question on biamping...

Discussion in 'Amps and Cabs [BG]' started by L-1329, Jul 27, 2005.

  1. L-1329


    Aug 8, 2004
    I have been experimenting with biamping my Avatar's and have a question for those of you who run biamped rigs live. What I have is an Avatar 210 neo and B212, run off an Eden Navigator+poweramp. The Nav has a biamp crossover that I have never used. until now I had to run bridged mono for my other two cabs so that was out.

    With the Avatar's it seems to add some clarity over the full range tone, but I am only able to play at very low apartment levels. My question is how does this kind of setup project, and sound out in the back of a room? I am curious if the two different types of cabs would project evenly, or if the overall sound would change when loud out in the back. I wouldn't want to hear either cab predominantly, but if the tone 'stays together', so to speak, this might be worth trying. Any experiences?
  2. I have an SWR SM900 (bi-ampable with seperate hi & low poweramp channels) and Yorkville 2x10 & 1x15 cabs. I've tried numerous times to use this set up in bi-amp mode and always come to the same conclusion - it looses balls.

    When testing running bi-amp, I used the two seperate channels of the poweramp (2 x 240watts @ 8ohms) and then switched to using one channel for both cabs (1 x 350watts into 4ohms) and tried to really keep the volumes the same using my ears.

    I don't think that I get a cleaner tone from bi-amping and what I loose is a full and large tone without anything missing. I'm not sure excatly what is going on sonically but to my ears it just sounds cleaner, fuller and bigger running a full range signal out of both speakers.

    Try it and see what works for you but keep in mind that (I believe) most of the bass players out there are using full range signals/amps into various cabs.
  3. I ran a bi-amped rig (1x15 & 2x10) almost exclusively for
    about 13 years or so. In the last year or so, I've started
    running full range. I love the tone I'm getting now way more
    than when I was bi-amping.
    I don't know about all of the physics of it, but I do know that
    my two speakers are set up to cover basically the same
    frequencies, so bi-amping didn't really gain me anything.
    Basically, all I was doing was losing out on some power, punch,
    and other things that are generally desireable in bass tone.
    I don't know if that'll help you or not, but that's my experience.
  4. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    The idea behind bi-amping is that you use loudspeakers that are designed optimally for each portion of the audio spectrum.

    And then instead of taking the high-power, full-range signal put out by the power amp and inefficiently and imprecisely splitting it into frequency ranges through a passive crossover, you split up the audio spectrum at line level, amplify the frequency ranges separately, and put them into their respective loudspeakers.

    The benefits are greatest with full-range audio and less so with bass. You'll especially hear no improvement if you just use loudspeakers that are good over pretty much the same frequency ranges. For example, if you use two cabinets that might be different but are still both good for bass, what's the point? OTOH, if you have one loudspeaker that's good for, say, 25 Hz to 800 Hz, and another good for maybe 500 Hz to 8 kHz, you might get some good results if you actively cross over at around 600 to 700 Hz.
  5. Spot on. There's little advantage to biamping a 2x12 cab and a 2x10 cab because they're so similar, but biamping a 2x15 and a 2x10 for example can have some real advantages.
  6. I was running a bi-amped setup for years and preferred it. I still have my current setup but no longer gigging.

    Right now it is an Alembic F-1X and a Stewart World 2.1 driving a SWR 2X10 and an 18

    I also used to biamp a Bag End AF1A-C with a GK 800RB

    One thing, like Bob Lee mentioned above, your speaker choice will be crucial in a good sounding bi-amp system. What you are using for a sub will only sound good if it was designed to be a sub. A 15 or a 2X12 that was designed to be a full range speaker will not work as well. Any good 2X10 will work fine for the high end.

    The last thing I would say about the two set-ups I have used is that they lacked balls. It does have less punch than say a 4X10 but a proper bi-amped system has balls-a-plenty. The low's coming out of that Big Ben was very clean and was enough to shake the fillings from your teeth. Paired with the 2X10 it had plenty of definition.

    To answer your question, will the sound stay together. Yes, if your B212 can reproduce all the low's a sub should and the 210 with the highs you should be able to dial in a great sound. You will have to keep in mind that because the two speaker are handling different frequencies you will have to stand back a few feet to know what it will sound like out front.

    There are some pros and cons though. With the 18 I had it came in very handy on outside gigs because of the small PA that our band had but in smaller or boomy sounding clubs it was a little troublesome. Also in smaller clubs I was sometimes stuck right in front of my system and could hear mostly only the 18, on the stage it sounded muddy but out front was fine. The pro's are it was a very high-fi sound, allot more cleaner bottom than a full range. My problem with the 18 might be solved with a proper 15. Bag End makes a good 15 for a sub.

    I say experiment away, if you like what you hear see if you can get your hand on a sub to try out. Try both the 2X10 or the 2X12 as your high cab with a sub. With my F-1X I was also able to run the 2X10 full range with the 18 on the low channel.

