I am in the process of reassembling all of my wiring and equipment after purchasing a new HDTV and stand. The stand has two shelves. The bottom shelf is about 1 inch off of the carpeted floor and the second one is about 10 inches off of the floor.
I intend to put my VP-150 on one of the two shelves. I was thinking that, from an acoustic standpoint, it would be better to put the VP-150 on the top shelf. But, would a 9 inch difference really make any noticable difference?
I may eventually get a second VP-150 and mount it to the wall above the TV, but that is not in my near term plans.
Thoughts/ Comments?
The closer to a straight shot at the listener the better. You can angle the speaker upward and improve it if you put it on the bottom shelf, but if on the top shelf, the angle may end up being a lot less and thus not even look like it is "propped up".
As for getting a second center channel, that is usually considered a big "no, no" as the sound waves can cancel each other out or something like that. Look into it before trying it. In my first home theater, I has 2 center channels, but I had gotten a little circuit from an electronics guy at the time (this was a good 6+ years ago) that put a fraction of a second delay between the two speakers. It was quite odd, but seemed to do the trick in that the perceived sound was louder. Of course, I was doing a lot of "hacking" of my system to get a larger sound envelope around the listener. This was back when 5.1 was the only game in town and I had the electronics guy that I knew make me some boards that would "mix" various channels for me. For example, out of my 5.1 receiver, I was pushing the two center channels, the front right and left, the surround right and left, and then what I called the "front left-center and right-center" which were a mix of the center and either right or left channel into a seperate speaker for each of these new "mixed" channels, and I also mixed the two surround channels into two speakers that were at the back (today these would be similar to the 6th and 7th speakers in a 7.1 setup). So I was getting descrete 5.1, plus speakers inbetween then that were mixed with each input on a seperate volume control so that I could tweak it a little. It made for what seemed like at the time very good sound. 10 speakers, 2 subwoofers (one powered, and one passive under the seating platform), and Bass Shakers all around. By today's standards I am embarassed to even mention it.
So point of the long story is that look into the dual center channels as it may be more problems than it is worth.
Good luck!
I think Amie and Ian Colquhoun (the Axiom first family) run two VP150's - one above and one below their FP screen.
My sense, like Nick's, is that having the center channel as close as possible to both the vertical and horizontal planes of your mains is best. Having it on the bottom shelf would run some risk of reflections and reinforcement from the floor, which might not be a good thing.
But, you know, the only way to really find out about your ears in your room is to test out both scenarios.
Nickbuol and Ratpack,
Not true re using two centers and "the sound waves can cancel each other out."
When you run two center-channel speakers in parallel, connected in phase, there is no more cancellation takes place than what occurs all the time when you listen to two speakers in stereo, or 5.1 speakers in DD or dts 5.1, when any two speakers share common audio signals--and they do, all the time.
Without going into tedious acoustic detail, what cancellation occurs--it's called "comb filtering"--isn't enough to cause serious problems. If it were, exactly the same effect would occur with two stereo speakers, or any two speakers run in mono with the same signal.
Comb filtering results from interchannel crosstalk--the signal from the left front speaker reaches your left ear, then goes around your head and reaches your right ear slightly delayed by the time it takes the signal to go around your head.
Similarly, the signal from the front right-channel speaker reaches your right ear, then, a millisecond later reaches your left ear. At high very frequencies, these signals alternately cancel and reinforce each other because the wavelengths are so short. You can hear this effect by playing pink noise and sitting exactly between your two front speakers (in stereo). Move your head slightly to the left and then to the right. You will hear the high-frequency part of the signal become slightly louder then softer as you move your head laterally to the left and then to the right. Note: It's very subtle and tricky to detect but it's there and it occurs all the time as you listen to any material throught more than one speaker.
Seems like I went into tedious detail after all! But the point is, this effect is simply not audibly significant. It does not prevent our enjoyment of stereo or multi-channel playback. People who rant on about phase-coherent loudspeaker designs are simply not aware of these basics of acoustics and loudspeaker playback.
Likewise, running two center channels in some installations has real advantages in anchoring dialog and vocals firmly at the middle of the screen for large front-projection installations. If can work very well when there are placement difficulties for a single center channel speaker.
Regards,
I will be upgrading my VP100 to a VP150 due to the system moving to a larger TV and area and with the information you supplied I'm wondering if running a VP100 and a VP150 together in that scenario would pose any audio problems?
My thinking is *if* I've got an extra, can I utilize it?
Tomtuttle,
You are correct re Axiom's "first family". With really large screens and one center way above or below, the dialog may seem separated from the screen, which is why Ian installed two VP150s, running two centers in parallel. Big improvement in his particular room because the phantom center signal images virtually in the center of the screen.
I tried a number of listening tests using dual centers and it worked fine.
Incidentally, there's more to say about interchannel crosstalk. It does lessen stereo separation somewhat. Years ago, both Bob Carver ("Sonic Holography) and Matthew Polk worked variations on circuits that eliminated interchannel crosstalk; in Carver's implementation, it was installed in his preamps. Polk had a number of speaker models (I forget what fancy name he come up with) that had similar ciruits in the speakers.
The problem in both cases was that you had to sit more or less exactly on axis for the circuits to work properly. If you did, you sometimes got spectacular increases in stereo separation.
Unfortunately however, there was an annoying "phasiness" to the sound that you could hear all the time, because your ear/brain was simultaneously receiving and processing in-phase, out of phase, and special crosstalk-cancelling signals. I think it was too much for our auditory system system to sort out. The only way to avoid interchannel crosstalk is to listen on headphones. That way, each ear receives only the signals that are intended for it.
Regards,
Brotherbob,
It shouldn't pose any problems if you run the two centers--the VP150 and VP100, in parallel. The impedance would be less, so you'd want to be sure your receiver's center-channel amp would drive them OK, but other than that, you should be fine.
Regards,
Thanks Alan, that's good to know! I believe the impedance issue will be just fine with the Rotel RB-1095.
Hmmm, actually running a 6 ohm VP150 and an 8 ohm VP100 in parallel will be 3.4 ohms impedance and it looks as though the 1095 has a minimal speaker impedance of 4 ohms so I guess that wouldn't work. If I'm calculating right.
Oh well.
Thanks folks!
I'm going with my inclination and put it on the higher of the two shelves and see what happens. I suspect that I will be pleased.
Still haven't decided whether I "need" to get a new receiver or not.
Decisions, Decisions, Decisions!!!
LOL!!
Like I stated in my message, I had 2 center channels before with no problems, and that the information at the time was based off of information (from AVS) from years ago. I admitted that it was somewhat of a speculation at the time and that others would know better.
Rick, you calculated correctly(1/8+1/6=1/x, x= 3.43 ohms), but these things in reality don't have to be cut that fine and it's quite likely that what you're considering would work well.
I agree with JohnK. Try it with your Rotel. It will likely be fine, because the combined impedance curve won't remail at 3.4 ohms across the entire frequency range. Impedance curves are rarely a straight line. Impedance rises and falls with frequency.
You can't hurt your Rotel. It will either accept the load or, worst case, shut down temporarily. I doubt the latter would occur.
Regards,