SVT3Pro fart

bugsy · #1 02-26-2011, 11:29 PM

Mine is roughly 10 years old.
recently after awhile of playing i have been noticing when i hit a low note the speaker makes a loud fart.
The fart noise is actually louder than the note i play (if that makes sense?)
Like a distorted fart sound.

It doesnt happen all the time, only seems to happen when i dig in or hit the note hard.

I swapped cabs and still producing the fart noise.

I dont play an active bass
swapped cords
swapped cab cords
swapped basse, but it does seem to happen more often with hollow body Hofner, but also with my Dano longhorn

i opened the head and all 4 tubes glow but the two (12ax7s) at the front dont seem to be as bright as the 2 at the back, which glow up quickly.
the 12au7 glows slighly as much as the front 12ax7s

I can only think of changing the tubes
Anyone else suggest anything?

I dont have access to any amp tech but i may also take it to an electronic repair guy. He may see something wrong.
Solder joints?

rodl2005 · #2 02-27-2011, 12:17 AM

Dunno whether I've ever heard a PRO fart!

Sorry - couldn't resist...

Pre amp tube'd be MY 1st guess. Sorry I can't be of more help. It's been a fair while since I owned a 3PRO & I can't even remember WHICH tube would be the best to try & swap. Actually whay not try swapping the same type- AX7 with AX7 etc... can't hurt & MAY find your prob.

JimmyM · #3 02-27-2011, 02:58 AM

ya, time to change a tube. sounds like one of them is on its way out.

mophead · #4 02-27-2011, 06:54 AM

I would get rid of the amp.

Foz · #5 02-27-2011, 07:19 AM

10 years old?

Might be worth having the bias checked as well. Added new pre tubes and corrected the bias on my old 3-pro and it perked right up [louder, punchier].

fenderhutz · #6 02-27-2011, 07:26 AM

Yup I had three of them do that, wasn't a tube.

It's the vibration rattling the chassis.

Take your knuckles and tap like you are knocking on a door near the front of the amp on the top panel. See if it does it again, my hunch is yes.

Pro-Tech in DC couldn't even fix it.

Those amps are junk and prone to fail. The only SLM era amp that was horribly faulty in my mind. It got so bad with those that even Atomic Music in Beltsville wouldn't take them in trade.

Sorry to be blunt, but there are two reasons I left Ampeg for years. One was quality control on the Vietnam stuff was laughable, and secondly after my third SVT 3 PRO replacement I walked away.

allexcosta · #7 02-27-2011, 07:28 AM

Quote:

Originally Posted by fenderhutz

Yup I had three of them do that, wasn't a tube.

fenderhutz · #8 02-27-2011, 07:31 AM

Was my main gigging amp. Wasn't happy.

I am giving Ampeg another shot with the Micro VR. So far, so good.

4Mal · #9 02-27-2011, 09:39 AM

Quote:

Originally Posted by bugsy

Mine is roughly 10 years old.
recently after awhile of playing i have been noticing when i hit a low note the speaker makes a loud fart.
The fart noise is actually louder than the note i play (if that makes sense?)
Like a distorted fart sound.

It doesnt happen all the time, only seems to happen when i dig in or hit the note hard.

I swapped cabs and still producing the fart noise.

I dont play an active bass
swapped cords
swapped cab cords
swapped basse, but it does seem to happen more often with hollow body Hofner, but also with my Dano longhorn

i opened the head and all 4 tubes glow but the two (12ax7s) at the front dont seem to be as bright as the 2 at the back, which glow up quickly.
the 12au7 glows slighly as much as the front 12ax7s

I can only think of changing the tubes
Anyone else suggest anything?

I dont have access to any amp tech but i may also take it to an electronic repair guy. He may see something wrong.
Solder joints?

This distorted noise, is it coming form the amp itself or through the speaker. I put some miies on an older 3Pro and while I felt a lack of headroom, the amp itself sounded nice at lower volumes and it seemed very well constructed. It was sitting on a 1x18 & 2x210 SWR stack so it got it's share of shake applied to it...

My only real complaint withthat amp was the lack of headroom. I could top it out in rehearsal pretty easily. The 3 pro is about the quietest amp I've heard at it's rating - are you asking more of it than in can deliver ?

Jim C · #10 02-27-2011, 10:06 AM

Quote:

Originally Posted by fenderhutz

Pro-Tech in DC couldn't even fix it.
Those amps are junk and prone to fail. The only SLM era amp that was horribly faulty in my mind. It got so bad with those that even Atomic Music in Beltsville wouldn't take them in trade.
.

