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Ampeg SVT-CL popping noise when switching standby off

KeenVox

KeenVox

Guest
Aug 22, 2018
8
1
Hamburg, Germany
#1
Hello all,

I'm new to the forum. Pleased to be part of this awesome community.
I've got a problem with my Ampeg SVT-CL and couldn't find any answer through the search function.
Everytime I go from standby to playing I get two short pops from my cabinet. After that everything plays clean and without any noise.
When I look a the bias light while the popping occurs, they flicker red after that everything is green. I've checked the powertubes with a wooden stick, but don't get any noise or any weird sounds.
Any suggestion what could be the cause?

Ps. Sorry for my wonky english.
 
#2
I have no idea what the cause is, but I've never found stuff like that to be an issue that should cause much concern. However, you are always welcome to contact Ampeg CS and get their opinion.
 
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#5
KeenVox said:
Hello all,

I'm new to the forum. Pleased to be part of this awesome community.
I've got a problem with my Ampeg SVT-CL and couldn't find any answer through the search function.
Everytime I go from standby to playing I get two short pops from my cabinet. After that everything plays clean and without any noise.
When I look a the bias light while the popping occurs, they flicker red after that everything is green. I've checked the powertubes with a wooden stick, but don't get any noise or any weird sounds.
Any suggestion what could be the cause?

Ps. Sorry for my wonky english.
Click to expand...

IMHO nothing unusual, this is probably just the tubes warming up. I wouldn't worry about it, unless the noise is really loud or constant. Several of my amps do the same thing and it almost always turns out to be a tube that may last for years if you just leave it alone. The bias lights flicker red when the pop occurs because the tubes pull extra current when they make the noise.
 
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#6
Jim C said:
+1
My SVT hums lightly when the cord is remode from the input jack when it's not in standby.
It's done this for 20 years.
Click to expand...

A couple of my amps do this as well, including my Skunk SVT. Next time I open up one of these amps I will check the switching jacks for bent/dirty contacts. I can get the SVT to stop humming if I partially insert a 1/4" plug and jiggle it a bit. Insuring there is no corrosion where the jack screws to the front panel can also help.
 
Last edited:
#7
Good idea.
I should try cleaning the jacks with Deoxit (with 1/4" jack in and out cleaning with a rag).
Superticious? Maybe, but if it ain't broke...
 
#8
Usually this issue is due to arc'ing somewhere. The problem is finding it. There are many possibilities.

A known issue that causes standby related pops in the CL is the high wattage resistors in the power supply. Start by inspecting them carefully, look for any black cabon traces. Replace any if necessary.
 
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#11
Generally this is not a big problem, applying and removing the plate/screen voltage often causes pops due to the fast rise time of the applied voltage. I have several test fixtures that do this for the same reason.
 
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#13
Thanks for all the replies. As it seems it's no big problem, I think I'll let it be for the moment. After the two short pops I can play without problems and the pops aren't that loud either. If it can't hurt any other parts I'll be fine.
I think I'll wait till I need to replace the next set of power tubes to retube the whole thing and if it still persist I'll carry that beast to my tec.
 
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#14
BossOnBass said:
Had the same problem with a different tube amp. Problem turned out to be three bad resistors around the power tubes.
Click to expand...

This is a possible cause, but not very likely. If doing a re-tube, I always like to check for current sharing between tubes for this reason.
 

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