Twin Reverb Issues

DRedmon

New member
I'm having some serious, or maybe not too serious issues with my Twin. It's a 2003 '65 Ri. Ever since I bought it used from Guitar Center for $800, I've been having issues here and there. About a month ago, I had my local and well trusted amp repair and rental put some new tubes in, check up on the speakers, bias, etc. He even moved around the wires and tied them together for the least hum possible, because that was one of the original problems. It cost me about $250 for the greatly needed full tube replacement including the price of the Electro Harmonix tubes and everything else. It seemed to do the trick, almost no hum or rattling at all. The only thing I noticed right off the bat was that it distorted a quicker than the previous Fender Groove Tubes. The place I got it done by is called On Stage Services, they do all the work for GC in my area.
Everything was great until about a week after, I was rehearsing with the band and all of a sudden I get this weird crackling noise about 20 minutes into playing. It sounds almost as if I'm losing connection with one of the instrument cables and regaining it right away. I'm going from the Twin to a Boss Blues Driver and straight into the Gibson SG Standard. I thought that's what it was but it only happens when you crank the amp past around 5 hit a chord or sometimes even a note hard. We usually do have to turn up quite a bit, our drummer is a very hard hitter. I also notice that when I pick a little harder or hit certain notes, not even cranked past 3, I hear a sort of buzzing sound coming from the amp, like speaker distortion except a little different; pretty muffled actually. This issue was not fixed at all by new tubes. The speakers are both Jensen C12k's, and I would hate to have to replace them. After all the shop did say the speakers tested fine. In addition to all the other issues, a couple days ago, I was playing with it a little while my drummer was practicing, and I was able to turn it all the way up to 8 with no issue, it was just as loud as the drums! I wasn't exactly sure what happened there but I'm out of town and haven't tried it since.
Also I'm plugged into the regular channel with the bright switch off, treble around 4, mid around 6, bass around 6. Volume is usually 5. If I turn the bright switch on, the muffled notes from what sounds like speaker distortion get MUCH worse. Please help me out, I'd REALLY appreciate it!
Thank you,
Daniel
 
Re: Twin Reverb Issues

Try in it some tubes that are known to work. Tubes may well be faulty even if they're new.
 
Re: Twin Reverb Issues

1. A TR that is functioning properly does not really "distort". If your amp is, as you say, "distorting quicker": there is a problem with the new tubes, the bias, or something related to the work that was done.

2. It seems that you have a problem (the crackling) related to vibration. As your volume increases, so does the air movement from the speakers, and THAT is moving a tube in its socket, or something similar.
IF that is the issue, you might be able to replicate it simply by (some what) gently moving the tubes in their sockets with the volume up about half way. What is otherwise known as "chop-sticking".

That is just a couple of things that MIGHT BE causing the problems.
IMO...your tech should be able to explain what is happening with #1, and I am assuming you mentioned that situation to him already.?
good luck
 
Re: Twin Reverb Issues

Thanks, he said the new tubes were all around 95% output after biasing them. I'll call him back though.
 
Re: Twin Reverb Issues

You need to clarify what that number means. I cannot imagine ANY amp tech biasing a Twin at 95% quiescent.
 
Re: Twin Reverb Issues

You need to clarify what that number means. I cannot imagine ANY amp tech biasing a Twin at 95% quiescent.


The tubes that he put into the amp have 95% output. He biased the amp before putting the tubes in I'm assuming, I'm not good with stuff like this.
 
Re: Twin Reverb Issues

Well.....you cannot bias the amp if the tubes are not installed.
Regardless, you need to get back with your tech.
best
 
Re: Twin Reverb Issues

Check all tubes by process of elimination before you do anything else.
Also...check your leads too.
 
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