Ampeg SVT VR rattling

dannytrivelli · #1 02-10-2011, 07:28 PM

Hey guys,
I just grabbed an ampeg svt vr off ebay and when i first tested it it seemed fine. Then i brought to my studio for rehearsal and cranked it and a few days in i started getting a very loud rattling in there. Loud enough that I can hear it over myself AND my band. It may be that I just know its there so I can hear it regardless of how loud we are, its in my head now, I don't know really. But I know it's there. Also I haven't heard it in the past week but I was also getting a loud high pitched noise coming from the amp when we were rehearsing about 2 or 3 weeks ago that Im not sure where it was coming from.

Any ideas on the rattling? or that high pitched noise? incase it comes back. Im not sure when or if the tubes have been changed at all. Could it be something to do with the tubes? Do I need to change them?

What do you guys think?

dmot002 · #2 02-10-2011, 08:12 PM

It sounds like a microphonic tube and tube rattling going on. I had a Marshall vintage modern guitar amp that had KT66's in it that rattled real bad. Killer sounding amp though. I would make sure all the tubes are seated well in their sockets.

Nightlyraider · #3 02-10-2011, 08:37 PM

You may not ever be all get rid of all the tube-rattle, but that should defintely NOT be so loud as to cut thru in any sort of band setting.

A microphonic pre-tube is a different story however, and you are actually amplifying those vibrations through the power-amp section as well.

dannytrivelli · #4 02-10-2011, 09:22 PM

Ya my first gut instinct was its a microphonic tube. I did all the usual tests(cranking the gain and tapping, checking them out in the dark etc.). The tapping tests, I didn't get any ringing or irregular noises coming through the cabinet so I then thought it might be something else. The back middle 6550 seems to be burnt out.

I was planning on replacing the 6550s anyway with a vintage pair considering I have no idea when the last time the previous owner changed them, if they did at all.

JimmyM · #5 02-10-2011, 11:04 PM

well a vr can't have very old tubes in it. but new made tubes on the average just don't last like the old stuff does, so now and then you have to replace them. but if you have only one power tube out, at the most you'd only need to replace 3. svt's group their power tubes in 3's and they're biased separately.

johnk_10 · #6 02-11-2011, 12:00 AM

it could also be a physical rattle. the VR has two springs on the output tube retainers, whereas the vintage ones have clips on the tube bases.

IME, the springs can sometimes rattle and if you find that to be the case, just insert a short length of silcone fuel line hose (as found in rc planes)with an inside diameter that fits over the springs to silence them. i didn't need to do it on my VR, byt i did need to on my Traynor YBA200-2 which did have a 'rattling' tube problem.

it's hard to see them in this pic with the rear cover screen on, but you should get the idea:

kosmicwizard · #7 02-11-2011, 12:28 AM

It is easier for me to see those tubes than to tell what tone is made by a maple fretboard, John. So rest easy. Cheers.

NickMonti · #8 02-11-2011, 07:30 AM

I'm having the same rattle issue, although not loud enough to be heard over a band.

The fuel line over the spring trick should work.

Thanks.

dannytrivelli · #9 02-11-2011, 09:01 AM

John,
I'm not much of a gear junkie so i'm sorry if Im not following you. How exactly do I put the fuel line in? And also where can i get the tools? Local hardware store?

Also, are they're instructions anywhere on the net on how to do it?

johnk_10 · #10 02-11-2011, 10:06 AM

the only tools necessary are some scissors to cut the fuel line. you just slip a short piece of tubing over each spring on the tube retainers. it couldn't be much simpler than that.

blastjv · #11 02-11-2011, 10:21 AM

I put those silicone rings on the tubes on mine and then the spring retainers over them to solence the springs. Seems to work well.

-JV

brothernewt · #12 02-11-2011, 11:48 AM

Check the feet screws also... I had the nut on the top come loose from one, the bolt held the foot on by the wood but the nut was rattling around. Not nearly loud like you're describing though.

JOE EDO · #13 02-11-2011, 07:53 PM

Quote:

Originally Posted by brothernewt

Check the feet screws also... I had the nut on the top come loose from one, the bolt held the foot on by the wood but the nut was rattling around. Not nearly loud like you're describing though.

Not any more my friend. Some red locktite on those feet screws solved that once and for all. Lovin the VR!

dannytrivelli · #14 02-12-2011, 08:15 AM

im gonna try the silicone rings,
thanks guys