Negatives of using Y-adapters in preamp outs? - AVS Forum
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post #1 of 29 Old 05-26-2012, 03:22 PM - Thread Starter
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My current setup requires two centers, and bi-amping my main front speakers. So, I have three Y-adapters that are being used from the preamp outs on my receiver. One is for the two centers. I have the "center" signal going to two different channels on my multichannel amp, and then to the speakers themselves. The same is true for my front main speakers. I have the "front L" and "front R" signals split to go to separate amps, then to the speakers. In theory, my Def Tech BP7001SC are receiving the best possible situation because the highs have their own amp, as do the mids (the lows are covered with an internal amp in the speaker). Are there any negatives to doing this?
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post #2 of 29 Old 05-26-2012, 05:19 PM
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As long as the amp inputs are of similar high impedance, none.

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post #3 of 29 Old 05-26-2012, 05:48 PM
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I'll second Kal on that.

The lazy man finds the easiest way ... Ben Franklin
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post #4 of 29 Old 05-26-2012, 05:55 PM - Thread Starter
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Quote:
Originally Posted by Kal Rubinson View Post

As long as the amp inputs are of similar high impedance, none.

How would I know? Check the specs of the amp and the specs of the receiver?
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post #5 of 29 Old 05-26-2012, 06:18 PM
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Quote:
Originally Posted by patricksull View Post

My current setup requires two centers,

I'm curious as to why your setup requires two center speakers.

Bill

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post #6 of 29 Old 05-26-2012, 07:58 PM
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I've seen a few home theaters with double centers. They are setup side by side for added overall length. If the theater is of large size, it helps with off axis dialog for people sitting to the left or right. Again, this is for fairly large home theaters I've seen these installed in.
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post #7 of 29 Old 05-27-2012, 08:54 AM - Thread Starter
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My room is approximately 17X25, and I have tried a couple different centers. One just doesn't fill the room well enough. I can't be the only one with two centers, the Anthem D2V has two center outputs.
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post #8 of 29 Old 05-27-2012, 10:56 AM
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I also run dual centers in the theater setup. I got some solid copper type ones from ebay,hong kong.
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post #9 of 29 Old 05-27-2012, 10:58 AM
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Hope its ok to post ebay links.If you need some quick and cheap, home depot sells the wire type for about $3.00





http://www.ebay.com/itm/SOLID-METAL-...item2318d148e2
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post #10 of 29 Old 05-27-2012, 11:10 AM - Thread Starter
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Quote:
Originally Posted by Dezmond View Post

Hope its ok to post ebay links.If you need some quick and cheap, home depot sells the wire type for about $3.00





http://www.ebay.com/itm/SOLID-METAL-...item2318d148e2

Thanks Dezmond! I already have mine, but that post could help the next guy who's looking for them.
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post #11 of 29 Old 05-27-2012, 12:44 PM
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Quote:
Originally Posted by Venomous View Post

I've seen a few home theaters with double centers. They are setup side by side for added overall length. If the theater is of large size, it helps with off axis dialog for people sitting to the left or right. Again, this is for fairly large home theaters I've seen these installed in.

Actually, it will generally result in irregular dispersion due to the horizontal plane interference.

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post #12 of 29 Old 05-27-2012, 03:07 PM
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Quote:
Originally Posted by Kal Rubinson View Post

Actually, it will generally result in irregular dispersion due to the horizontal plane interference.

I've contemplated two center channels before but was uncertain of the results. Would you care to elaborate on your statement?
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post #13 of 29 Old 05-27-2012, 03:28 PM
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Quote:
Originally Posted by johnson636 View Post

I've contemplated two center channels before but was uncertain of the results. Would you care to elaborate on your statement?

