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Time to change tubes (Ampeg SVT 4 Pro)

#21
Put the amp in stereo and plug one cab in amp A, play, and then unplug the cab from amp A to amp B and play again. If the problem is still there, then it might not be a power amp issue.
My problem was actually a soldering issue on amp A. I could only use the power amp B.
 
#22
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.
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It sounds like a worn-out fan. Mine will make a little noise on the initial start-up and then goes away. This amp is still in production and Ampeg should be able to tell you which places can help you with parts if you give them a call.

You might solve the problem by opening the amp and using a can of air to clean the rotating center area.
 
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#23
Lock the fan rotor and see if the noise goes away. Or, you can unplug the fan if it's not soldered.

Note, this is a temporary troubleshooting step and not a cure.
 
#24
baxter_x said:
Put the amp in stereo and plug one cab in amp A, play, and then unplug the cab from amp A to amp B and play again. If the problem is still there, then it might not be a power amp issue.
My problem was actually a soldering issue on amp A. I could only use the power amp B.
Click to expand...

I’ll try this but I have a berg hs410 and a dg212n I can try at the same time. I’ll do both, and then A/B and see which one sounds the worst, if at all. Thanks for suggestion. I only picked up the berg today actually. At an amazing price...450CAD and it’s like brand new looking. Not even pilling on the fur cause I used a fabric removing machine. Think I got a good snag?
 
#25
JimmyM said:
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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my head is like..idk 10-14 years old? Any way to tell how old the amp is? Thanks for the suggestions I will look up mouser and try to figure out what fan is inside the head. Shouldn’t be too difficult, I hope.
 
#26
120mm x120mm x32mm
24 volts
80 cfm

Ampeg will usually use a cheaper sleeve bearing fan.
so they make a ton of noise when they start to go out.
go with another sleeve if you want or ball bearing

you can use most 120mm fans
needs to flow 80 cfm or higher
and be 22 to 24 volts

far as i remember its temp control fan and voltage measured around 12 to 22 volts
and the regulator was set at 22 volts

just typical 24/28 volt muffin fan 120mm x 120mm
 
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