Bi Amping with the same amp?

[Clipped and Shorn]

I am setting up a Fisher 800C receiver in another studio. The Fisher has stereo hookups for speakers #1, speakers #2, and a rear speakers. The selector switch allows for speakers #1, speakers #2, or speakers (#1+#2). Would it be possible to hook up speakers #1 to the woofers and speakers #2 to the midrange horns and play this as a "bi-amp" by selecting the (#1+#2) mode. This thought crossed my mind when I realized that some old crossover units I was planning to use in this situation are not working properly.

This also brings up another question for another thread having to do with what went wrong with one of these crossovers (Altec N500). I thought these units were in good shape but one of them is apparently not sending anything to the high frequency. I opened them up and saw some components sitting in some kind of black rubbery sealant. I could not visually see anything that looked burned out or anything. Can these things be fixed? How does one isolate what went wrong inside that crossover?

-c7s

[maxg]

I think you are describing biwiring as opposed to biamping. On my old Accuphase which had speaker A and speaker B outs you could, with appropriate speakers, connect the A to the upper connectors of the speakers (treble and mids) and B to the lower connector (bass).

As my speakers only have a single set of connectors I never got to play with this but I am fairly sure the manual described it as biwiring.

I have never understood how the amp managed to differentiate the possibility of biwiring from the possibility of connecting 2 separate speakers, in which case you want all the signal to do down each pathway.

To make things more complex too I think that if you do connect both sets of cables to a single set of speakers then the impedance that the amp sees is halved. I remember on the back of my old Yamaha receiver that there was an impedance switch. Set to 8 ohms it required 16 ohm speakers to biwire. You had to set the impedance switch to a lower setting (4 ohms?) in order to biwire with 8 ohm speakers.

Of course I may have that entire thing the wrong way around. I am working from my befuddled memory here.

[Stephen328]

i Think, that as long as your amp has 4 true output channels than you can technically bi-amp. This is in no was bi-wiring becuase your not running 1 output to two inputs. I was thinking of doing this with my Yamaha M-4 and a pair of rb5s or rf-3s. I know that my M-4 can drive 120w into 4 channels at 8 ohms, and 170w into 2 channels at 4 ohms. But It cant drive 4 channels with 4 ohms. I think that the halfing the impedance rule is only true for bi-wiring, not bi-amping. So technically I can bi-amp at 8 ohms at 120w a channel right?

[lynnm]

C & S

The A/B switch on your receiver or amplifier simply parallels 2 pairs of speakers. If you were to connect the Low frequency to the A side and the High Frequency to the B side of a pair of speakers that are set up for Biwiring or Biamping you would as Max suggests simply be biwiring.

[Invidiosulus]

C&S I believe that to actually bi-amp you would need a preamp with an active crossover to split your signal into high and low to send to seperate amps, these amps would then separately power the woofer and mid-tweeter. The obvious advantage to this would be your ability to have an amp with much greater power for your low frequency and a smaller amp for your high's. I have never heard this in a Hi-fi setup, my only experience is with my Gallien-Krueger electric bass amp which has 380 watts for the low's and 50 watts for the high's.

http://www.gallien-krueger.com/PRODUCTS/HEADS/700RB/700rb.html

I'm guessing that bi-wiring means that the passive crossover in your speakers has to work less to seperate the high's and low's, it would just have to roll off any unwanted frequencies.

As mentioned I would check and make sure your amp can handle the load of wiring that way.

Peace, Josh

[Stephen328]

Theres 2 types of bi-amping: passive and active. Passive uses the internal speaker crossover, while active uses an external crossover. I'm describing passive bi-amping, using 4 channnels on 1 amp.

[mobile homeless]

C&S, I dont think I would suggest this as an option since it is using the same amp and the impedance load will be freaky/taxed with what I think would be no reward sonically. I genearlly tell everyone NOT to every use the "speaker b" outs. It would work but the funky load would be a strange mix I would imagine, not actually knowing how the receiver goes about doing it.

You are actually biwiring with that amp but I dont know how it will affect the amp sonically. I think it would WORK. Whether it would be smart or produce superior sound, I am more doubtful.

kh

ps- btw, pick up that Harley book I recommended in the Robinson 25k listening room thread.

[Clipped and Shorn]

Interesting considerations here. I also received this info:

"

Nope. You can't hook the Fisher up like that. If you do, you will be sending a full-range signal to the horn and possibly burn it out. You must always assure you send only signals ABOVE 500Hz to those horns.

The problem with the xover could be anything. You'll have to send it to a qualified repair center."

I have consequently found a couple of repair services which I will investigate.

-c7s