One bar surround

[legendaryfrog]

Hi everybody! today, my aunt asked me to go to circuit city to help her buy one of those expensive new-fangled "virtual" surround bars. the cheapest one we found was 1k. waaaaaaaaay too much for us. Instead of buying one, im thinking about building one using pvc as the backing and TB drivers. just a question, but is there anything special used in these? ie: weird xo, driver placement or cabinet deign?

[legendaryfrog]

ivs heard that the driver spacing needs to be the same distance between your ears.

[wigginjs]

I was under the impression this involved a measurement mic and DSP?

[Tenson]

You are not going to build one at all easily. They work by ultrasonic pulsing steering the wave I think.

[andrewmc]

Supposedly they do some auto-setup and bounce sound off your walls to create the surround effect. Sounds like a DSP at work:

http://www.audioholics.com/productre...Projector1.php

[v-bro]

http://www.bigpicturebigsound.com/po...dbar-890.shtml

It's based on cancellation, this works fine as long as you sit exactly in the middle (for surround illusion). On stereo mode this review states you can enhance the width of the soundstage as well. (I find this dubious..).

A couple of years ago I got to test a very cute blue box from Sennheiser that did exactly the same thing, even the 'test-tone' seemed to really go 'round... But this didn't work when I listened from an uneven distance from the speakers....

[Tenson]

I think that Polk one works very differently to the Yamaha. The Yamaha really does make sound come from behind you if I remember correctly (haven’t read that huge long review).

I seem to remember that the Yamaha one works by ultrasonic pulsing. If you take two tones (can be any frequency, but they need to have the correct relationship to each other) and sum them, there will be a lower frequency tone created as a result of the phase relationships. So, the Yamaha uses ultrasonic sounds which overlap in this way at a position which is behind you, thus the lower (audible) sound actually does come from behind you, even if the inaudible ultrasonic sounds come from the speaker in front.

Now I may well have some of that ar5e about face but I am pretty sure that’s the basic theory behind it.

[v-bro]

AAAhhh finally found it on the net:
http://www.stereovideo.cz/old/9907/profil2.html

http://buy.sennheiserusa.com/ASP/Sen...Res/dsp360.jpg

It's not the latest technology, so I don't know if the newer processors are more capable. I didn't find it really impressive, but if you insist on surround and don't want speakers to crowd your room it can be a solution.

[Geoff H]

I think I know what you want. However please tell us what your aunt expects from this thing.

I know of a few tricks to create a wide spatial effect in a confined space. They don't need anything special either. Certainly not 1K in your currency, or mine.

Geoff.

[legendaryfrog]

my aunts expecting something that will somewhat surround her. it doesnt have to be up to POLK surroundbar standards, just decent sounding