potential gear damage when BiAmp. 803s ?

[Eliav]

HI

Other than getting dedicated / separate current for high/ low passes which should serve acoustics better, Is there any potential damage to the speakers or the amplifier when using thsi method ?
are the speakers and amp. supposed or initially engineered to operate this way- or is it "the way of the poor" to get more power out of our gear ?
(using rmb 1095 with 803s)

Thanks
Eliav

[ZX10 Guy]

What you are proposing is called passive biamping. I've done this in the past with my N804s. Passive biamping will not produce more power output from the amps nor will it increase the overall volume level. Passive biamping in theory will allow your amps to supply my current under high load demands from the speaker. The idea is that you are seperating the power robbing woofers from the mids/tweeters. If you have a dedicated channel in an amp driving just the woofers, any resulting coloration from power amp strain will not filter over into the mids/tweeters. There are also two different ways to set up passive biamping (for that matter active too.) The first is called horizontal biamping. Horizontal is the configuration where you take a stereo amp and drive only the woofers of both speakers. The other amp will only drive the mids/tweeters. The second method and to me the most preferred is vertical biamping. Vertical biamping is taking one stereo amp and using it to drive only one side. So you have one channel of that amp driving the tweeter/mids and the other channel of the same amp driving the woofers. By doing vertical biamping, you are again halving the load on the amp distributing the load of driving the woofer across two independent amps. The theoretical benefit of doing passive biamping is to throw additional power supplies into the mix and distributing the load across 2 stereo amps. In my opinion doing passive biamping using one multichannel amp does nothing unless it's of the design like a Bryston where each of the individual channels has its own independent power supply.

Active biamping is using an external crossover (either passive--not powered or active--powered) between the preamp and the amplifier. This is where the efficiencies of biamping is fully realized. By filter out frequencies that are not needed in a particular channel driving a particular speaker, you gain a lot in power delivery and sound performance. I forget what the numbers are. But to do this with a B&W speaker, you need to remove the passive crossovers in the speakers and directly wire the amplifier to the respective drivers in the speaker. This is probably a task many of us won't do. Plus you need to spend time figuring out the proper crossover points and slopes which many of us also don't have the equipment nor the expertise to do. It's also been said that cascading crossovers is not a good idea where you leave in the passive crossovers in the speakers and add the external line level crossover. I don't fully understand the reason this is a problem because people are doing that by feeding their amps off the high pass crossover outputs of subs.

The setup I had was a combination of passive and active biamping. I had my N804s powered by 2 Carver TFM-25s in a vertical biamp configuration. The HGS12II I used to a mate up with the N804s fed the channels of the amps used to drive the woofers of the N804s. I still ran the channels of the amps that fed the mid/tweeters full range. The result was very good to my ears.

One other word of caution. If you decide to use different makes of amplifiers (and even amplifiers from the same manufacturer but different models), you need to ensure that they are gain matched.

[Eliav]

Wow !

Thanks a million. My understanding is that on everydays regular usage with "normal" loads the sonic benefit from passive biamp is negligible, I also understand there is no potential damage to the gear if I use the configuration I have mentioned.
Gtreat, thanks again
Eliav

[akhter]

What you are proposing is called passive biamping. I've done this in the past with my N804s. Passive biamping will not produce more power output from the amps nor will it increase the overall volume level. Passive biamping in theory will allow your amps to supply my current under high load demands from the speaker. The idea is that you are seperating the power robbing woofers from the mids/tweeters. If you have a dedicated channel in an amp driving just the woofers, any resulting coloration from power amp strain will not filter over into the mids/tweeters. There are also two different ways to set up passive biamping (for that matter active too.) The first is called horizontal biamping. Horizontal is the configuration where you take a stereo amp and drive only the woofers of both speakers. The other amp will only drive the mids/tweeters. The second method and to me the most preferred is vertical biamping. Vertical biamping is taking one stereo amp and using it to drive only one side. So you have one channel of that amp driving the tweeter/mids and the other channel of the same amp driving the woofers. By doing vertical biamping, you are again halving the load on the amp distributing the load of driving the woofer across two independent amps. The theoretical benefit of doing passive biamping is to throw additional power supplies into the mix and distributing the load across 2 stereo amps. In my opinion doing passive biamping using one multichannel amp does nothing unless it's of the design like a Bryston where each of the individual channels has its own independent power supply.

