'66 Ampeg Reverberocket II can cap question

[gui_tarzan]

So this model has a can with a 70/40/40 @ 450v and the closest replacement I can find is an 80/40/30/20 (525v). I'm not concerned about the 80uf section, but if I use the 30uf section in place of the second 40uf is that going to be enough for the last stage of the power supply in this amp? My gut says yes due to very loose tolerances in caps but I just wanted to double-check.

[xtian]

Sure, no problem.

[Invertiguy]

Most electrolytic caps are +50/-20% tolerance anyway, so 30uf isn't really that far out of spec. If you're still concerned, you could always put the 30uf and 20uf sections in parallel to get a 50uf cap, which is more than enough.

[gui_tarzan]

Yeah, I thought about that. Thanks guys, I figure it's better to ask than do something stupid and cause more problems.

[Leo_Gnardo]

So this model has a can with a 70/40/40 @ 450v and the closest replacement I can find is an 80/40/30/20 (525v). I'm not concerned about the 80uf section, but if I use the 30uf section in place of the second 40uf is that going to be enough for the last stage of the power supply in this amp? My gut says yes due to very loose tolerances in caps but I just wanted to double-check.

If your replacement is CE make plans to replace it again soon come, and then again. I'm not much for playing idiot's delight with CE multisection caps and even moreso considering their high prices. I put in 50+50/500V cans (Ruby, F&T, LCR, JJ) and fly another 47/500 axial in there to cover the 3rd section. Needs a clamp for the 50+50 cap. I've done scores of old Ampegs like this and nary a failure.

[Stevem]

Good thing these are / where not high gain amps, as the can cap / all circuits grounded to the same point thing makes for un-needed hum.
When I do these amps for a customer that plays the darn thing I put in all separate caps and leave the shot stocker hanging there for looks, just not hooked up of course!

[Leo_Gnardo]

Good thing these are / where not high gain amps, as the can cap / all circuits grounded to the same point thing makes for un-needed hum.
When I do these amps for a customer that plays the darn thing I put in all separate caps and leave the shot stocker hanging there for looks, just not hooked up of course!

In 60's Ampegs, besides the multisection typically there are a couple of single caps filtering the preamp feeds. Old Ampegs are notorious for imperfect grounding schemes - I've spent many an hour optimizing some especially for customers who play quiet jazz and can't stand buzzes in their amp. It CAN be done, and the old trick of bringing the last filter's negative lead to ground near the input circuit seems to help.

Haven't had an Ampeg customer yet who complained about their silver cylinder being replaced with a black, blue or any other color one. OTOH Fender owners seem to have a different attitude sometimes - for Champ and Princeton I often leave the original in place & fly a collection of singles in right over it inside the chassis.

[gui_tarzan]

That's something to consider as well.

[RightLurker]

If it's of interest, Fliptops.com specializes in Ampeg parts and has the correct replacement can cap. I think it costs around $38. Based on my experience, they are great to work with.

[gui_tarzan]

Thanks but it says the domain is for sale.

?

[Stevem]

If your model rocket has the 6U10 tube in it, I would get some NOS spares while they can be had!

[didit]

Thanks but it says the domain is for sale.

?

It's http://www.fliptops.net/

[gui_tarzan]

That's better. Thanks!