transport, which is IMO ridiculous.

Optimizing the DAC digital filter is harder.  There are several approaches:

1) DAC that has discrete D/A implementation and custom filters

2) NOS or ladder DAC that has NO digital filtering

3) DAC that has selectable filters

Optimizing your choice in output stage has several options:

1) tube output stage

2) discrete transistor output stage

3) minimum # of op-amps in the output stage

4) active output stage with feedback that linearizes the behavior

Optimizing the DAC power system is much harder.  With some DACs that have external power supplies, you can upgrade and improve this.  Adding an AC voltage regulator like the Plasmatron from VHaudio.com helps a lot, but not inexpensive.

IMO, trying to use cables or filtering to make it sound more analog is the wrong garden path.  It ultimately sacrifices dynamics and detail.

Steve N.

Empirical Audio

If the jitter is truly low from the transport, then the problem is likely the DAC.  If the DAC does not have a good volume control technology in it, this could be the problem too.  Perhaps not that much better than the preamp, just different.

I want you to try modifying the CD disks themselves.  This will lower jitter even more.  There are several steps you can take:

1) get a really good treatment solution from Jena Labs and treat the disks.  Spray it on and then rub with a lint-free cloth outwards.  I believe they provide the cloth.

2) try putting the disk under a fluorescent light, up close for 20 seconds before you load it

3) use a degausser, like those used to erase the older cassettes on the top of the disk - this removes charge

4) the best treatment is actually to put a rubbery coating on the top of the disk, avoiding the center where it is chucked

Another thing you can do is rip the CD and then rewrite it to a Mitsui Gold audio master blank disk, after treating the blank disk.

It's actually must simpler just to rip the disk and then play it back using a computer audio solution, like USB or Ethernet.  I also makes your entire library more convenient and you don't have to listen to tracks that you don't like.  Jitter will be much lower than any transport too.

Steve N.

Empirical Audio

Ground-loops don't generally cause harshness, only HF background noise.  Some reclockers provide galvanic isolation, so eliminates ground-loop.

Cables make a big difference and you should be using the best I2S or the best S/PDIF you can get, without breaking the bank.

The problem with virtually ALL transports is that the S/PDIF output signal has a fairly long risetime.  This makes it jitter-prone at the receiving DAC, and makes the requirement of at least a 1.5m long cable.

Faster risetime from a computer converter or a reclocker will reduce added jitter, but requires a really good impedance match at driver and receiver and the cable.

Steve N.

Empirical Audio

I bought this plastic spray from Home Depot and put a shield over the disks I made from thin card stock to protect the center hub.  This rubbery coating makes a BIG difference.  You used to be able to buy rings made of similar material and glue them to the disk.  The other things make a small difference, but audible if you have a resolving enough system.

Steve N.

Empirical Audio

BTW, its not a magnetic charge, its static charge.  The degausser evidently bleeds it off.  I know that removing static charge helps, however you do it.  Some people put the disk on a large solid piece of grounded metal.

Steve N.

Empirical Audio

I used to mod DACs, about 20 different ones.  They all had strengths and weaknesses and many had poor design features that were obviously copied from another manufacturer that knew little about it too, even Sony did this.  The most common thing I found was insufficient power decoupling for the D/A chips and the op-amps.  Another thing I found was ground-planes that were broken-up, sliced and diced by traces, causing crazy current return paths.  Another is too many op-amps in series.  These things usually lead to an un-dynamic sound and a thinness, even harshness.  This is the deficiency with most preamps and amps too.  Another typical thing they do is put a 50 ohm BNC for the 75 ohm S/PDIF input connector.  Duh!!

Steve N.

Empirical Audio

Bruce - often older D/A chips sound more musical because of the limited digital filtering and ladder-DACs used etc..  I used to sell a tubeDAC called the Spoiler with ladder DAC in it.  Very musical  The problem with them is that they don't render the HF transients very well and they don't support hi-res.  Need a newer D/A technology for this.  To get the beauty of the older chips and the speed of the newer chips in the same design, it requires a really good designer and implementation, including excellent power delivery.  PD includes power supply, wiring, ground-plane correctness, regulation and decoupling.  All of these are critical, particularly with D/A chips.  Very few designers have a good grip on all of these aspects.

Steve N.

Empirical Audio

Want to make your digital really analog-like?

Power all of it from a Plasmatron from VHAudio.com.

Chris brings these around to shows and everyone that tries one, buys one, including me.  This is different than other AC conditioners.  It is an AC power regulator.

Steve N.

Empirical Audio

Ive been impressed with the Chord DACs and Resonnesence.

Steve N.

More expensive:

Empirical Audio, dCS, Ayre, PSAudio, Playback designs, Bricasti

Here is a top-tier PCM DAC shootout that has been ongoing for several years and involves many DACs (73 pages of posts):

https://forum.audiogon.com/discussions/absolute-top-tier-dac-for-standard-res-redbook-cd?page=73

Lower  cost to consider:

Sony HAP-Z1es, Wyred4sound (particularly driven using I2S), Metrum Acoustics, Rega, Bryston

Have not been impressed with the pro-audio/studio DACs...

Maybe the solution is just an in-line voltage divider.  All it takes is 2 resistors to drop the voltage a little.  RCA in/RCA out and 2 resistors.  This would at least show if this is the problem or not.

Another cause could be DC-offset.  IF there is DC on the SE or balanced signals all the time, or DC that increases with volume, this can cause many amps to have problems, even self-destruct.  Measure this with no music playing with a DC voltmeter at different volume levels.  Should not be more than 10 millivolts.  .01V.

Steve N.

Empirical Audio

AC power and particularly DC power can have a huge effect.  I personally stay away from typical conditioners that have filtering in them because they can reduce dynamics.  I have found the Plasmatron from VHAudio to be the best AC regulator for digital.

DC power for digital is equally dicey.  If the regulators are not really fast responding, you get higher jitter and reduced dynamics.  This is why I design a version of regulator that is really fast for digital and a slower one for analog.

Steve N.

Empirical Audio

- Tried Harrison Labs attenuators, the highs were rolled off, so not a good test.

Resistive attenuators must be installed at the destination or you will have roll-off due to the cables.

Sounds to me like your DAC is the problem.

Steve N.

Empirical Audio

What kind of IC’s are you using?  How long?

Steve N.

Empirical Audio

iPurifier is a great tool for Dolby Digital and DTS jitter reduction. I use it in my home theater.

For PCM, I recommend the Synchro-Mesh.  Some jitter plots:

https://www.audiocircle.com/index.php?topic=154408.0

For digital coax cables, I recommend my Reference BNC (RCA adapters) for $275.  Cable jitter plots:

https://www.audiocircle.com/index.php?topic=154425.0

Steve N.

Empirical Audio

I do use the iPurifier on my HT with a fast reacting LPS.  If you use a Sbooster, I think this would work good.

Steve N.

Empirical Audio

Maybe one from ciaudio.com would beat a wall-wart?

Steve N.

Empirical Audio