How hot do your tube amps run?

[hydro]

General question - my Mesa Express 5:50+ head seems to get pretty hot when it runs. I'm not sure how hot I should expect it to be.

I have been running in 25W mode, driving a 4x12 at 8 ohms and about 9 o'clock on the volume. No issues or problems with it; just noticed, for example, when I pull out the instrument or speaker jacks, they are noticeably warm. This is after the amp's been on for a while too, so maybe this is all to be expected.

Second question - probably stupid - I know I am not supposed to run the amp without a speaker load, but is it safe to have it switched to standby and then pull the speaker cable to put into a different cab? I've done this to a/b speakers and cabs before.

 

[Gearjoneser]

Re: How hot do your tube amps run?

Turn off the lights and look at the tubes. Make sure the gray plates inside the tubes don't have their own orange glow. That would mean the bias is too hot. If the tubes are operating within normal range, don't worry too much about it. Maybe put a little clip-on fan aimed at the back.

One thing I do with some amps is to leave a tiny gap between the power tube bases and sockets, rather than having them pushed all the way in.

 

[Andrew Lamprecht]

Re: How hot do your tube amps run?

One thing I do with some amps is to leave a tiny gap between the power tube bases and sockets, rather than having them pushed all the way in.

What would that do?

 

[Gearjoneser]

Re: How hot do your tube amps run?

What would that do?

My rationale is that a millimeter gap might cut down on the direct heat to the chassis.
I could be wrong in my thinking though. The tube retainers are still holding them firmly.

 

[Boogie Bill]

Re: How hot do your tube amps run?

Any tube amp will get hot. Normally, my 6L6 and EL34 Mark III, Mark IV and Mark V amps will get very warm, but certainly no warmer than any other 6L6 amp I've ever used. They have a built-in fan, which can be unplugged when recording.

I have two EL84 amps, the Dyna-Watt 4xEL84 (35 watts) DC-3 112 combo gets scorching hot, enough to make me think that something IS wrong with it--except it sounds GREAT. The Class A Maverick 212 also gets very hot, but the Class A amp DOES have a fan. This amp is more along the lines of an AC30, and the ACs are known for eating tubes. I like the tone and versatility of the Mesa Maverick over the AC30, and fortunately have not experienced any tube-life problems, knock on wood.

My old Marshall EL34 4010 combo would get quite hot. I worried about it when I first got it and used a small clip on fan for while--until I realized that the hotter the thing got, the better it sounded.

If you have any concerns, I'd advise you to give the guys at Mesa a call. You have quite a bit of diagnostic information in your Owner's Manual, but they can walk you through it. As to your STANDBY switch question, you should be okay, but again--give Mesa a call for a definitive answer.

Good Luck!

Bill

And to GJ---

The millimeter gap does nothing to dissipate heat--it is transferred by the metal prongs of the tubes to the metal connectors of the sockets and then on to the chassis. I'd definitely want those tubes pushed all the way in and seated firmly--and then clamped in. You don't want something working its way loose in transportation.

My two cents.

All the best...

Bill

 

[hydro]

Re: How hot do your tube amps run?

My tubes look OK, from what I can tell. The amp sounds like I expect it to and performs well. The transformers do get really hot also, maybe it's just the way the chassis is laid out that it gets a bit warm. It's a lot of amp in a fairly small chassis.

 

[VanDerchuck]

Re: How hot do your tube amps run?

I've measured temps upwards to 140° Fahrenheit in a quad el34 set up. That's pretty damn hot. If your tubes look fine but your worried about it try adding a fan. I added a 12volt computer fan blowing air out of the chassis. Powered it with a 9volt power supply and it worked just fine. Brought temps down to 110°. Still warm but not severe.

 

[Mad-Max]

Re: How hot do your tube amps run?

My Mesa Mark V tends to go pretty hot, even with the right bias setting. You have no worries. I personally think the tone is better when the tubes are ran hotter.

 

[Petrovsk Mizinski]

Re: How hot do your tube amps run?

It can be safe for many, perhaps, most amps to change impedance/disconnect the load in standby, but it's not something you should make a habit out of.
It doesn't take any more time out of your day to just power down the amp completely before changing impedance/disconnecting a load.

 

[zzmoore]

Re: How hot do your tube amps run?

I've measured temps upwards to 140° Fahrenheit in a quad el34 set up. That's pretty damn hot. If your tubes look fine but your worried about it try adding a fan. I added a 12volt computer fan blowing air out of the chassis. Powered it with a 9volt power supply and it worked just fine. Brought temps down to 110°. Still warm but not severe.

To the OP.....it is all effected by proximity...but this is about what I find as well.
Tubes are 1,000 degrees on the inside heater.
Power tubes will burn your hand after just a minute of play.
A Lot of mesas have a pretty small foot print...what you are experience is probably normal. Shoot an email to Mesa or give them a call, they will ease your mind.

You are safe if the Stand By is on...all you basically have at that point is an amp full of night-lights.
Just be careful...if you are pulling the speaker cable from the cab, and not the amp, you are setting up the worst case scenario...if you have a brain fade and forget to hook things up for one of a thousand reasons.
But you are right there switching, so there should be no loading problem.
best