8" Woofer MTM - Trainwreck?

Will a 8" woofer MTM work - without sounding like a phase shifting secret military weapon?

Not going to use boxes shown, going to mock up MDF boxes with simple port in back; maybe slot port at bottom (tuned to 50hz).
Some experience with this woofer, so thinking 40 liter box. No particular shape, stylish "tall" rectangle.

Woofer: http://www.madisoundspeakerstore.com/approx-8-woofers/silver-flute-w20rc38-08-8-wool-cone/


Tweeter: The Madisound Speaker Store

Amp(s) Rotel 990BX, have an extra so open to suggestions about active xo or something similar. A passive xo would be great, designing one is out of my league :confused:

Does anyone think this is a good idea or waste of time?

Also can anyone recommend the spacing/distance woofer to woofer?
 

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What Dave said. A 2 or 3" fullrange for a tweeter and notching baskets to get the distance minimized would be good "spacing". A 1" neo dome does drastically minimize size but can't practically go low enough unless you're planning on listening at less than a Watt. You can't get two 8's close enough to both play up to 2kHz and not make an absolute mess of everything.
 

Jay1111

Member
2013-02-14 6:16 am
AZ
I may work up to that some day wesayso....

Trip down memory lane for some (pic) sim matched MS suggestion of F3 - 60Hz in .64ft3 box. Not going much bigger, only .7ft3 each.

SF woofer is the 8" 8ohm version :eek:

Are you planning on having the drivers wired in series again like your 6.5" SF build? If so using the 4 ohm version would make more sense. If going with parallel wiring then yes the 8 ohm version is good.

The published parameters are also pretty different then what has been measured, so take that into account

ChadGray.info
 

Jay1111

Member
2013-02-14 6:16 am
AZ
My 6.5" MTM has XO near 350Hx, and we are workig on one that XOs even ower. Of course it isn't limited by using a dome tweeter.

dave


And there are plenty of very good mtm designs using standard dome tweeters crossed over much higher. Not everyone thinks FAST is great, and that 1/4 wavelength is needed. 1 wavelength of the crossover point is what is required. Does Jeff Bagby not know how to design a speaker?

My RS180 MTM Design

If ODougbo gets the drivers as tight as possible his 8" MTM will actually have tighter CTC spacing then the linked MTM, with the possibility of crossing just as low. The 8" drivers wont be as good as the 7"s off axis, but that isnt what we're discussing here...
 
notching baskets to get the distance minimized would be good "spacing"

How about butting the woofers and offsetting the tweeter? That's fairly common. I've not quite caught on to the MTM business of having the tweeter squeezed in there. I don't see the advantage, I see only compromises.
 
I've used the SF 8" 8ohm recently and have a lot of experience with the SB29RDCN that Jay1111 is mentioning. He's right, it's a freak and can cross much lower than any dome I've used. It also responds well to waveguides. AND it has the sensitivity to keep up with those woofers.

I've also used the SF woofer in a FAST configuration using a little 3" buyout tang band with active cross over.

Both methods have their compromises. If going with the dome tweeter method, careful you don't screw up the vertical and horizontal polars by crossing to high. Even at 1.5khz, you're going to get lobing and horizontal tweeter flare. With the FAST method, watch out for break up and beaming way up top.

In my experience, there isn't a single full range driver that can make treble as nice as the SB29. And in my experience, there isn't a single dome + 8" woofer that can make midrange as nice as a full range. With a lot of care, you can probably get the dome to integrate pretty darn good, but you can't fix the issues a full range brings to the show. On the other hand, getting it right is no easy task. When I paired the SF and SB29 I used a Dayton 8" waveguide and that got my XO down to 1khz. That worked out pretty good. I didn't finish the project though.