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Cleaning a Vintage Ampeg SVT

Discussion in 'Amps and Cabs [BG]' started by ampegsvtca, Jan 7, 2004.

  1. I have a vintage Selmer/Magnavox Ampeg SVT and I am getting some noise from a scratchy volume pot on channel 1 and also noticed that a couple of the switches are scratchy as well. Are there any high voltage capacitors in the preamp that can kill me? Also how hard is it to clean pots and switches once I have the preamp section removed from the amp cabinet. I would love to take it to a tech but no one around here knows these amps very well and all the other techs are too busy so I thought that I could save money and time and do it myself.
  2. A little contact cleaner sprayed into the switches and knobs should work fine. Just spray it in and turn the knobs and flip the switches back and forth. If any crud runs out of them, wipe it off.

    There IS a 400 volt filter for the preamp, but if you discharge the amp first, it shouldn't be a problem. Simply turn the amp "off" while playing through it without going into standby. That will discharge the filters.

    It's VERY easy, provided you have some self-lubricating contact cleaner with the little spray straw. Just make sure you get the end inside the pot opening on the back.
  3. VicDamone


    Jun 25, 2000
    I can't give any technical advise.

    I purchased an SVT new in 1970 and have truly regreted selling it. I auditioned one through a new 8-10" cabinet last year. The tubes looked very new but the rest hadn't been touched. It sounded awful, nothing like I remembered.

    I think there are parts such as oil filled capacitors etc. which age and probably need replacement as well as switches and pots. Like an old Ferrari the SVT should be serviced by an experienced person. Spend the money, ship it for service if need be. You WILL be amazed.

    In proper working order the Ampeg SVT is like no other amp.

    The company that calls itself ampeg today should be ashamed of itself for not producing this great workhorse. Yeah, I've heard all their bullshiit excuses about how much it would cost to produce it today. So what, people are going to buy it no matter how much it costs. The diet classic svt? Puleasse.

    I'm sorry...thats my opinion.
  4. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    For the controls make sure that the cleaner has lubricant in it or those puppies will freeze up. If you shop at Radio Shack, get TV tuner cleaner.

    During my brief ownership of an early '70s SVT a few years ago, the volume controls were so scratchy I had to remove the back covers, pull the shafts out and use cleaner and a pencil eraser to get the hardened goo off of the resistive element and the wiper. After I did that, they were as smooth as new ones.
  5. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis

    Works for me.....lets have some more activity on the subject. I need stuff to forward to folks.. make more noise, and lets have new names too.

    As far as cleaning pots, yeah, just make damn sure your "contact cleaner" doesn't have any abrasive stuff in it. The old "Tuner cleaner" stuff did, and it can polish the working part of a pot right out of existence. Seen it done by DIY repair folks.........they were NOT pleased when told......

    Nowadays, that stuff is probably obsolete, but some contact cleaners may have abrasive in them too. Spray a little and make sure it isn't gritty first.
  6. I know that it is off from my original topic but you can also put my vote in for a vintage svt reissue like the 1987 Ampeg SVT-HD. I am really curious as to how close it would sound compared to the old ones. Try not to cheap out on anything like the volume and tone pots the old ones are metal where as the new ones are made of plastic if I am not mistaken.

    As for my cleaning project I will probably use something like Caig Labs Deoxit or R5. Thanks Psycho for the safety advice on the capacitors.
  7. Greg R

    Greg R

    Mar 11, 2003
    Avonmore, ON
    I've been using GC Electronics Big Bath for years and it works great. Instant evaporation. As far as Ampeg goes, I love my PR1832 cab but none of the available amps at the time did anything for me. When A/B'd with my J bass the Mesa 400 was quieter when turned to 12 o'clock, facing away from the cab with no hands on the strings. It might seem trivial, but I like amps to be quiet when I'm not playing anything. The Ampeg had an audible hiss as did most of the other amps I tried that day.
  8. Rickenbackerman


    Apr 17, 2001
    Laurel MD
    All Caig labs products are the shiznit. Deoxit works *great* on dirty pots.

    And to Ampeg Insider - I agree with ampegsvtca. Take the look of the modern SVT-AV, lose the gain knob, add the second channel, use 12DW7's, and make the trannies as alike as you possibly can to the old ones. That's a good start, I think.

    Oh, also, find a better connector for the pre/power connection. That molex is a major pain in the ass.
  9. drd07


    Jan 19, 2003
    I too have to clean out the pots in my amp. Does that solve the "shshst" noise when moving the knobs a little? Just follow psycho's advice on cleaning them? If they are making noise, does that come from the pots?
  10. Mine only make noise when you actually turn or switch them, the amp is really quiet otherwise.
  11. Yes. You're hearing minature arcing on the pot elements. Clean off the crud and there shoud be a consistent, quiet turn.
  12. drd07


    Jan 19, 2003
    Thanks Psycho. I finally got my vintage SVT and got it back from my tech. He fixed the standby switch and went through the amp. I tested the SVT last night and loved it at rehearsals. It is definately the best tube amp, period!

    My tech said that you might notice a scratch when moving some of the controls. However, when I went through the amp, it didn't happen at all!