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Old 11th November 2009, 01:13 PM   #11
adelias is offline adelias  Greece
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Quote:
Originally Posted by jkeny View Post
BCherry,

- Similarly, you have taken out USB socket and put in 2 resistors - can you say about these
USB is still there, the transformers from both BNC and COAX outputs have been replaced with resistors.
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Old 11th November 2009, 01:18 PM   #12
jkeny is offline jkeny  Ireland
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Yes I know USB is still there, I just wanted to know about the value of the resistors & what the advantage is to putting these in the USB line.

Same for the transformer replacement - why replace with resistors & what values?

Sageek, I like your location - it looks like we are all heading towards this form of accommodation
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Old 11th November 2009, 10:38 PM   #13
bcherry is offline bcherry  Hong Kong
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Quote:
Originally Posted by jkeny View Post
BCherry,
I just saw this thread now as Danny pointed me to it. Nice set-up & fully agree with your conclusion about the Musiland.

Can I ask some questions:.........


In my mods, so far, I've found the external PS to be the biggest improvement, the clock change probably on a par with it but I need to live with it for a while yet to evaluate it's contribution. .
Thanks for joining in and interested in your experiences.

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. Agreed that 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 impledance 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. ..."

Yes 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.

regards
Brian
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Old 11th November 2009, 10:45 PM   #14
bcherry is offline bcherry  Hong Kong
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Quote:
Originally Posted by danny_66 View Post
hello bcherry,
Nice review!
Finally there's a transport that can change my portable in a high quality music server.
Do you sell such a clock and PS?
Hi Danny
Yes. We were using products off our shelf for this:
Projekt chassis, EZ Ultimate Clock and Power supply and regulated DC supply:
Active Modules | Diy HiFi Supply
Projekt X Chassis 70 x 170 x 240mm with 7mm anodized aluminum faceplate | Diy HiFi Supply

the 24.000mhz 0.5ppm TCXO clock is not listed but we have a few in the cupboard.

regards
Brian
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Old 11th November 2009, 11:18 PM   #15
jkeny is offline jkeny  Ireland
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Originally Posted by bcherry View Post
Thanks for joining in and interested in your experiences.

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. Agreed that 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 impledance 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. ..."

Yes 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.

regards
Brian
Brian,
I have a 01US model - the one with PCM1793 DAC on-board so this is what I've been working on up to now. I haven't used it for digital output yet.
I wonder about replacing the SPDIF transformers with resisters - you lose galvanic isolation which seems to be ameliorated somewhat by the 10R in the ground leg. But if the transformers are corrupting the signal, at high levels, then they have to be replaced. If this mod gives better drive into 75ohm without a penalty in ground noise, then it's worthwhile?

However fmak has reported very good eye pattern tests at 24/192 over on audioasylum but I don't think he did any high volume tests. It would be interesting to hear about this aspect from the expert you quoted. Any idea what transformers are better suited - I don't know of any that do 24/192KHz?

I tried bypassing the 3.3V reg with a battery but didn't find any sound improvement. However that was a while ago & now I believe since changing the clock, the DAC is more resolving so I might try it again. Would be interested in your experience when you do this.

What resistors did the expert put in the USB in lines. On the D+/- lines? Why?

Last edited by jkeny; 11th November 2009 at 11:22 PM.
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Old 12th November 2009, 12:03 AM   #16
jkeny is offline jkeny  Ireland
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Originally Posted by jkeny View Post
What resistors did the expert put in the USB in lines. On the D+/- lines? Why?
Sorry, looked again, no resistors on USB input but you mentioned removing 4 smd resistors - can you say from where?
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Old 12th November 2009, 01:04 AM   #17
bcherry is offline bcherry  Hong Kong
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Quote:
Originally Posted by jkeny View Post
Sorry, looked again, no resistors on USB input but you mentioned removing 4 smd resistors - can you say from where?
OK. The 'lesser of two evils' story:

"The M01USD has two outputs, I treated both (even though you only connected one).
The original circuit has a two resistor circuit to attenuate the signal (too much may I add) and match the impedance (which is the wrong impedance).
I removed the four attenuator resistors. As you had no 0603 SMD resistors in stock I shorted the series ones. I then fitted through hole resistors you had into the transformer holes. This was simple quick "jury-rigged" job...,

... I agree, in theory transformers are good, in practice they need to very good and need careful use."
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Old 12th November 2009, 03:04 PM   #18
jkeny is offline jkeny  Ireland
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OK, so is it the resistors that are incorrect (attenuating the signal too much) rather than the transformers? Did you try changing the resistors without removing the transformer?
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Old 13th November 2009, 05:36 AM   #19
bcherry is offline bcherry  Hong Kong
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Quote:
Originally Posted by jkeny View Post
OK, so is it the resistors that are incorrect (attenuating the signal too much) rather than the transformers? Did you try changing the resistors without removing the transformer?
The transformers used are unable to handle the desired levels and bandwidth so must be removed.
Yes, resistors are wrong values as mentioned.

I didn't try listening with resistors changed and transformers in place. However I have some more suitable transformers coming so should soon have something to report and will post it here.

regards
Brian
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Old 13th November 2009, 06:06 AM   #20
Gopher is offline Gopher  United Kingdom
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What the hell are you guys talking about in this thread? I haven't understood a word of it.

You're all getting carried away with the technology. Spend more time listening to good music instead of fiddling around with your rinky dinky little computers and latest low latency drivers FFS.

I just put a CD in my old Sony and music comes out. Simples!

Last edited by Gopher; 13th November 2009 at 06:12 AM.
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