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Ampeg SVT-HD Club? The #500!!!

Discussion in 'Amps and Cabs [BG]' started by SUNNyday r., Feb 28, 2008.


  1. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    That was the SVT-100 that had 100 made. The SW SVT's were a run of 500.
     
  2. Yes, but there were some SVT'HD made that were not Skunkworks from leftover MTI stock. 100 units seems to be the number for the SVT-100 for sure, I'm not as sure about the non-Skunkworks SVT-HD's...it may have been fewer than that. Did you check out the one on eBay?
     
  3. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I never heard of any SLM SVT's made before the Skunkworks except the SVT-100. None are mentioned in the Ampeg history book. Not saying they don't exist, but I would think they'd be mentioned in the book if they did.
     
  4. It's not in the Ampeg book. I got the info from a first-hand account of an SLM guy. And the more I think about it, the production might have been more like a dozen or two.
     
  5. Found it. This is from Dave Ryan in a thread here on TB

    "Skunkworks" SVT

    Seventh post on the page:

    "SLM Inc purchased the rights to Ampeg 1986. When we bought the company there wasn't much left. 2 tractor trailer loads of misc parts, documents & some amplifiers.
    There were about 50 unfinished MTI SVT-HDs & 100 MTI V-5s & some misc units, a couple of V-4s, some V-3s, a VT-40 etc...
    What SLM decided to do was build up any stock we had & get it on the market ASAP. So we built cabinets for the SVT-HDs chassis, we used the "Skunk Works" cabinets as we did not see the advantage of having to build 50 MTI style cabs, then building 500 SW cabinets.
    They were also missing back plate panels, so we used the "SW" panels that say "Made in America by SLM Inc 1400 Ferguson Ave". This had lead a lot of people to believe, later on down the road, that these are "SW" SVTs, they are not. They were assembled by SLME from left over MTI chassis. Myself & the chief engineer put these 50 SVTs together, biased & tested them, out the door they went."
     
    JimmyM and kranahan like this.
  6. P A U L

    P A U L

    Oct 18, 2015
    Los Angeles
    diagram from inside the head:

    svtpre.

    I don't have the head on hand (at the rehearsal room), but the power section had a pair of 12BH7's. I picked up a couple NOS GE 6C4 tubes, as they aren't being produced anymore, so it seems. I still have the Philips 6C4 & it sounds fine. Glad it wasn't the rattly tube...
     
    JimmyM likes this.
  7. kranahan

    kranahan Supporting Member

    I finally replaced the jet engine of a fan with the Fliptops one. It is significantly more quiet. I was playing with the fan unplugged because it was so darn loud... Ha.

    IMG_3321.
     
  8. Wasnex

    Wasnex

    Dec 25, 2011

    I didn't see this when you posted in February. Sorry for the late response.

    The 12DW7 is essentially half 12AX7 and half 12AU7, the 6C4 is basically half a 12AU7, and I believe the 12BH7 is a lot closer to a 12AU7 than a 12AX7.

    I believe the MTI and Skunk amps ran 12AX7s in place of the 12DW7s. It's just matter of swapping a few resistors and plugging in the new tubes. I believe the 12BH7 and 6C4 were used until the SVT CL and SVT II (non-pro) were developed.

    Here's the mod to convert a 12DW7 equipped SVT to run 12AX7s. Click the thumbnail to expand.

    upload_2018-10-25_12-39-39.

    I don't remember for sure one way or the other what my Skunk is running, but I don't plan to bother with the mod either way since, IMHO, the amps sounds like an SVT should.

    The SVT CL and SVT II (non pro) preamps are pretty different from earlier SVTs. These amps used only 12AX7s, 12AU7s and 6550s. A pair of 12AU7s replaced the 12BH7s in the power amp.

    Keep in mind, one of the 6C4's function in the vintage preamps is to mix the signals from channel 1 and 2. Basically the tube was not required since the new amps only had a 1-channel preamp.

    The SVT VR retained 12DW7 equivalent functionality in the preamp by routing the signal in and out of 12AX7 and 12AU7 tubes. This arrangement leaves one 12AX7 section unused.
     
    P A U L and JimmyM like this.
  9. P A U L

    P A U L

    Oct 18, 2015
    Los Angeles
    which one did you get? Mine, has an on/off switch added, but, I'd still like a quieter fan...
     
  10. kranahan

    kranahan Supporting Member

    P A U L likes this.
  11. P A U L

    P A U L

    Oct 18, 2015
    Los Angeles
  12. P A U L

    P A U L

    Oct 18, 2015
    Los Angeles
    correction... I typed the wrong #...

