Tubes up or down?

[xtian]

Most D style and Fender amp heads are arranged tubes down, chassis bolted to the tops of the cabinets. What's the logic here? Has two obvious drawbacks: heat from the tubes rises and cooks the chassis, and it's a PITA to install and remove the chassis. Oh, and the chassis collects dust.

Designers must have made this choice on purpose. Just wondering why.

[M Fowler]

Not sure but I think they started off as combo models and then players wanted heads so the design stayed.

Mark

[Blackburn]

I'm not a big fan of this method either. I especially don't care for the tweed style. I've seen so many pics of caps in tweeds that have bubbled, looking like they survived a volcanic blast.

Marshall's where it's at! And Wrecks of course!

[Reeltarded]

Up with tubes!

[Phil_S]

I can't think of a good reason to hang tubes from the ceiling except in a combo where choices and compromises are necessary.

[sepulchre]

I imagine mounting the chassis 'tubes up' and then having long flying leads to combo style controls would invite hum. But hey, just thinkin.

[Aurora]

Considerin all the combos that have been built, it can't be too much wrong hangin' them tubes from the ceiling, can it?

[VacuumVoodoo]

I can't think of a good reason to hang tubes from the ceiling except in a combo where choices and compromises are necessary.

Not a big compromise to install amp with tubes up IMO. Combo cabinet is a folded horn...altogether an ugly sob.

[martin manning]

Some early combos had two chassis, which kept the controls up high, the power tubes upright, and the CG low. I worked on a Supro like that with the signal out of the PI carried down to the lower chassis on lamp cord. It was quiet, and removing one panel provided access to the preamp. Fender's tweed designs are great for serviceability, with complete access gained by removing a single panel, plus the bottom of the cab is available for storage of cables, etc. Placing the tubes on the bottom keeps them near the back for good ventilation. When the controls moved to the front it made sense to keep the tubes underneath and near the back. I don't see the BF design as being difficult to service, with only one panel and four screws to release the chassis, and this is no different from a Marshall head.

[overtone]

I can't think of a good reason to hang tubes from the ceiling except in a combo where choices and compromises are necessary.

Not a big compromise to install amp with tubes up IMO. Combo cabinet is a folded horn...altogether an ugly sob.

impressive beast, altogether the Jabba the Hutt of amplifiers!

Vox had a lot of tubes up in a combo and even more sideways maybe staying closer to the controls.
But they did not seem to really get the thermal issue right in the process.

[Diablo1]

Some early combos had two chassis, which kept the controls up high, the power tubes upright, and the CG low.

Like this oddball. Preamp tubes in the top and hanging. Phase inverters and power tubes in the bottom chassis upright. A little more expensive to produce with two chassis.

[IMG:640:480]http://i56.tinypic.com/118j7kz.jpg[/img]

[martin manning]

That is basically what Supro did, except the upper chassis was open at the back, and the PI was upstairs. The economics of two chassis might not be too bad... Maybe the same power amp chassis could be used for different models, and the assembly might be easier.

[rp]

Pretty simple if you ask me, Dumble did it cause he stared out modding / recycling Fenders, Fender did it 'cause how lovely is it to just bend over slightly holding your guitar and twiddling the knobs on your Super Reverb, or your Deluxe Reverb up on chair? Elegant ergonomic design and big selling point if you ask me. Fender's engineers were born and raised w/ tubes and were probably sparkies in WW2 and knew the real world limits and weren't worried apparently. Vox too, and most old AC30s didn't blow up despite the terrible ventilation. But yes, IME building upside down sure does heat everything up in a 'seemingly' disturbing way. I like cool and try and stick to heads with grills front and back.

[Reeltarded]

ok ergonomics are upside down AND I have been hypnotized

[Cantplay]

Mmmmm, bacon.

John