Active biamping is using an external crossover (either passive--not powered or active--powered) between the preamp and the amplifier. This is where the efficiencies of biamping is fully realized. By filter out frequencies that are not needed in a particular channel driving a particular speaker, you gain a lot in power delivery and sound performance. I forget what the numbers are. But to do this with a B&W speaker, you need to remove the passive crossovers in the speakers and directly wire the amplifier to the respective drivers in the speaker. This is probably a task many of us won't do. Plus you need to spend time figuring out the proper crossover points and slopes which many of us also don't have the equipment nor the expertise to do. It's also been said that cascading crossovers is not a good idea where you leave in the passive crossovers in the speakers and add the external line level crossover. I don't fully understand the reason this is a problem because people are doing that by feeding their amps off the high pass crossover outputs of subs.

The setup I had was a combination of passive and active biamping. I had my N804s powered by 2 Carver TFM-25s in a vertical biamp configuration. The HGS12II I used to a mate up with the N804s fed the channels of the amps used to drive the woofers of the N804s. I still ran the channels of the amps that fed the mid/tweeters full range. The result was very good to my ears.

One other word of caution. If you decide to use different makes of amplifiers (and even amplifiers from the same manufacturer but different models), you need to ensure that they are gain matched.

I am using the 6 and 7 channel of my Arcam AVR300 to Bi-Amp the front L+R because the manual recommended this if the speakers allowed it and if I didn't use the full 7.1 setup. The amp is rate 140w per channel so am I getting 240wpc in this setup? Or am I still getting 140, but 2 separate amps are sharing the load?

[ZX10 Guy]

Wow !

Thanks a million. My understanding is that on everydays regular usage with "normal" loads the sonic benefit from passive biamp is negligible, I also understand there is no potential damage to the gear if I use the configuration I have mentioned.
Gtreat, thanks again
Eliav

Yeah. It really depends on how demanding a load your speaker presents to the amplifier(s). Passive biamping has been debated all across the internet forums ad nauseum. You have supporters on both sides. Normally, I would say try it and let your ears be the judge. But like I said, to truely do it right you really need to have two independent stereo amplifiers instead of using a multichannel amp. The entry cost to do passive biamping is pretty prohibitive for anyone to just try it on a whim. I happened to have 2 amps that I was running in bridged mode already so my cost was only the additional cables which really wasn't a cost as I was able to get a free loaner set from my local dealer. I liked what I heard as a result of the experiment. But I'm not discouraging those that want to try passive biamping with a multichannel amp. If you get sonic benefits from it then it's a win for you.

One thing I need to emphasize. Passive biamping will not damage any of your equipment provided that you REMOVE the jumpers between the two sets of speaker terminals on your speaker.

Also, you need to get a splitter if your preamp doesn't have two sets of preouts. There are other things you can do to further tweak your setup if you like to tinker around. I've heard people use tube amps for the mid/highs and gain match them to a solid state amp for the woofers. Another thing I've seen done which is what I did was to intermix cable types to get an ultimate sonic affect.

[ZX10 Guy]

I am using the 6 and 7 channel of my Arcam AVR300 to Bi-Amp the front L+R because the manual recommended this if the speakers allowed it and if I didn't use the full 7.1 setup. The amp is rate 140w per channel so am I getting 240wpc in this setup? Or am I still getting 140, but 2 separate amps are sharing the load?

You're getting the latter. The only way you'll get more power output is if you are doing active biamping whereby the amp channel is running more efficiently because it's only amplifying a limited frequency range.

[xk8boy]

Great explanation ZX10 Guy. For those true tweekers here, I've read that the power amp should ideally be next to or close to the speakers and far away from the pre/source components. Having the power amp next to the speakers reduces the length of speaker cables and hence lowers resistance and increases power. Having the power amp away from the pre/source reduces electrical interferences.

[ZX10 Guy]

Great explanation ZX10 Guy. For those true tweekers here, I've read that the power amp should ideally be next to or close to the speakers and far away from the pre/source components. Having the power amp next to the speakers reduces the length of speaker cables and hence lowers resistance and increases power. Having the power amp away from the pre/source reduces electrical interferences.

Yep, that's the other tweak I forgot too. Having the amp right next to the speaker only works if you do vertical biamping (which is what I recommend.) The shorter speaker cable length would have a negligeble affect on power output. You'd have to really be using some crappy cable and lots of it before you would see a significant change in power output. Sound quality is a different story as the concensus is that running shorter speaker cables is prefered due to electrical interference issues.