Two physically separated sources emitting the same signal will be in phase in some locations, out of phase in other locations. That creates both constructive and destructive interference.



http://en.wikipedia.org/wiki/Interfe...ve_propagation)

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post #14 of 29 Old 05-27-2012, 04:27 PM
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With all the talk about two centers from the same output (Y adaptor) how can Audyssey calibrate two seperate center speakers? Would it be an issue or can you trick Audyssey into thinking the two speakers are one? To me unless the AVR/prepro has seperate center channel outputs and the onboard RC can calibrate the two I do not think it is a good idea. But what do I know. Why not just spend the money one would on two center speakers and buy one good one.

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post #15 of 29 Old 05-27-2012, 05:40 PM - Thread Starter
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Quote:
Originally Posted by Bill Mac View Post

With all the talk about two centers from the same output (Y adaptor) how can Audyssey calibrate two seperate center speakers? Would it be an issue or can you trick Audyssey into thinking the two speakers are one? To me unless the AVR/prepro has seperate center channel outputs and the onboard RC can calibrate the two I do not think it is a good idea. But what do I know. Why not just spend the money one would on two center speakers and buy one good one.

Bill

I chose to buy Definitive Technology and their center channel selection is "weak" at best. I love their older towers (BP7001SC), and even their surrounds (BPVX), but their top of the line center (CLR-3000) lacks any true depth. By having two of them, I am able to accomidate that weakness (in my opinion anyway) But, to answer your question about Audyssey...I'll know before long. I have a Marantz AV7005 heading my way. Time will tell.
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post #16 of 29 Old 05-27-2012, 06:39 PM
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Quote:
Originally Posted by johnson636 View Post

I've contemplated two center channels before but was uncertain of the results. Would you care to elaborate on your statement?

Not again. This has been discussed many times on this forum (and on many others) since it also afflicts most horizontal MTM centers as well.

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post #17 of 29 Old 05-27-2012, 06:41 PM
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Quote:
Originally Posted by Bill Mac View Post

With all the talk about two centers from the same output (Y adaptor) how can Audyssey calibrate two seperate center speakers? Would it be an issue or can you trick Audyssey into thinking the two speakers are one?

Sure. It will EQ the pair as one.

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Why not just spend the money one would on two center speakers and buy one good one.

Agreed.

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post #18 of 29 Old 05-27-2012, 07:53 PM
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Quote:
Originally Posted by patricksull View Post

I chose to buy Definitive Technology and their center channel selection is "weak" at best. I love their older towers (BP7001SC), and even their surrounds (BPVX), but their top of the line center (CLR-3000) lacks any true depth. By having two of them, I am able to accomidate that weakness (in my opinion anyway) But, to answer your question about Audyssey...I'll know before long. I have a Marantz AV7005 heading my way. Time will tell.

How much power are you driving your center at?

I have a DefTech 8080HD center which is a tad smaller then yours and I am driving it with 450watts plus it's 300watt internal amp. I can get peaks of 110db at my back seats (14ft away) running just the center channel alone. I needed a CC that could keep up with my subs that have peaks over 125db, and the 8080HD does the job.

God loves me, but everyone else thinks I'm an a$$hole.
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post #19 of 29 Old 05-28-2012, 07:33 AM
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Quote:
Originally Posted by patricksull View Post

How would I know? Check the specs of the amp and the specs of the receiver?

Yup.

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post #20 of 29 Old 05-28-2012, 09:01 AM
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Quote:
Originally Posted by Kal Rubinson View Post

Not again. This has been discussed many times on this forum (and on many others) since it also afflicts most horizontal MTM centers as well.

No problem.
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post #21 of 29 Old 05-28-2012, 09:37 AM
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Quote:
Originally Posted by Kal Rubinson View Post

Not again. This has been discussed many times on this forum (and on many others) since it also afflicts most horizontal MTM centers as well.

The problem is more the tweeters in this case, IMO.

But otherwise, yes, if the amps are of decently high input impedance then it should be fine. Solid state amps are usually of high impedance inputs if the inputs are [MOS]FETs. It can sometimes be a bit low with BJT inputs. Basically you just need the source to be able to supply enough current, and to be of low enough impedance compared to the load.

