That's a neat idea, and probably not totally undoable, but there are all of these components to fit in there...
Switching noise Pepper?
Ok, we are officially looking into designing a breakout PCB for that. Stay tuned.
6 days later
On Thursday, we placed the order for the PCB breakout. Once verified, we will ship it out to any Rev1 Pepper users who ask for it, free of charge.
giuliomoro wow that’s awesome !
Thanks to all for making this happen.
Perhaps you can drop a couple of them ( 2 peppers 
) in with my Trills
No rush, and I guess the trills will be going out soonish ?! ( excited for those to arrive !)
thetechnobear No rush, and I guess the trills will be going out soonish ?! ( excited for those to arrive !)
Soon hopefully, they should ship from the supplier next week, but these days you never know.
thetechnobear Perhaps you can drop a couple of them ( 2 peppers
We'll keep that in mind, let's see if the timing works out.
giuliomoro
Should we just fire you guys an email to request one?
I will write here the instructions needed when we find the best way to do it. It's going to take a couple of weeks before we receive the PCBs
Oh great! Thanks for this
a month later
Hey there, Have there been any developments with this?
Hi Neil,
parts came in a couple of weeks ago, assembled and tested 10 days ago, then last week just disappeared because of shipping Trill. We are just picking up loose threads now. See announcement below
EVERYONE who has bought a rev1 Pepper and wishes for a radical improvements of the poor signal-to-noise ratio of the audio outs, we now have a remedy:
a dedicated PCB breakout for the circuit above which can be installed between the Bela cape and Pepper.
We are happy to ship out free of charge. Just email robert [at] bela . io for further details.
@thetechnobear , yours are in the post with your Trills already.
thanks giuliomoro , you are all stars
very much appreciated.
10 days later
boards arrived with my Trill - yah (thanks again)
a couple of questions:
(assuming above schematic is unchanged)
a) I assume all caps are non-polarised
b) C11 &C18 - what values - 1n?
if not do you have a pcb schematic - as the capacitors are hard/impossible to read 
but if they are all 1nF, then its no issue
c) voltage at top
it looks like (from top) -12v gnd + 12v, but there are 6 points...
so I use the ones with squares?
if so what are the holes without squares around for?
d) J1 pinout
I assume this is for L-/L+ R-/R+ in, and L-/L+ R-/R+ out... but I don't know which is which
e) fitting to Pepper...
how would you recommend to adapt pepper to use this board.
f) opamp
I don't have any NE5532N (I think thats what shown above)
but I have some TL072CP, that are the same pinout.
of course, happy to go buy some NE5532N, just means I'll have to wait a week or so for them to turn up
g) any other changes?
whilst I have Pepper taken apart, would you recommend any other changes?
e.g. you mentioned a different regulator, but from your graphs above that seem to have minimal impact
(if Im placing an order at mouser, may as well order other things i might need )
thanks again for all your help
Mark
I think @bela_robert has a small build guide drafted, which should answer most of the questions.
thetechnobear e) fitting to Pepper...
how would you recommend to adapt pepper to use this board.
This is the hard part. There is a bit of desoldering involved. We tried with some reduced-height headers, which seems to be working fine. Robbie should have some pictures/descriptions.
thetechnobear f) opamp
I don't have any NE5532N (I think thats what shown above)
but I have some TL072CP, that are the same pinout.
I think it should be fine. Not sure there is enough vertical headroom for socketing your IC, though, so ... you are committing to one or the other!
thetechnobear e.g. you mentioned a different regulator,
We now recommend the R-785.0-1.0 . This is a bit quieter than the "E" version that we had in the BOM at the very beginning. I don't think there have been any other changes to the BOM @bela_robert?
giuliomoro thetechnobear f) opamp
I don't have any NE5532N (I think thats what shown above)
but I have some TL072CP, that are the same pinout.
NE5532 is much lower noise then the TL072, afaik...
Hi all, I've put together a short wiki on the amp board which will hopefully answer the above questions: https://github.com/BelaPlatform/bela-pepper/wiki/Amplifier-Pepper
@thetechnobear the YouTube series is brilliant btw! Enjoying it very much.
5 days later
- Edited
thanks bela_robert for the BOM, will place an order .
(also the instructions look excellent, thanks for putting so much effort into this!)
glad your enjoying the series ... hoping next one will be with Trill
going to order some more grove to grove cables at same time as ordering above BOM
odd thing...
Ive noticed (rev 1 pepper) has a DC offset e.g. the sine example, is about 3v peak to peak (as expected) but its centred around 1.5v (approx)
is this correct? i don't remember noticing it before?
Im going to test my other pepper which is in a different rack, but I need to hook up my scope to do this.
as I say odd... as Id have thought I would have noticed this before...
EDIT:
ok, so my other pepper is the same, and given its in a completely different rack, and Im measuring it with a different scope - I'll assume this is 'normal' - or I did the same thing wrong in both builds
I think the reason Ive only just noticed is I was using a VCA to amplify, and the DC offset makes this distort and cut out when pushed too far... I think previously i was using an input module, which possibly removed the DC offset without me noticing (that'd mean I also would see on scope!)
I assume the above amp remove this DC offset? (its aim being to -5v to +5v centred on 0v)
is R49/R55 the biasing? i.e. if it wasn't exactly centred replacing with a trim pot might allow adjustment.
(but perhaps its not that relevant, a small DC offset is ok)
thetechnobear Ive noticed (rev 1 pepper) has a DC offset e.g. the sine example, is about 3v peak to peak (as expected) but its centred around 1.5v (approx)
is this correct? i don't remember noticing it before?
Yes that's right: the line out is DC-coupled, and we thought it would be a feature
- Edited
giuliomoro DC coupled is indeed useful
(I just can't believe i hadn't noticed previously ?!)
the question is how does it map to the API? ,
i guess we expect -1 to 1, to represent -ve, +ve , so 0 =0v
imho , in this context - DC coupling, just means I can continually send 1.0f and get 1.8v (or whatever peak is) continuously output... if it was not dc coupled, this would not be possible, since it would fall to zero. regardless of my code
Im assuming this is not a code change, rather how the line out is biased?
as above, I guess different in rev 2/one the above amp circuit is in place...
(and I assume salt is -5/+5)
The range you can achieve is 0.4V (sending out -1) to 2.2V (sending out +1).
PS: this was somehow documented here,
thetechnobear as above, I guess different in rev 2/one the above amp circuit is in place...
(and I assume salt is -5/+5)
Audio out on Pepper rev2, Pepper rev1 + amp board and Salt is the same: -5V sending -1 , +5V sending +1.