Axiom Home Page Forums General Discussion Home Theater Driving two sets of surround speakers

My proposed home theater room has two love seats each flanked with a floor-to-ceiling support column (14" square), and with a third column in between them:
column-seat-column-seat-column.
I am considering installing two sets of in-wall surround speakers - a left & right surround in the columns to "bracket" each love seat (create two listening zones, with the primary zone directly infront of my HDTV). I would like to drive both pairs in parallel from the surround outputs of the receiver, thus presenting 4 ohms (two 8 ohm spekaers in parallel) to my receiver's output (assume nominal 110 watts/channel and a speaker sensitivity of 90dB @1 watt). I am reasonably familiar with the nuances of speaker and amplifier power (logarithmic nature of dB) and am comfortable that this arrangement will work okay for my nominal home theater use (this will not overwork the amplifier, damage the speakers, or distort the surround channel), but I was wondering if I might solicit some comments from others.

Hi John, I've actually wondered if this was possible recently and it seems you are convinced it is. I'm wondering what you would be using for a receiver and/or Amp.Would this be possible for a center channel set-up( two speakers set to one receiver output?

John, welcome. About all that can be said is that it's highly likely that your plan has no problems.

One of the things that amazes me is how 'big' the 'sweet spot' is. We have a 20x14 room with M60's in the front, VP100 in the center, QS4's on the sides, and M3's in the back. Two La-Z-Boys are right in the middle of the room with a couch along one wall under one of the surrounds. The speakers are tuned for Dad's spot in the leather La-Z-Boy . My wife usually sits on the couch. I'm amazed at how good the sound image is even there - the right-side is emphasized as you'd expect but she still gets a good dose of the spatial effects.

I guess my point is these configurations are amazingly forgiving and it's probably worth trying anything to see how it does!

-Brian

Rampon - seems to me driving two centers in parllel would be okay provided the lower impedance did not overly tax your amplifier. This configuration might be more challenging than my parllel surounds because the center is typically working "harder" (most of the sound is from the center speaker). It would be good to review Alan Loft's article "Secrets of Amplifier and Speaker Power Requirements Revealed" (http://www.axiomaudio.com/power.html) to do some quick calculations.

I will be using a Pioneer VSX-1015TX receiver (120 watts/channel).

I will be using a reasonably good model Pioneer receiver (VSX-1015TX), but when I sent the Pioneer Tech Center an e-mail outlining my situation, I got a strong response saying that it would not work - the lower impedance would cause the amplifier to shut down; typical conservative answer you might expect from the factory. When I later called Pioneer to ask a different question, I asked the fellow on the phone his opinion. At first, he was pretty negative, but after I gave him some more details, he softened his concerns and agreed that paralleling the surrounds would likely be okay if the speakers were reasonbly sensitive. He also suggested I consider putting the speakers in series (180 deg out of phase) as this would eliminate any concerns about taxing the amplifier. Instinctively, this does not feel right, but it might be worth a try, if my parallel setup does not play well.

I agree the sweet spot is larger than one might think. What is unusual in my situation is the fact that these darn support columns get in the way of having a traditional 5.1 configuration. If we were willing to put our love seats in front of the support columns, we could use a traditional L/R surround setup. However, we want to have the love seats in between the columns, and the center column would block the sound from one of the surrounds (e.g., a person sitting in the right love seat would not be able to hear the left surround because it is blocked by the center column) - hence the twin zone idea came to life.

How big is this center column?

You don't have to have a direct "line" to the surround, it's diffuse anyways.

Do you have any pictures? That would help a lot.

Hello John,

Your instinct about series connection is correct: Don't do it if you want smooth frequency response, as series connection of multiple speaker pairs causes the impedance curves of the connected speakers to interact with eac other, which may cause peculiar response anomalies.

I have anecdotal feedback on the Pioneer 1015 with 4-ohm loads and it seems that so far it's OK with the 4-ohm M80s, as well as some insensitive 4-ohm Dynaudio speakers that a reviewer friend of mine used to review the Pioneer.

At Axiom, we also have a number of customers who are using the Pioneer 1015 with the M80s with no problems of current-limiting, overheating or protection-circuitry shut-down.

Regards,

Thank you Alan for your thoughts. My system is now in place and it sounds very good. It seems the duplicate (parallel) rear channels are holding up fine. I have a question about configuring my system for optimum speech clarity during quiet scenes, but I will post this as a new question for broader exposure.