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Time to change tubes (Ampeg SVT 4 Pro)

baxter_x

baxter_x

Nov 27, 2013
5,017
5,364
EU
www.hellofaride.fr
#1
Hi,

Since a several weeks and maybe a bit more, I hear weird noises coming out from my SVT 4 Pro.
Like little cracks, quick volume drops, slightly distorted sounds. Even without playing. I bought this amp used in 2009, and I think it was made in 2008. I never changed the preamp tubes since then.
Could that be the reason why I hear all these strange noises?
Anyway, that might be a good thing if I afford my amp new tubes I guess?

Thanks
 
#5
I don't know if swapping them around will help since I don't know what each tube does or how many are bad. If you have a known good tube, you could try swapping it out one at time till you find a culprit, or you can gently tap on each tube with a chopstick or butt end of a wooden spoon and see if any exhibit signs of being broken.
 
#7
baxter_x said:
Well... I'm gonna change all of them. It's been too long they haven't been changed, not to say never.
Click to expand...

Don't do this. Its a silly idea put about by people who sell tubes. Fix what the problem is rather than throwing money at half a dozen different guesses which it might be none of.
 
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#9
Fix what is the problem. If all the tubes are dead, then you have a much bigger problem than just the tubes. Problem might be some cracked solder or a corroded connector, that changing tubes won't address, if there is a tube problem, it will probably be just one, could be just one tube socket. Going directly to the expensive thing to do on the offchance is not a sensible plan.
 
#15
baxter_x said:
Well, despite cleaning the preamp PCB and swapping tubes, the noises are still there.
However, I noticed something interesting: It only happens in mono and not stereo.... Would you guys have any idea in this issue?
Click to expand...

I'm starting to have a bunch of issues with my SVT4-pro now, even tho this is a dead thread. Fan noise, some high pitch sound going from high to low and some squealing. doesn't really affect the tone, sounds like moving parts grating or something. Amp looks brand new inside. I wonder what the issue is.
 
#17
As5Hat said:
I'm starting to have a bunch of issues with my SVT4-pro now, even tho this is a dead thread. Fan noise, some high pitch sound going from high to low and some squealing. doesn't really affect the tone, sounds like moving parts grating or something. Amp looks brand new inside. I wonder what the issue is.
Click to expand...
Fan worn out, maybe?
 
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#19
JimmyM said:
Fan worn out, maybe?
Click to expand...

it could be the fan. Seems like an intermittent squeal. Changed the tubes so it didn’t seem like a power amp issue. If it’s a fan I can probably change it myself but getting the part might be hard. Any idea where I’d find amp parts in Canada? Perhaps a website that ships everywhere and has warehouses on both sides of the border.
 
#20
As5Hat said:
it could be the fan. Seems like an intermittent squeal. Changed the tubes so it didn’t seem like a power amp issue. If it’s a fan I can probably change it myself but getting the part might be hard. Any idea where I’d find amp parts in Canada? Perhaps a website that ships everywhere and has warehouses on both sides of the border.
Click to expand...
I would think you could find a proper fan with the same specs at any electronic supply house like Mouser. Very important to get one with the same specs, though. And I'm not sure if this has changed since Yamaha bought Ampeg, but JAM Audio has been their distributor in Canada for a few years.
 

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