Chassis Replacement

micahbell · #1 10-26-2011, 06:18 PM

I've got a bit of a problem I'm hoping somebody can help me with.

I just bought myself a new power amp, because I'm going to be touring next year and I want something bigger and better than my current power amp.

I picked up a early 60s Garnet tube amp - 4 6ac7s, a 6sn7 and 5 12ax7s.

It sounds absolutely beastly and I love it, but it needed a new power cable so I took it to my tech and he hooked it up.

As I was leaving I asked him if he thought it was tour ready or if anything needed to be done, and strongly advised me not to take it on tour, because the metal of the chassis was too thin, and if its bouncing at all in the back of a van the transformers will just bend the chassis and my amp will be toast.

I asked him if a custom road case would help and he said no, then I asked if it would be possible to buy an Ampeg chassis off ebay and swap them out, to which his response was that with the cost of having him do it, it probably wouldn't be worth it.

So, my question: has anybody done this? How much work would it be to do myself?

Does anybody make custom chassis, if I was to remove the everything and send them the chassis, would somebody copy it with heavier material for a reasonable price?

In the few short minutes I've played this amp I've fallen in love with it, but if I can't take it on the road it's really no use to me.

*edit on tubes*
Hm... the diagram on the top of the amp says there are 5 12ax7s, but when I took off the front grill to get a look at everything, there is just one tube up front. The chassis is drilled for five tubes, but only one is there. Looking through the holes in the chassis, it doesn't look like there is anywhere for them to *go* either.

bobcruz · #2 10-26-2011, 07:00 PM

Is there any way to creatively reinforce the existing chassis? Sorry I can't help answer your other questions....

Mr. Foxen · #3 10-26-2011, 07:05 PM

Any decent sheet metal worker can make a new chassis. Folding, welding and hole cutting are all that's needed. Plenty of amps are on generic chassis with extra holes for otehr moels. No worry there.

But really, the amp should be fine on the road if you don't abuse it. A shockmount case will take any impact out. Chassis bent by transformers aren't uncommon and aren't fatal. Not being able to take an amp on tour basically sounds like BS. The really early Matamp on aluminium chassis had a problem with bending, so they went steel, but that was on a Fleetwood Mac tour, with 60s vehicle suspension. I have no idea what the state of the roads compared then and now, but sure smooth ride tech has improved. Just be aware when you are carting it about.

will33 · #4 10-26-2011, 07:22 PM

Perhaps an oversized roadcase so you could stuff 2-3" of that foamy padding all around? A real shockmount with the springs would work for sure but can get rather spendy.

Mr. Foxen · #5 10-26-2011, 07:24 PM

Spend on a shockmount case, and you have a shockmount case at end of tour, spend on a new chassis, and serious tech time to transfer across and all you are left with is scrap aluminium and an amp that has lost its potential vintage value.

BassmanPaul · #6 10-27-2011, 09:52 AM

in order to replace the chassis you would need, in essence, to completely disassemble the amplifier and then rebuild it almost from scratch. Any resale value the amp had would be reduced to nil. Cost for such an exercise: considerable.

Feral Feline · #7 10-27-2011, 10:35 AM

For the amount of dosh it'll take to beef up the chassis, just have a BEEFy CLONE made, and then sell me the original. A win-win situation!

micahbell · #8 10-27-2011, 05:39 PM

Alright, thanks for the advice/thoughts.
On the weekend I'm going to dismantle the amp a bit and have a look at it with my buddy to see the situation and what can be done.
I'll try blocking it off under the transformers (if possible) before looking for a new chassis.

I also just realized I didn't post a picture of my new rig, so here it is!
Picture is bad, but the lighting in my basement sucks so I'm stuck with it for now.

http://i.imgur.com/0xmqE.jpg

Lo-E · #9 10-27-2011, 05:48 PM

While it's true that any sheet metal fabricator could easily make you a new chassis - possibly even an auto body shop, I agree with the others here that it makes little sense to replace the chassis in a vintage tube amp.

What you said about placing some sort of blocks or cribbing around the transformers for travel makes some sense, remember that it will be plenty hot in there just after a show when you are packing up and plan accordingly. Truthfully, I doubt you'd need any of that. There are plenty or Garnet amps out there that are still going strong since the sixties. They wouldn't still be in business if their amps fell apart on the road, and there's no shortage of Garnet amps on the road - especially in Canada.

Mr. Foxen · #10 10-28-2011, 07:01 AM

Usually the damage done by transformers to chassis is they bend inward, assuming it is a transformer at each end job. So maybe just put a piece of wood between them to counter the tendency to collapse inward.

jungleheat · #11 10-30-2011, 04:52 PM

So you're worried that a 50 year old amp will suddenly "get bent"? If it hasn't by now, it seems unlikely that it ever would.

Again, if the chassis bends, that's exactly what you would have, a bent chassis. Shouldn't have any other effect on the amp, unless it bends so much as to bend the shaft of the volume knob or something (a $20 fix, if that).

If you like the sound of the amp that much, and are THAT worried about its roadworthiness, keep it as a dedicated "studio"/practice amp and get something more modern/durable for touring. You could even just get something like a Mesa 50/50 (or 2:50, they're basically the same thing) power amp for about $500 or so, which is probably less than you would spend replacing the chassis for the Garnet (which at the same time as mentioned would pretty much kill any resale value).

Personally, I would just check out the guts of the amp, see how durable it looks, keep in mind it's survived half a century already, and take my chances on the road (maybe babying the amp a little if necessary). Then, IF something happens, and IF that something causes the amp not to function at 100% THEN I would look into getting it repaired.

You're going about it backwards, trying to fix it before it breaks, which is a waste of both money and time, not to mention defacing what is probably a pretty cool vintage amp.