Well, my wife just gave me the green light to go ahead and purchase another Rotel RMB1075 amp. With the new amp and the 1075 I already have, I plan to bi-amp my mains and center channel then run my side surounds and add some back sorrounds with the remaining hannels. So I am looking for some suggestions for speaker wire for the front three. The runs are through the walls (in flexible conduit) and are roughly 35 feet long. I was thinking with going with some sort of 12/4 speaker wire. Any thoughts or suggestions?

One additional question: do I just use a splitter off my 950 to split the signals into the amps? I suppose I'll need 3 splitters and 5 more RCA interconnects.

Thanks in advance,
simp

I use Canare 4S11 speaker cable and it seems great to me. Being 4 conductors you could use it for your bi-amp application.

If the wiring will be in conduit, you should have no problem picking up something simple - I'd probably go with 12ga. Something like Keta's Canare would be a good match. If you were running through attic or crawlspace areas or dropping loose in the wall, the cable should be plenum rated, which would eliminate most or all of the stuff at places like Home Depot and the Canare (according to Canare's site, none of their audio cables are plenum rated).

To passively bi-amp (no external crossover circuit), all you need is a splitter at the pre-amp output on the 950.

Gonk,
Can you go into more detail on passive bi-amping? I mean, it seems to make sense to me that I'd be in pretty good shape sending one full signal from one amp output to the high/mids and a seperate signal from a seperate amp output to the lows. I always thought that passive meant I was sending the same output from the same amp across two sets of speaker wire, one to the mids/highs and one to the lows. I must have it wrong. Maybe I misunderstood the difference between bi-wiring and bi-amping.

Thanks for the info,

simp

Your original idea (bi-amping using the extra amp channels provided by the second five-channel amp) is an example of passive bi-amping. I'm by no means the expert on bi-amping around here, but I can give you a quick overview.

Passive bi-amping: split the pre-amp output signal and feed it to two amplifiers. This option can provide some more power reserve, but the concensus from some of the forum's resident wizards is that bi-amping with a pair of 100W amps is not going to offer much if any benefit over using a single 200W amp.

Active bi-amping: take the pre-amp output and run it through a crossover circuit to create two signals - a high-passed signal for the speaker's tweater (and possibly the mid-range driver as well, depending on the speaker) and a low-passed signal for the speaker's woofer. The two signals then go to two separate amplifiers, and the output of those amplifiers goes to the speaker. To make this work, you have to get into the guts of the speaker and re-wire around the speaker's crossover network so that the speaker connections go straight from binding posts to drivers. This approach offers the most practical benefits for bi-amping, but the knowledge required to implement it (both in building a crossover that properly matches your speaker and in bypassing the speaker's original crossover) makes it impractical and unwise for most of us mere mortals.

Bi-wiring: one amp channel drives one speaker, but two speaker cables connect the amp channel to the separate sets of binding posts on the speaker. The theory here is that your high frequency drivers don't have to deal with reflected "noise" in the speaker cable from the woofer. It's fairly common (I've actually got a few speakers at home wired this way as I type this), but again the resident experts seriously question the practical value in this arrangement. It's probably just as well to use good quality jumper wires and a single speaker cable as it is to biwire - especially when you've got to run 35 feet from amp to speaker.

Excellent description. Thanks for setting me straight. I was straight on bi-amping and bi-wiring, but I was not aware of the passive vs. active bi-amping.

Getting back to the speaker wire. My only concern about the Canare 4S11 speaker wire is that it's 14 gauge, not 12.

thanks,
simp

Gonk,

A couple internet searches led me to some info on plemum rated wire. From what I've read, it is only required when wires enter an air duct (common in a commercial building). The outside coating on plenum rated wire burns at a higher temp an therefore does not send toxic gas into the HVAC system if it were to burn.

Why would plenum rated wire be required in a regular household wall? Something I'm missing? I ask becuase I'm getting ready to run some wire to my surrounds.

Your definition of plenum rated cabling is quite accurate - in commercial installations, it is required when the cabling is run exposed in a ceiling space that is used as a return air plenum (the ceiling void is used as a duct, reducing sheet metal cost and saving always-precious ceiling space). Attics and crawlspaces in homes are usually not used as plenums, but there can be cases where wall spaces are used for return air or attics serve as plenums. (There can also be cases where it wasn't intended to be a plenum but ended up that way, such as my crawlspace when we bought the house a year or so ago - previous owner had to have all the supply ductwork re-hung and sealed back up because it had fallen off the floor joists and was dumping into the crawlspace more places than it was reaching the supply registers.) I'm not sure how picky residential code is about requiring plenum-rated cable, but it's not a bad idea to use it if you can get your hands on some.

From the electricians point of view you don't need plenum rated wire in a house. Plenum rated means low smoke when a fire is burning the outer jacket letting off far fewer hazardous chemicals. The flexible conduit you have in your walls is probably plastic and isn't plenum rated. Most residential codes don't require it. Nice job having the flexible conduit in the walls by the way! Good luck Jim

Belden's description is:
Plenum — A compartment or chamber to which one or
more air ducts are connected and that forms part of
the air distribution system. A description for a cable
that passes the UL 910 CMP flame test requirements.

Look at the Belden site for tons of info.