Amp volume fades in and out

[syscokid]

The Tung-Sol is $20 more than the other for the set. Thats some bull!!

Same factory, yes, but the tubes are built differently from each other. It also doesn’t mean that the Tung-Sol is $20 better… but it could be .

This is why pin 5 voltage is critical.

I will get on that after work.

AMS is your friend…

Also verify that the phase inverter tube is good.

One thing is also to have a look at how they are lighting up, but not always telling.

Yes, yes, yes! All the tubes! Test in a dark room. However, there are some preamp tubes that have their heater filaments very encased in their plate structure which makes it much more difficult to see a lit up heater filament.

 

[67plexi]

the way I was trained was visual inspection then voltage chart the amp AC input primary AC output secondary voltage then DC voltage B+1 through B+5 Power tubes DC then Phase Inverter DC then Preamp DC last if that's OK heater AC voltage then tube tester
if that checks out adjust to factory spec. If failed components found you need to know why
I quit working on amps got tired of customers bitching about the price of tubes to replace my stock at current prices

 

[Mitch Pearrow SJMP]

I do hope you get it all sorted out buddy.

 

[LiveeviL2000]

I do hope you get it all sorted out buddy.

I'll check what I can on my own. There is a really good place here called Fuchs that does nothing but amps. I'm probably going to take it there instead of me guessing all day. Their rates arent too bad.

 

[Mitch Pearrow SJMP]

I'll check what I can on my own. There is a really good place here called Fuchs that does nothing but amps. I'm probably going to take it there instead of me guessing all day. Their rates arent too bad.

I do hope it’s something simple.

 

[67plexi]

Andy Fuchs does good work

 

[LiveeviL2000]

Andy Fuchs does good work

That is the reputation.

 

[LiveeviL2000]

OK the weirdest thing, I unhooked everything. Then hooked the amp up to only my Randall cab, I've been playing and noodling for almost 3 hours and the sound hasnt faded.
Could it have been the Carvin cab? or maybe the combination of the two cabs?

I don't get it.
Mind you if that is the fix, I'm not complaining. Just weird.

 

[Deleted member 1331]

Impedence mismatch making it work too hard? Possibly

 

[LiveeviL2000]

I had the amp set at 4ohms.
Both cabs are 212 with 16ohm speakers.
Possibly a loose wire/cable maybe?

 

[fitz]

I had the amp set at 4ohms.
Both cabs are 212 with 16ohm speakers.
Possibly a loose wire/cable maybe?

Check the wiring in the Carvin cab.
Put a meter on the output and make sure you're seeing the right impedance.

 

[Mitch Pearrow SJMP]

I would do as @fitz said.
Could very well have been a mismatch ,, or a bad connection with the other cab.

 

[fitz]

By output, I meant the cab jack.
Although now that I think about it, I've occasionally had strange volume issues from just a loose speaker cable. or dirty jack.
Try some Deoxit on the amp & cab jacks, and maybe check the continuity on the speaker cables.

 

[Jethro Rocker]

Mismatch shouldn't make amp cut though. And back in. But a loose wire in a cab could.

 

[LiveeviL2000]

Mismatch shouldn't make amp cut though. And back in. But a loose wire in a cab could.

Everything seems fine.
Checked the output on both cabs and it’s fine.
I’m thinking something was loose.
I hooked the Carvin to it for a while and it’s fine.

 

[Mitch Pearrow SJMP]

Everything seems fine.
Checked the output on both cabs and it’s fine.
I’m thinking something was loose.
I hooked the Carvin to it for a while and it’s fine.

Check all of your speaker cables..

 

[LiveeviL2000]

Check all of your speaker cables..

I did. And I don’t get it.
Regardless, I’m selling the Carvin tomorrow and getting a JCM900 412. I know a guy who is selling off 6 cabs for $300 a piece.
If I can I want to get a full stack. But for now, the money I get for the Carvin will pay for the b cab.
He doesn’t want his wall of Marshall’s anymore. He’s selling all but the middle stack and the stack all the way to the right.

 

[mcblink]

I did. And I don’t get it.
Regardless, I’m selling the Carvin tomorrow and getting a JCM900 412. I know a guy who is selling off 6 cabs for $300 a piece.
If I can I want to get a full stack. But for now, the money I get for the Carvin will pay for the b cab.
He doesn’t want his wall of Marshall’s anymore. He’s selling all but the middle stack and the stack all the way to the right.
View attachment 89789

That's a nice deal, I wish I knew someone selling off their wall for 300 a pop!

Hell yeah!

 

[Mitch Pearrow SJMP]

Congrats on the incoming cab.
Great deal as well

 

[Deleted member 1331]

Mismatch shouldn't make amp cut though. And back in. But a loose wire in a cab could.

It might if the output tubes are failing, I believe.