Amp problem: Loss of volume

[Jeffrec]

The other day I replaced the bridge pickup in my SG and was testing it out (Seth Lover). The first time, I played all went well. The next day I plugged in, waited for the tubes to get heated, then hit the standby switch. The amp made a lot of crackling and other noises for a moment, then I began playing. After a minute or so, I noticed a big drop in volume and the sound got pretty thin.

It's an early '90's Crate Vintage Club 50Watt 2X12 with El84's that I got new. I've never had a problem with it and it's always sounded great. I re-tubed it a few years ago with GT El-84's and 12AX7's. My first thought is that I may me dealing with a loose or bad tube (I hope that's all it is). I'm going to check it out this weekend. If that's not it, does anyone have any ideas?

Thanks guys in advance.

 

[RealtyViking]

Re: Amp problem: Loss of volume

More than likely going to need new power tubes. Especially in a Vintage Club as they run the power tubes very hot. A couple years on a set if you play regularly is longer than expected. As a rule of thumb, I assume a year on a set is average and keep an extra set for each amp for just these situations.

 

[Jeffrec]

Re: Amp problem: Loss of volume

More than likely going to need new power tubes. Especially in a Vintage Club as they run the power tubes very hot. A couple years on a set if you play regularly is longer than expected. As a rule of thumb, I assume a year on a set is average and keep an extra set for each amp for just these situations.

Thanks. That's what I was thinking. I'm got some spare GT's (matched to what's in there now) I'm going to check it out tomorrow. Can a tech change the bias to reduce the heat on the power tubes? I know the Crate is fixed bias.

 

[Bludave]

Re: Amp problem: Loss of volume

Jeff, take it to Richie Johnson. He's in Bohemia and he is awesome. IF the plate voltage can be lowered and the tubes can be biased cooler he should know what needs to be done. NY Music & Repair. If you need his number PM me. He is the only guy that I let put his hands inside my amps!

 

[RealtyViking]

Re: Amp problem: Loss of volume

Don't lower the voltage as it is part of the sound of the amp, which is great. Vox AC30s suffer the same issue with EL84s and it is just part of getting such a great tone. A fan placed behind the amp will help. Sovtek tubes sound great in that amp, are inexpensive, were part the original design spec and hold up better than many other tubes.

If you want to do anything look into clipping the high pass cap. It is the one and only thing I have seriously contemplated doing to my VC5115. I might have my tech install a hidden switch to turn the cap on and off which will act like a top boost on the old AC30s. If you only play humbuckers it more than likely is not an issue. Single coils at lower volume get too much treble that can not be eq'ed out otherwise.

 

[Jeffrec]

Re: Amp problem: Loss of volume

Don't lower the voltage as it is part of the sound of the amp, which is great. Vox AC30s suffer the same issue with EL84s and it is just part of getting such a great tone. A fan placed behind the amp will help. Sovtek tubes sound great in that amp, are inexpensive, were part the original design spec and hold up better than many other tubes.

If you want to do anything look into clipping the high pass cap. It is the one and only thing I have seriously contemplated doing to my VC5115. I might have my tech install a hidden switch to turn the cap on and off which will act like a top boost on the old AC30s. If you only play humbuckers it more than likely is not an issue. Single coils at lower volume get too much treble that can not be eq'ed out otherwise.

Thanks! This is good info.

 

[Jeffrec]

Re: Amp problem: Loss of volume

Ok. I got a matched set of Ruby (JJ) El84's from Doug's Tubes. Popped them in yesterday, and she runs like new. Volume is back and it sounds amazing again. I also put an Electro-Hamonix 12AX7 in V1 for the hell of it.

 

[Bludave]

Re: Amp problem: Loss of volume

So you didn't take the amp to Richie? Is this a set bias amp? You need to be careful, if its not sel biasing you could be running way too much voltage and wind up blowing through those tubes pretty quickly..

 

[Jeffrec]

Re: Amp problem: Loss of volume

So you didn't take the amp to Richie? Is this a set bias amp? You need to be careful, if its not sel biasing you could be running way too much voltage and wind up blowing through those tubes pretty quickly..

Hi Dave,

Yes its fixed biased. With the matched tubes, I won't run into any problems.

 

[Simon_F]

Re: Amp problem: Loss of volume

Glad you got it fixed Jeff. This thread reminded me of when I bought a used DSL 50 on eBay a few years ago. When it arrived I plugged in my favourite Les Paul and got that terrible sinking feeling when the sound was really thin and weedy, even when I cranked the amp a bit. Then I switched to the neck pickup and had one of these moments...

I'd put a new bridge pickup in the guitar a couple of days before. Thought it was OK when I tested it but it turns out my soldering was bad. Nothing wrong with that amp!

 

[Jeffrec]

Re: Amp problem: Loss of volume

Glad you got it fixed Jeff. This thread reminded me of when I bought a used DSL 50 on eBay a few years ago. When it arrived I plugged in my favourite Les Paul and got that terrible sinking feeling when the sound was really thin and weedy, even when I cranked the amp a bit. Then I switched to the neck pickup and had one of these moments...

I'd put a new bridge pickup in the guitar a couple of days before. Thought it was OK when I tested it but it turns out my soldering was bad. Nothing wrong with that amp!

Love that clip Simon! It's great when a "problem" turns out to be a simple thing. My initial thought was that it was going to be something major.

Cheers!