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Ampeg SB-12 Serial Number Location and starting restoration thoughts

Discussion in 'Amps and Cabs [BG]' started by billdeg, Oct 9, 2017.


  1. billdeg

    billdeg

    Mar 12, 2006
    Where is the serial number for a 1967 Ampeg SB-12? I believe it's a '67 because the schematic on the inside says 9/66, assuming they then produced and sold it in 1967. It has the speaker on the left side when facing from the front.

    Also...just getting started to restore it. It has all original tubes so I want to at least see if the 12AX7's are the reason it can't take much of a signal before breaking up, especially when using a bass guitar lower notes. The volume is ok. Using a theremin through it (as a sine wave tester) works fine. Anything plugged into the bass jack can barely be heard. There are likely solder joints that need TLC, etc. It's a little rough in there but not as bad as I have seen. The light bulbs work, lights up the glass Ampeg plate.

    I already fixed the wires to the speaker, the ground wire is just dangling and needs to be extended to the plug (Or I may come up with something internally). Seems like the speaker is intact, not ripped but I have read here where people say they can't handle the input from a modern bass guitar. Sounds great at low volumes. I could always just mic it I guess.

    Not sure if I will sell, trade or keep yet. I take in these strays...and that's why I have too many amps. :)

    Bill
     
  2. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Check out the TB Portaflex Wiki: Ampeg Portaflex Wiki | TalkBass.com

    There is an extensive SB-12 cabinet restoration in the restoration section.

    The best way to estimate the date of manufacture is to look at the pot date codes, a code starting with 137. Most ‘67’s had a black cabinet with a silver inlay around the front. There’s an image of a ‘67 in the model’s page of the wiki.
     
    Last edited: Oct 9, 2017
    bobyoung53 and Bass 45 like this.
  3. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    With a bass with typical Fender vintage-style output, it should start breaking up right around 11:00 on the volume dial. And bear in mind it's only 22w.

    Serial is usually located inside the cab and under the head, though it's entirely possible they disappeared. And that ground wire unhooked may be at least partially the reason for your problems, though it's impossible to diagnose over the internet. That's more Beans' speed anyway, so just do what he tells you :D
     
    bobyoung53 likes this.
  4. billdeg

    billdeg

    Mar 12, 2006
    thank you. Funny I cleaned up the amp and put alligator clips on a few broken traces to get it to produce a sound, not expecting much. Although it was a rough you could really hear a beautiful bass thwump sound especially in the midrange when not pushing in too much of a signal.
     
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  5. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    SB-12 is just as kickass as any of them.
     
    bobyoung53 likes this.
  6. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    They were favored by east coast Jazz and studio musicians. Some players prefer the SB-12 over the B-15N.
     
  7. billdeg

    billdeg

    Mar 12, 2006
    New 12AX7's made a big improvement, I can now get past the "11 o'clock" problem a lot of people describe here.
     
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  8. billdeg

    billdeg

    Mar 12, 2006
    Then it must be a '66.
    It looks exactly like this (but not as nice):
    https://images.reverb.com/image/upl...90,w_620/v1505256708/xlezqqvhxqpnm1x1mxvg.jpg
     
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  9. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    beans-on-toast likes this.
  10. shadven

    shadven Supporting Member

    Dec 30, 2009
    Tampa, FL
    I rock therefore I am.
    I have '66 SB-12 and it is a beautiful sounding amp. It is almost as loud as my B-15. The latches complete the circuit for the speaker... that's cool.

    Rich, warm, deep bass tone. I've never heard another 1x12 bass amp that comes close.
     
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  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Nothing is cut and dry with Ampeg. Revisions were phased in, depending on stock. There are even hybrids where some changes were made but not all of them.

    The best way to estimate the date of manufacture is to look at the pot codes, add a month or two.
     
    JimmyM likes this.
  12. billdeg

    billdeg

    Mar 12, 2006
    The schematic has "9/66" printed on it, and so the earliest it could have been sold was 9/'66. It has the 1966 design though, but it might have sat in the show room into 1967, who knows. I could not find anything else that had a date, no serial number anywhere. Did not check the date on the potentiometers, I'll disassemble the head again at some point soon and check. Sounds like Cream bass Disraeli Gears
     
    JimmyM likes this.
  13. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    The schematics were not up to date. They would make a batch and use them till they were gone. An amp with a 9/66 schematic date could have been made in ‘67.
     
  14. I did an outside house party gig once and the owner of the house had an SB-12 for the bass and I couldn't believe how loud and good it sounded, kept right up with the rest of the band, nice punchy tone.
     
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  15. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    Had a blue diamond 67 single baffle B15, definitely no cut and dry dates when it comes to ampeg (or most manufacturers for that matter).
     
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