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Sub cab?

Discussion in 'Amps and Cabs [BG]' started by Chris_AtariDoll, Dec 15, 2003.


  1. Chris_AtariDoll

    Chris_AtariDoll

    Dec 8, 2001
    UK
    I am thinking about changing the cabs in my rig... and i was thinking about a cab to handle the real low freqs (>100hz) it is gonna be used with a 4x10 and the sub cab it will be getting about 550w @ 8ohms or 1100w @4ohms.
     
  2. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    What's the budget?

    An SWR Big Ben or an Acme Low-B4 would both do a fine job.

    Alex
     
  3. Chris_AtariDoll

    Chris_AtariDoll

    Dec 8, 2001
    UK
    Probably around the £500 mark.

    I have a warwick 1x15 cab at the moment, but it just doesnt seem to drop. looking for something to really shake the place, when i use my synth fx.

    Would a PA sub cab do the job?
     
  4. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    You could get an B4W shipped over here for about that. Spend another £75 and you can get standard version with the mid and high drivers which is an awesome sounding one-cab-does-it-all monster.

    I used one of those Warwick 1x15" cabs at an outdoor gig last year in parallel with my pair of Low-B2s. It had nowhere near the output of the Acmes, either in terms of maximum volume or deep bottom end.

    Very few PA subs goes really low, they just have lots of mid-bass boom for maximum kick drum loudness. The ones that go deep tend to be rather big, heavy and/or expensive.

    Alex
     
  5. jondog

    jondog

    Mar 14, 2002
    NYC metro area
    You need a crossover to effectively run a sub cab. You can't daisy chain it w/ your 4x10 (or you can but it won't sound as good). A PA sub will work fine if you are feeding it only <100hz and plenty of power. The Yamaha 18s have good reviews. I use an EV 18 in an inexpensive cab and I love it!
     
  6. Chris_AtariDoll

    Chris_AtariDoll

    Dec 8, 2001
    UK
    thanks for the help...

    i know a guy who builds boxes for Car audio SPL competitions. I mite see if he can come up with something. What do you think is the best size drivers to use?? a single 18 or a pair of smaller ones?

    I'm looking for something 'off the shelf' but getting the guy to build me something may be an option.
     
  7. Chris_AtariDoll

    Chris_AtariDoll

    Dec 8, 2001
    UK
    Im using a Ashdown RPM-1 Pre amp and using the onboard x-over to run seperate hi and lo signals to a Peavey 2600 poweramp (2x1100w @ 4ohms) one channel running the 4x10 and the other the sub.
     
  8. jondog

    jondog

    Mar 14, 2002
    NYC metro area
    Well that's plenty of power! :)

    The Yamahas are down to $300 new here, so I don't know if you're saving money having something custom done, unless you can find a nice used driver (always taking a chance, especially w/ subs, but I found one) or your friend will give you a discount. If you do go w/ a custom cab, make sure to have it designed according to the parameters specified by the mfr. or a box design program like winISD.
     
  9. Chris_AtariDoll

    Chris_AtariDoll

    Dec 8, 2001
    UK
    if only warwick made a passive version of this:

    [​IMG]

    it would look great under a Warwick 4x10
     
  10. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Eeeww... band-pass subs... Very narrow frequency response, lots of distortion, awful group delay. Best kept for SPL competitions IMO where it doesn't matter whether or not you can discern the pitch of the note or if it feels responsive to your playing.

    I'd keep away from car subs - they may seem very loud in a car and handle loads of power but they'll struggle to keep up with your 4x10", far too inefficient. If you're looking into getting a cab built, how about something with an Eminence Magnum or Kilomax 18", lots of power handling, low Fs, plenty of excursion, doesn't need too big a box.

    Alex
     
  11. No.

    You used the magic words "synth" and this is going to take you down to 26 Hz. PA mains won't do this, and neither will the Yamaha sub and I have experience with that one. Acme specifically recommends against using their cabs with synths, because they are not designed for it.

    You are looking for vented cabs tuned right around 26 Hz. Normally, this low frequency is the domain of true subwoofers. Subs are very inefficient, and this requires multiple subs and a kilowatt to drive them.

