[FallenAngel]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif I just stumbled over this thread....I have a PPAV2 which I love to bits. How will the SQ of the PPAS compare?

Different class, but definitely the best portable you'll hear.

 

[SpudHarris]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif Different class, but definitely the best portable you'll hear.

I like the sound of that..... Ok, I'm gonna work my way through the whole thread so I know the history etc.

Wouldn't mind getting one or maybe two boards to the UK??

 

[FallenAngel]

Make sure not to forget the original PPAS thread either.

I have 2 prototype boards, I think I'll be building both, but since I won't get to them for 2 weeks, I might be convinced to let 1 go.

 

[SpudHarris]

FallenAngel, any chance I can PM you?

 

[FallenAngel]

Quote:

Originally Posted by SpudHarris /img/forum/go_quote.gif FallenAngel, any chance I can PM you?

Only if you flip a coin and it lands on Heads.

PM your address, I'll send it off for how much I paid for them. Unfortunately, a recent intake of some very good Whiskey makes it a little hard (and not worthwhile) to remember the exact price so just PM me your address with a public statement promising to build the prototype ASAP and I'll send it off tomorrow.

 

[SpudHarris]

Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif Only if you flip a coin and it lands on Heads. PM your address, I'll send it off for how much I paid for them. Unfortunately, a recent intake of some very good Whiskey makes it a little hard (and not worthwhile) to remember the exact price so just PM me your address with a public statement promising to build the prototype ASAP and I'll send it off tomorrow.

It landed on heads, honest. Haha, no worries I'm quite fond of 'Jamesons' Irish Whiskey myself.....

The most complex amp I've done so far only stretches to the Mini3. I'm working through the thread slowly and I starting to worry that I may not be up to the task. I'll pm you later (got to go to work now

).

Nigel

 

[pinkfloyd4ever]

oooooo baby! I've been testing it with my stock iPod and MP3s and it sounds delicious!

Can't wait to get a RCA-mini adapter made so I can hook it up to my Alien. I actually had it playing music tuesday night, but I had some major clipping whenever I'd turn the volume past 12 or so, even with the ipod volume down low so that it was quieter than I'd ever listen to normally. I changed the gain resistors to 4.32k for a gain of about 5 (as opposed to the default gain of 10) and it's been working beautifully in the 30 minutes or so of actual listening time I've had so far. DC offset is around 1-2 mV, occasionally up to 4mV at peaks.

Oh and to you prototypers (especially our new one, Spud--welcome, always good to have another prototyper), soldering the pot to the opposite side works perfectly for fixing that pot problem <--anyone building one on a production pcb ignore this)

is it normal for there to be a significant voltage drop thru the rail splitter? I'm measuring a total drop of about 2 volts. My battery is about 11.7v and board is +/- 4.8

more impressions to come of course

 

[tcpoint]

I got mine working. My first impressions are very favorable. I really need to listen for a few hours. The voltage drop occurs across the jfets that isolate the power rails (not the rail splitter). I ended up using a ad8599 and an ad8065 for the opamps.

 

[tcpoint]

One quick note. Shouldn't the power to the buffers be Vdd and Vee instead of Vp and Vn, respectively? The Q3, Q4, Q6, Q7 Jfets are supposed to isolate the rails for the opamps, not the buffers. The original PPAS does this.

 

[FallenAngel]

Quote:

Originally Posted by tcpoint /img/forum/go_quote.gif One quick note. Shouldn't the power to the buffers be Vdd and Vee instead of Vp and Vn, respectively? The Q3, Q4, Q6, Q7 Jfets are supposed to isolate the rails for the opamps, not the buffers. The original PPAS does this.

They look to be correct on my prototype, U2 and U6 are the opamps, U4 the TLE.

EDIT: Oops, checked that they were connected to U2 and U6, not that they were NOT connected to buffers.

My mistake.

 

[error401]

Quote:

Originally Posted by tcpoint /img/forum/go_quote.gif One quick note. Shouldn't the power to the buffers be Vdd and Vee instead of Vp and Vn, respectively? The Q3, Q4, Q6, Q7 Jfets are supposed to isolate the rails for the opamps, not the buffers. The original PPAS does this.

I think you're right actually. I spent some time pondering what the heck the point of the JFETs were if all power went through them, but that makes a little more sense. I guess I missed it in the original schematic.

I'll have to rework it. Ack!

 

[TzeYang]

Beware that if all power goes through the FETs, it might starve the output buffers.

 

[dhp]

good to see that the ppas was well regarded...

 

[tcpoint]

I really like this little amp.

 

[fierce_freak]

Any updates?