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square back Ampeg early 70's cab dimensions

Discussion in 'Amps and Cabs [BG]' started by fnordlyone, Nov 22, 2013.

  1. I have the dimensions published by Ampeg for vintage 8x10:
    I want to build a 2x10 that will have the classic sound. I thought perhaps start by building a cab 1/4 size of the Ampeg enclosure. I need the interior specs. I assume the published specs are exterior; also, that they are using 3/4 ply. I wonder about the hight, does it include the feet? Anyone with the interior dimensions of an old cab or educated guesses, build experience? I have a couple of CTS 1975 speakers, I'd like to use.
    appreciate any help,
  2. punkrocko


    Jun 18, 2002
    Nashville, TN
    The internal dimensions of each sealed chamber are approx.

    25.5" long x 10.625" high x 12.5" deep.

    Those published dimensions must include the feet. My '71 cab that I measured was 46.25 tall from bottom to top.
  3. P Town

    P Town

    Dec 7, 2011
    I am pretty sure the original speakers are 32 Ohm impedance, so if you are using speakers that were used in an original SVT, you will not be able to obtain a useable total impedance with only two of them. If you are not using the same speakers, it is hard to predict if you will obtain a sound like an SVT.
  4. Thank you, kind sir! Exactly the data I was looking for, fnord!:D
  5. Thank you for the response. The speakers I'm trying to find a new life for are 1975, beyond when ampeg used cts. I have an idea that they came from a earth sound research cab. I bought a 2x12 cab that was rated 16 ohm from dude at the same time. It was meant as half a M412 (guessing PA speakers). Anyway the 10's which are marked on square mags with a rubber surround: 10400; under it 137 7544 (green numbers). On the paper: 1065-1. 2 and 1/2" voice coils with aluminum covers with black 3/4" center breathe hole. The covers match the 4x12 speakers (not CTS) from the ESR cab. I only paid $40 for them so I doubt much trickery was involved. The ERS 12" speakers are 8 ohm… so hoping the CTS are 8, too.
    f n o r d!
  6. will33


    May 22, 2006
    Got a cheap multimeter?.....find out. Any reading between about 5.3 and 7 would indicate an 8ohm speaker. 3.something would mean 4ohm. Anything around 11-14 would mean it's a 16ohm speaker.
  7. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I was once told that the target design volume was one cubic foot for the speaker that they used. So in your case, two cubic feet for two speakers. The Ampeg 810 cab chambers were close enough.
  8. Hey, my friend. I built the cab and it sounds great… Turns out my old eyes misread and the speakers are 1976 CTS. I even poked three holes in one (repaired with elmers and toilet paper), and they sound wonderful. Was only guessing that these CTS might still match sound profile of the early peg cabs. Turned into a really nice punchy 2x10 that never really farts out, though has trouble with the lowest 4 notes on the B string. Thank you so very much for the info that allowed me to make the build.

  9. punkrocko


    Jun 18, 2002
    Nashville, TN
    Hey, that's great. Glad to hear it worked out for you.