Fusion 8100 versus UMC-200 / UPA-700

[B-613 Command]

Nov 11, 2014 20:46:54 GMT -5 fusioneer said:

Wanted to add my data point on bi-amping -- I run it on my Fusion and it works fine. It does seem to make a bit of difference though I couldn't swear by it, it takes too long to rewire and I lose confidence in comparisons made a few minutes apart. I'm not able to max out the volume of the Fusion with my place & ears (like the poster above), so I don't know if it pushes the limit further, nor do I care.

Moreover, I asked Chad from Emotiva support whether it's a good idea and he said why not, it can only help. I asked because I wasn't sure if there were specifics of the Fusion that would make it counterproductive, for example output power dropping for each amplifier if 5 were in use vs 3, even if the extra two weren't very demanding. That does not seem to be the case.

So given that, it's free (I was already wired from previous trials and I have amp outputs available) so why not. What you get theoretically is the more *demanding* half-speaker going through a separate amp and separate wire from the more *sensitive* half-speaker, which seems like a good idea. What you don't get is a doubling of the power; you get the sum of the demands of the two half-speakers, but one of them is going to be the limitation and you know which one. So unless the loads on each happen to be identical, it's less than a doubling. If you need double the power, you want the larger amp not the bi-amping.

Good points.

Another benefit of bi-amping is this - if you think about it - an electric generator and an electric motor are nearly identical. One converts motion into current and the other current into motion. They use the exact same laws of physics and the same parts to do it: an electrical coil inside a magnetic field. My point is your woofers can act as either one - and do act as both. When the amp applies current to move your woofers they move. When the sound stops the current drops but the woofers are still moving - their momentum keeps them going - and that motion creates an electric current - in this case they're acting as an electric generator - and that current is pushed up the wires to guess what - the crossovers. From there it moves into the capacitors on your mid and tweeters and quickly maxes them out. What you get is called "bass dropout." It's a form of distortion.

By separating the electrical systems into 2 you eliminate this noise. It improves clarity and consistency in the highs and mids. 

I think most people heard of bi-amping and immediately thought wow twice the power to my fronts = twice as loud! But it does't work that way. 

[Gary Cook]

Nov 11, 2014 23:34:00 GMT -5 B-613 Command said:

Good points.
Another benefit of bi-amping is this - if you think about it - an electric generator and an electric motor are nearly identical. One converts motion into current and the other current into motion. They use the exact same laws of physics and the same parts to do it: an electrical coil inside a magnetic field. My point is your woofers can act as either one - and do act as both. When the amp applies current to move your woofers they move. When the sound stops the current drops but the woofers are still moving - their momentum keeps them going - and that motion creates an electric current - in this case they're acting as an electric generator - and that current is pushed up the wires to guess what - the crossovers. From there it moves into the capacitors on your mid and tweeters and quickly maxes them out. What you get is called "bass dropout." It's a form of distortion.
By separating the electrical systems into 2 you eliminate this noise. It improves clarity and consistency in the highs and mids. 
I think most people heard of bi-amping and immediately thought wow twice the power to my fronts = twice as loud! But it does't work that way. 

I have this feeling Keith is going to drop in on this discussion, maybe tomorrow, so I'll keep my response short as I am sure he will explain it far better than I ever could.

That may occur with underpowered/overrated amps that have poor speaker control. Which is most certainly not the case with Emotiva power amps which have very high damping factors.

Amplifier damping factor (DF)is defined as “the ratio of the load impedance (loudspeaker plus wire resistance) to the amplifier internal output impedance.” This basically indicates the amplifier's ability to control overshoot of the loudspeaker, i.e., to stop the cone from moving.

Cheers
Gary