Hi,
I have a modified 351 Ampex. The output sound lacks clarity in higher frequency.
here come two samples:
a guitar on a tlaudio
http://idoia.com/electrical/tla-1.wav
same on the ampex/
http://idoia.com/electrical/ampex-1.wav

Can this be caused by bad tubes ?
Thanks for your anwer.
Alex

Unfortunately I can't hear the clips here at work, but there are many variables that may attenuate frequency response.

Tubes tend to go out in a slow-motion blaze of glory, so check to see if one or more tubes are glowing brightly compared to the others.

Chances are that older amps that are starting to fade a bit will need a cap job.

I recaped them all, so that is not the cause of muted higher frequencies.
After some research these are known signs of old and tired tubes. I have bought new ones so I will wait and see.
BTW, if any of you has experience with tubes and advises me on what to buy as ECC82 and ECC83 for my preamp that would be great.
Thanks!