Peavey Classic 30 question - disconnect speaker, use cabinet.

MatthewShreddery

I recently picked up a 112 cab for my Peavey C30 combo. It's one of the peavey ones, 16 ohm blue marvel speaker. Looks great.

Anyway, I want to know if I can just disconnect the combo's built in speaker and run a speaker cable from the ext.out to my cab?

Will this be safe to do?

The reason is the tubes rattle when I use the internal speaker, which is a shame as I'd like to use 2x12.

Cheers

ICBM

It's definitely safe if the external cabinet is 8 ohms. The jack has a switch in it - the intention is to run both the internal 16-ohm speaker and an external 16-ohm cab at the same time.

It's *probably* safe if the external cabinet is 16 ohms.

Make sure you tape or otherwise cover the connector when you've pulled it off - only undo one of them.

You're best to replace the valves though - these amps are a bit notorious for killing them, so a spare set (keep the old ones, even though they rattle) is a good idea. You don't need to bias it or anything,

MatthewShreddery

Thanks mate - you're always giving great advice. Much appreciated.

Why only undo one of the connectors?

What would be a sign of trouble in using 16ohms? I mean, will the amp just blow up, or will there be slightly more subtle warnings?

I've got new valves on the way.

ICBM

There's only any point in undoing one, and it will stop the wires flapping around .

The signs of trouble from running into too high impedance would likely be blown valves when the amp is cranked - you may not get any other warning. If you're not cranking it there's no risk really, it just may not sound quite as good.

crunchman

ICBM said:

You're best to replace the valves though - these amps are a bit notorious for killing them, so a spare set (keep the old ones, even though they rattle) is a good idea. You don't need to bias it or anything,

I'd go further than that.  Your best bet is to replace the amp.  Even if nothing goes wrong with it, it will get expensive on valves.  I had to replace mine at least once a year when I had a C30.  Since I've been using 6L6 amps I can go for years on a set of power valves with the usage I have.

When something does eventually go wrong it is a pig to work on because of the way the circuit boards are arranged, and will probably cost a lot to fix.

MatthewShreddery

Why do you think it eats valves? Is it because they get rattled to death (which can be tamed with a tube tamer/using a cab instead of internal speaker)?

crunchman

EL84s are not the most long lived or robust valves.  The C30 runs them very hot as well - well over their rated design voltages, although its not the only guitar amp to do that.   It has an unusual bias arrangement as well.  Most EL84 amps are cathode biased, which is kind of self adjusting.  The C30 is "fixed" bias but you can't adjust it like you can on most fixed bias amps.  That does mean that you can't set the bias to the optimum level which may also slightly shorten the life of the valves if you have a set of valves that run hot.

I've had combos with 6L6s that have lasted for years (Hot Rod Deluxe, Lazy J 20).  I'd imagine that the amount of vibration would be similar so I think it is more to do with the EL84s and the voltage they are run at.  The HRD and the Lazy J are relatively low plate voltages compared with some 6L6 amps so they are probably not being stressed by the voltage but fundamentally I think it is a more robust valve than the EL84.  You only need 2 6L6s instead of 4 EL84s so they tend to work out cheaper even though the individual valves are more expensive.

I've not got a lot of experience with other EL84 based amps so I don't know how the Peavey compares to them for valve life.  They would probably be somewhere in between.  @ICBM could probably tell you more on that.

MatthewShreddery

Cheers for that info.

I still love my C30 regardless.

crunchman

MatthewShreddery said:

Cheers for that info.

I still love my C30 regardless.

I liked mine when I had it - until I had a problem with it and had to think about fixing it.  It's not designed to be easily maintainable.  I'd imagine that Peavey just shove whole new circuit boards in if they get a warranty claim.

MatthewShreddery

Yea I've heard that too.

Mine's about 12 years old - bought it used, and it's still on its original valves. 

I've a full set of pre and power amp valves coming in the post so I look forward to hearing the difference. The old valves must be knackered , but the amp still gets damn loud.