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Do you have to biamp to use a sub?

Discussion in 'Amps and Cabs [BG]' started by Tash, Apr 26, 2005.


  1. Tash

    Tash

    Feb 13, 2005
    Bel Air Maryland
    I'm still looking for the ultimate low end bass amp, and I'm reading up on subs like the Whappo Grande. I'm wondering if you have to biamp to use one of these or if you could place pair it with a full range cab. Would the higher frequencies of the full range signal damage the sub, or would they just roll off into nothingness? Same with the low freq. into the full range cab.

    Thanks.
     
  2. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    The same signal will reach each cab if you just chain em.
     
  3. Tash

    Tash

    Feb 13, 2005
    Bel Air Maryland
    I know that...what will that actually do to the cabs is more my question?
     
  4. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    The cabs would play like you were using them on their own, except the wattage is divided evenly between em, which shouldn't be a problem using a solid state head, as the lower impedance should balance it out. The sub wouldn't replicate most of the higher freqs and hence would not be damaged in any way. Check out the frequency ratings on cabs, that will tell you how they replicate sound.
     
  5. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    Well, it would waste power and probably muddy things up where they overlap in bandwidth. A simple passive crossover would certainly help. An inductor on the sub and a capacitor wired into the other box is all that's needed. Contact the manufacturer for recommendations.

    My DR250a and Tuba24 use this setup, and it does noticeably clean up the 100-200Hz vicinity, where they overlap. I had them built with the crossover components only on the Speakon inputs, and without on the 1/4" ins, so I can use the 250a by itself (if I lose my mind).
     
  6. Tash

    Tash

    Feb 13, 2005
    Bel Air Maryland
    Thank you all for the insight. Lets say I want to seperate the ultra lows from the highs. Is it possible to do this without using seperate amps?

    Example: Head (bridged mono)
    |
    |
    Crossover ----Full Range cab
    |
    |----------Subwoofer

    Or do I have to go something like this:

    Preamp
    |
    |
    Crossover---Channel A---Full Range Cab
    |
    |----------Channel B---Subwoofer

    Hope my little diagram makes sense.
     
  7. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    it all depends upon the cabs and the sound you're after.

    biamping (in this case biamping means sending highs to one cab and lows to another) works great if the cabs in question are optimized for those frequencies. most bass cabs are more or less "full range" none times out of ten a 2x10 and a 1x15 will sound better run full range rather than biamped (just listen to how anemic a 2x10 sounds with 150 hz and up by itself sometime)

    running one cab full range and sending just the lows to a sub for additional lows isnt as uncommon as you'd think. A few very good soundmen i know do this with their pa setups with excellent results. So your idea isn't so far fetched, but you do have to use seperate amps or a two channel poweramp. In fact, i experimented with this quite a bit when i had my alembic F1X. That unit has high, low, and full range outs and in the product literature they suggest trying different combinations including full range to one cab and lows to a sub. it can sound awesome.
     
  8. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    That's pretty much accurate, Mike, but a bit vague.

    There are two ways to divide the lows from the highs.

    One involves biamping. The crossover is located before the amplifier sction (at tline level), so two amps are necessary. This is typically what is done with PA of reasonable quality. It is really the best and most flexible way to go about things, but it is more costly and complex.

    The simple way to do it is what I decribed above, which gets the job done for many bass rigs, but lacks flexibility. The nice thing about biamping is the quick and easy adjustment of crossover frequency, and individual level controls for each frequency band.

    Whether a cab sounds anemic or not high-passed at 150Hz isn't really the point here. Reducing the interaction between the two cabinets is, however. A HP filter on the top cab also prevents wasting amplifier power. How efficient are most 10" speakers at 50Hz loaded in a regular cabinet? Not very. Why waste amplifier power trying to force a mid-bass driver to do something it wasn't really designed for? That's why I prefer the use of LP and HP filters when feasible.

    I think judging the level of complexity and cost that you're willing to deal with is important here as well.
     
  9. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    Tash, your first diagram is what I do, BTW. It does leave you at the mercy of the two speakers' impedances and sensitivities for proper balance, though EQ can help overcome this. Can you post with some detail about the impedance, sensitivity and freq response specs?
     
  10. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    OK, I don't know what you're using for a top box, but that Whappo Grande has some impressive specs, with a price tag to match! 98dB sens. & 19Hz(-6dB) is something special, to be sure. It does go up to 400Hz, which I don't really see as all that useful. I'm sure your other cab does fine from 100Hz on up or so.
     
  11. pickles

    pickles Supporting Member

    Mar 23, 2000
    Ventura, CA
    I've never played a bass setup that sounded better biamped than full range. You always loose a little something at the crossover point (the amatuer physicist in me blames phase misalignment between the cabinets in the range where the crossover slope is allowing the two to interact).

    Actually, I have the same problem with subwoofers in home audio systems, so I run 2-way MB Quart twin 6.5" towers full range. Crossovers are OK for tweeters for my ears, just not for subs.

    Just for kicks, I'll try biamping my current setup since the Alembic F1-X is supposed to have a killer crossover, and the Big Ben is supposed to be a sub. I doubt I'll like it.
     
  12. It depends on what crossover you're using. 4th order crossovers can sound pretty bad in a bass rig. The 24db per octave slope is much too steep for my tastes and the dividing line between the top cab and the bottom cab is too abrupt. Using a 2nd order crossover makes all the difference. The transition of frequencies from top to bottom cab is much smoother. Alembic and Eden use 2nd order crossovers.
     
  13. pickles

    pickles Supporting Member

    Mar 23, 2000
    Ventura, CA
    What does SWR use?
     
  14. 2nd order - 12db per octave.