Hi Matt .I wouldnt use those caps .They are polyester which is the worst performing dielectric for this application and audio in general .I may be able to help you out with some high grade caps if you want to , just PM me
HI Tez My CD player is a modded CD94mk2 . I wanted a one box reference player with a longer term goal of building a killer dac .The output stage is based on AD827 and
AD847 .these are exceptional compared to standard stuff and there is no room for a valve output stage anyway .
WRT caps, Regarding the caps ESR and ESL definitely play a part but the dielectric definitely has a major impact on sound quality.Dielectric absorption seems to be a major contributor to sound quality and resonance likely to have an impact .damped foils like tin and copper sound sound superior to aluminium foils and metallised film.
WRT OP stage, I encourage you to try an open loop approach, they generally sound better than any opamp. A lot of PPL have had luck with AD844 running open loop.
Do a search, there is plenty of info around.
WRT caps, for signal coupling my results are varied. For example Munforf metalised silver / oil easily beat Rel Cap Tin / Polystyrene in my DAC. Polystyrene has lowest DA of
any and Tin is 'supposedly superior to metalised. Maybe the oil improves DA - I have not seen values for DA with these oil filled caps.
For digital PS bypassing form factor and impedance can make more difference than DA or DF. The rule here is smaller is better and a big part of the ESL is the leads
themselves.
But we are talking bit decoupling so it's an in between area. The cap is definitely connected to audio OP (indirectly) so DA may well be fighting form factor ESL/ESR
for a stake in the overall sonic results. It's fun this stuff!
So the big question is, for this application what is the most important characteristic, since we can't really have them all.
I'd love to get some of those copper PPS caps - can you spare enough for 1 DAC - or are they available anywhere?
I have plans to assess the differnt size dem caps .It has taken some time for me to source the high grade caps for this due to the unusual size pf values. .I was able to get some soshin SE mica caps for this .This cap is very expensive in Japan and not your average mica cap .They are 120pf which pushes the frequency up quite high but the mica caps are ideal for this .
I may look at reclocking the dem way down the track for a comparison , but could open a can of worms .
I have also changed the grounds on the dac board in the mk2 as the arrangement waa sub optimal and was an improvement also , but have changed back while modding as it made it more difficult to remove boards easily.Once I am finnished I will implement the revised ground .
What have you done to grounds?
Also WRT copper PPS caps, I have another sig coupling application in electric guitar where I need a very small cap that has very good audio quality.
However I need an ongoing supply for this application.
cheers
Tez