Damaged Crossovers????


2007-11-16 11:08 am
Hi guys.

I recently bought a rotel power amp (970bx mk11) to bi-amp with my Rotel Integrated (ra-971 mk11). The 971 was sounding great, bu i thought i would experiment. I linked up the amps, with the power amp driving both left and right bass speakers and the integrated driving the tweeters on both sides.

Now when i turn it up past half way i get a funny distortion (as though the bass speaker is being fed too much power). I have tried removing the power amp and reconnecting the jumpers in the speakers but it is the same just running with the integrated.

The speakers are TDL Nucleus 2.

Have i damaged the crossover in the speakers (my logic with the problem is that the 2 amps may have "connected" through the crossover and blown something).

Should i have instead driven each speaker off 1 amp (ie left driven off the powere amp). Any help gratefully received).

Great forum by the way.

I read a review of the speakers that indicated they had a lot of port noise. This could be what you are hearing, but I can't say for sure.

I'm guess you could also just be overdriving the woofers. These are relatively small speakers, so you can't expect much from them.

I suggest that if you want bigger sound, you get bigger speakers.

Sorry, I couldn't be more help.

Thanks for the reply. As you can probably tell i am new to this kind of thing.

The sepakers were working fine before i bi-amped and now are not. they are rated 100w and the amps i am using are both rated at 70wpc each. So, as i believe it, theoretically they should be well matched.

What would be the correct way to bi-amp. Would it be to power 1 speaker per amp or, as i did, the tweeters using 1 amp and the woofers using the other.
By my way of thinking, there is a physical link (through the crossover) between the tweeter and woofer. The way i set them up would effecitvely put a siganl from 1 amp into the tweeter and the signal form another into the woofer. Thus potentially having two signals trying to use the same path but head to head (technical explination i know, Not!!!!!). Could this blow the crossover?

When I speak of 'overdriving' them, it is not so much a matter of power, as it is driving them beyond their physical limits. In short, it's a mechanical thing, not an electrical thing.

To Bi-Amp, which I personally think will only give marginal improvement at best, you need to remover the jumper on your speaker terminals (that's speaker, not amp).

If your speaker are made to be bi-wireable or Bi-Amped, there should be four terminals on the back; Two postive (red) and two negative (black) with a metal jumper of some type connecting + to +, and - to -.

Inside are two separate independent crossovers, one specifically for the highs and one specifically for the lows. The external jumper ties these two together.

To Bi-Amp you need four amps, or more accurately four amp channels. You could use a multi-channel A/V amp. You could use two Stereo amps. You seem to have two stereo amps.

Your main amp channels (left and right) should go to the woofers of your speakers. Your secondary amp channels (left and right) should go to the tweeters.

Naturally you want the LEFT woofer channel to be connected to the LEFT primary amp, and logically you wan the LEFT tweeter to be connected to the LEFT channel of your secondary amp.

If that's what you did then it shouldn't have cause any problems. The high and low crossovers are still there inside the cabinet doing their job.

However, I personally don't see much to be gained by bi-amping, especially for speakers this small. And I contend that there is NO point is bi-wiring. Bi-wiring doesn't fix the problem it claims to fix, it does in fact make the very problem worse.

Unless you really abused your speaker when you had them Bi-Amped or unless you wired them in some crazy and unlikely fashion, you shouldn't have done any harm.

That probably doesn't help much.