Tube Amp Archive

So you got a scope, so now get two 50 watt 8 ohm heat sinked load resistors and a double pole double throw HD switch and your set with a 4 and 8 ohm set up to test with. We did. We got 4 4 ohm 50 watt resistors and an ON-OFF-ON switch to do 4/8/16. Worked like a charm. Like Scottie said, we are a l...

Here's a pic of our amp for reference. Scottie didn't have a good one. I tried to get an "overview" pic. If you need a close-up, let me know.

Hi kids! Thanks again for all the suggestions. We won't have time to work on the amp until next weekend (10/16). We will update you when we've given your suggestions a try. And keep 'em coming. We know we are close to solving this and having a working amp...

Yes it's the wire that comes off of one of the output jacks to the main circuit. Disconnect it anywhere carefully set aside. If the noise is gone it's in the NFB, so either the OT phase on the power tubes is backwards so swap the ot primaries or swap the PI output to the tubes. ~Phil Pulled the NFB...

sluckey wrote: ↑Wed Oct 07, 2020 2:53 pm I just noticed that your output tubes are really spread apart. What happens if you pull the two inner tubes and operate only on the two outer tubes?

I pulled the inner tubes. We have no issues with them out. We also pulled the outer tubes. No issues there either. Only with all 4 tubes.

Are you cutting the load in half when to run it with four tubes? Not sure what you mean by this. What we did was cut the power down by removing 2 of the tubes. This resolved the issue. We did this to swap out and test all tubes and all sockets. We got this idea from the link below: https://www.prem...

Hi kids! Thanks for the input. We are going to check on this over the weekend. We will let you know what we find.

here is a sample of what we are hearing when strumming the guitar with the volume above 3.