That's right, there are two PCBs. One's the amp and the other's the PSU. Yes, that'll be something I'll take care of when I build an enclosure for this. It won't be a problem to have them in opposite corners... as you can already figure out this PIMETA is being used as a desktop amp, so it won't be a problem to have a slightly larger enclosure for that purpose.
Thank you for the tip tangent, I've read your notes on this amp and you recommend to play with R4 to change the gain. That's what I'll do, I have some spare resistors here to lower the gain.
EDIT: (31/05/11) Well I've redone the PSU entirely, thicker traces, much cleaner and logical design, more capacitance, bypassed both regulators with tantalum caps, recommended on the datasheet. Same with the amp board... thicker traces... I've added more ground surface around the three channels so I can bypass everything as per the opamps and buffers' datasheets recommendations. 0.1 uF ceramics for the opamps and 10 uF tantalum + 0.1 uF ceramic in parallel for the buffers. I also lowered the gain from about 4.7 to 3.8, that's more than enough for my SR850.
All I have to say is WOW! Bass now has a much stronger kick and clarity, while everything else is as clear and sparkling as before, probably even better!! I literally dropped my jaw with some songs. Those buffers are really benefiting from those caps at its power pins... as a result, now my headphones are actually getting all the current they want! Soundstage grew bigger... it got more 3D! so did instrument separation and clarity. BTW I'm using the amp without input caps because DC offset is below the milivolt range. Much cleaner sound just from removing them. I think this DIY pimeta is at its apex... dunno what else I can do besides stacking the buffers, but they're already running at full WB mode, heatsinked... more than happy with what it's become, an excellent desktop amp. I'm in love with it
Have a look at the new designs if you want
Edited by vodkex - 6/26/11 at 6:05pm