Re: Hum hunter. Audio Isolator.
Posted: Mon Jun 24, 2019 6:05 am
Reply my own post. Did a lot of attempts and little things to get rid of this loud hum and buzz.
It may help some forum-mates, here is the list of actions.
1) RFI/EMI filter. I went for the cheap solution (no furmann), a schaffner FN filter housed in a small box with a in and out plug.
Used as main plug (amp, multi-effect, pedal board) it works fine and helps a lot. Make sure to get a Schaffner model with enough Amp capacity.
2) Change FX loop ECC81 and Inverter ECC83 driver valve. I took these selected valve from Tube Amp Doctor. Not cheap, but works fine.
3) Check V1 in preamp. Swapped valves, and I found one that was quieter than the others.
4) Put an audio isolator transfomer on the effect loop return (and turn up accordingly the multieffect output). As it's a lot quieter even without the audio isolator, I may use that trick only in recording situation.
Now even playing on Hi gain, the amp is quiet.
It may help some forum-mates, here is the list of actions.
1) RFI/EMI filter. I went for the cheap solution (no furmann), a schaffner FN filter housed in a small box with a in and out plug.
Used as main plug (amp, multi-effect, pedal board) it works fine and helps a lot. Make sure to get a Schaffner model with enough Amp capacity.
2) Change FX loop ECC81 and Inverter ECC83 driver valve. I took these selected valve from Tube Amp Doctor. Not cheap, but works fine.
3) Check V1 in preamp. Swapped valves, and I found one that was quieter than the others.
4) Put an audio isolator transfomer on the effect loop return (and turn up accordingly the multieffect output). As it's a lot quieter even without the audio isolator, I may use that trick only in recording situation.
Now even playing on Hi gain, the amp is quiet.