Dr Tony Balls wrote: Sat Dec 18, 2021 6:28 pm

Kniferide wrote: Sat Dec 18, 2021 5:38 pm Recently had a new power transformer put into my 63' Epiphone Pathfinder. It's mostly all good, other than the tone is slightly more throaty than it used to be. The only bad thing is, now there is a pretty annoying buzz in the reverb circuit. It sounds like single coil pickup buzz but it goes away when you turn off the reverb. Before it took a shit, the reverb was completely quiet. Didn't have any weird noise at all. Not a big deal for playing, but sucks for recording completely, which is what I really want to have this amp around for. Ideas?

They probably put the power transformer ground in a weird place. The reverb recovery stage in an amp is especially sensitive and you'll get 60 Hz hum if you dont separate your power grounds from your preamp grounds.

Or if they didn’t move it, maybe the laminations on the new transformer are oriented so that they line up with the reverb transformer? If this amp has a reverb transformer.

You could easily test where it's happening by disconnecting the reverb tank and seeing if that stops the problem. If it doesnt, it's in the recovery stage. However, if you had this done in a shop you should just bring it back to them because they did an incorrect/incomplete job.

Dr Tony Balls wrote: Sun Dec 19, 2021 6:55 am You could easily test where it's happening by disconnecting the reverb tank and seeing if that stops the problem. If it doesnt, it's in the recovery stage. However, if you had this done in a shop you should just bring it back to them because they did an incorrect/incomplete job.

Thanks. I'll try those things. I tied a different tank (non original, but always sounded better to me) and it still does it. I'll see if it is still there when it is disconnected. It doesn't sound like 60Hz, more of a fizzly buzz. Unfortunately, the shop is one of those "cross your fingers and see if you ever hear a response" guys. He did change teh reverb tube. He said the one in there wasn't working, but I had never had a problem with it before taking it in. I'll see if he gave me the old tube in the box of replaced parts he gave me and see if just swapping it helps. It's pretty annoying, when I turn the reverb on it sounds like I'm switching to a single, single coil regardless of what guitar/pickup combo I'm using. Dead quiet when reverb is off.

Kniferide wrote:He did change teh reverb tube. He said the one in there wasn't working, but I had never had a problem with it before taking it in.

Could be as easy as this. I was working on a Deluxe recently that was giving me some annoying little problems like this. I was getting more of a crackly sound than a fizzy one, but it was remedied by swapping in better tubes for the reverb driver and recovery.

Tom Wanderer wrote: Mon Dec 20, 2021 8:18 am

Kniferide wrote:He did change teh reverb tube. He said the one in there wasn't working, but I had never had a problem with it before taking it in.

Could be as easy as this. I was working on a Deluxe recently that was giving me some annoying little problems like this. I was getting more of a crackly sound than a fizzy one, but it was remedied by swapping in better tubes for the reverb driver and recovery.

Are you using a footswitch? I have a couple of amps that buzz when you plug in a certain type of footswitch where the cable becomes some sort of antenna. I'm unsure if its a shielded or unshielded cable that causes the problem. If using a footswitch, have you tried it without?

I was using with and without footswitch, and I did use contact cleaner on the RCA jacks and re-tension the negative part of the RCA plug. Nothing made a difference until I changed the tubes. All the 12AX7 and 12AT7 tubes in the deluxe were a mixed bag of newish and old stuff, some ok, some super cheap. They needed addressing and the pins needed cleaning. I agree that the footswitch can sometimes be an issue, but there would probably already have to be an issue in the reverb circuit if the footswitch leads were picking up that much interference.

Swapping in some quality tubes that were known good and tested did the trick. If there was no issue with the reverb before and the tech replaced the reverb tube(s) and now there's a weird noise, I would say that's a pretty good place to start. A cheap or shitty preamp tube can cause a lot of headaches. And if that's all it is, it's an easier fix than pulling the chassis and getting out the soldering kit. And it's also easier than trying to deal with an unresponsive shop and having to dog them to finish the repair.

I tend to go to worst possible scenario when I've got a problem with an old tube amp, and I'm always amazed (and relieved) when it's just a tube. And it often is.

Nut slot height.

I haven't adjusted a nut for ages. I can't really remember the best technique for finding a good height. Some seem to say measure it, others do it by eye.

Any tip would be fab!

Adam_I_III wrote: Mon Dec 20, 2021 2:37 pm Nut slot height.

I haven't adjusted a nut for ages. I can't really remember the best technique for finding a good height. Some seem to say measure it, others do it by eye.

Any tip would be fab!

I usually measure using height over the first fret as the metric. There are many online tables that show suggested height over the first fret for such a thing,

Dr Tony Balls wrote: Mon Dec 20, 2021 4:37 pm

Adam_I_III wrote: Mon Dec 20, 2021 2:37 pm Nut slot height.

I haven't adjusted a nut for ages. I can't really remember the best technique for finding a good height. Some seem to say measure it, others do it by eye.

Any tip would be fab!

I usually measure using height over the first fret as the metric. There are many online tables that show suggested height over the first fret for such a thing,

Checking your work related: if you hold down the string on the second fret and the string is touching the first one, you've gone too low. If your sight isn't great (mostly useful for the plain strings) and you don't have any feeler gauges, you should be able to hear a ping if you hold down the second fret and tap at the first fret with your other hand.

tommy wrote: Mon Dec 20, 2021 4:46 pm and you don't have any feeler gauges

Nobody should have this as an excuse. My notes on electric guitar action say .010" and .024" action (treble and bass side) at the first fret. Can be approximately measured with a high E and a D string from a standard 10 gauge pack.