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post #22 of 29 Old 05-28-2012, 11:52 AM
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The problem is more the tweeters in this case, IMO.

Nope. It is a problem with midrange speakers, too, whenever they are laterally separated by more than 1/2 wavelength at crossover or other overlap range.

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post #23 of 29 Old 05-28-2012, 05:03 PM
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Quote:
Originally Posted by Kal Rubinson View Post

Nope. It is a problem with midrange speakers, too, whenever they are laterally separated by more than 1/2 wavelength at crossover or other overlap range.

I didn't say it doesn't affect midranges. I just believe it to be even worse for tweeters.

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post #24 of 29 Old 05-28-2012, 05:23 PM
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I didn't say it doesn't affect midranges. I just believe it to be even worse for tweeters.

Would you care to expand on these thoughts. In other words why do you feel it effects the tweeters more so than the midrange drivers? Maybe you can give Kal and the rest of us some technical information we were not aware of.

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post #25 of 29 Old 05-28-2012, 05:27 PM
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Quote:
Originally Posted by Bill Mac View Post

Would you care to expand on these thoughts. In other words why do you feel it effects the tweeters more so than the midrange drivers? Maybe you can give Kal and the rest of us some technical information we were not aware of.

Bill

Just since the smaller wavelengths from the tweeter are going to interact much more. Like when building speakers, it's the most important to keep the tweeter as close to the midrange as possible, whereas in a 3-way it is not really important to keep the woofer all that close to the midrange, and it is generally not important to keep a subwoofer close to the speakers, either. Placement is just more important for tweeters.

That's why the Axiom VP150 is a stupid, stupid piece of equipment.

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post #26 of 29 Old 05-28-2012, 05:52 PM
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Rather than debate the subject & theory why not dig in deeper with a known reference...
I would suggest Dr.Toole's book available form Amazon in softbound or electronic..

http://www.amazon.com/s/ref=nb_sb_no...ds=floyd+toole

For your reference, Dr.Toole headed the Harman International R&D team for many years, as well as teaching many classes that we have taken..
He makes a strong presentation, I think in Chapter 6 about center channel loudspeaker placement..

Dr.Toole also was instrumental in the development of the JBL Synthesis high-end AV system that sells for about $100K..
Also he was the 1st to present the benefits for multiple subwoofers over 10 years ago..

Just my $0.02...
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post #27 of 29 Old 05-28-2012, 05:54 PM
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Quote:
Originally Posted by Bill Mac View Post

Would you care to expand on these thoughts. In other words why do you feel it effects the tweeters more so than the midrange drivers? Maybe you can give Kal and the rest of us some technical information we were not aware of.

Well, since it is a function of frequency and distance, tweeters need to be much closer to each other or to the midrange to avoid the problem.

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post #28 of 29 Old 05-30-2012, 02:02 AM
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I too have two "centre" speakers (old KEF Q floorstanders), together they sound MUCH better than the dedicated centre they replaced (same lineage). In the mid-line position (the sweet spot) you have constructive interference, double the amplitude and it's not an issue really. Room correction (not Audyssey) auto-calibrated -3dB. I'd love to try the 60lb ref KEF centre (WMTMW design) since I have older KEF ref for fronts but it costs something like $5K or $6K.

Sitting sideways is always going to be a compromise of some sort isn't it, it's no longer the sweet spot for RC, you're nearer one side of the room and speakers than the other etc.

Audiosceptics accept audio trials using 25 people. A recent Oxford study with over 353,000 patient records from 639 separate clinical trials shows for every 1,000 people taking diclofenac or ibuprofen there would be 3 additional heart attacks, 4 more cases of heart failure and 1 death every year.

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post #29 of 29 Old 05-30-2012, 05:44 PM
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This is my center, custom built Dynamic 4T center from clearwave loudspeakers.At 55 inches wide who needs two center speakers.
LL
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