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8" speaker for a champ style cab?

Discussion in 'Amps and Cabs [BG]' started by deepestend, Jul 3, 2014.


  1. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    I've been reading the archives, but thought I'd make a post to see if there are any fresh opinions.

    I built a little 20 watt SS amp (the tiny giant) and am having John Mergili make me a tweed champ style cab.

    Now I need an 8" speaker! This is for late night home practice on bass and guitar.

    I seem to be hearing a lot about alpha 8a's. Is there anything else I should consider?
     
  2. Doug Parent

    Doug Parent Supporting Member

    May 31, 2004
    San Diego, Ca.
    Dealer Nordstrand Pickups.
    Sent you a PM about an 8" woofer.
     
  3. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    Pm'd back.
     
  4. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, ChopShopAmps
    Eminence Beta 8
     
  5. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    Why the beta vs alpha?
     
  6. basscooker

    basscooker Commercial User

    Apr 11, 2010
    cincy ky
    Owner, ChopShopAmps
    Alpha IS a better fit, nevermind....20 watt amp. I was thinking better power handling, but in this case, Alpha. :whistle:
     
  7. In addition to the Alpha and Beta 8's consider the Faital 8FE200 and Dayton PA200-8.

    To use any of these with bass, even at 10-20w, you will need to either seal or port the cab. Or you could put a nice guitar speaker in the 'Champ' cab and incorporate a jack for the speaker (like the real Champ), so you could plug in the Champ/guitar speaker or a separate, compact bass cab.
     
  8. Steve Dallman

    Steve Dallman Supporting Member

    I'm sort of partial to a Jensen Mod.
     
  9. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    This setup obviously has it's compromises! How is the jenson compared to the alpha?
     
  10. The Jensen is a great guitar driver, but is a poor bass guitar driver due to its high Fs and minuscule excursion capability. I was actually thinking of this driver when I suggested a guitar driver in the Champ cab and a bass driver in a dedicated cab. The Jensen Mod 15 is a nice bass guitar practice cab driver (in an open back cab).
     
  11. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    The limitation of this project is an 8" speaker w an open back. That's why I was thinking of the alpha.
     
  12. I think you will be VERY disappointed with the Alpha 8 (or most any 8) in an open back cab for bass guitar Provided that you won't be playing guitar and bass through the amp at the same time, your best option is a separate bass cab (IMO).
     
  13. Woodstockz

    Woodstockz

    Sep 23, 2011
    San Diego, Ca
    +1. You will be disappointed with any open back for bass guitar.
     
  14. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    I have a big rig in my practice space. This is the all purpose at home amp for guitar, bass, and uke. Home practice. I realize that it's not perfect. Plus, I'm in a NYC apt.

    That said, should I try to get it closed back?
     
    Last edited: Jul 4, 2014
  15. For a functional (even for 'quiet' practice) amp, closing the back is essential. You will be WAY glad you did. You probably don't want to inlcude the tube amp in the enclosed cab (cooling concerns).
     
  16. Not necessarily, I've got a champ-style cabinet with some valve jr. electronics in it, with an unlabeled 8"
    driver I got at a music store, it's open back. It doesn't push the bass, but it puts out well detailed mids at a respectable level. Just don't drive the speaker hard and you'd be fine. Closing the back and probably even stuffing it a bit would be a good idea to protect the speaker at higher levels and help to not-reduce bass, but if you don't do it, the speaker won't explode if you're sensible about it.

    Well, if you want to save a few bucks, the MOD wouldn't be a bad speaker to get, it's cheap, and I've been told that the MOD series sounds great for guitar at least. It's been mentioned before that they have a miniscule excursion - but with a 20 watt amp I'm not too worried about that, at practice volumes you'd be able to tell when the speaker is having enough, even when playing along to a CD player, just keep it sensible. That said, the Alpha 8 would be able to go deeper with its 3 mm excursion and 125 watt thermal rating. There is no wrong answer, but if I had to pick, I'd go with the Eminence - living in Canada I can get them cheaper than the Jensen and I'd trust it to handle the low end a bit more. Either way, who says that you can't have it both ways, open AND closed back? the back and front panels are just 1/4" or 3/8" birch ply, which isn't exactly hard to work with, you could just make a third back panel that could either screw in or buckle in relatively quickly with latches - as well as some extra paneling to seal it off better, and then you could have it open back or closed back whenever you want. With my cabinet, I wasn't too concerned because I intended to play it only with a guitar, but I ended up doing the inevitable, and the amp hasn't collapsed yet.


    [​IMG]
    [​IMG]

    Please note how small of an opening that is, you could just glue some more plywood onto the inside of those two panels so that they overlap with the third, and then screw through them to provide a better seal. Also, that's not birch ply, it was some hardware store special that they called birch, but looks and acts more like basswood or possibly poplar, it was leftovers from another household project, besides the valve junior, I only spent $40 on the whole project for some grill cloth and the speaker - everything else was scrap, and besides a jigsaw for cutting out the baffle, I didn't use power tools.

    Edit: I neglected to mention the functional importance for closing the back of the cabinet. It's primarily for the low-end, if you leave the back open, then the omnidirectional nature of the low-end frequencies would mean that the speaker, through its own movement, would cancel out the low end due to the reversed phase of the back side of the speaker. This isn't such a problem with the directional mid and high frequencies though, so leaving the back open would have less bass. Closing the back would also produce a sealed cabinet, if done properly, which would not only seal off the movement of the rear-side of the speaker but also make the air inside the cabinet push back against the cone's movement, providing some resistance and acting as a "pillow", helping to prevent over-excursion - which would be more of a risk with the open-back cabinet.
     
    Last edited: Jul 4, 2014
  17. Let me rephrase: If you want to hear bass when you practice bass guitar, you will be VERY disappointed with the Alpha 8 or most any 8 inch driver in a small champ-size open back cabinet. I love playing bass and, yes, I love bass. I would rather practice through headphones than through a 'bass-less' cab.

    BTW, nice build. Different strokes for different folks.
     
  18. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    Okay you guys... had the builder add a panel to make it closed back (optional)! Thanks again.

    Any other comments or suggestions are appreciated.
     
  19. that's basically the rub, honestly I'm more apt to plug the champ amp into my 410 than I am to play through the 8" if I'm playing with other people, but on my own and when I'm being quiet (people are sleeping, etc...) I find that it gets the job done well enough, I have thought about closing the back though, you're definitely right about lows being disappointing. Thanks for the complement though, the joinery isn't the best, it was my first time in a long time, but I'm still proud of the results.

    As for other suggestions, the only thing I can think about is to enjoy the amp, it seems like a fun project.
     
  20. deepestend

    deepestend Supporting Member Commercial User

    Feb 21, 2003
    Brooklyn via Austin and NOLA
    Guitar/Bass Builder and Social Media at Sadowsky
    Just finished this up last night and it sounds pretty good for what it is. Will post some pix and clips later.
     

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