Hey Guys,
I just finished my first amp and it was going to be a cab but moved on to being a head, the issue i have is will it get to hot to be hung upside down? its a lightning amp. Should i work on reversing it or leave it hanging?
Thanks
Upside down head
Moderators: pompeiisneaks, Colossal
Re: Upside down head
> it was going to be a cab but moved on to being a head, the issue i have is will it get too hot to be hung upside down? ... Should i work on reversing it or leave it hanging?
I'm confused. Maybe I'm not clear what a "lightning" is.
Many 1960s Fender-like combos (amp and speaker in one) have the tubes hanging down, and tend to run hot.
Many (not all) amp-only heads set the chassis on the bottom and the tubes stick up. Tube heat tends to rise away from the chassis, tend to run cooler.
In either case: tube amps run hot, and the difference bottles-up or bottles-down is usually small. "Heat rises", but heat also goes everywhere.
And if you use good parts, didn't jam the hot-bits too close together, and you don't hear flesh sizzle when you touch the chassis after an hour, it's not really "too hot". Some of my oldest tube amps run too hot to touch yet won't die. The outside of my Fisher runs hotter than the outside of my toaster on a hard morning. (Modern toasters have safety regulations; the 1960 Fisher apparently didn't.)
If it is for-sure too-hot, then tubes-up or tubes-down is not going to really un-fry your bacon. Either re-build it larger or add a fan. But you have to be really clever to pack tubes that tight.
And in general: don't think too much. Tube amps were stuffed in many places in many ways, under pressure of war-time demand, or rush-to-market, or just get-er-done.
Try It And See. If it does "run too hot", it won't (shouldn't!) go up in smoke right away. It'll be many minutes getting warm, like an old cast-iron V-8 engine. At 30 minutes, you probably don't want to leave your hand on the chassis, that's normal. With brand-new parts (or old dusty parts), it'll stink slightly as the "new" (or dust) cooks off. All that is normal in any tube amp.
The other issue, when you flip a chassis over, is the knobs go "the other way" across the front. But popular amps have been built both ways. And of course the labels are upside down. But on a dark stage, who cares?
I'm confused. Maybe I'm not clear what a "lightning" is.
Many 1960s Fender-like combos (amp and speaker in one) have the tubes hanging down, and tend to run hot.
Many (not all) amp-only heads set the chassis on the bottom and the tubes stick up. Tube heat tends to rise away from the chassis, tend to run cooler.
In either case: tube amps run hot, and the difference bottles-up or bottles-down is usually small. "Heat rises", but heat also goes everywhere.
And if you use good parts, didn't jam the hot-bits too close together, and you don't hear flesh sizzle when you touch the chassis after an hour, it's not really "too hot". Some of my oldest tube amps run too hot to touch yet won't die. The outside of my Fisher runs hotter than the outside of my toaster on a hard morning. (Modern toasters have safety regulations; the 1960 Fisher apparently didn't.)
If it is for-sure too-hot, then tubes-up or tubes-down is not going to really un-fry your bacon. Either re-build it larger or add a fan. But you have to be really clever to pack tubes that tight.
And in general: don't think too much. Tube amps were stuffed in many places in many ways, under pressure of war-time demand, or rush-to-market, or just get-er-done.
Try It And See. If it does "run too hot", it won't (shouldn't!) go up in smoke right away. It'll be many minutes getting warm, like an old cast-iron V-8 engine. At 30 minutes, you probably don't want to leave your hand on the chassis, that's normal. With brand-new parts (or old dusty parts), it'll stink slightly as the "new" (or dust) cooks off. All that is normal in any tube amp.
The other issue, when you flip a chassis over, is the knobs go "the other way" across the front. But popular amps have been built both ways. And of course the labels are upside down. But on a dark stage, who cares?
-
joelmulpeter
- Posts: 8
- Joined: Mon Mar 26, 2007 4:52 am
Re: Upside down head
Thanks for your reply,
Sorry about the confusion by lighting i meant and matchless lighting, ac-15 essentially.
