Vintage Tube Amp - replace caps?

rsadasiv

rsadasiv

Burnin' Daylight
I've got a 40-ish year old silverface Bassman head. I bought it used and the seller indicated that he had not put a lot of maintenance into the amp ("you might want to replace the tubes at some point - I never did"). It works/sounds fine, but I brought it in to an amp tech to check it out and he is recommending that I replace the caps for $300.

I only paid $400 originally, but I do like (and use) the amp. Do I tell the tech to go ahead and do the work or just keep playing it as is?
 
Are you having trouble ie: noise?

If yes, have the cap job done as the tech will tune up your amp.

If no, jam away. You may need it in the future.
 
Modern Saint said:
Are you having trouble ie: noise?

If yes, have the cap job done as the tech will tune up your amp.

If no, jam away. You may need it in the future.
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No big noise problem. Works/plays fine. On the other hand, 40 years without any TLC is a long time.
 
After 40 years it's common to need caps replaced. Still, if it's not giving you problems and no caps are leaking, I wouldn't worry about it. To me, it's worth replacing the caps on an old Bassman if they need it.
 
rsadasiv said:
No big noise problem. Works/plays fine. On the other hand, 40 years without any TLC is a long time.
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Caps issues are kind of a touchy subject. When a tech mentions cap job, they usually just replace the electrolytic caps. Over time of use and none use, these caps start to leak (think battery) and start having difficulty doing what they were designed for. This is do to being under stress from the High Voltages that they operate at. With tube amps, they can tolerate the changes more while SS will have many issues.

Pros of a Cap Change
  • Better efficiency
  • Tighter Bottom End

Cons of a Cap Change
  • Costs
  • Without amp while being serviced
 
PunkKitty said:
After 40 years it's common to need caps replaced. Still, if it's not giving you problems and no caps are leaking, I wouldn't worry about it. To me, it's worth replacing the caps on an old Bassman if they need it.
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This is how I look at it. You just don't want them leaking all over the place.
 
I really need to get my old 71 SF recapped so I can use it without worry.
They still look ok but I got a good bit of noise going on.
So right now it just sits in my music room and gets played for maybe 30 min every month or two.
Should be my priority expense for the new year I guess.
 
Sounds a little pricey for a cap job, honestly. A set of power supply filter caps for a twin reverb is about $65 (just priced it out yesterday). You're looking at something similar for a Bassman. I can't see labor being that much.

Now, is he swapping out more than the filter caps?
 
I re-capped my SF Twin last year. I only replaced the electrolytics though. I bought the orange drops too, but was happy with how it sounded after doing the electrolytics and didn't want to screw anything up by messing with it more than I needed to.

If you're comfortable using a soldering iron, it's not very hard to do. Download a copy of the schematic & wiring diagram for your amp to make sure you're using the right values and replace them one at a time, paying attention to the polarity. The nice thing about old amps is the point-to-point wiring boards/posts make it very easy to replace parts. Much easier than a PWB.

I bought my parts from justradios.com, http://www.justradios.com/. They specialize in parts for old tube electronics.

Edit: $300 sounds about right if they're doing all the electrolytics, and not just the power/filter caps. I was quoted $250 by Pete Cage (http://www.audiocage.com/) up here in Damascus, MD. Not too far from Silver Spring.
 
wagdog said:
Sounds a little pricey for a cap job, honestly. A set of power supply filter caps for a twin reverb is about $65 (just priced it out yesterday). You're looking at something similar for a Bassman. I can't see labor being that much.

Now, is he swapping out more than the filter caps?
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That's what I was thinking. Hopefully there's more rolled into it for $300.
 
GilmourD said:
That's what I was thinking. Hopefully there's more rolled into it for $300.
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Yeah, for $300 I'm thinking all the electrolytics would be getting replaced. Still seems pricey.

WRT the post above about doing it yourself: DO NOT do it yourself if you don't understand how to drain filter capacitors, test if they're drained and safely work on your amp. No, it's not difficult, but it's also not difficult to make a mistake and for bad things to happen. Yes, I think $300 is pricey (even w/all caps replaced), but it's worth it if you don't know what you're doing.
 
wagdog said:
Yeah, for $300 I'm thinking all the electrolytics would be getting replaced. Still seems pricey.

WRT the post above about doing it yourself: DO NOT do it yourself if you don't understand how to drain filter capacitors, test if they're drained and safely work on your amp. No, it's not difficult, but it's also not difficult to make a mistake and for bad things to happen. Yes, I think $300 is pricey (even w/all caps replaced), but it's worth it if you don't know what you're doing.
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First time I did a filter cap swap I practically crapped myself discharging the old ones. LOL Now's it's like whatever.
 
wagdog said:
Yeah, for $300 I'm thinking all the electrolytics would be getting replaced. Still seems pricey.

WRT the post above about doing it yourself: DO NOT do it yourself if you don't understand how to drain filter capacitors, test if they're drained and safely work on your amp. No, it's not difficult, but it's also not difficult to make a mistake and for bad things to happen. Yes, I think $300 is pricey (even w/all caps replaced), but it's worth it if you don't know what you're doing.
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I don't know what I'm doing. :embarrassed:
 
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