[Avro_Arrow]

Trident will be a portable amp in the tradition of the PPA.
 
 
This thread is to express interest and discuss design goals.
 
Happy reading!
 
(continued from a conversation started about here)

 

[wakibaki]

OK. With what dimensions and exactly what kind of power supply? Mobile phone battery?
 
w 

 

[tomb]

Actually, something like the PPAS, but with a better planform and soldered/PCB connectors?  That might mean the Hammond 1455C801.  There might be plenty of room for the basic circuit with SMD and then plenty to spare for a power supply/charger, even a separate PCB in the same case - like the lithium option on the Mini3.
 
Connectors on the PCB would be cool.  I hate wiring.  It reminds me of when I built RC model aircraft.  You could assemble a masterpiece, but unless you spent hours of elbow grease sanding everything - leading edges, corners, joints, planking, etc. - it would look like stink.*  It's probably blasphemy around here, but I despise wiring because it reminds me of sanding.  It's a mess - cutting, stripping, heat shrink, twisting, braiding - sore fingers, etc.  On the other hand, it's really nice when a PCB is finished, cleaned up and then simply dropped into a case, bolted up and you're done.
 
* It took me several years to build the Mini3 even though I bought the PCB's/custom-end-panels when it first came out.  It was because the 9V battery connectors had to be filed to fit.  That was too much like sanding.

 

[khbaur330162]

I'm interested. I vote for the name Puh-PAZ! PPAS pronounced phonetically.
 
But seriously, I'd be very interested in a few boards. Not an amp DIY'er myself so all this stuff about sanding battery harnesses and LiPo charging circuits etc. is over my head, but then again I wouldn't have these boards on an assembly line, or anything, I build it once and I'm good to go, putting a few hours into a build doesn't seem like a huge deal. However, I'd like to throw my preferences out there just in case this project goes anywhere. I'd very much like to see room made for a 1/4" TRS headphone out (this is important to people, right? it's not just me?), 10+ hours of playback somehow, if it's smaller than an L3 I'd say we've succeeded, and if there's a nice sounding cross feed circuit I'd say hell yeah to that, too. I'm not horribly worried about opamps and buffers used, I know nothing about all that, but I'd imagine people interested in a pocketable PPAv2 are concerned with SQ so perhaps they can worry for me.

 

[DingoSmuggler]

Not overly interested in a portable amp at this stage, but figured a throw in another option for the name...
 
Cerberus

 

[vixr]

very interested... standard stuff? RK097 pot, 1/8" in and out? Maybe in the 64 Ohms range to drive my HD-280s?

 

[Avro_Arrow]

 
I'm thinking, to keep the design compact and energy efficient, each

channel will be something like LME49990 with LME49600 buffer.
That should be able to handle low impedance headphones with ease.
No class "A" bias, no multi-loop feedback. You can run the buffer in
low bandwidth to save power or high bandwidth for better performance,
your choice.
 
RK097 with switch.
1/8 " in.
Maybe 1/4 " out, probably 1/8 " to save space.
12 NiMH AAA cells for power gives 18 volts freshly
charged and 14 volts nominal. Should leave about
3 inches by 2.5 inches for the board.
 
Here is a PPA vers a pocket amp:
 

 

[wakibaki]

So, use a couple of ICs and depend on them for short circuit protection?
 
What about transients? On-off clicks and pops?
 
12 * AAA is a lot of volume (bulk). Going for a proper dual-rail, or railsplitter? What about charging?
 
w

 

[vixr]

dumb post removed

 

[FallenAngel]

LME49990 / LME49600 really reminds me of "The Wire" headphone amp from diyaudio.
 
Putting together a combination of these opamps, built specifically for a portable chassis with battery board sounds like a great idea.

 

[scootsit]

I'd be interested in a board.
I was thinking of building an O2, but this sounds more entertaining, for some reason.
 
Just a thought, and I of all people should probably not be suggesting this, you and Tomb have both seen my SMT work, it's not good. BUT, if you move to largely SMT parts and ICs, you should be able to cut the boards down pretty substantially. The regulators and opamps on the Pup are pretty tiny.
 
I also had an idea that might keep space down. You could use a qi pad instead of a recharge socket, that way it would charge inductively, and the qi pads are only a few mm thick. They generate something like 5V, so that might not work, but if you could find a way, it would cut down on space substantially.
 
It'd be cool if there was room in the case to throw a skeletonDAC or something in, too.

 

[Avro_Arrow]

Yes, I was not going to say it, but it would be like a three channel "The Wire" in that
it uses the LME49990/LME49600 combo...other than that, it's totally dis-similar.
 
I was thinking about the battery power. If we just leave a space for the battery
and put a jack on the board to connect directly to it, then the user would be free
to use whatever battery pack and charger that meets their level of technical
ability. Some may want to tinker with LiPo, some may want to stick with NiMH.
 
What's the opinion...integrated charger for a fixed chemistry or "up to you"
battery and external charger.
 
There will be some SMT, but no smaller than necessary.

 

[FallenAngel]

Leaving battery options up to the user is definitely a nice touch, and it allows for most versatility. Considering how easy it is to build a NiMH charger, that would be easy to implement on perfboard or even PTP. The LiPo stuff would be a nice option though.
 
As for SMT stuff, as I'm sure we'll all agree - 1206 is a LOT easier to solder than 805.

 

[vixr]

  Yes, I was not going to say it, but it would be like a three channel "The Wire" in that
it uses the LME49990/LME49600 combo...other than that, it's totally dis-similar.
 
I was thinking about the battery power. If we just leave a space for the battery
and put a jack on the board to connect directly to it, then the user would be free
to use whatever battery pack and charger that meets their level of technical
ability. Some may want to tinker with LiPo, some may want to stick with NiMH.
 
What's the opinion...integrated charger for a fixed chemistry or "up to you"
battery and external charger.
 
There will be some SMT, but no smaller than necessary

awesome...

 

[FallenAngel]

Any thoughts on the case to use? I'm particularly partial to the availability and ease of use of the 1455C series.