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2 Channel multiple position listening, is it possible?

post #1 of 15
Thread Starter 
In a large room 24 x 26' with 8' ceilings (workshop) is possible to set up 2 channel audio to sound good (maybe not great) in multiple positions through out the room?

Originally I was going to put 8 speakers in the ceiling in a grid fashion to separate the garage into 4 "stereo" 2 channel cells. Now after doing more reading about how ceiling speakers are great for noise, but not good sound, I'm trying to figure out a good location to eventually mount the speakers along the wall (not in wall).

In the simplest form, say I have a speaker at the left and one at the right of the front of the room in the corners. Can these be aimed/setup so that when they are 20' apart and I stand anywhere but in the middle I don't get blasted by the one channel I'm standing closer to?

I have multiple speakers to work with, but only 2 stereo channels. Is it OK place multiple speakers through out the room to keep good stereo L to R balance when standing in different locations?

I want to try to maintain front imaging, this may not be possible. I also want natural sound and natural reflections, that is the reason I'm considering taking the speakers out of the ceiling. Even though the left to right balance and volume is very consistent as I move about the room. Not to mention in the ceiling they are completely out of the way. How can I maintain consistent volume in different locations?
post #2 of 15
My shop is 21'x28'x8. I have an old 5.1 system in there. I never throw my old components away. It's a joy to work in there. I'll admit I did tweak it with an Audio Control 1/3 Octave 30 Channel Spectrum Analyzer. The speakers are about 4' high except the sub.
post #3 of 15
post #4 of 15
Hmm. I'll second LTD02's post and suggest controlled dispersion horns located in the corners. This won't hog a lot of space in the workshop, and as far as larger sweet spots go, it's not perfect but it's not bad. Corner loaded, cross-fired, controlled directivity speakers sort of sound like your whole room is inside a pair of giant headphones. The scale can be huge and enveloping.

Another way to get an increased sweet spot would be to take a completely different approach and get something that will spray sound out in many directions. For example, a pair of the largest DefTechs such as the BP7000ST would probably be able to fill the room reasonaby well and sound decent doing it.
post #5 of 15
While I agree in general with the above, I think of my own shop/garage setup. It was never intended to replicate my HT and it's medium sized sweet spot. Consider being in the middle of your HT and looking straight ahead. That doesn't happen in my shop. I'm all over the place and facing in different directions. Sometimes getting something from a drawer puts me close to a speaker. That's the reality of music in a shop. Music is the second reason you're there. I do have a SACD player out there for 5.1, but mostly it's stereo from my wireless WDTV streamer. Like I mentioned, about the only tweaking I did was to try to smooth the frequency response. Personally I wouldn't get too concerned with sweet spots considering your activity in there.
post #6 of 15
Thread Starter 
As the article states, I do want my speakers to not sound localized. I mainly do not want to hear dominant left or right while moving around.

The first concept of aiming the speakers to cross in front of the listening position is what I've been trying. My experience with car audio uses this same principle. So as I move left to right I'm on axis with the distant speaker making it appear the same volume as the closer speaker I'm near that is off axis.

I've already realized just two speakers mounted on the wall toed in and naturally reflecting sounds way better and dimensional than ceiling mounted. I want to be surrounded by the sound even if the imaging and sound field isn't accurate and the room is creating its own sound field.

That is the next thing I thought about trying, is aiming the speakers at the wall and using reflection. Another thought is I have car audio 7" 2 ways I'm using, the Q is probably high enough I could run in infinite baffle. The rear of the speaker is just the mid, and already 180 deg. out of phase from the front, when reflected would be in phase with the front? Would this work?

In the article it shows a pair if stereo speakers covering an area with good coverage left to right, but not front to back. Would it be possible to duplicate and mirror image of the same pair of stereo speakers on the other side of the room to cover that end? I would think that second rear pair at the other side would have to be set up so the sweet spot would not over lap the front pair?
post #7 of 15
What about a ghetto dynaquad arrangement for the rears? If you're limited to strictly two channel, that may be something to try out. (In case you don't know how this is done, it's pretty simple. For the rear speakers, connect the positive leads to the amp, but connect the negative leads to each other, not to the amp. This results in the difference signal being sent to the rears, which is any sound not equally present in the fronts; the more panned from the center image the sound is in the front speakers, the more it is present in the rears. The idea is that the image is determined by the fronts, and the rears are ambient fill. You can wire the rears out of phase relative to each other to further enhance the diffuse sound coming from the back of the room. Believe it or not, it actually works.)
Edited by Wayne Highwood - 9/26/13 at 12:33am
post #8 of 15
your best shot i believe for accurate sound across the entire room is a pair of controlled directivity speakers with about 90 degree horizontal coverage, two speakers, one in each of the two front corners, mounted high and aimed down slightly, horizontally pointing toward the center of the room...or the garage in this case. a cheap set of econowave speakers or seos speakers will do that.

i'm the 'publius' btw.
post #9 of 15
Thread Starter 
Quote:
Originally Posted by Wayne Highwood View Post

What about a ghetto dynaquad arrangement for the rears? If you're limited to strictly two channel, that may be something to try out. (In case you don't know how this is done, it's pretty simple. For the rear speakers, connect the positive leads to the amp, but connect the negative leads to each other, not to the amp. This results in the difference signal being sent to the rears, which is any sound not equally present in the fronts; the more panned from the center image the sound is in the front speakers, the more it is present in the rears. The idea is that the image is determined by the fronts, and the rears are ambient fill. You can wire the rears out of phase relative to each other to further enhance the diffuse sound coming from the back of the room. Believe it or not, it actually works.)
Cool, I was sketching this out, and then it made sense how you say the rears get the difference (in potential) between the two (positive terminals) of each channel.

