[DMurphy]

Hi   I'll let Jim handle any questions about what other approaches to the center channel issue we might be considering.  But as to your question about different sizes of W18's, I'm not quite sure what your concern is.  The off-axis dip is not primarily related to the size of the woofer.  It's the crossover frequency.  Although it does help to get the woofer centers closer together, and that's will happen with a smaller woofer, dropping down to, say, a 5" woofer won't solve it and will sacrifice power handling.  I have a plot of the Dynaudio Gemini MTM (two 5" woofers) with the mic placed about two feet above the speaker and maybe a meter back.  I'm guessing that's something like 40 degrees off axis, and shows what you would hear if you flipped the Gemini on its side and moved the mic off axis horizontally by that amount.   The plot is at the bottom of this page:  http://murphyblaster.com/content.php?f=gem_mod.html

[Fatawan]

Dennis:

In regards to different size W18's--it was my offhanded way of asking if you could make a 3-way design with a bigger woofer, smaller midrange, and the G2.

I like that graph, and won't be trying that at home! Although, in essence, many are doing just that with MTM configurations. I think I have couch viewing positions that would be easily 40 degrees off center.  I don't want this to happen to me!

[Fatawan]

Marbles:

How many degrees off center do you think that would be?  Graphs say alot, but they really don't tell me how things would sound(although I am certain the speaker depicted in Dennis' graph would not sound right at that position). This is an interesting discussion--I hope some good comes of it.

[DMurphy]

My guess is that at a normal viewing distance, 40-45 degrees off axis would be pretty extreme.  I think I've shown a worst cast scenario.  And even then, you might be surprised at how pleasant the Gemini sounds from that standing position.  I remember that at the DIY event in Iowa a couple of years ago, the top speaker in the medium $ class had the tweeter connected with the wrong polarity.  That produces a sharp null at the crossover frequency, not too unlike the null from the off-axis cancellation modes for an MTM.  I'm pretty familiar with the sound of a reversed tweeter, since the "reverse null" is often used as part of the design process.  After the event, I managed to get the winning speaker measured because I was pretty sure there was a polarity issue.  Depending on the program material, the ear can process that kind of dip as a feeling of spaciousness and relaxation.  But it isn't right, and sooner or later the loss in midrange presence will bug you.

[jsalk]

Two topics:

First, ask and you shall eventually receive.  Here is a computer-simulated plot of the HT3 low-end response based on the TC driver and the cabinet tuning...



Second, I normally never discuss potential future projects for two reasons.  First, I do not want to appear as if I am trying to generate advance interest in the speaker design that doesn't even exist.  Second, there is no guarantee that a given design, while great on paper, will result in a great speaker.  So I always think it is best to keep projects under wraps until they are fully developed.

That said, since there have been a number of questions here, I thought it might be appropriate to discuss our current thining on the center channel front.  

There are presently two new designs under active consideration.  The first is a center channel that will mate with the new V3 3-way.  Test drivers are already on the way.  The second is a high-end Veracity-series center channel.  Today I had a lengthy discussion with TC Sounds and they are in the process of designing a new woofer for this project.  They should have test samples in the next two weeks or so.

Both of these proposed designs will be 3-way center channels.  However, due to their size, both will be limited in terms of their application.  

The V-series center will be the smaller of the two, but still rather large.  As proposed, it will share the LCY tweeter and 4" Visaton midrange currently used in the V3, and will couple them with a pair of 6.5" Visaton woofers.  Even though it will be the smaller of the two new center channels, it will be considerably larger than the current Veracity HTC.

The new Veracity center channel will be even larger - a monster center channel as it were.  It is not intedned to replace the current HTC, but rather provide an alternative in certain situations. As envisioned, it would be the equal of the HT3 in every respect, but in a form factor that is more workable in most front-projected home theater applications.

While the drivers have not been finalized, my current best guess is a G2 tweeter, W18 midrange and a pair of 8" TC Sounds woofers.  

Both of these speakers are intended primarily for front projected home theater applications as they are most likely too large for most other applications.  (You certainly would not want to place the Veracity monster center on top of a conventional television - although the television may sit on top of it nicely).

Keep in mind that these designs are only in the early development stage and may never materialize for one reason or another.

The best set-up we can currently build is three HT3's across the front, two more in the rear and perhaps a pair of 18" subwoofers to plumb the depths.  But this is not practical in most cases.  While the HT1 is a very good option for a center channel, it is also limited in terms of its application. The fact remains that for most non-front projected systems, the current HTC is still the most appropriate option.  

If we didn't have good track record with it, we would certainly not offer it.  It is the center channel I use in my own home theater (front projector) and I'm personally very happy with it.  And those customers who own it seem to be very pleased with its performance as well.  

Granted, it is well documented that horizontal MTM center channels are not necessarily ideal.  But no speaker is perfect.  Speaker design is all about effectively managing trade-offs, some of which are dictated by the application.  Practical situations often dicatate the use of MTM center channels. Many people simply do not have a choice.  

Horizontal MTM center channels do remain the most appropriate option in many situations.  And if, in those situations, they provide a thoroughly enjoyable HT experience, is there really a major issue?  Charts, graphs and technical disertations are certainly interesting.  But in the end, it comes down to the experience.  If the speakers provide a thoroughly positive and enjoyable HT experience, then they serve their purpose.

In the couple of years since we began producing HTC center channels, we have yet to receive even one minor complaint with their performance.  To the contrary, HTC owners seem to be very happy with the speaker's performance.  And in the end, that is what really counts.

Those are my current thoughts on the center channel front (subject to change of course).  Your milege may vary.

- Jim

[Fatawan]

Thanks Jim for a very enlightening response. I am scheming now about TV placement(maybe pop it up on the wall?) to fit another HT1 in underneath. Or maybe I should wait for that Veracity Monstrosity, and, like you said, put my TV right on top and get HT3's for the front right and left....or maybe 2 HT1's, with their excellent off-axis response, would be enough for my room.....or 2 HT3's...or....or.....

I appreciate the look at what might be coming.

Take care.

[ctviggen]

[cut]
Both of these speakers are intended primarily for front projected home theater applications as they are most likely too large for most other applications.  (You certainly would not want to place the Veracity monster center on top of a conventional television - although the television may sit on top of it nicely).
[cut]
- Jim

This depends on what kind of TV you have.  I have a RPTV (ancient technology, I know), Pioneer Elite, and matching stand.  This is a very heavy (330 pounds), well built TV.  It could easily support a large center channel.  However, my TV is -- as already noted -- ancient (in the electronic world), and I think most TVs these days are too thin to support a center channel.

What are your thoughts on large, horizontally mounted center channel speakers?  I'm wondering about whether the line source aspects of a large center channel will draw attention to the speaker, as opposed to having the center channel be vertically mounted and more of a point source.  Does a large, horizontally mounted center channel speaker help or hinder the center channel "imaging"?

[jsalk]

ctviggen -

What are your thoughts on large, horizontally mounted center channel speakers?  I'm wondering about whether the line source aspects of a large center channel will draw attention to the speaker, as opposed to having the center channel be vertically mounted and more of a point source.  Does a large, horizontally mounted center channel speaker help or hinder the center channel "imaging"?

If you are talking about one of these proposed new designs, we can only speculate at this time.  But they would definitely be point source designs.  Think of it this way.

If we built a sealed HT1 (which we have successfully done in the past), the midrange and top end performance would be virtually identical to a normal ported HT1.  These speakers image very well.  The sealed version of the HT1 is 15" tall (9" wide) and the only drawback is in the area of bass extension.  This lack of bass extension is not a problem in the proposed center channel since we will cross to woofers at a frequency higher than the natural roll-off of a sealed HT1.  

Now, to either side of this sealed HT1, let's add a cabinet section with an 8" TC Sounds woofer (being developed).  In terms of the performance of the sealed HT1 portion of this speaker, all we have done is to widen the effective front baffle.  

Since the woofers are crossed low, any lobing caused by the interaction of the dual woofers will be well out of the critical midrange/top end of the speaker.  And since human hearing is generally less sensitive to volume differences at low frequencies, any lobing should be even less detectable to the point of being a complete non-issue.

Since we are using dual 8" woofers, the air-moving bass performance of this proposed center channel should be as good as the bass performance of the current HT3.  We just end up with a very large center channel - a minimum of 15" tall, perhaps as deep and maybe 40+" wide (although this is purely speculative as we cannot model it until the driver parameters are known).  It would be  roughly equivalent to an HT3 placed on its side and probably weigh in at 120 pounds.

Keep in mind that this is all purely theoretical at this point.  There are other technical issues that all need to fall in place for this to be a successful design.  But, in theory, this center channel design should be equivalent to using a standard HT3 as a center channel with the added flexibility of a horizontal format.

I hope all this makes sense.

- Jim

 

[DMurphy]

I would only add that I have had almost no experience with center channels.  I just got my HT system set up, and have it running in phantom mode.  So I certainly can't claim that MTM's don't provide perfectly satisfactory results for the large majority of listeners.  My current music listening speakers in my living room are (vertical) MTM's.  I spend a good bit of time listening while standing up (I run around a lot at night) and they sound fine unless you get very close to them.  So, as Jim says, it's what you really hear from where you really are that matters.  And my guess is that for HT set ups, the listening angles aren't extreme enough to introduce serious problems