CDP Mods

[Guido Tent]

Guido



Should this ground be physically/electrically seperated from the main ground or just connected as close as possible to the intended circuit (but still part of the original ground).

I know I belong in the remedial class!!!

Thanks

Fin

Hi Fin,

All parts on the PCB are connected to the ground (layer), and the ground of all external power supplies should be connected to that ground, closest to the circuits they feed

Ciao

Guido

 

[Lourens]

Simple thingss that are good are replacing the mains cable - supra lo-rad is good basic cable for this. I have made little boxes from thin copper sheet to cover ICs in the past. I made these by cutting out a box plan and folding it into a box to put over the IC, the copper edges on the base covered with insulating tape and a strip of blu-tak. This is then soldered by small length wire to the gnd plane. I have had good results with this and it only requires removal of the lid. Covering the digital ICs is good - big microprocessor somewhere near the transport (probably) for example. [/

Rotellian,
I totally agree on keeping things simple for a starter. Having said that, two follow-ups:
1. Do not hesitate to insert a high quality mains cable, IMHO it does wonders IF your amps and speakers are of high end quality also, of course.
2. I just finished the most recent upgrade on my Philips CDD-882 drive: putting 0.5 mm copper boxes over every chip, just as you described. I did the same in my DAC. A lot of work, but a major improvement: definitely more transparancy and air. Even though I did not ground any of these

I wonder, should ground all of these caps? And how should I do this, keeping in mind the very sensible posts on this grounding issues in this thread...
Any advise on that is very welcome!

 

[Fin]

Guido

All parts on the PCB are connected to the ground (layer), and the ground of all external power supplies should be connected to that ground, closest to the circuits they feed

Thanks, things are starting to become clear. Sorry you have to spell it out for dummies!

I assume the same goes for the 0V of a +/- supply?

If a seperate board is built for the analogue stage, including low pass filter, it's own PS and transformer, is the ground then kept seperate or connected to the ground on the main board?

In you article on decoupling, it says that the capacitor should be as close as possible to the IC. Does the same apply to capacitors around voltage regulators? In the diagrams for my CDP, they seem to be miles apart, relatively speaking!

Thanks Guido

Merry Christmas

Fin

 

[Guido Tent]

Guido



Thanks, things are starting to become clear. Sorry you have to spell it out for dummies!

I assume the same goes for the 0V of a +/- supply?

If a seperate board is built for the analogue stage, including low pass filter, it's own PS and transformer, is the ground then kept seperate or connected to the ground on the main board?

In you article on decoupling, it says that the capacitor should be as close as possible to the IC. Does the same apply to capacitors around voltage regulators? In the diagrams for my CDP, they seem to be miles apart, relatively speaking!

Thanks Guido

Merry Christmas

Fin

Hi Fin,

Yes, also holds for ground of +/- supplies.

If you have a seperate analog board, I'd suggest to interconnect the grounds using the screen of the interconnect you use for transfering signals from one board to the other.

Caps, especially the usual 100nF's should be close to the regs, otherwise they might go wild.

The problem, and major drawback of diagrams is that they have weak correlation with layout..........

merry christmas too

 

[Fin]

Hi Guido

We seem to be online at the same time for once!!!

Now I have a chance to thank you in real time for all your help.

Fin

 

[Rotellian]

hmm interesting on the 0v grounding. I once (one of very first things i did years ago) tried connecting a battery supply for the +/- 15v for my op-amps and i connected the 0v to the gnd plane near the op-amps in the analogue stage - this is part of the same pcb - but is mostly seperated only joined close to dac ( i believe what we've talked about and common in early bitstreamers) This resulted in a terrible sound. Must have got it wrong. Was thin and weak (mgiht be batteries fault). There is no direct place to connect the 0v to (cant connect to op-amps direct - dont have a gnd pin - unless im wrong!) I was thinking of modifying the ground plane to allow a more direct route back to the PS and connecting the )v to the same place and for the other transformer - would that be OK? (yes i too am in the remedial class - apologies.)


Merry Christmas to all.

 

[Fin]

Hi Rotellian

I have a word document which might explain why the batteries didn't work for you. If you want it, send my your email address so I can attach it.

Fin