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#370553 - 21/02/2018 20:52 Two speakers or one stereo?
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
I'm thinking of putting in-ceiling speakers in parts of my house, possibly going back to a multi-room amp in my hall closet.

One thing I'm pondering is whether I should install two speakers (one for the left channel and one for right) or one stereo speaker. From what I understand, stereo speakers are usually used in small rooms like bathrooms or walk-in closets. But I'm also wondering why I would need - or even want - stereo separation in places like a kitchen or dining area. I suppose it won't matter if my source can output a mono signal, but I'm looking at Sonos Connects for inputs, and I don't think they can do that...

So what would you folks suggest?
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#370569 - 24/02/2018 04:34 Re: Two speakers or one stereo? [Re: Dignan]
DWallach
carpal tunnel

Registered: 30/04/2000
Posts: 3717
If you've got the space for regular left/right speakers separated, then that seems like the obvious thing to do. That said, It's astonish how little my rear speakers ever do anything. Once in a while, some TV commercial will light them up, but mostly not.

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#370570 - 25/02/2018 06:16 Re: Two speakers or one stereo? [Re: DWallach]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
Originally Posted By: DWallach
If you've got the space for regular left/right speakers separated, then that seems like the obvious thing to do. That said, It's astonish how little my rear speakers ever do anything. Once in a while, some TV commercial will light them up, but mostly not.

This actually won't be for home theater purposes at all, just for music playback. It just seems weird to me to have two speakers in my kitchen playing separate channels of an audio track. It's not like I want to hear guitar in one speaker and piano in another or something. I want to hear the same thing at the sink that I'd hear at the table.
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#370571 - 25/02/2018 07:35 Re: Two speakers or one stereo? [Re: Dignan]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
Summing stereo music to mono causes changes that might be unwanted for you, depending on the type of music you listen to. Stereo is better sound if you can arrange for it.

Best solution is to put stereo speaker sets in each common listening location. Your example of hearing something different at the sink than at the table is merely a question of distance and speaker placement. Sound spreads out a lot, so it might sound fine in both spots even though the stereo imaging wonít be standard.

Music hopefully is produced to minimize mono-summing problems, but some issues are hard to fix in mixing and mastering, and they canít fix everything perfectly. Phase problems caused by mono summing can cause some instruments and voices to become louder or softer in the mix than the original artist intended.

I have no idea how things like those crappy little voice activated speaker pucks handle it. Perhaps they try to aim two speakers outward from each other to get some tiny amount of stereo separation. Possibly even with a bit of deliberate L/R phase nudging to prevent mono summing problems. Dunno.
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#370580 - 26/02/2018 14:16 Re: Two speakers or one stereo? [Re: Dignan]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
Just to clarify, when you say mono summing are you talking about the effect on a person's ears, or as a process in the equipment? I just wanted to be clear that the speakers I'm looking at have separate tweeters for each channel so they won't be mixing the two, it'll just go through one channel. Well, I guess the lower range would be mixed somehow... I'm not sure how that works...
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#370581 - 26/02/2018 18:37 Re: Two speakers or one stereo? [Re: Dignan]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
Quote:
when you say mono summing are you talking about the effect on a person's ears, or as a process in the equipment?


Both. It's a sliding scale. The scale goes like this:

- Completely summed before it reaches the speakers (0 separation).
- Speakers are super close to each other, such as being in the same enclosure (essentially summed unless the speakers are doing tricks with aiming and phase processing to try to mitigate the problem).
- Speakers are pretty close to each other but not exactly coincident, like in a boom box.
- Speakers are separated by approximately the correct intended angle, where you and the speakers form a right triangle (90 degree separation). This is the middle ground that mastering engineers are aiming for.
- You are directly between the speakers (180 degree separation but with some bleed over).
- Headphones (infinity separation with no bleed over).

Additive and subtractive phase interactions in the sound waves cause changes as you move up the sliding scale of separation. Instruments and voices recorded and mixed in stereo, depending on exactly how they're recorded and mixed (I can talk your ear off about mid-side micing and mono compatibility), will seem to decrease in volume as they become closer and closer to mono-summed. Instruments and voices recorded and mixed in mono and then placed into a stereo mix panned center (usually but not always lead vocals, bass, snare drum, kick drum) will seem to increase in volume as they become closer and closer to mono summed. The amount of perceived change can be as much as 6 decibels or more in either direction, as you get closer to the extreme ends of the scale.

The frequency spectrum of the particular instruments and voices is also a factor, since the amount of separation and the listening position will affect which frequency nodes are the ones most heavily affected. This is before we even get into the question of having the woofer summed but the tweeters not summed, which muddies the mess even further. So now you're not only talking about the balance of instruments changing, but now the issue starts to change the EQ response of each of those instruments too.

