A mini PPA v2,my first portable attempt.
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khbaur330162
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Avro_Arrow
MOT: Soundwerx Designs
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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".
Opinions?
FallenAngel
Headphoneus Supremus
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.
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.
Avro_Arrow
MOT: Soundwerx Designs
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So, three channel and battery power.
Physically how big? Battery in the same case as the amp?
FallenAngel
Headphoneus Supremus
As with all portable amps, the aim should be that it's not much bigger than the DAP used - 3" x 5-6" and not incredibly thick.
Battery inside the case is pretty much a given.
Battery inside the case is pretty much a given.
Avro_Arrow
MOT: Soundwerx Designs
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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...
Avro_Arrow
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H22
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Hi guys, it's me the op, I apologize for not keeping up on this, I have been so swamped at work and with other projects that I have not had much time to get back on this project.
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.
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.
khbaur330162
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I think it's cool both projects are going on. Honestly, I'd love the chance to A/B the two final products since they are so close in spirit. Will be following this.
HiGHFLYiN9
Member of the Trade: Zynsonix
Somehow I missed this earlier, but it's a very interesting project. Definitely interested in a board or two when available.
Heffa
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Good to see you back here again H22 - and I am still interested in your project
H22
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I'm considering a whole new re-design, using a larger case. Right now I'm testing a power supply option, using a boost converter to get 24 volts, going to test it out on my full sized PPA, then hopefully scale it down. The case I'm looking at is the y2 case, it's a bit bulky but not terribly large. Should allow enough room for good quality bypass caps and lots of battery reserve.
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