6.5" vs 5.25" in MTM

augerpro · 20th November 2006, 03:32 AM

Hi everyone. I need some advice. If I were to build a 3way MTMWW or MTMW what would be the tradeoffs of using 6.5" or 5.25" as the mid?

This speaker will be used for 2ch music and HT, sometimes at higher volumes, thus the multiple drivers. I've been reading some of Dr. Floyd O'tool's (sp?) findings concerning power response and it's effect on SQ, and some of the drawbacks concerning the MTM layout and it's off axis lobing around the wavelength between the mids' acoustic centers. Smooth power response and minimal cancellation between mids will be a design goal with these. Given that, I decided to use 5.25" for better HF off axis dispersion and the ability to have closer acoustical centers, minimizing off axis lobing.

So what am I losing by going this route? Low distortion even at higher volumes is important to me. Obviously the 6.5" would keep distortion lower at any given SPL. I assume power compression would be lessened at any given SPL with the larger woofer. So what else should I consider?

sreten · 20th November 2006, 12:54 PM

Hi,

MTM 3 ways don't make any sense to me at all.
2 ways do, but for 3 ways why have two mid drivers ?

/sreten.

croat47 · 20th November 2006, 01:13 PM

Sreten...could you clarify that? It looks like he may be using a woofer for the low end, making it a three way. If one were to use a larger driver for say...under 100Hz, then why not do an MTM with an additional woofer? Efficiency might be an issue depending on the drivers, but couldn't that be offset by multi-amping...or attenuating the mids (if you had to)?

sreten · 20th November 2006, 04:17 PM

Quote:

Originally posted by croat47
Sreten...could you clarify that? It looks like he may be using a woofer for the low end, making it a three way. If one were to use a larger driver for say...under 100Hz, then why not do an MTM with an additional woofer? Efficiency might be an issue depending on the drivers, but couldn't that be offset by multi-amping...or attenuating the mids (if you had to)?

Hi,

MTM(+nxW) versus TM(+nxW), two mids does not make sense to me.

One high quality midrange is the way to go.

/sreten.

croat47 · 20th November 2006, 04:35 PM

I understand that it does not float your boat: why? Is it cost? the MTM lobe pattern? Efficiency mismatches? Aesthetics?

Why not build MTMW where the W was below 100Hz or so? The MTM may be used because the designer/listener wanted the response of an MTM with some low end support but did not want multiple enclosures?

You have helped me before with technical help, but this seems to be more of an opinion than a technical arguement. I am curious from a technical standpoint.

sreten · 20th November 2006, 05:07 PM

Hi,

MTM + (W below 100Hz) is technically a 2-way MTM + sub.

/sreten.

croat47 · 20th November 2006, 05:43 PM

It's a semantics problem? I've been asking the technical basis of your opinion because I like the idea of the original post. All you've provided is further opinion based on your working definition.

If I were to talk about an MT setup with separate subs...that would be a 2-way plus subs. It's still a 2-way if I make the MT and integrate stereo subs into the same unit as the MT? Am I wrong when I say "3-way" to indicate that all three driver types are in the same unit?

What is the definition of a 2-way? a 3-way? Would the W have to come in at 250Hz to be a 3-way? In the end, why don't we just call everything 1-ways, plus T and/or plus W? Don't "full range" 3-ways go below 100Hz?

planet10 · 20th November 2006, 06:32 PM

An MTM -- unless using quite small drivers) forces the XO to the tweeter to be lower than i find optimal....

dave

croat47 · 20th November 2006, 06:54 PM

How small is "quite small"?

I have seen other debates about MTM's, so I will not delve too deeply.

Andy G · 20th November 2006, 07:42 PM

Quote:

Originally posted by planet10
An MTM -- unless using quite small drivers) forces the XO to the tweeter to be lower than i find optimal....

dave

Dave , if you have the tweeter positioned at ear level, and are listening to music rather than jumping all over the room, then lobing and combing isn't an issue, and the x-o is not forced to be low.