Music producers and mastering engineers try to fix this as much as they can with little tricks and compromises, but they can't fix it completely. God knows I've tried. The only true solution would be to mix entirely in mono, but then the music would sound flat and lifeless like an AM radio. Some of it can be mitigated by fiddling with the EQ settings on your stereo system, but that's not a perfect solution either, since you're trying to change the perception of lost or increased information without actually changing the source of that information.

The kind of ceiling speakers you describe, with the stereo inputs and dual tweeters, are intended for restaurants and such, or for people who don't care about the music itself, where it's meant as just background music and not for quality listening. You'll get variable results depending on the amount of electronic and physical trickery they're doing to try to make the speakers sound good. Sometimes speakers like that can actually sound quite good if they're a really good brand and everything is set up properly, but they'll always be a compromise of all the factors I cited above. Some people even like the way the music sounds after it's gone through that play dough fun factory, since it tends to increase the perceived volume of lead vocals panned center.

If you're getting high quality ceiling speakers with dual aimed tweeters, then at least try to set them up in the correct positions relative to each other, so that what little stereo projection they have are all aligned. If you install them in "69" positions relative to each other, then you'll have nodes where you're getting all right channel or all left channel from multiple sets of tweeters depending on where you stand.
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#370582 - 26/02/2018 21:40 Re: Two speakers or one stereo? [Re: tfabris]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
Originally Posted By: tfabris
The kind of ceiling speakers you describe, with the stereo inputs and dual tweeters, are intended for ... background music and not for quality listening.

Yep.

These are purely for entertaining and for throwing something on while cooking/eating dinner with the wife and kids. With a 3 year old and 4 month old in the mix, there's no "quality listening" these days anyway smile But if there were, I wouldn't use this system. I'd listen in my car or on my dad's old floor speakers in my office. Or maybe the speakers in my home theater. These ceiling ones are only going to be on when I'm talking to other people and we want to put the local classical music station on in the background.
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#370583 - 27/02/2018 09:38 Re: Two speakers or one stereo? [Re: Dignan]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
Cool. Now you can make an informed decision! smile
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#370585 - 27/02/2018 21:33 Re: Two speakers or one stereo? [Re: tfabris]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
Originally Posted By: tfabris
Cool. Now you can make an informed decision! smile

Your write-up was very helpful. It gives me a good idea of what to expect. In a couple places, I think I'll only be able to run one speaker anyway, so I'd want stereo models there for sure. I might just order all stereo models and if I want separation I can wire them as mono L/R channels.
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#370630 - 08/03/2018 04:28 Re: Two speakers or one stereo? [Re: Dignan]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
Ok, stupid question here, but how much bass should I reasonably expect to gain from installing an in-ceiling speaker vs open-air.

I ordered a pair of these, and I've hooked them up to a small amp on my desk, and they're just sitting on my desk propped up on their side.

Look, I know these aren't going to rattle the house with massive bass, and I'm sure the ceiling joist bay will keep some of that bass from escaping (I'm finding mixed opinions on building enclosures), but so far I'm pretty worried about the bass response from these things. The reviews all say that the bass is pretty good, but I'm wondering if that's something that will come post-install. Right now, there are some songs I'm playing on these where I know the bass parts really well and I'm not even hearing them, let alone feeling them.

Other possible problems could be my amp, which is a crappy little thing I got to power some speakers in my garage while I'm working, and the source is my computer. So I don't know where the trouble could lie.

*edit*
fyi, this is the amp I'm using. I might try to hook up an old receiver I have lying around...


Edited by Dignan (08/03/2018 04:30)
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#370635 - 08/03/2018 14:59 Re: Two speakers or one stereo? [Re: Dignan]
tanstaafl.
carpal tunnel

Registered: 08/07/1999
Posts: 5377
Loc: Ajijic, Mexico
Originally Posted By: Dignan
how much bass should I reasonably expect to gain from installing an in-ceiling speaker vs open-air.
Something I recall from my past days of IASCA car stereo competition might (or maybe not) be relevant here. (IASCA: International Auto Sound Challenge Association)

The lowest frequency you will attain is a function of the amount of cone area in a given enclosure. For example, a 12 inch subwoofer has a cone area of ~113 square inches. Compare to a pair of 10" speakers in a common enclosure at ~157 square inches, an increase of nearly 40%. You can attain lower frequencies with a pair of 10's than with a single 12. But that's not the biggest advantage. With the 12's you are pretty much constrained to a 20 Hz crossover frequency. The 10's are perfectly happy with a 100 Hz crossover, giving you a "richer" bass sound. Not just "blumph-blumph-blumph" like you her from the ricers' stereos, but actual music from the subwoofer box, with very tight "pomp-pomp-pomp" bass hits.

