Should I Bi-Amp my RTi150s? (1 Viewer)

[Joel McIntosh]

My Marantz 7300 with (105 watts per channel - 8 ohms) was too under-powered to handle my Polk RTi150s (especially when lots of bass was cranking out of the RTi150s). So I bought a separate amp (NAD 218THX -- stereo output, 225 watts with 280 dynamic power - 8 ohms). Right now, I have the RTi150s speakers wired exclusively to the NAD; however, I am wondering if I could get a more full, realistic sound by bi-amping the speakers (i.e., running the 150s mid-range and tweeter off of the Marantz and the woofers off of the NAD). What do you guys think? Is this a good idea? Is there any reason not to do this (i.e., will using two different brands/types of amplification create some kind of sound disharmony?).

 

[Cees Alons]

Joel,

will using two different brands/types of amplification create some kind of sound disharmony?

Not likely. They are driving different speakers (with quite different characteristics).

So, why not try? Make sure you drive 'em in phase.

Assuming here that you can indeed disconnect the drivers in your speaker boxes from each other.


Cees

 

[Stephen Hopkins]

Why would he need to disconnect the drivers from each other? They're not connected to each other. Each driver has it's own segment of the crossover and his speakers have bi-ampable terminal cups. All he has to do is remove the jumpers connecting the hi and low terminals on his speakers.

 

[Joel McIntosh]

Thanks Cees. Actually the RTi150 have a pair of input posts for the tweeters & mids and another pair of input posts for the woofers, so other than the expense of extra 12 gague wire and bananna prongs, this isn't a huge task. I was mostly wondering if there were some hard and fast rules about not bi-amping with different kinds of amps (a 105 watt A/V receiver powering the tweeters and mids and a 225 Class A amp powering the woofers seems as different as you can get). But, it sounds like from what you are saying I will not run into any trouble with this plan.

 

[Cees Alons]

Joel,

No, you won't.
The power going to the upper frequencies is significant lower than needed for bass. But you can only take some advantage of that if you limit the frequency spectrum before the end-amps. Furthermore, at approx. 100-200Hz it's still considerable.

I assume that the speaker box circuitry takes care of the proper frequency splits, but you could help, if there's an adjustment for it on your amps, to turn the lows a bit down on the midrangers/tweeters (listen while the other amp is off, determine the maximum adjustment that you just can't hear) and, less important, the highs on the woofer.

Because the amplifiers are different, you may need to make a point of adjusting the gain on each of them, to get a smooth transition from low to high.

Good luck, your sound stage will almost certainly improve.


Cees