Amp Hum/Dried Caps ?

SongsForTheDeaf

SongsForTheDeaf

New member
I am recording next week and really want to use my '76 Ampeg VT-22 but it has what sounds like 120hz hum



I figured it is the caps but I don't know for sure.

would it be safe to run this amp for a few hours recording next week ? I don't want to blow up the amp or anything but I also want to use it and the tech said it would take several weeks to be serviced.
 
Re: Amp Hum/Dried Caps ?

Generally speaking...If the amp is more than 10 years old,the filter caps should be replaced...I'm saying "normally"..The hum you hear,might be 60 cycle due to poor filtering in the power supply? Just a guess w/o hearing/seeing the amp? Tubes can cause a hum also(output tube(s)..

Sometimes you can see visual bubbling or stuff oozing out of the bad caps.Sometimes they blow and or turn colors..Take a look at them?
 
Re: Amp Hum/Dried Caps ?

Well.....you mention your amp is a 1976, are the caps that old.?
If so, I would certainly plan on changing all the Elytics.
It is ALWAYS worth giving the tubes a try.
"Probably" not much danger in using your amp...have you been using this amp...or has it been sitting for 15 years, and you are just now wanting to record with it.?
best
 
Re: Amp Hum/Dried Caps ?

zzmoore said:
Well.....you mention your amp is a 1976, are the caps that old.?
If so, I would certainly plan on changing all the Elytics.
It is ALWAYS worth giving the tubes a try.
"Probably" not much danger in using your amp...have you been using this amp...or has it been sitting for 15 years, and you are just now wanting to record with it.?
best
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I've been using it almost every day since I got it a few months ago used. The previous owner said he used it all the time too. But I never play for more than an hour at a time.

Not sure how old the caps are as there is sticker on the back of the amp of a Repair shop with their email so I assume it was looked over by them or serviced by them.. I stupidly didn't ask when I got the amp..
 
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Re: Amp Hum/Dried Caps ?

The early '60s Traynor amp that I found at my dad's farm has original filter caps in it. They still work, just not very well. It hums audibly at low levels, but cranked it sounds fine. You'll probably be OK for a little while for some recording, but I'd recommend changing them out as soon as you can. Keep an eye on your power tubes and fuses. If you start blowing either stop using the amp until you can have it serviced.
 
Re: Amp Hum/Dried Caps ?

GuitarStv said:
The early '60s Traynor amp that I found at my dad's farm has original filter caps in it. They still work, just not very well. It hums audibly at low levels, but cranked it sounds fine. You'll probably be OK for a little while for some recording, but I'd recommend changing them out as soon as you can. Keep an eye on your power tubes and fuses. If you start blowing either stop using the amp until you can have it serviced.
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Thanks I appreciate it. I will take it to record but bring my backup Ampeg just in case... My buddy said I could try lifting the ground from the power cord but that sounds very unsafe to me lol Does get me curious if it will help with hum though
 
Re: Amp Hum/Dried Caps ?

SongsForTheDeaf said:
Thanks I appreciate it. I will take it to record but bring my backup Ampeg just in case... My buddy said I could try lifting the ground from the power cord but that sounds very unsafe to me lol Does get me curious if it will help with hum though
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Don't do that! And the hum is more than likely not from a ground issue,but an issue within the power supply and or bad tube(s).
 
Re: Amp Hum/Dried Caps ?

I just found my VT-22 has an old Amperex 6an8a preamp tube in it... it is the only old tube in the amp still .. Could this cause the hum I am getting ? I could order a new one now if it is
 
Re: Amp Hum/Dried Caps ?

Yeah it is worth a shot.. I will order a new one and I replaced all the 12ax7s already but there is a 6cg7 in there too so I will order on of those aswell. Misewell get some 7027 power tubes matched while I am at it.... There are 2 different matched pairs of 6L6GCs in there now that I have switched around with other sets of 6l6s but it did not help the hum.
 
Re: Amp Hum/Dried Caps ?

SongsForTheDeaf said:
Yeah it is worth a shot.. I will order a new one and I replaced all the 12ax7s already but there is a 6cg7 in there too so I will order on of those aswell. Misewell get some 7027 power tubes matched while I am at it.... There are 2 different matched pairs of 6L6GCs in there now that I have switched around with other sets of 6l6s but it did not help the hum.
Click to expand...

I'll bet it's a power supply issue! Very common.
 
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