100W build running pretty hot

[benoit]

My build is up and running, and sounds nice, but the heat it's putting out is such that the standby switch is pretty warm to the touch when I go to power down. Is this something to worry about? I realize in a tubes down hundred watter some heat is inevitable but I don't want to put undue stress on the amp.

[kleinm]

What does your PT feel like? Does the entire thing feel hot (not just from the dissipated heat from the tubes)?

Check to see that all of your PS nodes are properly grounded. In the 100W Bluesmaster I just finished, I briefly forgot to ground B+4 (IIRC), and I noticed the PT was running much hotter than it should have given its current specifications.

[benoit]

I'll have to see how it feels when it's running. I guess it's hard to tell if it's just tubes or the whole thing. It's now about 15 minutes after a rehearsal and the PT is still pretty warm. It does seem to be a little warmer on the tube side. But would that really even matter much, since it's a metal housing and heat would get distributed pretty fast and evenly anyway? I'll have to double check the PS grounds later.

If the particular B+ node wasn't grounded would that have an audible result? I'm guessing what would happen is less filtering and maybe a noisier amp.

[Normster]

When you stuff the amp in a head cab, tubes down, it does get pretty toasty in there. To be sure, run the amp tubes up (out of the head cab) for an hour or two and see if the tranny still feels too hot. Usually it will be warm but not to hot to hold your hand on.

[benoit]

When you stuff the amp in a head cab, tubes down, it does get pretty toasty in there. To be sure, run the amp tubes up (out of the head cab) for an hour or two and see if the tranny still feels too hot. Usually it will be warm but not to hot to hold your hand on.

Good thinkin' Norm. I will say that running tubes down it's not too hot to touch at least on the side opposite the tubes IIRC. I'll try that next time I play it.

[benoit]

Double

[Funkalicousgroove]

These things just tend to run hot, point a fan at the back of it

[kleinm]

But won't the fragile harmonics diminish if the blue Smurf goo's surface temperature drops below 300 degrees K? Although, I read on TGP this can be countered with the use of both cloth-covered wire and carbon comps in the fan. Once the carbon comps start on fire, you'll get your fragile harmonics back.



Sorry, long day. Like I mentioned, I'd double-check your PS grounding, and if all tests well you're probably fine. I can't remember from your build pics, is your standby switch rated for the proper current? I bet its the standard Carling fair, and thus fine.

I totally agree, though. Its better to double-check everything to make sure its wired and behaving properly. I do the same thing. I bet you're golden, though! FWIW, I have decent heat coming off of the back of my 100W Bluesmaster.

[Funkalicousgroove]

I let amps cook for 8-12 hrs at a time when I'm testing them, the get plenty hot, but shouldn't burn you-

[Luthierwnc]

I put a recycled computer pancake fan on a tubes-down HRM build. It is set for about 2/3 speed with an on-off switch. It has it's own transformer which is just a wall wart stripped down to fit. Very quiet and moves enough air to make a difference.

I prefer tubes up, generally speaking,

sh

[ayan]

These things just tend to run hot, point a fan at the back of it

Word! SAme here, but although these amps get HOT -- especially the ones wirth Marshall iron and EL34s -- but I haven't had a single failure in alomst 10 years.

Cheers,

Gil

[glasman]

Has anyone noticed that the hotter they get, the better they sound? It seems to be the top end gets silkier as the amp warms up.

I get this impression everytime I play one of my amps.

['67_Plexi]

These things just tend to run hot, point a fan at the back of it

Word! SAme here, but although these amps get HOT -- especially the ones wirth Marshall iron and EL34s -- but I haven't had a single failure in alomst 10 years.

Cheers,

Gil

I'm more concerned about someone burning their fingers on the power or standby switch, they get roasting.
A good transformer is designed to be reliable right up to temperatures that would actually physically burn you before they actually broke down internally. A lot of transformer heat with a tubes down design is basically latent heat from heat rising from the tubes with nowhere to go but heat the chassis and transformer up. From my experience tube longiveity is definately longer with a tubes up design. For anyone that does run with a tubes down design, the best way to bias them is to initially set them on the cooler side and run with the amp in it's head shell for a couple of hours until everything is heated to a steady state, you'll be amazed how much the hotter the bias point gets to. It can increase 5 or 6mA. Readjust them to the required bias bias point while the amp is hot.