Bi-amping question, which will yield the best results?

Discussion in 'Archived Threads 2001-2004' started by MichaelO, Aug 9, 2002.

  1. MichaelO

    MichaelO Stunt Coordinator

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    I have a question concerning bi-amping. I am about to do this with my mains, my question is which of the following methods will give me the best results?

    First off let me tell you what I have. I have two identical power amps rated at about 250 watts per channel or 600 watts mono. My speakers are Infinity Kappa's which are rated to handle 300 watts and they are capable of bi-amping. I don't have an external crossover so I am stuck using the speakers internal one. As of right now I have the amps set up in mono mode where one amp is powering one speaker and the other amp is powering the other speaker.

    Anyways, I have heard two different methods concerning bi-amping.

    Method #1: Use one amp for one speaker and the other for the other one. Another words, one channel of Amp "A" will power the highs for Speaker "A" and channel 2 of amp "A" will power the drivers and so on.

    Method #2: Use one amp for the highs and one amp for the drivers (lows). Another words amp "A" would power the drivers of speaker "A" and speaker "B" while amp "B" would power the tweets for both speaker "A" and "B".

    Hope this makes sense.

    Anyway, what will yield the best results?

    Thanks in advance.
     
  2. Paul Clarke

    Paul Clarke Supporting Actor

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    In your case with identical equipment any differences would be more stylistic than anything. If the amps were different I would subscribe to the "B" scenario and share any differences in sound across the soundstage. But since you have matching pieces it doesn't really make much difference IMO.
     
  3. Wayne A. Pflughaupt

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    Michael,

    I agree with Paul. In your case either scenario is functionally the same.

    If you hear any immediate improvement, it may well be because you are running the amps in stereo mode. For most amps bridging degrades it sonic characteristics. IMO bridging is best left for applications where brute force is needed more than resolution – with subs, for instance.

    Regards,
    Wayne A. Pflughaupt
     
  4. MichaelO

    MichaelO Stunt Coordinator

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    Excellent, thanks guys. I will probably just hook them up one amp per side with one channel handling the highs and the other channel handling the lows. Just wanted to make sure I did it the best way.

    Also, thanks for the extra info Wayne regarding running the amps in mono mode (I didn't even think about it, I just assumed the more power the better), to think I could have been getting better sound by doing this earlier.

    Thanks again!
     
  5. Tom Brennan

    Tom Brennan Screenwriter

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    Niether makes any sense. If you're not crossing over before the amplifiers you're just putzing around. Get those reactive crossover elements out of the amp's path, then you'll be doing something worthwhile.
     
  6. Geoff L

    Geoff L Screenwriter

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    Tom dose tell it like it is!

    BUT as Mike stated this is what he has to work with... This is the important part of this question!

    The gains will be much smaller in sound quailty and more in just plain headroom and maybe some small phase issues to the good.

    Getting the ~{crossovers in front of the Amps}~ is the way to really do things right. And then the differences can be great. But as Tom calls it, "putzing around" is better than nothing IMO.

    I say go for it and agree with Paul and Wayne as to your use of how to Amp.

    Your Bi-amp attemp should bear some audiable differance besides just headroom/power. How much, you'll have to decied that.

    Regards
    Geoff
     
  7. Will Gatlin Jr

    Will Gatlin Jr Stunt Coordinator

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    Michael...

    I passive bi-amp my VT-2's (front/rear) with 2 Nak PA-7A II (John Threshold design/225 watts) for the mids/highs. I have 2 Onkyo M-508's (Grand Integra/250 watts) for the lows. This set-up tightened up my bass and gave me more vocals to my mids. When I go back to a single 2-ch amp, by bass is a little bit bommy, and my vocals are not up front like before. It works very well for me and others who have heard my system. Good luck!!
     
  8. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    First off.... Bi-amp.

    You get 5 times the effective power. The "power break" in music, depending on the type of music, is between 400hz and 200 hz. Generally, dense harmonics draw a lot of power. Bass notes below 100hz although they can be loud, are almost sinusoidal in nature (Almost no harmonics). They may be the easiest waveforms to produce.

    So if you bi-amp at or near the power break for your kind of music, when you add another amp of equal power, each amp is having to work half as hard. Since you doubled the available power, you have double the power with half the requirement to produce the same output. That's four times the available power.

