Scored a killer vintage Ampeg SVT

[PeterAM]

Tried to find rear pics of MTI's on Google Images but the only one I found claiming to be an MTI had round holes and no paint. However, some do confuse Skunkworks SVT's with MTI's. Maybe someone can chime in who has one. At any rate, I wouldn't worry too much about it.

Thanks JimmyM. It is indeed no worry, it would only be nice for cosmetics.

 

[PeterAM]

Ampeg amps were full of revisions. Post an image of your back screen, there may be clues as to if it's original.

Thanks for the pics.
I am sure looking at the serial number (paper sticker serial #335637) and the empty frame on the far right where a skunkworks would say "Made in the USA...", that mine is an MTI. I will have a look at the dates on the pots and transformers to estimate its year of manufacture.

 

[PeterAM]

Didn't happen to get this at a little old lady's garage sale, didja? 

I kid I kid. Great find!

Congrats and welcome

Thanks!
No, unfortunately it wasn't a garage sale bargain. These amps are pretty rare over here (The Netherlands) and still quite popular. Keeps the prices pretty high.

 

[two fingers]

That's the way you introduce yourself!


"Hey I'm new here. Check out my vintage SVT."

Is that your TransAm in your avatar?

If so....

 

[beans-on-toast]

Thanks for the pics.
I am sure looking at the serial number (paper sticker serial #335637) and the empty frame on the far right where a skunkworks would say "Made in the USA...", that mine is an MTI. I will have a look at the dates on the pots and transformers to estimate its year of manufacture.
View attachment 3236648

I’ve not seen one like that.

I suspect that it is a replacement grille. It doesn’t have the proper cord winders. The fasteners with the washers are inconsistent.

As is, it acts to keep you safe.

 

[PeterAM]

I’ve not seen one like that.

I suspect that it is a replacement grille. It doesn’t have the proper cord winders. The fasteners with the washers are inconsistent.

As is, it acts to keep you safe.

That is indeed the most important; keep me and tubes safe.

 

[PeterAM]

Took some pictures from the inside.
First impression: Best build amp I have ever seen! (I have seen a lot and have build quite some).
Second: The dents in the covers of the PT and OT tell me that the poweramp chassis has been dropped or so... without actually hurting the amp!
Third: R6, R7 and R25 have clearly been modded into values for 12DW7's. It should originally have carried 12AX7's as seen on the sticker. It presently also carries 12AX7's, hence the gain overkill; I will get some 12DW7's.
Fourth: One triad of 6550's has apparently failed somewhere in the past. One of the 1 ohm cathode resistors was replaced and the anode wires have been re-soldered on the PCB. I thought these amps were designed to take out the plate resistor when the corresponding tube would fail. Although, it seems that the plate resistors are 0.15 ohm instead of the 5 ohm on the 6550 poweramp schematics; 0.15 ohm is too low to take them out in case of tube failure, I guess.
Fifth: The numbers on the PCB's read: 210811-2 and 210811-1; presumably these are from 1981. The PT reads:3071-1 / 2 142-TK; the heaterT reads: 320829-2 / 2 132-TK; the OT reads: 320825-1 / 2 142-TK.
Possibly, the 82 in the OT and heaterT indicate that they are from 1982.
Does anyone know whether these are JP or US trannies?

 

[beans-on-toast]

In the power amp, check the hum balance pot date code, a year followed by the week of the year. Also check the bias and balance pots.

 

[lespaulbass]

regarding amps, that is a bad boy