Custom 50 combo reverb hum

[gdmiller88]

Just got a Custom 50 combo, and although I haven't had much chance to play it, I've noticed that there's a hum from the reverb. It gets worse as I turn the reverb up. Could it be a bad tube? The amp was a demo, so although I just got it, it's been used.

Any advice is greatly appreciated.

 

[László]

Could be a tube. Have you got one to swap out and try?

 

[gdmiller88]

I only have a couple spare 12ax7's, and I'm assuming the reverb is the 12dw7. I'll order one up and see if it helps. What are the 12AT7's for?

Thanks for the response!

 

[László]

I only have a couple spare 12ax7's, and I'm assuming the reverb is the 12dw7. I'll order one up and see if it helps. What are the 12AT7's for?

Thanks for the response!

No idea on what tubes are in the amp, because my PRS amps are different, but I think there are some amp manuals on the Support Page on the PRS site that you can download. In general, however, if you're getting hum raising one control, the first thing to check would be a bad tube.

 

[gdmiller88]

I just took a look, and apparently one of 12at7's is for the reverb. I know that 12ax7 and 12at7 are interchangeable, but would I want to use it? I've read it will reduce the tank's input drive, and not last very long. But viable to try as a temporary fix?

 

[CoreyT]

I have heard that both the 12at7 and 12ax7 are used for reverb in some amps besides the 12x7 being used primarily for the preamp stage..

 

[gdmiller88]

Well, I put in one of the 12ax7s, and it's still noisy. Wondering what my next step should be.

 

[vchizzle]

Did you buy the amp new or used? If purchased from a dealer, I would contact them 1st. Otherwise contact PRS customer service.

 

[mcbprs]

I think it maybe pickup from the transformers, I solved it on mine by moving the reverb tank into the speaker enclosure. I have seen a similar issue with Two Rock Custom Reverb heads if the reverb tank is fitted the wrong way round the tranformers induce mains hum into the reverb .