    Look in to the Beyma 15K200 driver. It tunes at 27 Hz, has an SPL of 96 at 1W/1M, which is on a par with the Acme. This driver requires 3.55 cubic feet for this tuning. It will have a roll off, with F3=61 Hz, but it will still go all the way down to sub-synth level, and with a reasonable efficiency.

    [ edit ]

    I found a source for the Beyma PDF files, and have added several to my spread sheet. These are VERY interesting drivers, and fill niches not touched by Eminence or the other major manufacturers.
     
  12. well, not to be a pain, but this isn't wholly true. if the cabs are designed efficiently enough, you don't need a crossover.

    this is the thinking behind AccuGroove's design with the Whappo Grande. I use one all the way down to 23Hz and it rocks!!

    :D

    from the seriously low end,


    Stew
     
  13. jondog

    jondog

    Mar 14, 2002
    NYC metro area
    OK, so I guess I know nothing about subs :meh: :)

    You don't have to have a xover, but the Whappo design is the exception rather than the rule. Xovers help you get the most out of your amp because you don't waste power sending frequencies to cabs that are not designed to produce them.

    The Yamahas are rated down to 30hz. My buddy's band uses 'em and they thump. I think I saw that JT uses 'em in his bass rig. Not all synths are subharmonic. What type of synth are you using Chris?
     
  14. LOL

    nah, I still think a crossover is a good idea *most* of the time. I just wanted to point out that it can be bypassed in the right circumstances.

    ;)

    from the low end,


    Stew
     
  15. I have to disagree.

    If that were the case, that means all those pros hanging tens of thousands of watts driving tri-amped systems have got it all wrong. One very good reason for a crossover is waste. It is a 100% waste of power, sending signals to a driver that it cannot produce. Another good reason is keeping 23 Hz out of your 10" drivers, because they cannot hope to produce it. The best they can do is self-destruct.

    The Whappo Grande appears to use a Beyma 21L50 driver. If so, the 21L50 requires a net cabinet volume of 10.4 to 15 cubic feet for correct tuning.

    Link to Calculations

    The 21L50 requires a port diameter of 9.0 inches, or 65 square inches, to avoid chuffing (MACH 0.045). Using a smaller slot port of 48 square inches (MACH 0.100) still results in a port that displaces about 0.7 cubic feet.

    Using the Whappo Grande cab dimensions, I come up with a net volume of about 4.8 cubic feet. This is FAR too small a volume for the 21L50 to perform down to 19 Hz at -6dB. At small signal level (1W/1M), the 21L50 in 4.8 cubic feet is -20dB at 19 Hz when tuned at 33 Hz. This driver cannot accept more than 150 watts at 19 Hz, before it over-excurses. It will take the full 800 watts all the way down to 26 Hz in this cabinet and is down -14dB at 26 Hz. Impressive.
     
  16. well, you're now speaking in lingo way over my head, but if you say it's true... okay.

    I've been gigging for the better part of this year with no crossover and it's a killin' rig.

    I'm glad I never taught my ears science!

    from the ill-informed low end,


    Stew
     
  17. Johnny BoomBoom

    Johnny BoomBoom Supporting Member

    Jun 8, 2001
    Glasgow, Scotland



    Hmmm, I have pinged Ashdown a couple of times about a product that is mentioned in their ABM 500 users manual but does not appear on their product list on their website!

    In the Sub-Hamroniser section, it mentions that their is a separate line out for use with a 400 watt powered sub-woofer cabinet (allegedly made by Ashdown). I have not had replies to my emails yet - but maybe it's an avenue worth pursuing????

    Then again, maybe not......
     
  18. Chris_AtariDoll

    Chris_AtariDoll

    Dec 8, 2001
    UK
    hmmmm interesting, i have been talking to martin @ ashdown quite often over the past few weeks, as he is building my pre-amp at the moment. i will ask him about it.
     
  19. Chris_AtariDoll

    Chris_AtariDoll

    Dec 8, 2001
    UK
    i use a digitech and ibanez synth bass pedals, i uses them for some serious low freq sweeps in one song and i will also be using the sub harmoniser on the pre-amp quite a lot.
     
  20. Johnny BoomBoom

    Johnny BoomBoom Supporting Member

    Jun 8, 2001
    Glasgow, Scotland


    *Mr Burns voice on*

    Excellent....

    *voice off*


    If you find anything out....I'd be interested!!!