Bi-amping Rules


I wasn't sure if this question belongs in the amp or the speaker section but I figured I'll post it here. Those of you who have bi-amped your speakers, what's the general rule for deciding which amplifiers are better for low frequency vs. the high frequency drivers. I recognize an accurate answer will depend on the particular speakers and amp combinations but I'm looking for general rules of thumb from personal experiences and not application specific recommendations. For the sake of the argument, let's assume the amps are different but the gains on both amps can be adjusted if that matters. Thanks.
128x128kalali
I bi-amp with two identical amps, and I mean identical.  Despite being about 25 years old they are 5 numbers apart (serial number) built on the same day, same shift, same parts bins.  One amp runs the left speaker and one the right.  The left channel of each drives the woofer module and the right the electrostatic panel of a very power hungry vintage pair of Acoustats. 
@danvignau I suggest using an EQ instead of touching the filter levels. Behringer have one that is digitally controlled 1/3 octave where you can save settings and recall them anytime you like and they are not very expensive. For normal use you will just of course leave it in "By-Pass" and if you want to keep it completely out of the signal chain simply connect it to the Tape Monitor Loop of the Pre-amp.

Good recordings does not in general need any altering but eg an old VHS- or cassette-tape might benefit a lot from some tweaking/restoration. You might also like to call it a REMASTERING and there is NOTHING WRONG with trying to get the most out of a crappy recording using whatever apparatus you like! Including EQ, Noise Reduction, Expanders or Sonic Enhancers etc... It is not "puristic" but it might sound a h_ll of a lot better and if that is the only recording you have there is NOTHING WRONG with trying to restore it "to its former glory" using what ever means you have available!

BUT: Don't touch the filters! They are part of the Amp-Speaker combination and should NEVER be changed once they are properly aligned! Of course that is just my humble opinion and you are of course free to turn any knob you want... :-)

@midareff1 I agree 100%! Two identical stereo-amps with one for each channel is DEFINITELY the best way to go when Bi-Amping...
BTW: I've gone back to passive x-overs but not with the original components in the filters but instead 14AWG Jantzen coils and their Superior Red Z-Caps.

Does this sound better or worse than my active Nakamichi arrangement?
Hard to tell since what is best since the amps and cables have also been altered.
At lower levels YES! But if I try to "wake up my neighbors": NO!

I ran the system in passive configuration with a Linn Majik-I and THAT sounded a h_ll of a lot better than the Naka combination but that little VERY NICE amplifier just did not have the oumff since it only produced 2x33W at 8ohms and that is not enough to drive my speakers to more than approximately 85dB.

So what is best? Active or passive x-overs?
There is simply no correct answer to this question!
They both have their uses and issues....

For high power systems: Go active!
For low level systems: Leave the speaker design to the manufacturer...

Of course it is a free world and anyone is free to do anything they want but the original question in this thread was about using different amps in Bi-Amp configuration and my answer is: YES, you can do that!

BUT: YOU will become a SPEAKER DESIGNER if you try!

Nothing wrong with that! There are thousand of them out there and you might be just as good as they are but believe me when I say that it is NOT an easy thing to design a good amp/speaker system.

It all boils down to what you want to do! Cracking the skulls of 75 000 people at an arena or sit at home listen to a singer-songwriter at "bedtime" levels?

If what you want is the first alternative: Go active!
If it is the second and you want to keep it simple: Don't bother!

If you are anywhere in between it is all up to you! :-)
Hi: Back in the Nineties; I used a Bi-Amp set up. I was using some Adcom stuff the GFP565 as it has three sets of out puts. I used a GFA 535 with about 60watts/Channel. So, When I bought some Polk Audio SDA SRS 2.2 speakers, I needed a bigger amp! I stumbled into a Great deal on a Bryston  4B they were rated at 200watts/ channel then. Even then I was aware of Polk tweeters blowing fairly easy with too much power. My previous speakers were DCM Time Windows (first series). What I did was put the 4B into the "Bass" end of the Polks;(6x 6 1/2 mid woofers into a 15" sub bass radiator each speaker), then used the GFA 535 to run the tweeters and the Time Windows. I never blew any tweeters! That set up had 10; yes ten tweeters. The bonus was the best Holographic stereo soundstage I have ever had or heard. I had the DCMs on the side walls 6-8 feet from the Polks and Image at about 270 degrees in front of me. My case was I got new gear and did not want to part with the old gear yet? Once you know a sonic signature in your set up you can use that to get "other" results. When I played Jimi Hendrix's "Purple Haze" he sounded outside the window singing in and between the two right speakers. I told people this and when I played it they were amazed? I guess what I am getting at is A lot of previous people are right on " Bi Amping Blues". I wanted to experiment. Out of fear of blowing tweeters and  having Extra Gear, so I Bi Amped for fun, and got an extra Bonus in soundstage. That set up was the most fun to listen to of any set up I have had. It unlocked recordings secret information; and that was fun. I think you take all the information and experiment? Something does not work, try something else? Gear is easy to sell and buy now. You can always follow someone else's pattern or electronic IQ, mix and match until YOU are happy.   B
What I don't get about the entire concept of using SS for low freq and tubes for high freq is there will always be a dramatic power differential.  So how can you begin to balance out the sound levels coming from your tweeter and woofer when the amps delivering the signal are themselves delivering noticeable different volumes?  To me that means that the tube/SS suggestion has always seemed sort of useless unless you automatically include an electronic crossover and the ability the sound balance.  Am I missing something here?