Axiom Home Page Forums General Discussion Home Theater QS8 Questions from a newbie.

Hello to all. I've learned a great deal reading the posts here in this forum. I'm in the process of designing my HT and have decided to go with the Axiom speakers. I will be doing a 7.1 HT and I've got a couple of questions regarding the QS8 surrounds and their placement.

1. A lot of the literature that I've read shows two basic placements for surrounds. The first is at 110 degrees (20 degrees behind the listener) with the "null" area pointed at the listener. The second both speakers having the null area pointed at each other inline with the listener's ears at a 90 degree angle from the front center channel. Which one of these works best for the QS8?

2. Regarding 7.1 rear channel placement, I've read that the speakers should be at least 4 feet apart on the back wall, but I've yet to find a recommended distance from the back of the listener's head to the back wall. Any suggestions?

3. I've also read a lot of debates over whether to use dipoles or direct-radiating speakers for the back channels in 7.1. I have not however seen anything said about quadpoles like the QS8's. Which speakers would work better for the back channels, the QS8's (which I will already have for my side surrounds) or a pair of M22ti's?

Thanks in advance for any info.

BigMikey

Hi BigMikey,

My apologies. I think I overlooked answering your questions.

1) True dipoles should be placed with the null towards the listener at each side. Other bipole, quadpole and the like do not create a null, so they are very flexible regarding placement--up to 20 degrees forward or to the rear of an imaginary axis across the listening area.

2) Every room is different. Experiment. There are no "rules" about 7.1, because it is a derived matrix format, not a real movie surround format. So you may get a kind of mono-like effect (like the old ProLogic produced; its surround signal was mono, and bandwidth limited in the surround channels). I'd say at least 4 feet apart, but whatever works best.

3) First, all movies are mixed in 5.1 Dolby Digital with dipole surrounds to each side of the control room. Multichannel audio uses direct radiators to the rear, but in my listening tests, I still prefer multipolar radiators for DVD-A and SACD, as well as for Dolby Digital. Others may prefer direct radiators like the M22ti's, and some use VP100s as surrounds. Why don't you try a couple of old direct radiators in a 7.1 mode and see how they sound?

The audible differences in the sound field radiation of bipolar, dipolar, or quadpolar (Axiom) surrounds, tend to be nuanced, but QS8s tend to be very forgiving of imperfect placement and difficult rooms. Mine are at different heights and distances and produce a wonderful sense of envelopment without sacrificing directional acuity when called upon.

Regards,

Alan,

Thanks for your reply. I do have a follow up, specifically relating to the QS8. I know that dipole/quadpoles are designed to be hung on walls to work efficiently, but unfortunately one of the side walls is missing in my family room because it opens up to the kitchen. Could I effectively mount the QS8 using a stand on that side. Will I be sacrificing any sound quality? Thanks in advance.

Hi,

Of course you can use a stand for the QS8 on the other side or the listening area. The farther away you place it to the side, the greater the balance of reflected vs. direct sound will reach the listener. Indeed, because the QS8 radiates in so many directions, a large proportion of the sound reaching listeners is made up of early and later reflections from the ceiling, walls, the floor, and objects near the listening area.

This explains why placement of the QS8 tends not to be nearly so critical as direct-radiating surrounds, and also why they are still able to generate an enveloping sound field with assymetrical placement at different heights and positions from the listeners.

Regards,