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Ampeg 8x10 speaker replacement

Discussion in 'Amps and Cabs [BG]' started by davelowell, Feb 28, 2004.


  1. davelowell

    davelowell

    Jan 18, 2001
    stl, mo
    So, Petebass helped a lot with getting my cab rewired, but it's driving and farting out, so I think I will try getting new high power speaks. I like the sound at low volume, but I play an SVT, come on, in a rock band, so I'm gonna be turning up.

    Any suggestions? The cab is an Ampeg 8x10, square back early 70's. I don't know the internal volume of the cab, so I don't know where to start on that one.

    Ampeg Insider, I was told I have newer Eminence 10's that are used in the newer cabs made by SLM. Can you tell me some codes that should be on the Eminence speaks I have in there to determine wattage?

    Thanks, Dave
     
  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    If there is a little silver label attached to the side of the magnet, you can obtain info via email direct from Eminence. All you need to do is send a message with the Spec. No. to info@eminence.com and they'll tell you the Thiele Small parameters for the speaker as well as its power ratings, etc.

    It is important that you include the Spec. No. from the speakers that you have...Eminence won't answer if you just ask for info on an Ampeg SVT 10 in. speaker.
     
  3. davelowell

    davelowell

    Jan 18, 2001
    stl, mo
    Thanks, Billy, anyone else have any info?
     
  4. make sure they are 32 ohm. ampeg oem are your best bet.
     
  5. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    I agree. The 8x10 SVT's are a bit unique. The fact that they're a sealed cab makes it hard to find an alternative replacement speaker.

    Perhaps you could get the existing speakers reconed? It will probably work out cheaper and you end up speakers that are as new. Just make sure they use the proper bits & pieces..........
     
  6. Rockbobmel

    Rockbobmel Supporting Member

    Eminence told me that their Legend series 10s would be a good replacement. :hyper:
     
  7. davelowell

    davelowell

    Jan 18, 2001
    stl, mo
    I think they are fairly new speaks, so reconing seems like a no go to me. I was hoping to get more wattage and thickness, bass response, from high power speaks.

    Maybe this cab is just not for me. I can't believe it, though, that every other bass player I respect around here that plays newer Ampeg 8x10's sound so much better to me. I love the head, but am dissapointed in the cab.

    Thanks for your help, fellas.

    Dave
     
  8. TimmyP

    TimmyP

    Nov 4, 2003
    Indianapolis, IN
    The SVT drivers are good sounding and very robust. The problem is the cabinet. Way back when, we ordered a bunch of SVT drivers to make clones. But to save time and money, we we left out the panels that divide the cabinet into four sections, so instead of a 4x(2x10), ours were 8x10. Our clones sounded much better! They lacked the low mid "bark" of the "four little boxes" that comprised the factory box. Here's the poop:

    The width of the box causes a resonance at about 275Hz.

    The depth causes a resonance at about 540Hz (this is almost exactly an octave above the width resonance - the box depth used was not a particularly good choice).

    The height of each 2x10 section has a resonance at about 615Hz. This is just above the depth resonance, and there are FOUR little boxes.

    So, the 4x(2x10) has a BIG bark from 540Hz to 615Hz, and small one an octave and change below it.

    If you leave out the dividers (or saw them out with the smallest scroll saw you can find), you remove the 4 resonances at 615Hz and replace them with a single resonance at 145Hz. You now have a much more pleasant sounding box that requires a lot less eq.
     
  9. davelowell

    davelowell

    Jan 18, 2001
    stl, mo
    TimmyP, did you make square back cabs, or the kind with the towel bar? Same size?

    Do you get a bassier, fuller sound? I am reluctant to remove the panels of wood, what if I don't like it still, and I just ruined a vintage cabinet?

    Just thinking out loud.

    Dave
     
  10. My suggestion is that if you feel you need to make this modification, maybe you should be considering a different cab.
    Not all people would agree that it sounds better. You will get more low end but you will sacrifice midrange punch and clarity.
     
  11. Rockbobmel

    Rockbobmel Supporting Member

    I thought the main idea of the compartments was a tighter punchier sound with quicker recovery time. (Physical damping)
     
  12. Yep, and it also minimizes phase anomolies caused by the backwaves of the drivers...
     
  13. TimmyP

    TimmyP

    Nov 4, 2003
    Indianapolis, IN
    To answer several questions/comments:

    This was before they made the tiltback version.

    I don't consider the midrange of a stock box to be punchy and clear, I think it's obnoxious.

    The backwaves are going to have an effect regardless of the cabinet's internals. It's a tradeoff. Given that you have eight drivers reproducing the highs, you are going to have a lot of comb filtering anyway. We found no downside to the performace of the 8x10 as opposed to the stock 4x(2x10) - we all preferred the undivided box.

    I definitely would not cut a vintage cabinet, if it is indeed worth more $ owing to it's age. I'd sell it and get an Acme box.
     
  14. davelowell

    davelowell

    Jan 18, 2001
    stl, mo
    Excuse my ignorance, why an Acme box?
     
  15. TimmyP

    TimmyP

    Nov 4, 2003
    Indianapolis, IN
    I think the Acme boxes go deeper and sound better than anything I have heard. (I've not heard any Augilar or Epifani boxes, but I think I have heard most of the other "talked about" boxes.)
     
  16. davelowell

    davelowell

    Jan 18, 2001
    stl, mo
    4x10, I assume? Would an early 70's SVT have enough power for it? Would it be as loud or louder than my Mesa Road Ready 2x15?

    Thanks guys!

    Dave
     
  17. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Timmyp, I'm interested in the mathematics behind this. I've taken an interest in cabinet design and I'm learning a lot from TBers. I have never read anything that describes cabinet design in this way. Could you elaborate a little?
     
  18. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    hhhhmmmmm........ I just ran simulation of the Ledgend BP102 through WinISD pro and it seems they're right. The frequency response seems similar to the that published by Ampeg (both are -3dB at aprox 60Hz). It's 200w per speaker instead of 100 but it achieves a similar Maximum SPL of 132dB, and the same sensitivity of 100dB with 1w at 1 meter.

    It looks like it will work, and that's good to know. I have no idea of the voicing or colouration of the Eminence speaker so I can say if it will sound the same. But it certainly won't suck. And won't give you any more bottom end, certainly not as much as the 2x15 you're used to.
     
  19. Rickenbackerman

    Rickenbackerman

    Apr 17, 2001
    Laurel MD
    Dave, are you sure the cab is wired correctly? Even having one speaker out of phase will screw the sound royally. Have you done the 9V battery test?

    What do the speakers look like? Ampeg mostly used three different kinds over the years:
    CTS alnico
    Eminence square magnet
    Eminence round magnet

    My '71 cab has original mid-70's eminence squarebacks, and my '76 cab has the same speakers, but I had them all reconed by Ted Weber. The Webers sound fantastic.

    FWIW I've played through a bunch of different 8x10's, and my Weber reconed cab sounds better to me than any of them, including the newer 810E.