It is a ceriatone kit and it seems he has quite good knowledge of layouts. It will be placed in hard wood cab which will hopefully not bubble the finish. Being a smaller amp I'm hoping the heat will be minimal. The head will be an open back anyway and i might put a small gap at the front so the air can pass right through.
Sorry about the confusion by lighting i meant and matchless lighting, ac-15 essentially.
It is a ceriatone kit and it seems he has quite good knowledge of layouts. It will be placed in hard wood cab which will hopefully not bubble the finish. Being a smaller amp I'm hoping the heat will be minimal. The head will be an open back anyway and i might put a small gap at the front so the air can pass right through.
Re: Upside down head
Here's a pic of a Traynor amp from the 60's and 70's. There were various versions running up to 80 and 100 watts. A lot of them are still going strong with their tubes "hanging" in there! 
[img:504:312]http://www.lynx.bc.ca/~jc/yba1C.gif[/img]
Stew
[img:504:312]http://www.lynx.bc.ca/~jc/yba1C.gif[/img]
Stew
Re: Upside down head
I prefer heads to be 'tubes-up' as it helps get heat out of the chassis but Mark Sampson has been quoted on more than one occasion as saying that he deliberately designed his amps as 'hangers' to force them to run hot.
Certainly in the DC30s (not sure about the Lightnings) there are lamps in there to help get it to run hot (and these aren't anything to do with the front panel illumination). Weird, but true.
Whether or not it's a good thing is open to debate, but you'll be closer to the alleged 'design' if you make it a hanger.
Certainly in the DC30s (not sure about the Lightnings) there are lamps in there to help get it to run hot (and these aren't anything to do with the front panel illumination). Weird, but true.
Whether or not it's a good thing is open to debate, but you'll be closer to the alleged 'design' if you make it a hanger.
Re: Upside down head
Leave it hanging.
The Ceriatone Lightning is clearly made to hang: the labels would be "wrong" if you set it tubes-up.
That's an enormous chassis for basically a two-EL84 amp. My Fisher hi-fi has four such tubes in half the area. My little Traynor isn't this big, and has done OK since 1976. Genuine AC15s are cramped, and many of them have survived.
> hard wood cab which will hopefully not bubble the finish.
Depends of course what you use for finish. Some take heat, some don't.
What I'd actually worry about is heat drying the wood. More on the inside surface than the outside surface. Differential shrinkage will make solid wood warp and crack.
Is it possible to mock-up the cab without finish, even in pine or plywood, and let it cook for some hours? Feel how hot it gets?
But amps like Stoo's, about the same physical size but 5 times the power, haven't bubbled their Tolex yet. My Traynor 24W's Tolex is beaten and stained and ripped and the shine is oxidized off, but I don't see heat damage. The cool back and warm top are equally tired. A good modern finish "should" be fine.
The Ceriatone Lightning is clearly made to hang: the labels would be "wrong" if you set it tubes-up.
That's an enormous chassis for basically a two-EL84 amp. My Fisher hi-fi has four such tubes in half the area. My little Traynor isn't this big, and has done OK since 1976. Genuine AC15s are cramped, and many of them have survived.
> hard wood cab which will hopefully not bubble the finish.
Depends of course what you use for finish. Some take heat, some don't.
What I'd actually worry about is heat drying the wood. More on the inside surface than the outside surface. Differential shrinkage will make solid wood warp and crack.
Is it possible to mock-up the cab without finish, even in pine or plywood, and let it cook for some hours? Feel how hot it gets?
But amps like Stoo's, about the same physical size but 5 times the power, haven't bubbled their Tolex yet. My Traynor 24W's Tolex is beaten and stained and ripped and the shine is oxidized off, but I don't see heat damage. The cool back and warm top are equally tired. A good modern finish "should" be fine.