I won every IASCA competition I entered with that setup.

tanstaafl.


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#370636 - 08/03/2018 15:07 Re: Two speakers or one stereo? [Re: Dignan]
K447
addict

Registered: 29/05/2002
Posts: 674
Loc: Toronto, Ontario, Canada
Originally Posted By: Dignan
...
*edit*
fyi, this is the amp I'm using. ...
Quote:
Parallel 6600 UF fever philips filter capacitance, meet the needs of the high power peaks
wink

Try your speaker with a test mounting in a large rigid cardboard baffle or box. You should hear a significant change in speaker tone and base response. Obviously not the same as your actual ceiling joist cavity, but should be an audible difference.

If your ceiling speakers are open back, consider packing some accoustic wool ( Rockwool (nťe Roxul) mineral wool type material) into the joist cavity, and perhaps boxing in the cavity with vertical material to create a proper box of sorts up there.

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#370639 - 08/03/2018 20:38 Re: Two speakers or one stereo? [Re: Dignan]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
Originally Posted By: Dignan
they're just sitting on my desk propped up on their side.


Absolutely without question, speakers sitting there in open air, without an enclosure (either a box, or, the ceiling space as a box) will not produce any bass. There has to be a controlled amount of pressure separation between the listening space (the front of the speaker) and the back space behind the speaker. Whether the enclosure is a sealed one or has a tuned port, either way, you need that separation.

Most car speakers work so that the speaker is in some kind of enclosure, or, there is a separation between the inside cabin of the car and the back side of the speakers. For example, on the rear deck your speakers have the back side in the trunk and the front side in the cabin, or in the doors your speakers have the back side as the "outside of the car" (the doors vent to open air) and the front side as the cabin.

Without this, you'll get zero bass response. So your desk test was not valid.

Think of it like this: Have you ever had a situation in your house where you do this?

- Normally when you close an interior door, say, your bedroom door, you are used to how much force to use when swinging it shut.
- But then one day you happen to have the windows in your bedroom open, or perhaps the front door of the house open, or both.
- On that day, you go to close your bedroom door and you just fscking SLAM it inadvertently because you didn't realize that so much less force would be needed to close it.

That's from the pressure differential. As soon as you open up the outside windows the pressure has a place to go and there is no back pressure. Bass on speakers works just like that. If you have a speaker sitting there in open air, there's no back pressure and nothing to "push" against to make low frequency sound waves.

Make sense?
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#370644 - 09/03/2018 03:57 Re: Two speakers or one stereo? [Re: tfabris]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
Originally Posted By: tfabris
Think of it like this: Have you ever had a situation in your house where you do this? ...

Tony, in researching this I've come across some metaphors for how it works, but that is absolutely the best one. Yes, I know exactly what you're talking about (I have a small laundry room leading to the garage where it happens all the time).

I'm going to start with a cardboard box enclosure, I think. I'll update with my impressions when I finally get around to it.
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#370645 - 09/03/2018 05:26 Re: Two speakers or one stereo? [Re: Dignan]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
Donít bother with a cardboard box. A cardboard box will flex too much amd wonít be a large enough enclosure, and you still wonít get a good idea of their final performance.

If it were me, I would just go whole hog and install them in the ceiling. If the reviews say theyíll have good bass, I would just trust the reviews.
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Tony Fabris

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#370647 - 09/03/2018 07:56 Re: Two speakers or one stereo? [Re: tfabris]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31164
Loc: Seattle, WA
Also forgot to say: thanks, Iím glad you liked that metaphor. smile

Itís just what I always thought of when thinking of speaker enclosures.
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#370650 - 10/03/2018 05:30 Re: Two speakers or one stereo? [Re: Dignan]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
Well, I did do a cardboard box test and was very positive! I see what you mean about flex and I think you're right, but I think I had about as good a test as I could. At first I wasn't looking forward to carving up some Amazon shipping box, but then I realized I had something better...the box they came in! Duh. So I just slipped them back into the container they came in, and while I think I'll get more bass from a stronger surround, I was already much more pleased with the results.
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#370651 - 10/03/2018 05:32 Re: Two speakers or one stereo? [Re: Dignan]
Dignan
carpal tunnel

Registered: 08/03/2000
Posts: 12039
Loc: Sterling, VA
BTW, I have these wired in parallel, so they're acting as mono left and right. Next I want to wire one up for stereo and see what my impressions are. The way I see it, these are already in the price range I was looking for, and they sound good. If I'm running wire already, it's a minor cost to run 4-conductor wire over 2-conductor. Then I have the option of wiring it either way. I'll need some extra equipment in the closet for the extra lines, but that's easier than swapping out the wires or the speakers.


Edited by Dignan (10/03/2018 05:34)
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