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Old 6th September 2012, 01:01 PM   #1
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Default What gauge enclosure for KT88 AMP?

Guys, Im looking at several enclosure options and am between a hammond (18 gauge) and a cake pan (14 gauge). Wondering if anyone has any experience with the hammond or can tell me if the 18 gauge is strong enough for some serious transformers?

Thanks!
Fat Daddio's Anodized Aluminum Cake Pan 12"x16"x3" Deep | eBay

Hammond Mfg. - Aluminum Chassis & Bottom Plates (1444 & 1434 Series)
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Old 6th September 2012, 02:01 PM   #2
palmas is offline palmas  Portugal
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Nop, it will flex if you add serious iron on it!
need some sort of structure to keep it in the original shape.
For those big iron beasts I use 5mm duraluminium...
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Old 6th September 2012, 04:49 PM   #3
kevinkr is offline kevinkr  United States
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For about the cost of a flimsy Hammond chassis you can have Dirty Dawg Amps make you a brawny custom aluminum chassis, here: Amp Chassis

I built my GM70 amps on 12GA DD custom chassis, the output transformers weigh >10lbs - no deflection at all.

I am a very happy customer having had a fair number of custom chassis made DD, quick turnaround too. Highly recommended
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Old 6th September 2012, 04:58 PM   #4
smbrown is offline smbrown  United States
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I've had Dirty Dawg make several chassis now for me, they are outstanding! I add an 0.125" bottom plate & similar thick front panel and the things are very strong. Turn around time and customer service are great!
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Old 7th September 2012, 09:36 PM   #5
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Thanks guys, I've contacted DD and Yaeger and will likely wind up with one of each for diff projects. Thanks!
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Old 8th September 2012, 01:34 AM   #6
Loren42 is offline Loren42  United States
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I used an 0.050" thick Hammond chassis made of aluminum!

But, I mounted the transformers on a 1/4" plate aluminum that is bolted to that chassis and then I added a 1/4" vertical brace at the front of that transformer plate inside the chassis where you can't see it. It divides the tube audio section from the power supply section and it provides unparalleled rigidity to the whole thing.

My amp does not flex or sag and as you can see I have lots of iron on mine.

Click on the image for the full sized view.

Click the image to open in full size.

All the metal is black anodized. Here is the bottom view with the bottom cover off:

Click the image to open in full size.

Essentially, this is two mono blocks on a single chassis. It probably weighs 50 lbs.
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File Type: jpg t-rexinternal.jpg (163.0 KB, 136 views)

Last edited by Loren42; 8th September 2012 at 01:50 AM.
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Old 8th September 2012, 03:34 AM   #7
Pano is offline Pano  United States
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Be kind, please resize your photos for the web.
(I've done it for you)
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Old 8th September 2012, 03:58 AM   #8
ChrisA is offline ChrisA  United States
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Quote:
Originally Posted by jhl1963 View Post
Guys, Im looking at several enclosure options and am between a hammond (18 gauge) and a cake pan (14 gauge). Wondering if anyone has any experience with the hammond or can tell me if the 18 gauge is strong enough for some serious transformers?
Get one of these in 12 ga. That is a "deluxe" chassis. The metal is really thick and he makes them custom size for cheaper than Hammond. He can weld the corners if you ask but You don't need that if you plan to build a wood cabinet for your amp.
Amp Chassis

Here is one of his chassis in a wood cabinet I'm building. It was the first "test fit" and it worked the four bolts up from the bottom fit perfectly in the "clip nuts" in the chassis. I used #10 machine screws. The photo is of the rear. Later there will be some kind of from panel with exotic veneer
https://www.dropbox.com/s/h4nu7pdyae...%20chassis.jpg

Here is a photo of a "deluxe" chassis where I hope you can see the metal thickness. It is not the chassis design you want as this one was custom made for me for some portable gear. But see the metal thickness compared to screw head or nut on the switch. It is thick stuff.
https://www.dropbox.com/s/nes72pnq0w...gle%20view.jpg

One other thing. See how I have mounted the transformers in the above photo. This why is MUCH stronger then the stand up style. The iron core becomes part of the structure rather than a weight sitting on top. Also the lead wires are better protected. This amp is a low power stereo amp with EL84 power tubes but I would do a KT88 amp the same way

In either case be sure and buy a bottom plate too.

Last edited by ChrisA; 8th September 2012 at 04:09 AM.
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Old 8th September 2012, 05:06 AM   #9
AJT is offline AJT  Philippines
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ga.12 is 1/8 inch thick......i have used ga#13 before...
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Old 8th September 2012, 12:14 PM   #10
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Originally Posted by Tony View Post
ga.12 is 1/8 inch thick......i have used ga#13 before...
Here is a thickness chart for you. 12ga is not 1/8 or .125 thick

You can easily beef up a thinner chassis by making what is called a top hat channel and have something that is lightweight and strong. its a simple process of making an offset on each side of a metal piece. See http://www.youtube.com/watch?v=j9wdotHTtZQ
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Last edited by Original Burnedfingers; 8th September 2012 at 12:19 PM.
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