Tweaker 40 Excessive noise in "Hot" (both channels)

[garyecobb]

Hello All, I am brand new to this forum - I did do a search for my topic and didn't find anything so I'm entering a new one. I hope that's OK.

I have a Tweaker 40 that I really like, most of the time. I am trying to set up one Clean channel and one Hot channel. Either channel makes excessive noise when turning up the Gain in the Hot setting. I also notice that even with the Gain all the way up in the Hot mode I am still not really getting the overdriven sound that I am looking for.

I am playing through a Marshall 1960A cab in Mono mode on the amp's 4 ohm setting with a new speaker cable (tried 2 of them with the same results). I also tried it through a Mesa Thiele single 12 cab and it does the exact same thing. I have a friend with the same amp and he has not noticed this noise (that he can recall).

Does anyone out there have any tips for correcting this? Is this supposed to be normal noise because if what I'm asking the amp to do?

Also, has anyone replaced the 6L6 tubes with EL34 tubes? Is this possible to do?

 

[webrthomson]

Hey and welcome!

I'd swap the preamp tubes, with a known good one, one at a time - it's likely that's all it is

So (amp off) swap V1, amp on test for issue - repeat for a all other positions till the issue goes away - bingo bad tube found!

 

[garyecobb]

Thanks for the advice, it is appreciated. I will definitely try this over the weekend and reply back with results.

 

[webrthomson]

No bother - most any weird noise in a valve amp it's worth checking the tubes first - if it's not the preamp tubes then check the power tubes too.

I would do the preamp tubes in the correct order - you're tube layout is here:

http://www.egnateramps.com/EgnaterProducts/Tweaker/Tweaker40/Tweaker40Specifications.html

With the power tubes you should normally see them glowing orange, red tends to indicates the bias is too high or the tube is dying, and you can test these by putting the amp into the mode / channel that you are getting the issues on and gently tapping them with a pencil - if you get odd noises the tube is on it's way out and you should replace. I would guess that you need a matched pair of 6L6's for the Tweaker 40 - so if one goes you probably need to replace the pair.

Lastly you also need to think about biasing if you replace the power tubes - this is the process of setting the correct draw for the tubes when they are effectively at rest. Normally this is not a difficult process but it depends how happy you are inside your amp with a multimeter!

I know that all sounds like a lot but do one thing at a time and start with the preamp tubes as they are the least fuss

Best of luck and let us know how you get on!

Ross

 

[garyecobb]

Hi folks, it turns out there is nothing wrong with the amp . It is probably either something to do with our rehearsal space power or that I swapped in a bad cable when I was testing (though I'm usually pretty careful about that). I just thought I'd reply, on the off chance that anyone is wondering what ever happened. I did learn a lot about all the electronics and tone modifications in the process, so it's all good for me at least.

This is an excellent forum! Very impressed (and with the amp too).

-gc

 

[webrthomson]

Hi folks, it turns out there is nothing wrong with the amp . It is probably either something to do with our rehearsal space power or that I swapped in a bad cable when I was testing (though I'm usually pretty careful about that). I just thought I'd reply, on the off chance that anyone is wondering what ever happened. I did learn a lot about all the electronics and tone modifications in the process, so it's all good for me at least.

This is an excellent forum! Very impressed (and with the amp too).

-gc

Nice one - given the pretty poor state of modern valves it's good to be able to do this kind of issue resolution and like you said you now know your amp pretty well