What do I need in order to bi-amp speakers

polkfarmboy

I can imagine some of you guys snorting at my question but its worth asking

I just started thinking about this whole bi amp deal after getting some power hungry monster speakers. What things do you need in order to supply separate power to bass and highs in my case that would be a relatively efficient electrostat panel.

Do you need 2 diff amps and 2 sets of speaker wires ? how can you send the signal for bass and highs with only 1 rca cable ? What are the dangers and some other stuff I need to know in order to not trash a pair of speakers in the process

WilliamM2

If the highs are relatively efficient, what would you hope to gain? An extra 5 watts a channel?

You would use a y-splitter to send the signal to two amps, with two sets of speaker wire.

Passive bi-amping really isn't worth it though. I'm bi-amping my center at the moment, just because I have the extra amp channel. I didn't even have to re-calibrate the levels, so I gained nothing in power.

SCompRacer

polkfarmboy wrote: »

I can imagine some of you guys snorting at my question but its worth asking

I've been active crossover and horizontal bi-amping a pair of hybrid ESL's for years. I believe active crossover is the key to get the bang out of it.

Do you need 2 diff amps and 2 sets of speaker wires ?

Yup. Preferably same amps or you can run into balance problems.

how can you send the signal for bass and highs with only 1 rca cable ?

A Y adapter like William mentioned.

What are the dangers and some other stuff I need to know in order to not trash a pair of speakers in the process

You need a stable amp for the panels that will handle highly variable impedance loads along with a highly capacitive load. ESL panels can vary from 2 to 120 Ohms. The speaker cables for the ESL panels shouldn?t be highly capacitive. My amps don?t have any protection circuitry to prevent them huge power spikes that can set in if it kicks in and out.

You can also vertical bi-amp, one for each speaker.

tonyb

Am I missing something ? If your speakers are relatively efficient as you say, why bi-amp them ?

DaveHCYJ

What is the difference between active and passive? If passive is just splitting the signal to 2 amps with one amp for the highs and one for the lows, then what is active?

Also for a speaker with decent midrange like say the RTi A9 or the new LSiM towers, wouldn't you gain a fair amount out of bi-amping?

polkfarmboy

The speakers in question are Martin Logan Vista and the 8inch aluminum woofers are notoriously power hungry compared to the panels so the both need a dose of the old frankenstien juice

nguyendot

Passive biamping = splitting SAME signal to two amps. Those two amps amplify the same full range signal and send it to the speaker. The speaker still uses its crossover to filter out the lows from the high section and the highs from the low section (throwing away power). You don't gain much if anything at all here because you are still using the lossy crossover in the speaker.

Active biamping = sending the signal through an electronic crossover which removes the unnecessary signal from highs/lows and sends them to the amplifiers. The amplifiers are now only amplifying the part of the signal intended for that part of the speaker and not wasting it on amplifying signal that won't be used. Then you run this to your speakers, which should have the crossovers removed so you get no loss there. If you have a three way speaker, generally you triamp.

It's a lot of work.

Also, PFB... you've been here long enough to know the answer to this question. Why are you asking it when it's been answered about 1000 times in the forum? You know where the search button is, use it. And don't hit it too hard or you might knock your tv off again.

DaveHCYJ

Wouldn't there also be a quality gain (not just power gain) when doing an active biamp since you aren't running through the crossovers? Or I guess it depends on the quality of the component doing the filtering prior to amplification.

nguyendot

Yes it is going to be heavily dependent on the crossover.

gp4jesus

I agree w/both nguyendot's posts particularly the 2nd.

"The speaker still uses its crossover to filter out the lows from the high section and the highs from the low section (throwing away power)[in the form of heat]. You don't gain much... ...because you are still using the lossy crossover in the speaker."

The ever-so-slight advantage is you have a separate devices, and if it applies, separate power supplies, handling the different frequency ranges.

this link will explain the drastic differences & answer most of your questions. Pour your yourself a tall one as the author is a thorough engineer.

cheers tony
http://sound.westhost.com/bi-amp.htm

CoolJazz

"The speaker still uses its crossover to filter out the lows from the high section and the highs from the low section (throwing away power)[in the form of heat]. You don't gain much... ...because you are still using the lossy crossover in the speaker."


Actually, a crossover does not dissipate as heat. It presents a high impedance and does not draw current for rejected frequencies.

For the same reason (high impedance doesn't draw current), the high level crossover does not present the same load on an ampifier output stage when bi-amping in the so called "fools bi-amp". However, you do not enjoy the benefit of the line level crossover removing a portion of the audio band and the resulting lesser intermod products.

This may be the first time I've ever heard of a ML panel being called "relatively efficient"!

CJ

gp4jesus

Another important advantage of active vs passive, all the XO's characteristics (frequencies, slopes,phase, type [Bessel, butterworth]) remain intact regardless of volume over time.