My first tube amp, need help...

[blue_lateral]

Recapping would be a good idea. In the power amp though someone may already have done some of it. Those orange drops are probably not original. They're good replacements, though. The black tubular ones are sprague black beauties. In general, old plastic tubular capacitors are paper (horrible) or paper-in-oil (worse). There was one version of the black beauty that was mylar (good), I think they were the ones with red lettering, like yours. It's probably worth looking up.

If it's quiet (not humming) then the filter capacitors (the can and probably the big orange round one) are doing their job. Some will say replace them anyway. I notice your power transformer is fused, though. If one of the filters shorted it probably would just blow the fuse, rather than toasting the power transformer.

I am not familiar with the green cornell-dubilier ones in the preamp. I'll bet they're paper. If they are you should replace them. Leakage is their common failure mode. They can be tested for leakage like this
http://www.tone-lizard.com/VTVM.htm
or this.
http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html
but it's generally not worth the trouble. Nobody complains about the sound of paper capacitors if they're good. It's just that they're never good.

PP 6bq5 amps can be really sweet. I think you're gonna love this thing :thmbsp:

John

 

[kfa888]

Recapping would be a good idea. In the power amp though someone may already have done some of it. Those orange drops are probably not original. They're good replacements, though. The black tubular ones are sprague black beauties. In general, old plastic tubular capacitors are paper (horrible) or paper-in-oil (worse). There was one version of the black beauty that was mylar (good), I think they were the ones with red lettering, like yours. It's probably worth looking up.

If it's quiet (not humming) then the filter capacitors (the can and probably the big orange round one) are doing their job. Some will say replace them anyway. I notice your power transformer is fused, though. If one of the filters shorted it probably would just blow the fuse, rather than toasting the power transformer.

I am not familiar with the green cornell-dubilier ones in the preamp. I'll bet they're paper. If they are you should replace them. Leakage is their common failure mode. They can be tested for leakage like this
http://www.tone-lizard.com/VTVM.htm
or this.
http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html
but it's generally not worth the trouble. Nobody complains about the sound of paper capacitors if they're good. It's just that they're never good.

PP 6bq5 amps can be really sweet. I think you're gonna love this thing :thmbsp:

John

Nice, thanks for the info. :thmbsp:

 

[Charivari]

BTW I did deliver speakers to Seattle for you, am storing some speakers for you and let you keep the HPM's

The delivery and storage are in no way equal to being forced to take the HPMs back with me ... and I did bring 4 KLHs back here with me to save you a trip to deliver them.

- JP

 

[kfa888]

and I did bring 4 KLHs back here with me to save you a trip to deliver them.

- JP

And in doing so did Blue a favor not me. I wasn't about to take a loss AND deliver those half way across Washington.

So... Maybe you can make him take the HPM's.

 

[Charivari]

And in doing so did Blue a favor not me. I wasn't about to take a loss AND deliver those half way across Washington.

So... Maybe you can make him take the HPM's.

Perhaps. I can't force the HPMs upon him, though, as I left those in Seattle. When I left my place Friday with those sitting in my truck's jump seats, I swore they would not be returning, one way or the other.

- JP

 

[kfa888]

OK, back on track. So I play with the amp a little more this morning and hook it up to my Utahs, sounds good BUT, the amp now has an issue. I think it is tube related. In mono I get sound out of both speakers. In stereo I get sound out of one and a slight hum out of the other. If I swap the tubes left to right I get sound out of one speaker in mono and no sound in stereo? Seems weird to me. Also as the amp heats up it starts distorting a little.

As I really want to use this amp and I personally do not poses the skills to fix it I think I am going to take it to someone that knows what they are doing and has all the test EQ to make it right.

 

[Kegger]

Recapping would be a good idea. In the power amp though someone may already have done some of it. Those orange drops are probably not original. They're good replacements, though. The black tubular ones are sprague black beauties. In general, old plastic tubular capacitors are paper (horrible) or paper-in-oil (worse). There was one version of the black beauty that was mylar (good), I think they were the ones with red lettering, like yours. It's probably worth looking up.

If it's quiet (not humming) then the filter capacitors (the can and probably the big orange round one) are doing their job. Some will say replace them anyway. I notice your power transformer is fused, though. If one of the filters shorted it probably would just blow the fuse, rather than toasting the power transformer.

I am not familiar with the green cornell-dubilier ones in the preamp. I'll bet they're paper. If they are you should replace them. Leakage is their common failure mode. They can be tested for leakage like this
http://www.tone-lizard.com/VTVM.htm
or this.
http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html
but it's generally not worth the trouble. Nobody complains about the sound of paper capacitors if they're good. It's just that they're never good.

PP 6bq5 amps can be really sweet. I think you're gonna love this thing :thmbsp:

John

All good points, except I like Paper in oil caps. (but old ones like these should get replaced)

 

[Kegger]

Yes if your planning on using the amp it should get rebuilt and all the old caps replaced.
Can't tell anything you have going on if the amp is need of a rebuild and it sounds like it does.
As was stated some of the caps look fairly fresh but others after closer inspection do look rather old.

OK, back on track. So I play with the amp a little more this morning and hook it up to my Utahs, sounds good BUT, the amp now has an issue. I think it is tube related. In mono I get sound out of both speakers. In stereo I get sound out of one and a slight hum out of the other. If I swap the tubes left to right I get sound out of one speaker in mono and no sound in stereo? Seems weird to me. Also as the amp heats up it starts distorting a little.

As I really want to use this amp and I personally do not poses the skills to fix it I think I am going to take it to someone that knows what they are doing and has all the test EQ to make it right.

 

[kfa888]

An AKer PMed me with a guy in portland that does tube amps. Just got off the phone with him, cool guy, I take it in next week :thmbsp: