Here is one negative comment:
I am sorry to hear of the troubles but, frankly, the HTM61 is not a promising
design, simply judged from the published information and pictures. It is one of
a myriad of so-called dedicated center speakers that have been offered to
(foisted on) the uninformed who think that a horizontal array in a horizontal
box is acoustically correct for this application (or any other).
The ideal center is designed pretty much on the same principles as any other
speaker, so three identical floor-standers or bookshelf speakers is fine.
Unfortunately, the public seems to think that horizontal arrays are correct when
they are merely accommodations to convenience and visual aesthetics.
"Music in the Round"
Contributing Editor, Stereophile
and here is the relevant part from the Norton review in Ultimate AV Mag:
The problem was the HTM61 center channel speaker. Despite the pedigree offered by its FST midrange, it blended poorly with the left and right 683s. Its sound was thicker, duller, and less opena characteristic that was different depending on whether I was seated on-axis or off to the left or right by about 30-degrees (it was also different in the two directions). This not only reduced dialog intelligibility but also significantly reduced the "jump factor" of the whole system in full surround mode. Yes, the HTM61 was stand mounted below the screen, which placed it less than two feet from the floor/ But that position has worked well with innumerable center channel designs that have lived there before.
What the measurements will show remains to be seen, but a few basic in-room measurements indicated nothing obviously defective about our sample of the HTM61.
When I substituted the similarly priced Revel Concerta C12 for the HTM61 the soundstage and clarity opened up considerably. In fact I lived with that setup for a couple of weeks as I reviewed other gear and movies on the system.
But that setup was hardly appropriate for this review. So when I got down to serious business I tried something else. The vital front channels and the subwoofer, of course, had to be all B&W. So I pulled one of the 685s from surround duty and pressed it into service as a center channel.
There are, of course, downsides to using a small bookshelf speaker as a center channel. When positioned upright (the only way I recommend), such a speaker could look awkward when sitting atop a big-screen TV. But with today's more compact digital displays, it could be easily positioned on a real bookshelf above or below the screen. A little creativity in this area, such as surrounding the speaker with booksadmittedly a novel idea for a bookcase these daysshould make it acceptable to the interior decorator in the family, as well as minimize the adverse affects of shelf mounting. (This sort of speaker nearly always sounds best when located well away from surrounding walls and on stands that place the tweeter at or near ear height.)
If a 685 is mounted above the screen and you can't tilt it toward the viewing area, try positioning it either tweeter up or tweeter down to find the best-sounding option. Just don't mount it horizontally!
Speakers such as the 685 are also generally sold in pairs. If you use a 685 as a center, that will leave you with a single, an odd man out speaker. If your dealer won't sell you just one (unlikely, since the speaker is not only sold in pairs, but also packed that way), and you can't find an audiophile friend who is considering the same system, you could use the extra 685 for a center surround if your receiver allows for a 6.1-channel option (most do).
While not intended as a center channel speaker, the 685 performed the job remarkably well. Apart from a slightly more pronounced top end directly on axis, common to nearly all speakers, its balance was consistently good across a seating area approximately 30-degrees on either side of centerand respectable even beyond that. Since it was mounted relatively close to the floor, I used the provided foam plug to fill half of the port (filling it completely leaned out the balance too much for me, but your mileage may vary). In this configuration, well-recorded voices were consistently natural-sounding.
The 685 kept up with the most action-heavy soundtracks. Crossed over at 80Hz, I heard no obvious distortion or overloading from it even in the heavy metal chaos of Transformers played back at theater-like levels in my 3200 cubic foot room.