A Surprising Sound When I turned on my SVT

[thomasjbass]

Hey guys and gals,

Had a very disappointing experience tonight when I went to turn on my SVT-CL. I have attached a sound file that hopefully might help someone point me in the right direction. Not sure exactly what it is. Biased the tubes once everything was up and running. It makes this noise, but yet when I plug in I can still play through with some clarity. If anyone can offer advice or if perhaps you have a good amp repair person in Southern California I would greatly appreciate it. HELP

[JimmyM]

i know suzi! hung out with her a couple times when i was in germany doing shows for her husband.

but i don't see the file.

[thomasjbass]

Didn't attach the first time, but hopefully this will help with some direction.

[stiles72]

Sounds like the fan. My 3-Pros make a similar sound when they are first turned on, but eventually it stops. Maybe check the blades to see they arent touching anything.

[thomasjbass]

Would the fan cause the noise when the amp is plugged into speakers? If you put the amp into standby you don't hear the noise, as soon as you put it into full power you hear the noise...

[JimmyM]

wow, first time i ever heard that sound from an amp! i am stumped, but there are a good handful of amp guys on here who could probably help you figure out what it is.

[thomasjbass]

Thanks JimmyM...

[JimmyM]

i did nothing but you're welcome

[EASonBass]

Ampwerx Repair
1935 East 7th Street
Long Beach, CA 90813-5104
(562) 591-1423

[thomasjbass]

Thanks EASonBass

[jmattbassplaya]

I thought it sounded like a fan too, but I honestly have no clue what it is. Sounds like it's time to take it to a tech.

[johnk_10]

that's a pretty weird noise and does sound like the fan, but is it coming thru the speakers or is it happening acoustically? i'm in socal and could diagnose & fix it.

[thomasjbass]

It is coming through the speakers. When you disconnect the speaker wire or put the amp into standby you don't hear it at all...

[Tim1]

Thomas, I am pretty sure that on my SVT VR the fan only comes on when you switch out of standby and into full power so (if th eCL is the same) it could easily be the fan, depending on whether it is coming from the speakers or the amp itself. Sure sounds like fan blades catching to me, and is similar to the sound I had on a CL I returned, which turned out to be fan. That said, if you have somene of the calibre of johnk close you are very fortunate - just take it to him.

[Tim1]

Just read your last post - must have come through while I was typing. Time for a tech, I reckon.

[thomasjbass]

Thanks Tim1. Looks like its time for a fieldtrip to see you johnk

[JimmyM]

Originally Posted by johnk_10

that's a pretty weird noise and does sound like the fan, but is it coming thru the speakers or is it happening acoustically? i'm in socal and could diagnose & fix it.

+1. thomas, john's the dude when it comes to tube amp repair, especially ampegs.

so could that be a microphonic tube picking up vibrations from the fan?

[johnk_10]

on a VR, the fan runs both on and off of standby . i thought it was the same way for the CL's too, but it's been a while since i checked. either way, it sounds like a simple fix to me.

[Tim1]

Just checked and my fan only comes on when the VR is out of standby. Then I searched SVT fan on TB and found a post from Jerrold saying that if it is set to 240 volts the fan is governed by the standy switch so all is well as we are on 240v downunder . Seems a bit weird that it is dependent on voltage configuration but never mind.
It never ceases to amaze me the wealth of information available on this forum. I haven't been caught with the voltage drop and not coming off standby yet, so it may be fine on 240 volts (or New Zealand power supplies are better regulated?) - time will tell. I suppose I really should do johnk's mod anyway although I do recall jerrold mentioning that on 240 volts you only need to swap a wire, no Y cord needed.

[Hutzbordello]

reverb...