With all pots fully CW the input sees 1.6k, or 800 Ohm in mono-mode. Can your source handle that?
Not sure. I bought cheap hong kong wireless microphone systems to feed the boxes.
But when I tried them I sent signal from my mixboard and it still doesn't work right.
Do you use 5532s, as stated in the schematic, or other op-amps? Are the op-amps socketed?
Just what they sent, 5532s. They were soldered directly by a friend. Is there any chance to use better ones here?
Are the pots scratchy?
Nope.
What is the impedance of the headphones you're using?
32ohm
What are you using to power this? The supply splitter is ... minimalistic, to say the least.
A socket PSU plug 1200mA. This should be enough for one unit.
Have you contacted Paia?
Yes, but no satisfying answers came from them yet.
I would expect more problems with this circuit for high in/out levels than for low ones.
I noticed, they distort very quickly :?
The bad thing is I organized 6 units which costed 600€ at our end I got
crappy headphone distribution amplifiers. Is there any chance to MOD
these to work better. I feel really embarrassed and desperate now :sad: