Music Server Computer transport - Hop On!

[bcherry]

Originally Posted by GTHICM

Another ready made alternative that may offer increased options for interface to different dacs, including i2s, is the Empirical Audio Off Ramp converter. Although it would appear to be more expensive than the Musiland upgrade path, although it is not clear to me that it really is, given the cost of all the additional components and parts for the upgrade, it seems a ready made solution.

Here is the link for further information:

Off Ramp Converter > Products : Empirical Audio

Thanks but we're not done yet. That one starts at $700 for base unit + $800 for Ultraclock and + ??? for upgraded power supply. So we can still go a ways and be well within the budget of these uber enablers.

[danny_66]

There's a new driver out 1.0.7.0
http://www.musiland.com.cn/downloads...on_1.0.7.0.zip

[Jim777]

This is an impressive set-up. I've always preferred everything to be transported through my computer, and I see you have done the same.

But why did you take out the USB socket? What was the purpose?

[bcherry]

Originally Posted by Jim777

This is an impressive set-up. I've always preferred everything to be transported through my computer, and I see you have done the same.

But why did you take out the USB socket? What was the purpose?

Nice hardware bits!

The USB socket is still there. We removed the Toslink connector.

[bcherry]

Musiland USB to DAC:
We left off last time with the resistors in place of the pulse transformer to the SPDIF. Getting rid of the transformer and adjusting the output to 75ohms really opened up the sound.


The new transformer parts arrive and we install one in place of the resistors. The other output still has the resistors so we are able to A/B:


Nov 20
Today we installed the upgraded transformer into 75ohms and had a preliminary listening A/B between Rout and TXout. I'll write more later after we do something more extended but briefly:
There were 4 of us and 3 didn't know which was which, Rout or TXout. We listened to one track, about 8 passes. After the first pass 2 of 4 listeners choose Rout as better detail and bass, 2 listeners choose not to comment.
By the third pass the tide changed to favour the TXout and by the last pass it was unanimous the TXout was best. It took a few passes to identify that the extra detail was really a kind of aggressiveness and the bass was somewhat exaggerated.


All agreed the TXout had more real detail and more tuneful bass. Dynamics were about the same. The listeners liked the word 'natural' to describe the TXout. Next week I'll check out some bass heavy tracks to find out if the lows are rolling off at all. I'll then install a TX in second output with a little different loading. Once we get a winner there then I'll do the BNC connection.


Nov 23
We confirm all the bass is still there, just less overhang. More listening also supports the differences noted above.


Comparing CD transport to Computer transport -- Round 2:
Today we compare the current setup to the CD transport. Earlier we were unable to hear a difference which is a first for our listening panel. We have 5 persons in our panel of listeners today,-1 female, 4 males and ages 25 to 40 except for me, saying goodbye to my 5th decade. I do the switching between CD and Computer transports, the others don't know which is which.


Music is a track from a Stereophile disk: Rendezvous. The first track leads in with some very delicate cymbal sounds. The second round was Michel Buble Fever and then Robbie Williams Straighten Up and Fly Right.


Once our ears 'warm up' we do hear differences between transports:



3 listeners feel the Computer is more natural and retrieves more hall sound, ie ambience. One listener says the CD transport has a faster pace and is more lively. The #5 listener can hear no differences. 3 feel the Computer is better overall, one chooses the CD transport -- all by a small margin.


Both sound very good. It seems we are now at a level where differences are more a falling of the shadow rather than markedly better or worse.



Next we'll turn attention to the computer power supply. We want to get rid of that SMPS brick and power from a regulated linear supply. We need 19v/3.9A and I think we can do that with a substantially heat sinked filament supply.

[jkeny]

OK, bcherry, spill the beans, what SPDIF transformer are you using? Capable of 24/192 - have you listened to high-res?

[jkeny]

I tried 3.3V battery (LiFePO4) substitution of regulators & noticed no improvement.
Looking at the datasheet for the regulator, AMS1117, it's noise output is 0.003% of the output voltage - so for 3.3V output, the noise is about 100nV (for 1.2V noise is 36nV). I thought batteries would have bettered this noise value but I'm only listening to this using the PCM1793 internal DAC?

[jkeny]

Mistake in units above - noise is 0.000099V which is 99uV which is nowhere near as agood as other regulators Power supplies and regulators | Peufeu's Electronic Stuff

So batteries should improve this significantly?

[bcherry]

OK an on-the-ground tech report:

"I had an unmodified Musiland for use as simple SPDIF generator and found my receiver had problems locking consistently (I was debugging the software control for this receiver). Putting a 'scope on the signal out of the musiland showed this, left picture.

The actual signal level is around 200mV peak-peak and there is a huge 100mV spike on each transition.

First, this is WAY below the IEC 60958 type II specification of 0.5 - 1V peak-peak (and low enough that some receivers designed to this standard will not trigger reliably). Secondly the waveshape is UGLY. And NOISY. Brrrr... No wonder the poor receiver was constantly complaining about unlocking.

Okay, out come the original transformers to be replaced by the "magic part" (sorry, cannot reveal which, it is pretty decent but most important it's parasitics are consistent and I know what they are).

Remove the original disastrous resistive divider. A corrected divider was applied AFTER the transformer, with an impedance that correctly terminates the transformer; drive is now from a very low source impedance (the buffer in the Musiland is < 10 Ohm Z-Out).

After that the trace was much more like it, correct levels at around 0.8V Peak-Peak, minimal rining on the edges, but the traces where still furry. So I added an SMD CLC filter (1uF/0.1mH/1uF) between USB input and main circuit (musiland has a place for a choke on the PCB but does not fit, shame, things would be much quieter with choke) and I added a 220uF/10V Os-Con as bulk filter capacitor. Now the traces are not furry anymore. As shown but with different scale to allow for the different output level:


A quick before/after listening test showed that most of the hard and mechanical sound quality has gone, now we do not only get all the bits, but most of the music as well.

Doing the full mod with clock and seperate supply is still quite a bit better, but the basic mod alss gives a major step up in sound quality. Oh yes, and I can go back to debugging my receiver control software, for now we have a lock absolutely rocksteady (and the clocks out of the receiver are SO MUCH less jittery, before you could see the jitter with the naked eye on the 'scope!)..."

[glt]

Originally Posted by bcherry

OK an on-the-ground tech report:

...So I added an SMD CLC filter (1uF/0.1mH/1uF) between USB input and main circuit (musiland has a place for a choke on the PCB but does not fit, shame, things would be much quieter with choke) and I added a 220uF/10V Os-Con as bulk filter capacitor. Now the traces are not furry anymore. As shown but with different scale to allow for the different output level:
---..."

Hi, I've been following this thread with a lot of interest. Thanks for the reports. I suppose the filter above is for the USB power lines?

I've modded a Musiland 01-MINI and extracted the spdif and i2s lines.