For music listening I really like the MTM with a first order series, so regardless of theoretical issues you can cross higher than normal dictates.

Others have heard this style of speaker, read reply #16 on this link.
http://www.audiocircle.com/circles/i...topic=29980.10

20th November 2006, 01:13 PM	#3
croat47 diyAudio Member Join Date: May 2005 Location: Eastern Shore, Maryland	Sreten...could you clarify that? It looks like he may be using a woofer for the low end, making it a three way. If one were to use a larger driver for say...under 100Hz, then why not do an MTM with an additional woofer? Efficiency might be an issue depending on the drivers, but couldn't that be offset by multi-amping...or attenuating the mids (if you had to)? __________________ Regards, Aaron

20th November 2006, 04:35 PM	#5
croat47 diyAudio Member Join Date: May 2005 Location: Eastern Shore, Maryland	I understand that it does not float your boat: why? Is it cost? the MTM lobe pattern? Efficiency mismatches? Aesthetics? Why not build MTMW where the W was below 100Hz or so? The MTM may be used because the designer/listener wanted the response of an MTM with some low end support but did not want multiple enclosures? You have helped me before with technical help, but this seems to be more of an opinion than a technical arguement. I am curious from a technical standpoint. __________________ Regards, Aaron

20th November 2006, 05:43 PM	#7
croat47 diyAudio Member Join Date: May 2005 Location: Eastern Shore, Maryland	It's a semantics problem? I've been asking the technical basis of your opinion because I like the idea of the original post. All you've provided is further opinion based on your working definition. If I were to talk about an MT setup with separate subs...that would be a 2-way plus subs. It's still a 2-way if I make the MT and integrate stereo subs into the same unit as the MT? Am I wrong when I say "3-way" to indicate that all three driver types are in the same unit? What is the definition of a 2-way? a 3-way? Would the W have to come in at 250Hz to be a 3-way? In the end, why don't we just call everything 1-ways, plus T and/or plus W? Don't "full range" 3-ways go below 100Hz? __________________ Regards, Aaron

20th November 2006, 06:32 PM	#8
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	An MTM -- unless using quite small drivers) forces the XO to the tweeter to be lower than i find optimal.... dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

20th November 2006, 06:54 PM	#9
croat47 diyAudio Member Join Date: May 2005 Location: Eastern Shore, Maryland	How small is "quite small"? I have seen other debates about MTM's, so I will not delve too deeply. __________________ Regards, Aaron


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20th November 2006, 03:32 AM	#1
augerpro diyAudio Member Join Date: Aug 2006	6.5" vs 5.25" in MTM Hi everyone. I need some advice. If I were to build a 3way MTMWW or MTMW what would be the tradeoffs of using 6.5" or 5.25" as the mid? This speaker will be used for 2ch music and HT, sometimes at higher volumes, thus the multiple drivers. I've been reading some of Dr. Floyd O'tool's (sp?) findings concerning power response and it's effect on SQ, and some of the drawbacks concerning the MTM layout and it's off axis lobing around the wavelength between the mids' acoustic centers. Smooth power response and minimal cancellation between mids will be a design goal with these. Given that, I decided to use 5.25" for better HF off axis dispersion and the ability to have closer acoustical centers, minimizing off axis lobing. So what am I losing by going this route? Low distortion even at higher volumes is important to me. Obviously the 6.5" would keep distortion lower at any given SPL. I assume power compression would be lessened at any given SPL with the larger woofer. So what else should I consider?

20th November 2006, 12:54 PM	#2
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, MTM 3 ways don't make any sense to me at all. 2 ways do, but for 3 ways why have two mid drivers ? /sreten.

20th November 2006, 05:07 PM	#6
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, MTM + (W below 100Hz) is technically a 2-way MTM + sub. /sreten.

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