Fixed a duff tuner for a pal - failed voltage regulator. After fixing,
plugged it into my test amp in the workshop it sounded very lacking in
top. For other reasons I tried it into my main system and it was fine.
Back to the test amp - no top. The test amp is normally fed off a fairly
low impedance pre-amp and isn't DC coupled, and did and does sound fine
off that.

The tuner output is an non inverting op-amp at unity gain with 10 µF in
series with the output with 100k and 0.001µF across that so I'd think
pretty bomb proof. Both channels the same result.

Returned it to the owner who reports it's working fine.

Any clues as to what's going on?

--
*Wrinkled was not one of the things I wanted to be when I grew up

Dave Plowman London SW
To e-mail, change noise into sound.