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Music Server Computer transport - Is It Worth the Effort?

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In Reply to: RE: Music Server Computer transport - Hop On! posted by bcherry on November 04, 2009 at 06:49:06

So we finish the previously described modifications to the Musiland and install the Magic Black Box. The system boots up and recognizes all hardware. After a ten minute warmup we play music.

Playing 'Dreams of Likembe' we hear bass notes that weren't noticeable before. Soundstage is more focused and detailed, less starined. In fact a pervasive 'hardness' that was there before in varying degrees is gone.

This is a big step forward. The effect of swapping bad clock/good clock is sometimes subtle, sometimes way obvious depending on how much it's needed. In this case it is very obvious. If you've used vinyl playback it most reminds of what happens when you tighten up a cartridge that is loose in it's headshell -- things snap into focus, bass goes deep, there is more dynamic spread and less noise/more music.

But the real question is how does it compare to a standalone CD transport. Are we close?

We have 4 listeners present. We cue up the CD transport and the Computer transport - each playing through a Satch DAC. For about 20 minutes we play tracks from All For You (great voice) and Mozart Salsburg Sympnony (great strings), switching back and forth without knowing which is the source.

We can't hear a difference. This is the first time that happens (usually we hear a difference but may not be sure which is better until after a long listening session).

It may be that something else is masking the difference because surely there must be some. I plan another listening session with fresh ears and music (actually that listening session fell through as the 'ears' didn't show when expected so will do this later). We will either confirm or refute the result.

In either case this is encouraging because there are still more things we can do to make it better:
A linear DC supply for the computer to replace that SMPS provided.
Underclocking the CPU (we are only using 5% so if we underclock by 50% or so we can get rid of a lot of heat/noise, ie turn the hose on Dante's Inferno).
One other thing which we'll try before mentioning as it's a little 'unconventional'.

regards
Brian

DIY - Done Right!

Follow Ups:

Music Server Computer transport - Additional - bcherry 15:56:01 11/11/09 (3)
I have a CD94 here and had the Tentlabs CD player for a year - both CDPro based. But the one we use day-to-day is a prototype that never got into production. It uses a Sony transport and compares favorably with the CDPro machines.

The clock wires actually connect to the reclocker module; I just unplugged it for the picture. ... piggy back installation would be theoretically better but I didn't try it. Basically we just wanted to use what we had at hand as we sell the EZ Clock and Power supply shown as well as the regulated power supply (actually a DHT filament supply so very ideal for this). The items are listed under 'active modules' menu.

Transformer removal: I'll let the expert who did this explain his reasons.

"The Transformers used are not that great and do not handle higher levels well.

I have found that receivers of the cirrus logic ilk benefit from more signal than the normal 0.5V P-P.

So what we have done is place a low value resistor in the ground leg (10R - IIRC) to provide some ground loop isolation and a second series resistor with the output of the driving gate, to bring the impedance close to 75R, ...

This way we get around 1.5V P-P into 75R.

We will eventually fit different transformers that handle more level and have a better waveshape, for now removing them was a better option. ..."

...the 3.3v and 1.2v regulators are in the queue to receive some attention, among other things.

I'm not sure what contributed the most to the improvement as I only took a serious listen after all the mods listed were done. But it was well worth it and there seems to be more potential for improvement. A computer transport that beats a standalone cd transport seems to be within reach.
DIY - Done Right!
- Where We Are and Why - bcherry 17:52:13 11/18/09 (2)
  The replacement transformers have arrived. I'm just waiting for some SMD parts and then we will:
  - leave the RCA output with our resistors and 75ohm cable untouched
  - install the transformer on the second out and connect (with some SMD parts) that to a 2nd RCA output. This will allow us to switch between the current output (which is already significantly better than stock) and the output with the upgraded transformer.
  Thanks for the comments; I'm very interested in the other ways mentioned and will get one of those devices to compare.
  Some have asked why we are doing THIS instead of THAT.
  This is a vendor's forum. The idea was to see how far we can go with what we have on the shelf using the commonly and cheaply available Musiland (which gives us 24/192) and a computer transport.
  To recap:
  The Musiland needed a good clock, power supply, and the right cable. These things removed much of the performance bottleneck.
  In addition the chipset likes and is able to swing more voltage so we made the circuit changes for that, but the transformers (already marginal) were unable to keep up. So we used resistors and this has taken us to the current level of performance.
  Now we have the upgraded transformers and will try the next phase described.
  Regarding some of the other ways to get digital music playback I received this interesting email:
  
  "Brian,
  I had a look at several of these Media Streamers. Reviews of many can be found at the MPC Club website, they are worth reading for the comments on the music side of things.
  I do not wish to comment on the SPDIF output implementations in these machines, but yes, they work and bitperfect if the volume control is left at full.
  All these machines have a most basic software and interface section for the Music part.
  Worse, none to the best of my knowledge handle music playback in "gapless" mode, absolutely essential if live or classical albums are ripped into seperate tracks (or indeed such items the recent "Love" Album made from The Beatles back catalog or something like DSOTM by Pink Floyd.
  The only way around this would be to rip such albums as complete images, in that case these players lack the support for .cue files that allow individual track access in these whole CD Images.
  This basically precludes their use for music playback if one listens to anything where gaps inserted between tracks are unacceptable."
  DIY - Done Right!
  - MPC (Open in New Window)
  Edits: 11/18/09
  - Brian, please check out M2Tech - Jon L 11:06:35 11/19/09 (1)
    It's great to see what you are doing to improve sound quality on these devices. I have owned and tried various USB-to-spdif devices, including the pretty tricked-out ones from Empirical Audio.
    
    At the current time, the one that really catches my eye is the M2Tech converter, which reportedly already has great sound quality in stock form.
    
    It's only around $150, small, and does not require USB cable. Not much is known about what exactly is inside, but I can already see that disabling its USB-bus power to something else, even simple battery, will improve it a lot.
    
    Since you mentioned you will be testing other devices, please consider the M2Tech device as well!
    - USB-to-spdif shootout (Open in New Window)
    - RE: Brian, please check out M2Tech - bcherry 00:49:33 11/23/09 (0)
      Thanks for the link. That one looks interesting too. What a hullabaloo over USB cable length!
      
      DIY - Done Right!

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