So you are saying if I have a pair of speakers normally wired to an amp, then just add the second set to the same terminals?

What does the impedance load end up being per channel with all 8 ohm speakers?

I was thinking on a stereo receiver that has an "A" and "B" speaker terminal set. Then if the front L and R are wired normally with the rear pair in series with each other, then in parallel with the two front channels, they could all be wired to just the "A" channel. The other option to be able to add or remove this effect would be to wire the front speakers normally to the "A" terminals. Then wire the rear speakers in series the same way with the positive of each L and R speaker going only to the positives of the "B" terminals. Then when the "B" set is switched on the relay inside the amplifier activates to connect the "A" and "B" terminals in parallel anyway, achieving the same parallel wiring of the front and rear set, correct? With the ability to run normal front stereo, and the add in the rear dynaquad?

Quote:
Originally Posted by LTD02 View Post

your best shot i believe for accurate sound across the entire room is a pair of controlled directivity speakers with about 90 degree horizontal coverage, two speakers, one in each of the two front corners, mounted high and aimed down slightly, horizontally pointing toward the center of the room...or the garage in this case. a cheap set of econowave speakers or seos speakers will do that.

i'm the 'publius' btw.
Interesting, so pretty much you are suggesting a horn speaker?

What about dipole or bipole set ups?

One other hitch to the plan...I sometimes will be facing the front of the room while working, and at other times facing the rear of the room while working. Does it matter which end I put the speakers on, if my goal is to get the sound to surround me and not be able to tell the direction it is coming from?
post #10 of 15
yes, horn speakers.

dipole speakers are interesting, but they generally require placement out into the room, whereas horns can be mounted right in the corners.

bipole are something altogether different, are used to create a diffuse soundfield with reflections all over the place. they maximize ambience but at the expense of coherence.
post #11 of 15
"One other hitch to the plan...I sometimes will be facing the front of the room while working, and at other times facing the rear of the room while working. Does it matter which end I put the speakers on, if my goal is to get the sound to surround me and not be able to tell the direction it is coming from?"

you are making the problem more complicated than it is. :-)
post #12 of 15
Quote:
Originally Posted by Soundtastic View Post

Cool, I was sketching this out, and then it made sense how you say the rears get the difference (in potential) between the two (positive terminals) of each channel.

So you are saying if I have a pair of speakers normally wired to an amp, then just add the second set to the same terminals?

What does the impedance load end up being per channel with all 8 ohm speakers?

I was thinking on a stereo receiver that has an "A" and "B" speaker terminal set. Then if the front L and R are wired normally with the rear pair in series with each other, then in parallel with the two front channels, they could all be wired to just the "A" channel. The other option to be able to add or remove this effect would be to wire the front speakers normally to the "A" terminals. Then wire the rear speakers in series the same way with the positive of each L and R speaker going only to the positives of the "B" terminals. Then when the "B" set is switched on the relay inside the amplifier activates to connect the "A" and "B" terminals in parallel anyway, achieving the same parallel wiring of the front and rear set, correct? With the ability to run normal front stereo, and the add in the rear dynaquad?

If you use a stereo amp, use the "B" terminals for the rear speakers. It won't change the load presented, but it is convenient to be able to turn the rears (or fronts) on or off at the push of a button.

Regarding the load presented, since the rear pair are in series, and the difference signal won't have much bass to speak of, it shouldn't pose any issues. This approach (Hafler dynaquad/ambiance recovery) was actually suggested in the owners manual of an old NAD amplifier I have, and I don't think they would put it in there if it was overly risky practice. I've used 4 ohm mains and 8 ohm rears in this manner, and never blown up anything.

Also keep in mind that none of this will prevent you from localizing speakers with your ears as you wander around the shop. It's simply a way to expand the soundstage, requires no extra kit, works with any two channel source material, and it just happens to work as well or better than any DSP ambient processing I've compared it to. I think if you follow LTD's advice for the fronts and do the hafler thing for the rears you will be pretty close to your stated goal.
Edited by Wayne Highwood - 9/27/13 at 11:14am
post #13 of 15
Thread Starter 
Points taken. Can you make a suggestion for a horn speaker and mid? I have a separate plan altogether for sub placement. I looked at parts express stuff, is that the way horns are usually sold, driver separate from the horn? Does the horn have to be in an enclosure?
post #14 of 15
No, the horns don't necessarily need to be in an enclosure, lots of cinema speakers like that with the horns mounted outside the bass bins.

As for recommendations, I haven't heard these myself, but the Pi Four kit and larger SEOS kits seem like they would fit the bill perfectly for the fronts. Those are about the most cost-effective options.
post #15 of 15
Thread Starter 
I have a plan for the subwoofer, these are going to be crossed over at about 60 Hz. The Pi speaker gives me the idea, but they are pricy for my budget. The Pi speakers you suggested use the Eminence PSD2002 horn driver, which I see Parts Express also sells separately. I would plan to use something like that, but now I need a mid and crossover for the horn and mid.

What do you suggest for a mid and crossover?

How does the horn and mid connect to the crossover to offer 8 ohm impedance?
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