New amp buzz

[Jazzer2020]

I figured I'd post here to get the quickest response to my problem.

 

I am finishing off a couple of amp projects.

 

I have taken a couple of Fender combo amps and split them into head a speaker cab.

I just added a 1/4" female phono jack to one the speaker cabs.

 

I had constructed a few speaker cables several months ago and am using one of those.

 

Now, as I connected the head to the speaker cab to test out the amp I am getting a buzz from the amp that

I wasn't getting before.

 

It sounds like it might be a grounding issue.

 

I tested out the first amp (same setup except I used a Neutrik female 1/4" jack) and it was perfectly quiet.

 

Any ideas what I should do to test and fix?

I don't have any grounding on the back panels of either amp where I mounted the jacks.

 

TIA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Jazzer2020]

I just did some troubleshooting and was able to isolate the problem.

 

First I disconnected the new cable going from the speaker to the female 1/4" jack.

Then I connected the original speaker cable, and used an extension cable to reach the cab head.

 

I had tested the amp out a few weeks ago like this and didn't notice the buzz then.

 

This time however, the buzz was still there with this 'original' connection.

 

Then I played with the pots.

When I got to the reverb pot the buzz was isolated. More gain on the pot -> more buzz.

Turned the pot to zero and the buzz was gone.

 

So now I can still use some advice on what to do next.

Is this a tube issue or something else?

 

TIA

 

 

 

 

[Jazzer2020]

What a learning experience the past 24 hours have been!

 

Today as I was playing my guitar again I had the reverb tank opened up on the floor.

I was moving it around to see if it made a difference with the noise.

 

It was hit and miss. Not much was being accomplished.

 

Then I got tired of playing the guitar I was using.

 

I picked up another one and plugged in.

Bye bye noise!

 

Bingo!

This guitar has a humbucker pickup, the other one has a P90.

 

 

[Jazzer2020]

This is turning into a bit of a weblog.

 

Shortly after I posted last night I thought to myself it didn't quite make sense.

 

The reason being, before I did the project (separating combo into head and speaker cabs) I was playing the P90 guitar with the amp for years and this buzz/hum was never there.

I was getting a great clean jazz sound.

 

So something else must be at play here.

 

An amp tech guy yesterday mentioned that the new proximity of the reverb tank to the transformer might be causing the noise. That is why I was moving the tank around yesterday to see the effects.

 

But I'm not sure this is the problem...