Pro-Tech did repair 2 bad solder traces in one I had (separate occasions)
I was never blown away by the tone try as I might, and tube rolling did not make that much of a difference
Still, many here like them

fenderhutz · #11 02-27-2011, 10:39 AM

Quote:

Originally Posted by Jim C

Pro-Tech did repair 2 bad solder traces in one I had (separate occasions)
I was never blown away by the tone try as I might, and tube rolling did not make that much of a difference
Still, many here like them

I actually liked the tone because it paired really well with pedals. For the record, if anyone cares, you can get the same tone out of the Eden Nemesis stuff.

TONYTHOMAS1956 · #12 02-27-2011, 10:56 AM

Ive owned one for over 12 years and recently had the same problem(only problem) Had the tech replace mosfets and biased the amp and its perfect again. It is a SLM model and wouldnt think of parting with it.
Do a search on the 3 pro and you will find articles on the problem.

Jerrold Tiers · #13 02-27-2011, 11:40 AM

Quote:

Originally Posted by 4Mal

My only real complaint withthat amp was the lack of headroom. I could top it out in rehearsal pretty easily. The 3 pro is about the quietest amp I've heard at it's rating - are you asking more of it than in can deliver ?

Turn up gain, turn off "ultralow", max the "tube gain". Volume galore.
Make sure the input light is flashing when you play.

As for teh noise, make sure the above is OK.

After that, a tech should check the power stage to make sure all mosfets and "source resistors" are good. it almost sounds as if there is a protection circuit problem. A bias problem can also potentially cause that, but it's a long shot.

bugsy · #14 02-27-2011, 01:54 PM

just to add, its MIA and its the first thing that has ever gone wrong and i havent opened the top till now.
its done alot of travelling in a road case

I dont want this to be a bashing thread about brands, i am just after some help with my problem.

Thanks to all replies

bugsy · #15 02-27-2011, 01:56 PM

Quote:

Originally Posted by 4Mal

This distorted noise, is it coming form the amp itself or through the speaker.

speaker, I put my ear to the cabs to find the source
I thought it was a blown speaker at first.

prd004 · #16 02-27-2011, 02:12 PM

Quote:

Originally Posted by fenderhutz

Yup I had three of them do that, wasn't a tube.

It's the vibration rattling the chassis.

Take your knuckles and tap like you are knocking on a door near the front of the amp on the top panel. See if it does it again, my hunch is yes.

Pro-Tech in DC couldn't even fix it.

Those amps are junk and prone to fail. The only SLM era amp that was horribly faulty in my mind. It got so bad with those that even Atomic Music in Beltsville wouldn't take them in trade.

Sorry to be blunt, but there are two reasons I left Ampeg for years. One was quality control on the Vietnam stuff was laughable, and secondly after my third SVT 3 PRO replacement I walked away.

I disagree, been playing the same SLM era SVT-III PRO since 94, not one problem. Been my main amp the entire time, never let me down. Hundreds of gigs and probably thousands of rehearsals later I still love it!

dmot002 · #17 02-27-2011, 02:24 PM

Could be bad caps ..... Have it checked ..

JimmyM · #18 02-27-2011, 02:29 PM

you know, if you get 10 years of service out of an amp without having to take it to the shop, i think you're doing pretty damn good. but then again, i come from an era where there was no internet to encourage impatience with good gear.

time to give back to the amp that served you well for 10 years and put a little cash into it. or sell it for a fraction of what it costs new

but if you service, have it done right...take it to a good tech.

DaveAceofBass · #19 02-27-2011, 02:46 PM

Tap on the tubes when the amp is on, the one that makes a ping sound is bad.

stiles72 · #20 02-27-2011, 03:41 PM

Quote:

Originally Posted by JimmyM

you know, if you get 10 years of service out of an amp without having to take it to the shop, i think you're doing pretty damn good. but then again, i come from an era where there was no internet to encourage impatience with good gear.

time to give back to the amp that served you well for 10 years and put a little cash into it. or sell it for a fraction of what it costs new

but if you service, have it done right...take it to a good tech.

+1 I've gigged a pair of 3-Pros for the last ten years and the only maintance or problems I've had is needing to replace tubes at about the 5/6 year mark, and just then about two years ago I had to get the bias adjusted.