SVT transformer dims request

[jelle]

At the moment I'm drawing out a chassis for an amp that I plan to use ampeg SVT power and output transformers but I cannot find info about the dimensions of the holes that have to be made in the chassis to accommodate these transformers

Does anybody know the dimensions of the holes that are needed in the chassis?

Thanks,

Jelle

[David Root]

Assuming you mean the classic original SVT, you're in luck. I have a '75 SVT. I'll be in my shop tomorrow and if I can lift it onto my bench without putting my back out I'll measure the mounting hole dimensions and report back.

They're both laydown, or Z-mounting, so you will need the bell cut-out dimensions too. I trust you know that this iron will cost you close to $600!

Is this going to be a bass amp?

Unless someone already has this information now, of course!

[jelle]

David,

Thanks for your offer! I appreciate it a lot.
I also need the dims for the big square/rectangular hole where the wires go through. A drawing would be appreciated.

Thanks,

Jelle

[David Root]

I just edited my post re the bell cut-outs.

[jelle]

David,

Please keep the info coming. Via the ampage I learned that this amp also has a separate heater transformer. I'd be interested in the dims of this one too.

Also a pic of the position of these transformers compared to eachother (to prevent hum) would be great!

I hope it is not too much too ask but it would be appreciated a lot!

This will be a guitar amp....

Thanks,
Jelle

jwelagen (at) hotmail.com

[David Root]

OK, here's the word:

PT and OT mounting centers are the same. They are 4 3/8" x 3 1/2". The PT cut-out is 4 1/8" x 3 1/8", to accomodate the lower bell. The OT cut-out is 4" x 3 1/4", because it has no lower bell.

The lamination stacks on both transformers (ie the outside dimensions)
are 5 1/4"x 4 3/8" viewed from above, so you need to know this for locating them on the chassis. They are at the center of either end of the longer chassis dimension, which is 18 1/4" x 12 1/4" with the PI and driver tubes in between. There are two can caps on top and three more filter caps underneath, which is a bit messy. I would relocate all filter caps upstairs as can caps in a new build.

The preamp tubes are on the separate preamp chassis and connected by a 10 or 12 wire umbilical cord. (This amp has 14 tubes in it, 9 on the power chassis and 5 on the preamp chassis).

The filament transformer is on the same side as the PT, immediately below it in the lower left hand corner of the chassis (viewed from underside of chassis). It is an X-type ie upright mounting and the mounting centers are 2 3/4" x 2". It should be rated 6.3VAC @ 13A minimum. IIRC the original is 16A. I just tried to check that on schematicheaven.com but it's not working, seems to have been shut off, "account suspended"!!

I would guesstimate both transformers weigh 11-13 pounds each. I suspect Mercury Magnetics is the only source of exact clones, if that's where you're going. You will need a steel chassis at least 16 ga. thick, or minimum 1/8" to 3/16" aluminum. Why not just buy an old V-9, that is the guitar amp version of the SVT I think? But that would take all the fun out of it, right?

I'll take some pics tomorrow. Good thing I didn't put it back together yet!

[Richie]

I sent a blown SVT OT to heyboer to build one.. i think it was about 210.00 and shipping.. not bad compared to the other prices.
I'd say they can build one. Or they may have both tranny specs to build a set.

If your building your own chassis.. you might look at these..
http://cgi.ebay.com/1970s-FENDER-300-wa ... dZViewItem

They are NOS for a PS300 they are as big if not bigger than the SVT trannys.. and if you ever heard one of these amps against an SVT..
you might have a different thought about that amp. They are a very good bass amp. 300watts etc..

I think the guy has the PT and all the other trannys.. just something to think about.. good quality trannys for about the price of half the SVT set.

[David Root]

Sounds like a good deal to me. Good to know there are alternatives. Mercury ARE good, but they're VERY proud of their product too!

[jelle]

David,

I owe you a beer! Thanks a lot for the info! I really appreciate it.

And Richie: I'll take a look at those fender trannies too. Great info!

Thanks!

Jelle