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Who's Bi-Amping???

Discussion in 'Amps and Cabs [BG]' started by jokerjkny, Jun 24, 2003.

  1. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    Hey all,

    who's doing the "Bi-Amp" thing, and does it really work?

    i'm thinking about getting a 3x10, but also a 1x15 to see if it'll fill out the bottom end. BUT, should i try going bi-amped? then agin, does it really pertain to us anymore?

    seems like cabs and speakers of all sizes these days are made to be full range, and that splicing up the signal's would only "limit" and maybe even seemingly degrade an speaker cabs' performance that's used to seeing the full frequency range.

    i.e. would running my usual lower mid frequencies thru the 1x15 only ruin my tone, since thru a 10" speaker, it'd be obviously much punchier?

    i've got an Aguilar DB680, will be using it with my Low B'd basses, and am very curious if this would work out or not.
  2. jondog


    Mar 14, 2002
    NYC metro area
    I bi-amp.

    I tried it once before, and didn't like it. But now I play more 5 string, octaver, and low synth bass, so I tried it again and this time it worked out great.

    I run a BE S15XD on the top and an EV 18" on the bottom. You should check the specs on the cabs you're interested in. Yes, lots of manufacturers say "full range" but they don't often cover the low end all the way down to 30hz. My BE is only rated down to about 50 hz. In real life it can handle a low B by itself, but that B comes across with a lot more power and authority when the fundamental is handled by the 18".

    Even if you don't go bi-amp, if you're looking for the punch of 10s in a 15, try Bag End.
  3. I bi-amp.

    There seems to be a rumor around that only 10s are punchy. I suggest slapping through an 18" JBL E155 or 15" E140 before dismissing larger drivers as either sloppy or slow. The cheap 15" drivers found in commercial bass cabs pale when compared to high end drivers.

    It is much easier to make a cheap 10" driver that sounds pretty good, because the cone+air mass (MMS) is so much less for a given magnetic motor strength. The other component for punch is the voice coil inductance. There is a specific amount of time lag involved when energizing a coil of wire. This is why coils are used as inductors in crossover circuits. Larger inductance coils in big drivers take more time to energize. 10" drivers typically have smaller diameter voice coils, and smaller inductance values.

    10" drivers have very little Xmax (cone excursion), are usually a high Fs, and have a taut suspension. None of which is useful for producing low frequency notes, which is why 10" cabs have a gutless bottom octave when compared to a properly engineered 15" or 18" cab.

    The solution is bi-amping. Each driver receives only the frequencies for which it is designed. The subs get the Lows, and the 10s get the Highs. An active crossover is required, and also a two channel power amp. The active crossover operates between the preamp level and power amp, and provides complete control of crossover frequency and individual channel gain. The gain control allows you to balance the output from the Lows and Highs. It is a Set and Forget adjustment that can be done by ear, or with an analyzer if you are picky. I use an analyzer plus graphic EQ to dial in the response to Flat.

    Bi-amping allows for adding additional High/Low pairs to suit the gig. A single 1x15 plus 1x10 is fine for small venues. Four 1x15 and four 1x10 will do for loud outdoor gigs. Daisy chaining cabs (parallel) using Speakon connectors makes adding cabs very easy. Four cabs is right on the 2 ohm limit, so take care here.

    Bi-amping increases my rack by 1RU for the crossover, and adds the burden of carrying more Speakon cables. Properly engineered low frequency drivers require larger cabinets, so I split all my drivers into 1x units for less weight and smaller size per unit. Two 1x15 plus two 1x10 and the rack mostly fills the back of my Toyota pickup.
  4. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    thx gav,

    on my Aguilar DB680, there's just a blend knob that splits the freqencies, and separate gain knobs for the highs and lows, so i guess i dont need the active crossover.

    my question is, even tho you say 10" speakers are no good for certain lower end octaves, the Epifani 3x10 (Frequency Response: 40hz - 16khz) and Epifani 1x15 (Frequency Response: 38hz - 16khz
    ) seem like they cover the same ground. so, would bi-amping be worth it in this case? seems like both cabs hit the same frequency area, so would i not gain anything from Bi-Amping? seems like i can just cruise with the 3x10 and not have to worry.

