1972 Ampeg SVT Dating Help

Discussion in 'Amps and Cabs [BG]' started by TheDialog, Sep 7, 2022.

  1. TheDialog

    TheDialog Supporting Member

    Nov 23, 2008
    Baltimore
    Hi team,

    A friend is trying to piece together some random parts.
    He has two Ampeg SVT's from 1972.
    One has transformers that date to the 5th week of 72 and the other to the 35th week.
    As you can see from the pics below the faceplates are different.

    I believe the darker blue with -/0/+ and mid Hz is a later 72 and the other is early 72.
    Can someone confirm when the plates changed and if this is correct?
    I know the Magnavox era SVT's had the darker blue plates' etching.

    Thanks!

    tempImageWUozTX.png tempImage0HG33r.png
     
  2. beans-on-toast

    beans-on-toast

    Aug 7, 2008
    Note, the top faceplate is etched, the bottom one is painted. Look for date codes inside, for instance on the large electrolytic capacitor and on the pots.
     
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  3. Wasnex

    Wasnex

    Dec 25, 2011
    IMHO specifically look at the bias pots. Good chance all of the original electrolytics are long gone.

    I don't know if the different colors are related to age, but AFAIK the earliest amps had the etched panels. Actually I thought all bluelines were etched. The bottom amp in the OP is probably transitional. Ampeg converted over to blackline graphics in either late 72 or early 73. So it's essentially an early blackline that used blue

    I have a blueline that I believe is a 69. It has the bare metal power amp chassis. The front panel is etched and the color of the lines appears about midway between the two colors in your image. It does not have the frequencies indicated on the mid-selector switch.


    Compare to
    [​IMG]

    See this post: Vintage Ampeg SVT timeline?
     
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  4. beans-on-toast

    beans-on-toast

    Aug 7, 2008
    Thought the same, a blackline with blue paint. Perhaps transitional or prototype blackline.
     
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  5. TheDialog

    TheDialog Supporting Member

    Nov 23, 2008
    Baltimore
    Was thinking the same thing as well.
     
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  6. Wasnex

    Wasnex

    Dec 25, 2011
    At some point the order of the pins were changed in the umbilical that connects between the power amp and preamp. If the intent is to mix the preamp and power amp from two SVTs, it's a good idea to check and make sure connections in the umbilical are wired the same in both.

    Other than that, AFAIK it should be no problem to mix and match.
     
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  7. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    Fliptops used to sell replacement blueline SVT faceplates that weren't etched and had the darker blue colored paint just like the lower amp...
     
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  8. beans-on-toast

    beans-on-toast

    Aug 7, 2008
    Could be. I bought one many years ago for a V4B, the quality was excellent. Later on, they started making them thinner, now they’ve been out of stock for quite a while. It doesn’t look like they intend on doing another run.
     
  9. Christiaan

    Christiaan

    May 17, 2022
    I can't date an SVT. My wife won't let me...
     
  10. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    I can't help with much. I will say that I owned a Magnavox era SVT years ago that was lighter blue like the top faceplate in your pics. I'm 100% positive.
     
  11. two fingers

    two fingers Opinionated blowhard. But not mad about it. Gold Supporting Member

    Feb 7, 2005
    Eastern NC USA
    I can't date them these days because of my age. They throw my back out every time I take them out.

    :wacky:
     
  12. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    The bare metal chassis were used on the V4 and B25 amps through 1970, I don’t know if the SVT was the same but it stands to reason that if they started painting one line black in 71 they probably did it for all of them.

    I believe Bill Hughes has said on here in the past the only SVTs made in 69 were the ones they made for the stones tour, with the 6146 power tubes and the relay tube, but I’d have to try to dig that up again.
     
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  13. My 72 SVT definitely looks like the top one
     
  14. 1972 Ampeg SVT Dating Help

    I've found if you lay your cards on the table early in the relationship, like family, kids, money it can help for both parties to see if this is a relationship to pursue.

    :)
     
  15. Wasnex

    Wasnex

    Dec 25, 2011
    Pretty sure the chassis on most bluelines is painted black.

    AFAIK the amps with bare metal chassis are pretty rare. Mine has no serial number that I can find. I would have to check to make sure, but I think the bias pots are dated 68, so I assumed it was a 69. Mine has the slot for the relay tube, but it's jumpered.
     
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  16. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    Found one of the threads here, his comments on the 68 date codes were that they were mostly stock on hand, the transformers are your best bet for dating as they were made for the amp.

    He also says they made around 50 amps with the bare chassis, so any bare chassis is going to be pretty early for sure.

    1968 SVT: myth or reality?
     
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  17. Wasnex

    Wasnex

    Dec 25, 2011
    The heater transformer has this code: 682920 which indicates 20th week of 69. Ref: Vintagebassworld.com | Ampeg SVT

    The PT is long gone and I recently installed a custom Heyboer. Can't read the end cap of the OT, without pulling the chassis (not going to happen today).

    IMHO, The latest it could possibly be is a 70. This amp did not have node H in the power supply. The schematic showing node H is dated Jul 1970. I assume no amps would have left the factory without node H after this time.
     
  18. Topkat13

    Topkat13 Supporting Member

    Feb 5, 2004
    I would start with a low-key casual conversation…maybe a lunch date or at a coffee house.
     
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  19. Luckydog

    Luckydog

    Dec 25, 1999
    agree, this is a possibility.
     
  20. beans-on-toast

    beans-on-toast

    Aug 7, 2008
    I believe that the black painted SVT chassis appeared some time in 1970 as I've seen SVT's from early 70's amps with the unpainted chassis. Also released in 1969 was the SBT, a transistorized SVT pre-amp. Mine is from that year from the date codes. The chassis is painted black.

    SBT front.JPG

    SBT back.jpg
     
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