    126!

    126.

    derp, derp... :)...
     
    kranahan likes this.
  13. P A U L

    P A U L

    Oct 18, 2015
    Los Angeles
    what are you guys doing for cap replacements. I see that CED took over the equipment from Mallory. They sell the FP 247 450V, 100/40µF, Electrolytic, but I can;t seem to find a new FP 146 450v 40mdf

    MALLORYFP146.

    CED doesn't seem to make that one...
     
  14. Wasnex

    Wasnex

    Dec 25, 2011
    I order parts from lot's of places...but a lot come from Mouser: Mouser Electronics - Electronic Components Distributor

    or Digikey:
    DigiKey Electronics - Electronic Components Distributor

    I ordered custom made twist lock capacitors for both of my SVTs from Hayseed Hamfest | Life's Too Short for Restuffing Can Capacitors.

    You can order kits from Fliptops.

    Capacitor Kits


    CE MFG also makes twist locks. Capacitors - CE Manufacturing | CE Distribution

    Here's a retail source for CE MFG Search | Antique Electronic Supply
     
    kranahan, beans-on-toast and P A U L like this.
  15. P A U L

    P A U L

    Oct 18, 2015
    Los Angeles
    cool, thanks...

    I'm pretty familiar w/ CE MFG/Dist. & Fliptops. I had just replaced that cap above, w/ one I got from Fliptops & after a couple hours, something else went. So, I'm looking at just doing a cap job, as I don't want to just keep putting it back on the bench. I was hoping to keep it somewhat in vintage state, but, I'm guessing that that's not going to happen. CED bought out Mallory's tooling equipment & do CP copies of some models, like the FP 247, but not the FP 146.

    I've found a couple resources for some old stock (some used, some new), but my tech doesn't want to use old cap's, because they could have dried out & chance of failure, etc. So, the new FP 247, at CED, he's fine w/, but, not buying from a random source w/ old stock floating around...

    I might look into what they'd charge to make me up a set at HH, if they aren't too expensive. How do they look?
     
  16. Wasnex

    Wasnex

    Dec 25, 2011
    One of the main filter caps in my Skunk shorted about a week after I received the amp. I was playing and the amp sounded great; then the electricity in the house dimmed and the amp went silent. I don't think my Skunk saw much use, so it may not have been turned on for an extended time.

    I went ahead and did a complete cap job as I don't have the test equipment to evaluate capacitors. I did save the old capacitors, I tried a couple of them recently when I was troubleshooting another amp and they pulled the voltage down...so more than one was junk.

    I would advise against using old capacitors. They need to be used or they break down. Pretty sure that's why the capacitors in my Skunk shorted out.

    The capacitors I ordered from Hayseed are covered with a black paper insulator. I think they look great and the insulator was a few dollars extra. The turn around was fairly quick and they were about the same price as the CE MFG caps.
     
    Last edited: Jan 3, 2019
    P A U L likes this.
  17. P A U L

    P A U L

    Oct 18, 2015
    Los Angeles
    thanks, I'll see what they can do for me... :thumbsup:...

    I had mine sitting in the garage for 25 years, so, it's prone to have dried cap's.
     
    Wasnex likes this.
  18. kranahan

    kranahan Supporting Member

    Alright.. I've been perplexed for too long!

    I've been trying to find knobs that actually point in the right direction on my amp. I purchased the amp with the original channel 1 knobs but it had replacement channel 2 knobs that point in the wrong direction. They are pointed 180 degrees from where they should be.

    I've purchased several D-shaft knobs but they do not work because they all of them have the point on the curve of the D-shaft. For some reason, my amp needs the point on the flat side of the D-shaft.

    Are all of the Skunkworks this way or were my pots put in wrong?!? Also, are there any D-shaft knobs that have the point on the flat side of the D-shaft?

    Here's a recent picture (purchased one knob on Reverb that works for channel 2):
    IMG_3321.
     
  19. Wasnex

    Wasnex

    Dec 25, 2011
    Perhaps the pots have been replaced. Are the keys on the shafts in the proper position? I think some of the original pots are no longer available, and the available replacement pot has the leads on the wrong side. So the replacement pot is mounted upside down and flying leads are using to connect the pot to the circuit. Hope that makes sense :confused:o_O.
     
  20. kranahan

    kranahan Supporting Member

    That could be it but the original knobs point in the correct direction. Also, all of the pots/shafts are installed the the same way... That's why I'm confused!

    Can you explain this question in more detail: "Are the keys on the shafts in the proper position?" I don't really understand.
     

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