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jeffslife
Joined: 17 Apr 2010
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Location: ohio usa
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| Posted: Thu Feb 27, 2014 7:05 pm Post subject: Two centers ? |
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A friend brought over a nice pair of Klipsch speakers, he said one quit working and asked if I would take a look at it. It turned out to be the crossover. It was under warranty so I got one sent and replaced it. I tested the speakers and really liked the midrange sound a lot. So I split the output off the pre amp hooked up both channels, put the tweeters to the center and let fly. I really liked it ! A LOT ! The vocals were clear and it really punched up the rest of the center channel soundstage. I have never seen 2 centers before but I might just go this route.
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Nashou66
Joined: 12 Jan 2007
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jeffslife
Joined: 17 Apr 2010
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Location: ohio usa
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| Posted: Thu Feb 27, 2014 11:15 pm Post subject: |
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Nash I have no idea what you are talking about
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jeffslife
Joined: 17 Apr 2010
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| Posted: Thu Feb 27, 2014 11:18 pm Post subject: |
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Any reason not to use 2 centers ? Its like two bookshelf speakers on their side with the tweeters together in the center and the woofers on the outer edge. I gotta say the more I hear it the more I like it.
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jeffslife
Joined: 17 Apr 2010
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| Posted: Thu Feb 27, 2014 11:22 pm Post subject: |
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Ok nash, I googled HTS and think I know what you you mean. Room EQ Wizard. It looks a little over my head to say the least.
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ecrabb
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Joined: 13 Mar 2006
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Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Thu Feb 27, 2014 11:37 pm Post subject: |
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| jeffslife wrote: | | Any reason not to use 2 centers ? Its like two bookshelf speakers on their side with the tweeters together in the center and the woofers on the outer edge. I gotta say the more I hear it the more I like it. |
Yes, there is a reason not to do it. Most speakers have a dispersion pattern that's wide in the horizontal direction, but more narrow in the vertical direction. That's especially true of horn-based speakers like I presume the Klisch is. So, with two speakers laid in their sides, you probably have a narrow dispersion patter side-side, and a wider pattern vertically, which is exactly what you don't want. The frequency response is likely a mess for anybody sitting very off of center. You'd probably be better off standing the two speakers vertically under the screen than setting them horizontally.
That's why Athanasios mentioned REW. You can convince yourself that almost anything sounds "pretty good", so without measuring, there's no way to know for sure what's happening to the sound.
Also, one bigger, better speaker will be better than two cheaper smaller speakers.
What's your usual center, and what model is the Klipsch bookshelf?
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jeffslife
Joined: 17 Apr 2010
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Location: ohio usa
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| Posted: Fri Feb 28, 2014 12:07 am Post subject: |
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I think the Klipsch was rb 61 IIRC. It was a horn. I normally use my Pinnacle gold series center. I also have a polk rti a9 laid horizontally with the top centered on my seat. ( I only use it if I am the only one watching because its VERY directional and my seat is not centered. I am thinking of using 2 polks, they have tweeters , not horns and sound very good when you are putting some power to them. I would like to try 2 bigger better speakers. BTW the single polk sounds amazing.
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jeffslife
Joined: 17 Apr 2010
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| Posted: Fri Feb 28, 2014 6:05 pm Post subject: |
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Is there any reason why you shouldn't run two tweeters ? Even when they are next to each other ? When I look at "normal" center channel speakers there is usually a tweeter in the center with mids and/or woofers on each side of the tweeter. Most brands CC are simply a shorter version of their tower speakers laid in the horizontal. I can see that a horn would be directional by its very design but an ordinary round tweeter should have no such issue. ( it doesn't seem to have one when they put the exact same one in a center channel. in the exact same mounting position I might add. ) The one thing I have yet to see though is 2 tweeters. Has anybody seen 2 ? And if not why not ?
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ecrabb
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| Posted: Fri Feb 28, 2014 6:16 pm Post subject: |
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Horizontal speakers (as most center channels are designed) are a design compromise, with sonics as a secondary concern. Ideally, all three front speakers would be vertical. The reason you don't see multiple tweeters arranged horizontally is because it can sound terrible. Two drivers, horizontally, will very likely "lobe", or interfere with one another.
http://www.audioholics.com/loudspeaker-design/vertical-vs-horizontal-speaker-designs
As I mentioned before, you've much, much better off with one good speakers vs. two lesser speakers.
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jeffslife
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| Posted: Fri Feb 28, 2014 6:55 pm Post subject: |
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What about 2 good speakers ?
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jeffslife
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| Posted: Fri Feb 28, 2014 7:16 pm Post subject: |
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After reading that article it really didn't clear up any questions, it spoke of some issues created horizontally but also basically said it could mostly be overcome with a little more volume. More volume is not a problem for me. My center is driven by a Yamaha m85 amp, it has a lot of room to stretch out. I like it loud but clear.