    Where do we get 5 times the power? Bi-amping vertically seems to add just that additional available peak capability before audible distress so it's like having 5 times the power.

    This leads us to why you should Bi-amp Vertically.

    Vertical bi-amp is using a stereo amp for each channel. There are several reasons why you would do this rather than using one stereo amp for lows and the other for highs.

    1. Imaging is better. You're separating power supplies and all channel information from one chassis to another. The effect is the same as monoblocks vs. stereo amps.

    2. Dynamics are better. Generally when big bass transients occur, they appear in both channels. In this technique, when the power supply of the amp is hit by a big bass transient, the other half of the amp's supply is still unaffected (Well, maybe not as much anyways). So the overload capability is expanded, whereas a "bass amp" would have instantly and audibly crumpled under the demand. And should the bass channel temporarily overload in a vertical configuration, you may not notice it as readily because the rest of the music is not being clipped.

    3. You're forced to use the same amps

    I don't mean to argue with anyone this is my opinion along with other audiophiles I talked with at a Sonic Culture weekend featuring Avantgarde Loudspeakers. Some of them with 30 years experience in solid installation and live music recording.

    Good luck with your results.
     
  9. KeithH

    KeithH Lead Actor

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    Aren't we talking about bridging versus biamping here? In the stereo world, one can biamp speakers by using an integrated amp to drive the tweeters and a power amp (preferably gain-matched with the integrated) to drive the drivers. One can bridge the amps by using the integrated to drive one speaker and the power amp to drive the other. In the case of bridging, one increases the power in the system.

    I have my main stereo biamped with an NAD C 370 integrated amp and an NAD C 270 power amp. They are gain-matched. The C 370 drives the tweeters and the C 270 drives the drivers. This is a passive biamp configuration, as I do not have an external crossover and have not disabled the crossover in my speakers. Still, there was a noticeable improvement upon adding the power amp. Vocals are smoother and the sound is more layered. Using an active crossover should be better, but I am very happy with the passive biamp set-up.

    NAD rates the C 370 and C 270 at 120W continuous power per channel into 8 ohms, though they both measure out much higher (e.g., 185W continuous power per channel into 8 ohms for the C 370). NAD states that these two amps deliver 300W continuous power into 8 ohms when bridged. I haven't tried that yet. I wonder if my speakers could handle the power when the amps were bridged.
     
  10. MichaelO

    MichaelO Stunt Coordinator

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    Well I messed around with this all last night. I ended up bi-amping vertically as Chris describes above. I understand the concept of using an external crossover and have no doubts that is the best way to go. However, I can tell you right now that bi-amping and using the internal crossover is still a worthwhile project as my system sounds better. The bass is more articulate and the vocals seem to have a bit more presence to them. My first thoughts after listening to it were the same as Keith describes, the music seems to be smoother, more layered. I am very happy I made the change and wish I had done it sooner. Perhaps in the future I will try using an external crossover.

    Thanks again for all the info.

    Michael
     
  11. Geoff L

    Geoff L Screenwriter

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    Mike

    Glad to hear, you hear some difference! Having macthed Amps to stacks is the key in your set up.

    This area is very heavly debated when not using crosovers in front of the Amps. Most Audiophiles look down on this Bi-Amp approach with no crossover in front. Well, it's your stuff and if you hear a difference certainly who are we/they to argue.

    Glad to hear of your out-come in testing this approach. Chris offered good clear information and in a way that dose'nt feel negatively attacking if you know what I mean.
    Enjoy the new headroom and dynamics that surly are present, to what extent "for you" I think you explained well already regardless of the possible naysayers....
    Regards
    Geoff
     
  12. RichardMA

    RichardMA Second Unit

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    Some of the amp companies offer multichannel (Rotel)
    lower power all in one box amps for zone systems.
    They could be employed to power the tweeters in all
    of the speakers in a home theater system. Matched with
    a higher power multichannel or separates from the same
    company (or with the same characteristics) would be an
    efficient way to bi-amp all speakers. But I don't practice
    what I preach; I bi-amp using solid states for the woofers
    or midranges and lower output tube amps for the tweeters.
     

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