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Why does bi-amping speakers sound better?

Curious why it sounds better to bi amp speakers vs just running them off one amp?

i am trying to figure out which amp to buy, I am on the fence with bi amp or not.  Speakers are the old infinity kappa 8.1's.  Several years ago when I was married I bi amped my speakers so each speaker was seeing two channels from a parasound hca1500, I think that's the model.... 200w x 2 going to each speaker.  I also tried a single amp powering both speakers so each speaker was seeing 200w x 1.  

is it that I simply doubled the power that resulted in better sound, mostly noticed the low end of the speakers was tighter, more powerful etc.... and obviously I could also play louder.  

Or is is there something about letting one amp not work as hard due to only running high frequencies while the other amp gets to just work on the low end.  

I am 90% sure which brand of amp I want to get, just trying to figure out if I should bi amp or not.

as a example should I go with

two 2 channel amps at 400w x 2 so each speaker would get 400x2

or should I go with a single 800w stereo amp so each speaker sees the same 800w, just with one channel of a amp



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morrowaudio
60 posts
 
I have Avantgarde Duo-Omega gen II, 16 ohm. I am using the Ultra-linear OTL, one stereo amplifier for each channel, full range, so no electronic crossover in the signal path. The left and right inputs on each amp is combined with a little internal wiring change to avoid using a Y connector. The right channel output goes to the bass and tweeter. The left channel goes to the midrange horn. I did it this way because the midrange horn has no crossover, so the voice coil is connected directly to the amplifier. The sound is much better than running the amps in monoblock mode with double the power driving all the speakers. In the configuration I have, the output is 20 watts per channel. With the speakers have a sensitivity of 107db, there is plenty of power. This is the reference system in my home, where I test our cable designs. 
ctsooner
2,480 posts
 
intersting.  Thanks for sharing.  There are so many ways to set things up.  It all comes down to personal tastes (as it always does) and how speakers are designed.  This is why I always ask whatever designer made my speakers, what they recommend and go from there.  

Heck, I need an external crossover for my Vandy's and I had Ayre build it into my integrated amp so I could cut out some extra connections, plus they used premium parts as does Vandersteen, so I didn't lose anything.  
mortgagesbyme
4 posts
 
A long time ago I used a bi-amp setup with two Rega amps into a pair of Proac D-28.  The improvement over using one amp was very noticeable-night and day.  When I sold the amps, I talked someone into buying them both and try the bi-amping and that person fully agreed that the bi-amping made a big difference. 

I forget which way the bi-amp sounded better but I do remember trying it both ways; with one amp powering the left speaker and the other the right, and with one amp powering the left and right woofers, and the other amp powering the left and right tweeters.  But I do remember that while it was close there was an improvement doing it one way over the other.  I think that is worth experimenting with both methods so you can find what works best. 

I did not test to see if one more expensive amp would have sounded better than the two separate amps.  But my guess is that while a better amp sounds a bit better than one that is half the price, I just don't see the improvement being as dramatic as what I heard from bi-amping.  So I am a believer in bi-amping based on my limited tests. 
avanti1960
1,480 posts
 
because the amplifier that feeds the tweeter and midrange is not burdened with reproducing bass - which takes multiple times the power.
in a single amp configuration as the burden of reproducing low frequencies taxes the amp, the clipping can be heard as strain or glare through the midrange and tweeter. not good and very tiring to listen to.
with a bi amp configuration the midrange and tweeter amp can coast along unstrained and never clip.
also the midrange / tweeter are isolated from the clipping woofer amp.
clipping is usually not audible or objectionable at bass frequencies but it fatigues like no tomorrow at midrange and treble frequencies.
the benefits are definitely not from bi-wiring.  
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russ69
3,516 posts
 
I’m a long time Infinity loudspeaker owner. I think mono blocks (not bridged stereo amps) work the best and is the cleaner set-up. One set of quality speaker cables, less equipment, and less to go wrong and better channel separation. Simple systems are the best. Go for a quality amp, don’t cut corners there. If you can’t afford a pair of big bruiser amps, get one stereo amp. No AVRs, multi channel amps, or mid-range gear. Get an A/B amp, the lights will dim when the bass hits but by then it’s too loud anyway. Oh, and the bad news: Get a real stereo pre-amp. Your AVR is already holding you back. 
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