Squeezebox Duet

[Dan Giovanni]

The only thing I can think of Re. AC supply for VMID is some kind of frequency synthesis i.e not hifi use. I wouldn't worry about it. If I were looking to mod one of these, I'd use a filtered Vref and an op-amp buffer.

Re. the isolator, it is claimed to support "full speed" USB 2.0. Is there a difference between "full speed" USB and "hi-speed"?

[jkeny]

The only thing I can think of Re. AC supply for VMID is some kind of frequency synthesis i.e not hifi use. I wouldn't worry about it. If I were looking to mod one of these, I'd use a filtered Vref and an op-amp buffer.

Yep, sounds good idea

Re. the isolator, it is claimed to support "full speed" USB 2.0. Is there a difference between "full speed" USB and "hi-speed"?

Yep, about 468Mbit/s difference 12 for full speed & 480 for hi-speed

[MyNaim]

Behind again

How you going with the Receiver John? did you manage to get it working?

I got itchy fingers last night, after searching about in my stash I found one of those Burson clocks, I removed the onboard cheap oscillator and replaced it with a Guido Tent, supply was tapped into the main Paul Hynes PR3 , its a 5v XO so a 100R resistor was added from the out of the clocks inverter to ground because of the Receivers Xilnix is 3.3v.
The Receivers stock onboard XO was removed and the new clocks output ran straight to the Xilnix

Seriously this made one hell of a difference! everything just locks into place and that bass it trounces the modded Musiland for 44.1 material
Obviously this lash up is not ideal but was mainly as a test and gives me an idea how a better clock affects this unit, i wasn't actually expecting this much of an improvement with the Receiver , this was clearly heard with all three dacs

Amazes me those who claim all spdif sources are the same, I read some total crap on another forum from one of the ex members on here , that guy must have huge amounts of fur growing in his ears

Thanks Leo for the very good job you are doing. I do follow this thread very closely since your very first post

Could you possibly post some pics of the new job done ? It will definitely help to understand/follow ; I'm very new in the DIY sport but very much interested in following your mods)

Cheers!
Olivier

[leo]

Hi Olivier,

Thank you, thats much appreciated

It would be really hard to see whats happening with just a pic as is because of the other mods so I tried to edit an earlier pic before the inverter had its separate reg etc

The PR3 now runs Duet Receiver and also acts a pre reg for the clock (which has its own onboard regulation to the XO)

The clock I lashed up isn't optimal but was good enough to give me an idea what sort of results to expect, I hope to compare others at some later stage.
For now the Burson module using the Tent XO is giving very good results

The resistor R104 on the output of the inverter may be better off removed altogether if running a new clock direct to the Xilinx pin42

[janos_904]

All this work is seems to be a great and amazing microsurgery! What about the sound :-)?

[leo]

All this work is seems to be a great and amazing microsurgery! What about the sound :-)?

I also have a stock Receiver so i its easy to compare, lets just say I'm quite pleased with the results so far

[MyNaim]

Hi Leo

Thanks for the picture and the drawing, it has been really helpful.

I'm still not 100% XO-clear about where to connect the output of clock, it has to run to both output of 74HCU04 (R104 to be removed) and pin 42 of XILINX, is that correct?

Cheers
Olivier

[leo]

I didn't remove resistor R104 yet although I'd imagine it may be better to remove it

Standard unit is

Stock XO (clock) - 74HCU04 inverter - output resistor R104 - pin42 Xilnix

My unit , upgraded clock (tagged on output of R104) - pin42 Xilnix

Depending on the the new clock your fitting you can run it to the input of 74HCU04 or straight to pin42 Xilnix (main clock input).
The spdif output (digital out) and stock XO's all share the same 74HCU04 which is a compromise, because the clock I used was suited to run the Xilinx direct I ran it to the output of 74HCU04 (tagged onto the output side of the 74HCU04 output resistor R104) rather than 74HCU04 input if that makes sense

Sorry, I'm crap at explaining things by text

[MyNaim]

...Depending on the the new clock your fitting you can run it to the input of 74HCU04 or straight to pin42 Xilnix (main clock input).
The spdif output (digital out) and stock XO's all share the same 74HCU04 which is a compromise, because the clock I used was suited to run the Xilinx direct I ran it to the output of 74HCU04 (tagged onto the output side of the 74HCU04 output resistor R104) rather than 74HCU04 input if that makes sense

Sorry, I'm crap at explaining things by text

Hi Leo,

Thanks again for your replies and you're not crap at explaining; got another explanation I'm crap at understanding

When you said depending on the new clock, how do you know where it's supposed to go better ? For instance, the new tentslabs clock or the one from audio-gd ?

Cheers
Olivier

[ar-t]

I assume the clock you are using has a build-out resistor, on its output.

Pat