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Helix Dome MTM or Apollo MTM for center

3K views 9 replies 5 participants last post by  bear123 
#1 · (Edited)
I recently built a Fusion 8 MTM center channel and was very happy with it in my living room, but my TV died and I upgraded to a larger display. The Fusion 8 center will no longer fit :(:(:( and there is no realistic and feasible way to use it now due to the constraints of my room. Yes, anything is technically possible but I am unwilling to place the center channel on a stand in front of my fireplace which is the only way that it would now technically be possible. So within the constraints of placing the center channel on top of the mantle under the TV(which is mounted as high as physically possible), I need the center channel to be slightly under 8" high. This rules out *a lot* of options and there is nothing currently available from DIYSG with a horn loaded compression driver that will work.

So I am strongly considering the Helix Dome MTM which is 4 ohm and 91 dB with 7" woofs but 9.5" high. However, it looks like I could trim 3/4-1" off both sides to get the width down to 7.75-8" which would be perfect, and simply make the cab a bit deeper or wider to compensate. The Apollo has the exact same dimensions and is a 4 ohm 88 dB speaker.

They both use different tweeters, and the Apollo woofers seem like they have lower extension capability and higher excursion, but this does not necessarily make it a better option IMO as I will cross at 80 Hz. I am wondering if the Helix would actually be better as perhaps the woofers are higher sensitivity and would do mid and upper bass better than the Apollo. I need to look up the tweeters I suppose as well to check on sensitivity and power handling.

So I suppose I'm looking for advice or suggestions on these two solutions, and possibly opinions on the comparative ability between the two designs with the main focus being home theater capability.

The idea is that either of these options will be a much better speaker than the Hsu HC1 center channel I am temporarily using. I have DISYG HTM-8's for L/R.
 
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#3 ·
I prefer to use a center channel. I'm leaning towards the Helix Domes for the 91 dB sensitivity over the Apollo with 88, especially since I don't have an external amp. I think I have enough power to fully drive the Helix with my AVR but probably not the Apollo. The Denon X3300 puts out pretty good power into 4 ohms but nowhere near the 250 the Apollo will take. Might have to start saving for the D-sonic 3 channel :D

Do you have one of the Apollo/Helix designs? Thoughts on them if so?
 
#8 · (Edited)
With 8" woofers, I don't think I could get this to fit under my screen. 7.75-8" is max that will fit. As far as why it might not be as popular for those that can fit it, a comparable horn loaded compression driver design will have higher sensitivity. My Fusion 8 MTM center is 98.5 dB vs 93 for the Cobalt. I assume this is due to the tweeter. 93 dB is really good though for folks that don't have a huge room and maybe want the wider dispersion of a dome tweeter. Also the closer woofer spacing should have better off axis response than the Fusion 8 or any two way with a wide waveguide that spreads the woofer spacing out more. The Fusion 8 waveguide is not as wide as the SEOS and my off axis response across my sectional was really good, so apparently still within a narrow enough angle to still have a nice response.

I have another idea for my center channel but not sure yet if it will pan out.
 
#10 ·
Quad 6.5" drivers, horn loaded compression driver, 2.5 way design(frequencies limited on one pair of woofers to improve off axis response), 99+ dB sensitive, 7.5-8" high, 10-12" deep, as wide as it needs to be, 36" or whatever since most TV's are over 4 feet wide now. Front ported with ports on the ends. So basically a DIY Klipsch RC 64 III but better and much cheaper. I think the demand would be very good for a center channel under 8" high with the capability of a much taller dual 10" woofer center channel, or close to it that folks could put in their living rooms. Love love loved my Fusion 8 center channel but I just can't fit it now. It's up for grabs if I can let myself part with it.
 
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