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ecrabb
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| Posted: Fri Feb 28, 2014 7:53 pm Post subject: |
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| jeffslife wrote: | | After reading that article it really didn't clear up any questions, it spoke of some issues created horizontally but also basically said it could mostly be overcome with a little more volume. More volume is not a problem for me. My center is driven by a Yamaha m85 amp, it has a lot of room to stretch out. I like it loud but clear. |
How are you getting "some issues" that can "mostly be overcome with a little more volume" out of that?
| Quote: | | If anyone likes you enough to watch a movie with you, the center channel must reproduce all that content smoothly and predictably across all your seats. If you’re sitting perfectly in front of the center channel, having multiple drivers of the same type in a horizontal configuration can do the job just fine. But if you move slightly off-axis, or as any of the other seats will realize, having horizontally-aligned redundant drivers will cause some frequencies to be canceled and some to be reinforced. |
| Quote: | | The subtracting and adding of various frequencies at various angles can result in audible shifting in the speaker’s sound across the room. Not only does the off-axis frequency response suffer, but timing and phase response follow. Off-axis, MTM speakers can often sound hollow but the comb filtering, or lobing effect, can also shift the imaging away from the middle as a “phasy” sound. |
It does go on to say, "To compensate for the lack of intelligibility (of the audio, not the script), people typically turn their volumes up which then can then result in some domestic tension among spouses, children and neighbors." The problem isn't overcome; there is still lobing, you've just compensated for the lack of intelligibility by turning it up.
If you keep reading to where he's doing frequency response tests, and comparing the standard horizontal center, the same center turned on its side, and the matching vertical bookshelf, he sums up with this:
| Quote: | | So what have we figured out thus far? First, that the horizontally oriented MTM center channel has significant variation in frequency response at different angles. Second, that by vertically orienting the MTM speaker we were able to significantly reduce the variation, but this company’s horn performance suffers and otherwise compromises this plan. And third, the smoothest response and less expensive bookshelf performs better, while possibly matching your left and right channels with complete perfection. |
He continues by testing a low-end horizontal center with four identical full-range drivers and his this to say:
| Quote: | | If you were setting out to design a speaker with the worst off-axis response possible, you should use a whole bunch of identical horizontal drivers. |
He then tests a nice B&W center channel, both horizontally and vertically…
| Quote: | In order to easily test if the drivers or cabinet are primarily to blame for the off-axis response, or if the MTM configuration itself is the limiting aspect, we then rotated the speaker vertically and ran it through another set of measurements. Fortunately, this speaker’s cabinet is square on the ends and this is actually a possible mounting configuration for your home theater. Would it improve the frequency response?
In the 1/24 octave chart below, it is easy to see that we significantly improved the off-axis midrange response by vertically orienting the speaker. Any peaks in the midrange are very narrow, which is just the way they should be. There is still some off-axis attenuation to the tweeter, but it has also been improved.
<snip>
For this product line, three vertically-oriented center channels would be your least-expensive, highest-performance standard option. |
He then tests a very expensive B&W center channel, and improves off-axis frequency down around the crossover from the mid-bass drivers, but created other problems because of the speakers' vertical design. However, he points out that how Skywalker Sound uses three identical floor-standing “main” speakers across their front soundstage.
To me, there's an overwhelming amount of evidence in that article alone that a single vertical speaker is worse than a single horizontal speaker. With all that evidence, it's not exactly a big leap to be confident that two speakers designed to be used vertically, but used horizontally instead, would be the worst of all configurations. That will most certainly exhibit easily-audible uneven off-axis frequency response, lobing, and intelligibility problems.
Like I said, if you want better center-channel performance, look for one good speaker.
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jeffslife
Joined: 17 Apr 2010
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Location: ohio usa
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| Posted: Fri Feb 28, 2014 9:28 pm Post subject: |
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My pinnacle isn't exactly "crap" I think it sounds decent. Its a bigger center than most. That said,if its just me watching a movie and the Polk rtia9 is centered on my seat the overall sound is very good, the rear surrounds are also rtia9's maybe that helps. I don't know for sure but I do know that I like what I hear and enjoy the overall surround effect even more. I was a little taken aback by how much sound comes out of a large center, or to put it another way how much doesn't come out of a smaller center.
Yet it still doesn't drown out anything and the soundstage is tight.
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ecrabb
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| Posted: Fri Feb 28, 2014 11:25 pm Post subject: |
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Be careful with A-B comparisons between two speakers. Unless you're level-matching and switching instantly with a switch box from your seat, it's almost impossible to compare, other than perhaps to hear if maybe one sounds really bad, but then you don't usually need a second speaker to hear that. If one speaker is even a couple dB more efficient, and therefore that much louder, your brain will think it sounds better. It's how we're wired.
That being said, larger is usually better. Physics will only allow a small speaker to do so much. In general, a larger speaker will usually have a lower rolloff (more extension), will be more sensitive, sound less strained at louder SPL's, and will probably just "sound bigger" overall.
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jeffslife
Joined: 17 Apr 2010
Posts: 4190
Location: ohio usa
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| Posted: Sat Mar 01, 2014 1:39 am Post subject: |
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Steve, Thank you for all the help. At least I have a better grasp on why a certain speaker should sound better than another. When I do AB testing I sit and have someone hit the switch. What sounds GREAT in the front row sometimes sounds like crap in the back row. The hard part is finding a happy medium. A meter helps to get close but in the end only what it really sounds like that matters. I aint one for computer programs for sound imaging. ( its like saying before computers ALL HI FI's SUCKED ) which just isn't true. Although I do like AUDESSEY for movies it crushes ALL the sound in stereo and music really suffers. I am seriously thinking of making my own EXTRA LARGE CENTER. Or maybe just dialing in the POLKS a quarter inch at a time. A really big center really does sound amazing, I just want it to sound the same for everyone in the room as it does for me. I believe it can be done. I have seen people(on this very site) invert towers and stack them on top of one another. Everything says it would sound like crap but in reality I bet it don't. The truth is you never know for sure till you try.
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