new power tubes running hot, how to bias my C30?

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gbloomers
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Joined: Thu Aug 17, 2017 5:48 pm

new power tubes running hot, how to bias my C30?

Post by gbloomers » Thu Aug 17, 2017 5:58 pm

Hi,

A first post as Im assuming (and hoping!) that you guys have some wisdom with Peavey amps.

I recently bought a used Classic 30. I changed out the EL84 power tubes with a new set of JJs as I think the old Sovteks were rattly and on the way out. Now the amp get very hot, even only pushed up to 3/4 volume. It was pretty hot with the old tubes but I don't think to this level. I don't want my new tubes busted as I can't afford more. Im aware that maybe the bias is off and too much power is going to them causing them to be hot. Could anyone tell me how to go about setting the bias for this particular amp?

I know the official answer is 'go to an amp tech' but I'm a student and can't afford this. However I am pretty handy with my gear and have built many partscasters/pedals and amp mods etc. but just haven't had a go at biasing before.

Let me know if its just normal classic 30 behaviour too. Thanks for any help.

vypyrtrails
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Joined: Fri Jun 16, 2017 11:15 am

Re: new power tubes running hot, how to bias my C30?

Post by vypyrtrails » Thu Aug 17, 2017 7:37 pm

I am no amp tech.

The official answer is the BEST answer. Really is.

The inner workings of a guitar amp cannot be compared to working on guitars and pedals.

Just because the guitar amp is unplugged, there are parts that still hold lethal voltages. Only qualified techs know what components
these are, and if they need to be drained before making any kind of repair.

Now with this said, you already have the new tubes, thats half the cost. You just need to pay for bench time. That could cost $80.00 or so. Try and explain your situation to the tech, and work something out.

Not trying to be a jerk, just want you to be safe.

scottp
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Joined: Tue Dec 30, 2008 10:37 am
Location: Copperhill Tennessee

Re: new power tubes running hot, how to bias my C30?

Post by scottp » Thu Aug 17, 2017 7:43 pm

The classic 30 runs hot very hot the bias is fixed you just put in tubes and you're ready to go it's just the nature of these amps
Peavey limited hb, peavey studio pro 50.peavey escort 3000

ScottMarlowe
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Location: Denver, CO

Re: new power tubes running hot, how to bias my C30?

Post by ScottMarlowe » Fri Aug 18, 2017 1:07 am

If they're not redplating I wouldn't worry. Mine runs super hot too, but never had any problems other than it just being a hot running amp.

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