    BUT, if i do gain something from bi-amping, at what specific frequency would there be the split between these two cabs? in my case, i prolly should just use my ears, but i'd like a good analytical answer too, if you dont mind. :p
  5. One of the best sounding rigs I've heard was a 1x15 and 2x10 with horn bi-amped. I set the x-over at about 100 and enjoyed. The 15 was free to concentrate on everything below 100hz and the 10's handled everything else. This setup will also play louder than the same speakers run full range. You will need, however a stereo power-amp and a x-over, extra cabling etc, etc,. I've been using a single 4x10 cab for so long, I'm just too lazy to change.
  6. I bi-amp a pair of EV 15's and a pair of Eden 10's and I agree with bgavin completely. Anybody who says 15's are sloppy and slow has never tried quality drivers in a bi-amped system driven with a power amp that has a high damping factor. The response is stunning. The EV's do the brunt of the work in my system and are as tight as I could ever want. The Eden's are there just to add some sparkle to the upper mid and top end which the 15's don't do well.
  7. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    Oooooo, that's quite interesting. anyone else find this true?!
  8. BlacksHole


    Mar 22, 2000
    Rockville, MD
    I've been biamping for many years. In the setups I've used, it was not particularly louder than bridged mono, but it certainly has some advantages which I like. My favorite set up is separate tone controls for high and low as well as separate effects. In my case no effects on the low or just a sub octave and a touch of chorus on the highs.
  9. It's true although I usually cross over a little higher at 170hz. I don't know that bi-amping is necessarily louder than fullrange, but at high db levels bi-amping is much clearer which could give that impression.
  10. jondog


    Mar 14, 2002
    NYC metro area
    Yes, it's true. I think it's more true for the top speaker than for the bottom. In the end, each speaker has a smaller range to try to cover so you can push it a bit harder.
  11. I can get louder with my bi-amp system than running the same configuration full-range; only because the 10's don't give when you bi-amp. I don't know that there's any volume difference.

    That was my main reason for bi-amping, I couldn't get real loud without the 10s stressing over all the low end. (I have a bass with a preamp, and the bass knob is ALWAYS on +15). When I tried bi-amp I was amazed...all that gain and no stress :)
  12. redneck2wild


    Nov 27, 2002
    Memphis, TN
    I biamp a 4x10 (highs) with a 1x18 (lows) with the crossover set somewhere between 75hz and 100hz depending on the location.
    Using the same power amp (Peavey dpc 1000) with one channel going to each speaker:
    If I biamp with the crossover at 75hz I get a much cleaner sound than running each cabinet full range.
    Both amp channels clip with the gain around 1'oclock with normal playing when running full range signals to each channel.
    When running biamp, the Low channel clips around 3'oclock and the High channel only occasionally clips around 5'oclock (turned up all the way).
    The low end is much tighter biamped and the highs are crisper.
  13. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    Fremont, Ohio
    Editor-in-Chief, Bass Gear Magazine
    So, Joker, I take it you are convinced that the 15" is not going to go the way of the dinosaur, eh? :p :D

  14. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    hardy har har... :rolleyes:

    ;) :D
  15. Joker,
    I have an Epifani 3x10 that I match with a 1x15 EVM-B. I send a full signal to both and it sounds great. I did try biamping with a DB 680 before I sold it and found it great for Low 5 string stuff but I rarely go that low. I recall 100hz was my favorite c/o point. FWIW
  16. biamped!.. I bet the sound was to die for.
  17. Yep, it was sweet. Don't knock all 15s. I love my old EVs.
  18. There is a difference between ad copy and reality. I can claim to look like Mel Gibson and be hung like John Holmes... a plot of actual measurements would reveal much different results than the specs claim.


    To make noise at low frequencies, you have to move the air. Xmax * Sd = air volume moved. A 15" driver has 2.5x the amount of piston area as does a 10" driver. An Eminence Delta 10 displaces 55 mL and a Deltalite 2510 is 136 mL. A Selenium 15SW1P displaces 757 mL. The Adire Maelstrom displaces 1584 mL (!) which is why it makes so damn much noise at 26 Hz. 10" drivers don't move this much air.

    Where you crossover depends on the drivers involved. The ideal point is 1 octave below the upper rolloff point for subs and 1 octave higher than the low rolloff for the highs. This allows 1 full octave of headroom for each driver. These points are determined by measurement. If your sub begins to rolloff at 250 Hz, cross it over at 125 Hz. In a perfect world, the Highs unit would roll off at 62 Hz (octave below 125 Hz). Most active crossovers are 24dB/octave, which reduces the 1 full octave requirement by quite a bit.

    A real world example is the Eminence Magnum 18LF that begins to roll off at 600 Hz. The Eminence Legend B102 lower rolloff begins around 150 Hz. This pair is ideal for a 300 Hz crossover point. Both drivers have lots of headroom around the crossover point. Hmmm... wait a minute... I have this exact combination of drivers on my bench now... just waiting for cabs.
  19. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL

    just the answer i need. but oi... i just checked and saw that i gotta wait until my bank account gets up to speed... :meh:
  20. My prospective rig it Biamped...I'm thinkin with the..

    SansAmp RBI>Insert good crossover(Crossed over at about 100-125>QSC RMX2450 split into a BagEnd S15-D[Low] and a BagEnd S15X-D[High] with 1500W of kick in the teeth!

    Sound good to anyone else? I'd be in tone heaven(compared to the current single 15 setup I'm running, But I gotta get my stuff first.:( )

    I'll have it ASAP!

    In BASS:bassist: