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ColinTheAmpMan1 · 1st Jul 2018, 11:37 am

If that is what you want to use, it is the respected "Contempo" chassis. It is actually in two parts, one steel (cadmium-passivated) and one aluminium. I will quote from "Vox Amplifiers - The JMI Years" by Jim Elyea:

"The basic part of the chassis was the bottom, steel section. Of very simple construction, the bottom portion was a long, rectangular, three-sided box, with the two short ends open. The bottom edges of the long sides were bent out to form a pair of flanges that served as the base for the entire assembly. A pair of cage nuts was inset into each of the flanges to allow the chassis to be bolted to the wooden plinth. The steel chassis held the power section, including transformers and output tubes.
A separate aluminum chassis was bolted at right angles to the back side of the steel chassis. This aluminium chassis was basically an inverted "L" with a flange bent onto each of the long sides. This chassis held the preamp section and the top-facing control panel."

I currently have my AC30 chassis out of the cabinet and can give you the dimensions.

Width of steel chassis - 5.25"
Height of steel chassis - 1.25"
Width of flanges on steel chassis - 0.5"
Thickness of steel - 1/16"
Height of aluminium chassis - 5"
Width of aluminium control panel - 2.75"
Flange on aluminium control panel - 0.625"
Thickness of aluminium - 1/16"

The AC30 chassis is actually 21" long, but the AC15 must be shorter. Stephen Grosvenor, in his excellent book "A Service Engineer's Guide to the Vox AC30 Valve Amplifier", quotes the size of the cabinet of the AC15 single as 20" wide, 21" high and 10" deep. The AC15 Twin has the same height and depth, but the width is 27". Knowing that the control panel on the AC30 sits ~3.75" in from the outer edge of the cabinet, I would make an educated guess that the length of the AC15 Contempo chassis would be ~14" (bear in mind that the same chassis would have been put into both the Twin and the Single). There is also some addition to the covers of the transformers, such that bolts go through lugs on them and into the aluminium chassis to strengthen the joint between the two chassis. I should also add that on my AC30, the aluminium chassis only has a flange on the short leg of the "L", not both.

I have used Imperial units here, because I'm certain that Jennings Musical Industries would have done, but I had to convert to decimal fractions generally, as I don't know how to get Imperial fractions on this forum. I have used the American spelling of "aluminum" when quoting Jim Elyea, but the English spelling when they are my words. I apologise if any of this is confusing.

If I can give you any more info, just ask. My AC30 is out of the cabinet for a while, as I am giving it a bit of a restoration, putting period-correct carbon composition resistors and such like back in. Incidentally, don't use metal-film resistors in a classic amp like the AC30, even if it is a clone. It won't sound right. If you can't find carbon composition resistors, use carbon film - please!

Good Luck, Colin.

1st Jul 2018, 11:37 am	#5
ColinTheAmpMan1 Octode Join Date: Jan 2012 Location: Wimbledon, London, UK. Posts: 1,465	Re: VOX AC10 chassis dimensions If that is what you want to use, it is the respected "Contempo" chassis. It is actually in two parts, one steel (cadmium-passivated) and one aluminium. I will quote from "Vox Amplifiers - The JMI Years" by Jim Elyea: "The basic part of the chassis was the bottom, steel section. Of very simple construction, the bottom portion was a long, rectangular, three-sided box, with the two short ends open. The bottom edges of the long sides were bent out to form a pair of flanges that served as the base for the entire assembly. A pair of cage nuts was inset into each of the flanges to allow the chassis to be bolted to the wooden plinth. The steel chassis held the power section, including transformers and output tubes. A separate aluminum chassis was bolted at right angles to the back side of the steel chassis. This aluminium chassis was basically an inverted "L" with a flange bent onto each of the long sides. This chassis held the preamp section and the top-facing control panel." I currently have my AC30 chassis out of the cabinet and can give you the dimensions. Width of steel chassis - 5.25" Height of steel chassis - 1.25" Width of flanges on steel chassis - 0.5" Thickness of steel - 1/16" Height of aluminium chassis - 5" Width of aluminium control panel - 2.75" Flange on aluminium control panel - 0.625" Thickness of aluminium - 1/16" The AC30 chassis is actually 21" long, but the AC15 must be shorter. Stephen Grosvenor, in his excellent book "A Service Engineer's Guide to the Vox AC30 Valve Amplifier", quotes the size of the cabinet of the AC15 single as 20" wide, 21" high and 10" deep. The AC15 Twin has the same height and depth, but the width is 27". Knowing that the control panel on the AC30 sits ~3.75" in from the outer edge of the cabinet, I would make an educated guess that the length of the AC15 Contempo chassis would be ~14" (bear in mind that the same chassis would have been put into both the Twin and the Single). There is also some addition to the covers of the transformers, such that bolts go through lugs on them and into the aluminium chassis to strengthen the joint between the two chassis. I should also add that on my AC30, the aluminium chassis only has a flange on the short leg of the "L", not both. I have used Imperial units here, because I'm certain that Jennings Musical Industries would have done, but I had to convert to decimal fractions generally, as I don't know how to get Imperial fractions on this forum. I have used the American spelling of "aluminum" when quoting Jim Elyea, but the English spelling when they are my words. I apologise if any of this is confusing. If I can give you any more info, just ask. My AC30 is out of the cabinet for a while, as I am giving it a bit of a restoration, putting period-correct carbon composition resistors and such like back in. Incidentally, don't use metal-film resistors in a classic amp like the AC30, even if it is a clone. It won't sound right. If you can't find carbon composition resistors, use carbon film - please! Good Luck, Colin.