caps for 70s ampeg svt

[jcs]

my friend has a later 70s ampeg svt on his bench,he needs a 100mf-40mf can at 450 volts minimum..

anyone know where these can be sourced?

the old one is a sprague #270561-8

1 3/8 x 3 1/8 and the mounting center is 1 3/4 apart...thanks, jcs

[stokes]

www.fliptops.net try these guys they will get you as close as possible.It is sometimes impossible to find exact cap replacement values for older amps,when I have to compromise values I try for a little higher mf's and the same or higher volts.

[Amp Kat]

www.fliptops.net try these guys they will get you as close as possible.It is sometimes impossible to find exact cap replacement values for older amps,when I have to compromise values I try for a little higher mf's and the same or higher volts.

Yes I agree and I used an 80uf and a 30uf I believe that I got from CE Distribution in a can form to replace the old black paper type originals. The only problem is that 80uf also goes series to another cap and the ground on the cans are all tied together so you may want to use an axial to isolate that ground for a series connection. Actually there are two cans in the old svt 12DW7 type with 6-6550's. Something else you should be aware of is after you install the new caps your voltages will tend to rise quite a bit. There is a either 4.7k or 8.2k 15 watt dropping resistor that sets the preamp voltages and the voltage on the one I did was at about 600+ voltas and I think it fried that first 12DW7 so you may check that and make sure your getting the correct voltages off of the schematic. If not you might want to raise that resistor some to bring them down.

[jcs]

apparently vibroworld makes custom multi section caps for different amps..

anyone else custom build multi section cans?

thanks for the responses..

[J Martin]

You don't need any custom caps or the exact original values. You will have to use additional locations below the chassis, however, to fit every thing you need. Its not a problem because modern caps are a lot smaller than the old ones.

What I do is use the two original can positions for the first filter stage. Another pair of axial caps will fit in the compartment to the rear of the power transformer. Caps can also be put up front in a similar space.(I forget which side at the moment) In fact that area can be punched out for radial caps if you are so inclined. You will have to use electricians knock out punches for that as it will ruin the common chassis punches. Punching is optional as you should be able to fit axials in that space. I must have done about 15 SVTs over the last few years. Once you get it up on the bench, the rest is easy.

[stokes]

Like J Martin says,no need to pay extra for custom caps,a little imagination and you can fit them without punching holes,all the Ampegs I have done I've used Sprague axials and never had a problem.

[jcs]

thanks a bunch!

i will pass this info on, it sounds like this customer is determined to keep stock appearance/values as much as possible..

are the later 70s svts that collectible?

this tech is all of a sudden seeing older svts being used by bands again in the area,sheesh, they must have a forklift and a moving van!

[Amp Kat]

The whole problem is they don't make those exact values anymore and any that are that value are just as old and maybe dried up as the ones your replacing.Ampeg's technical program was sold to LOUD technologies and to be blunt about it they bloody well suck (S) The SVT is one of a kind and it's tone is very unique and they are loud but the value of the old 70's may be in the transformers even as big as they are theres said to be some mojo there.

[jcs]

amp kat, i was wondering myself how vibroworld.com actually makes these multi section-caps?

[Amp Kat]

amp kat, i was wondering myself how vibroworld.com actually makes these multi section-caps?

I'm not sure they do as they may just be a distributor for them but if you've ever seen an electrolytic inside it's nothing but a piece of foil wrapped up in a roll acting as plates. A multisection cap would have 2,3 or 4 wraps in one making the negatives all tied together or to the can itself. That's the bad part about mutisections is if you need to isolate the negative side your SOL but they are good on space in old Hi-FI's and some old amps. The SVT I did came out real nice using the cans as I didn't have to cram axials all over the place, just a few which fit quite neatly between the multisections.