If you start a interest thread I would be in for a few boards...
A mini PPA v2,my first portable attempt. - Page 7
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The first thing we have to decide is what we want this amp to be.
Is it to be battery powered or mains powered?
I can assume it will be a three channel amp.
We have to come up with a new name, I asked Tangent a while ago about
continuing development of the PPA and he said he was fine with is as long
as we did not use the name PPA. My suggestion is "Trident".
Since I have really loved diamond buffers in portable amps I'll definitely be in for a couple of boards and can help with any prototyping that happens for this project.
I'm thinking ultimately this should be the most insane portable amp we can DIY. Battery powered for sure; but a discussion into NiHM vs LiPo batteries would be useful. Not sure how comfortable people are working with LiPo chargers.
3 channel amp would be a safe assumption.
Using rail-rail opamps would be a good idea here, and for stability and simplicity, going with a JFET input opamp is probably easiest.
Trident sounds like a cool name, though the first thing it makes me think is Poseidon. :)
PPA buffer vers LME49600
I don't mind doing a diamond buffer...it keeps in spirit with the original, however...
I think the PPA buffer would limit op amp choices.
LME49600 with it's higher bandwidth and slew rate would allow the use
of higher performance op amps.
Also..."mini" seems to have been mentioned...
There appears to be some interest in this after all, so I think I will dust the mothballs off of it and start again in Ernest.
There are a few issues that need to be adressed on this little amp, first and formost being the power supply, my current amp has 3 lipo cells and a controll board, these barely fit in the case, and in fact are so snug that I think it's a safety issue. And to further complicate this, 3 cells really is not enough. It works fine with some op amps, but is not enough ( it seems ) for the 627/37 combo that I have in my full sized PPA.
The other issues are minor in comparison, mainly finding enough room for good quality bypass caps ( mainly for the opamp power rails) , I have a board layout that should allow for a for some whima surface mount film type, but I have. No idea if they will be a good or bad cap in that spot.
As far as putting a 1/4 trs plug on this thing, that would require a much larger case, and that may be the end all fix for it anyway, if a larger case could be found then a larger battery might also be implemented. I will look at all my old designes, and see if I can track down a good case and a reliable battery supplier.