    You may like it, you may not. I still love the sound of a good 4X10 and someday may go that way. It's really what suits you at the time.
  7. Did you switch polarity to one of the cabs? The full-range out and the high/low outs on the F-1X are 180 degrees out of phase with each other you know.
  8. oldfclefer

    oldfclefer low ended

    May 5, 2005
    Southern Ohio
    I'm biamped out of an F1X. I run an Ampeg BA115 for the highs and an ampeg B2R with a JBL 18" for lows. What I do is set up each amp/speaker combination separately when I run live. I set the crossover at about 800hz and fine tune according to the room conditions. Biamping gives me great control over my sound, enough punch and power to put it across, and that, in my opinion, is what you'll want in a live situation.
  9. Are you certain of this?

    Basically I tried the Full range 2X10 with the 18 in the lo-pass with the cross over below 150Hz, didn't like the results as much as full bi-amp so switched back. it was a short experiment. My main reason for bringing that up was to let him know he may be able to try different things other than just full range vs. bi-amp.

    I also checked the owners manual (I don't throw anything away) They show all the speaker options but no mention of having to reverse the polarity if you use a full range & bi-amp combination. I also just did a quick (very) search on their web sites forum with no luck.

    The manual is actually just one page so I think they may have left out allot. No schematic. The brochure has more technical info than the manual.

    I know what speakers being out of phase is, so if you are correct I must have been missing quite a bit in the frequency curve. No wonder I didn't like it. If I decide to try it again I can easily switch the polarity because I use the SWR's banana connections.

    What is your source for this info? I noticed you use one too. Just curious.
  10. I'm pretty sure. Any time you run a signal through a crossover you're going to get a phase shift. The high/low outputs on the F-1X go through the crossover, but the full-range output does not so there's a 180 degree mismatch.

    Browse through these archives from the Alembic club.
  11. Hey Mudbass,

    That's the place (alembic club forum) I tried searching earlier. I tried again, quite a bit actually. I could not find anyone with that problem. Most likely due to not many people using that combination.

    Also after mulling over what you state, it just doesn't make sense to me. Bare with me here, I don't know that much about electronics, just what I have picked up along the way.

    Two speaker being out of phase with each other simply means that one of the speakers has the positive and negative crossed so the cones are not flexing in synch, they would flex in the opposite directing of each other canceling out frequencies in a bi-amped system.

    So what you are saying that when using the crossover outputs, positive and negative are reversed, or how does a crossover affect polarity. This is the part I am having trouble with.

    I don't mean to beat a dead horse, just like to be edjamacated. :D

  12. Try doing a search with "phase" as your key word and you should come up with some discussions about phase issues with the F-1X.

    I don't know how or why it happens, that's beyond the limit of my poor old brain cells, but the way I understand it... Each order of crossover has 90 degrees of phase shift.

    1rst order -6db per octave cut, 90 degrees of phase shift.
    2nd order -12db per octave cut, 180 degrees of phase shift.
    3rd order -18db per octave cut, 270 degrees of phase shift.
    4th order -24db per octave cut, 360 degrees of phase shift.

    The F-1X (as do most bass preamps that have a crossover) uses a 2nd order crossover. The high/low outputs are 180 degrees out of phase with the instrument input, which is really no big deal until you try combining the high/low outputs with the full-range output. The full range output doesn't go through the crossover so it's still in phase with the instrument input, ergo, 180 degrees out of phase with the high/low outputs. This is easily corrected by flipping the polarity to the cab running off the full-range output.

    Two cabs out of phase have a tendancy to cancel each other out and you get sort of a unfocused, hollow sound which, unless that's the sound you're looking for, is not a good thing. :)

    Unless there's circuitry in the crossover to correct the phase mess, the output is going to be out of phase with the input and so far, at least according to the thread at the Alembic club, nobody's found any circuitry in the F-1X that does this. Alembic has been conveniently silent about the whole thing, but Alembic isn't known for the world's most responsive customer service anyway.
  13. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Bob Lee has the right tack on bi-amping. It works very well with speakers that are intended to operate in different frequency ranges, such as found in PA systems. It is of dubious, if any, benefit with electric bass cabs that typically share 80% of the bandwidth that they operate in. A more sophisticated crossover that would allow both amps/cabs to share duties over a wide range would work well, but that's not the way crossovers are configured.
  14. watspan

    watspan Supporting Member

    Nov 25, 2002
    madison, wi
    I run an ampeg pr1528he w/ a hartke 5000 250+250. the cab is built for full or biamp range. the specs list the 2x8 @ 200hx-20khz and the 1x15 @ 45hz-500hz. I set the crossover around 150-200 and it sounds real nice. with my style head, you need to biamp to get the full 500 watts. I like that you can pan from between hi and low cabs--real easy to tweak your tone--especially when using effects