15" 2-way vs Raal MTM

[Porthos01]

I am considering a 2-way Seos15 DNA-360 horn with an 15" Acoustic Elegance TD15m (considered to be one of the best made). On the other hand I am considering a 2-way MTM with the best 6-7" woofers (Revelator, Excel, Satori, etc.) with a Raal ribbon.

I am seeking the most transparent speakers which will disappear, have amazing low level detail, an immense soundstage and do this even at a whisper. Kind of stuck in analysis paralysis.

[Pete Schumacher]

Re: 15" 2-way vs Raal MTM

I am considering a 2-way Seos15 DNA-360 horn with an 15" Acoustic Elegance TD15m (considered to be one of the best made). On the other hand I am considering a 2-way MTM with the best 6-7" woofers (Revelator, Excel, Satori, etc.) with a Raal ribbon.

I am seeking the most transparent speakers which will disappear, have amazing low level detail, an immense soundstage and do this even at a whisper. Kind of stuck in analysis paralysis.

MTM with high quality woofers and RAAL will offer better detail and more realistic delivery at whisper levels. It won't offer the dynamic slam you'll get with the big 2-way, but there won't be any comparison to the depth of detail, transparency, and disappearing act that the smaller monitor will be able to deliver.

I'd suggest a 3-way with the AE woofer, a quality high sensitivity mid like the Accuton C173 or custom Audiotechnology 7" mid, and the big RAAL ribbon. You'll get the best of what both speakers have to offer.

[Porthos01]

Re: 15" 2-way vs Raal MTM

Thank you Pete!

I do not doubt what you say but I am left craving a little knowledge here. I am trying to understand why smaller drivers excel in depth of detail, transparency, and disappearing acts? Why would any 15" low distortion motor and a cone which has to move very very little be outperformed by smaller drivers which have to move more for a given SPL which equals higher distortion? You are not the first to have written this as I have searched the forums for days seeking answers.

It seems a larger woofer is highly desirable yet for some reason the smaller ones still outperform them above a certain frequency regardless of the larger woofers distortion measurements and woofer response. Is it somehow related to the woofers decay time at higher frequencies?

As far as your recommendation of a 3-way AE, Accuton, and RAAL goes...It's my dream speaker at this moment in time yet at $300 per driver which comes to around $2000 not including cabs is a bit beyond my price range. My price range tops out at $1000 but I can stretch it a tad higher as long as I keep telling myself these are supposed to last the next 20 years. There is also the problem of very few designs for these drivers due to costs.

[Pete Schumacher]

Re: 15" 2-way vs Raal MTM

Thank you Pete!

I do not doubt what you say but I am left craving a little knowledge here. I am trying to understand why smaller drivers excel in depth of detail, transparency, and disappearing acts? Why would any 15" low distortion motor and a cone which has to move very very little be outperformed by smaller drivers which have to move more for a given SPL which equals higher distortion? You are not the first to have written this as I have searched the forums for days seeking answers.

It seems a larger woofer is highly desirable yet for some reason the smaller ones still outperform them above a certain frequency regardless of the larger woofers distortion measurements and woofer response. Is it somehow related to the woofers decay time at higher frequencies?

As far as your recommendation of a 3-way AE, Accuton, and RAAL goes...It's my dream speaker at this moment in time yet at $300 per driver which comes to around $2000 not including cabs is a bit beyond my price range. My price range tops out at $1000 but I can stretch it a tad higher as long as I keep telling myself these are supposed to last the next 20 years. There is also the problem of very few designs for these drivers due to costs.

There's little doubt that the AE15 woofer will deliver excellent lows and mids even at low levels. They are phenomenal drivers. But what delivers the imaging and spatial queues are the high frequency drivers, and there is no finer tweeter than the RAAL.

[Porthos01]

Re: 15" 2-way vs Raal MTM

In that case I will stick with a smaller stand mount speaker and possibly add a high quality sub later down the line.

- How does a MTM stack up against a TM? Hopefully nothing is lost as it appears any time a new direction in audio is taken there is a new compromise. Which will image better and disappear?
- When it comes to cone material are some better then others for very low volume detail retrieval? The main materials are paper, magnesium, kevlar, carbon fiber, aluminum, fiberglass, polypropylene, and ceramic.

From what I have been able to gather most designers focus on harmonic distortion, smoothness of response, motor distortion, and the CSD to watch for cone breakup. Unfortunately sometimes people will comment that one driver has 'sins of omission' despite equal motors and very similar IMD and THD distortion measurements. This leads me to believe that perhaps some materials are better than others for the goal of low level details.

Should I just for the lightest and most rigid cone that has a good CSD and low distortion and ignore softer materials? Is paper capable of being just as resolving as lets say a magnesium or ceramic driver? This is of course assuming all else being equal quality (motor strength, Le, cost no object, etc.)

[Pete Schumacher]

Re: 15" 2-way vs Raal MTM

In that case I will stick with a smaller stand mount speaker and possibly add a high quality sub later down the line.

- How does a MTM stack up against a TM? Hopefully nothing is lost as it appears any time a new direction in audio is taken there is a new compromise. Which will image better and disappear?
- When it comes to cone material are some better then others for very low volume detail retrieval? The main materials are paper, magnesium, kevlar, carbon fiber, aluminum, fiberglass, polypropylene, and ceramic.

From what I have been able to gather most designers focus on harmonic distortion, smoothness of response, motor distortion, and the CSD to watch for cone breakup. Unfortunately sometimes people will comment that one driver has 'sins of omission' despite equal motors and very similar IMD and THD distortion measurements. This leads me to believe that perhaps some materials are better than others for the goal of low level details.

Should I just for the lightest and most rigid cone that has a good CSD and low distortion and ignore softer materials? Is paper capable of being just as resolving as lets say a magnesium or ceramic driver? This is of course assuming all else being equal quality (motor strength, Le, cost no object, etc.)

I've heard great drivers with a variety of materials. Scan Revelators use slit paper cones and achieve great linearity of response with excellent non-linear distortion performance. SEAS Excels use magnesium cones to similar effect at the expense of breakup modes higher up. Accuton uses ceramic cones with similar issues up high. Audiotech uses slightly softer cones for ultra smooth response and their motors are very linear. All these drivers can produce that "next level" of transparency you're after.

Between MTM and TM, consider putting the money you'd spend on two woofers and just upgrade to a better and slightly larger single driver, especially since you're contemplating adding a sub in the future.

Consider a two-way using the AT C-Quenze 18H and the big RAAL ribbon. You'll get decent bass response while waiting to complete your sub.

[PunkSweeper]

Re: 15" 2-way vs Raal MTM

Needs more raal tags

[Porthos01]

Re: 15" 2-way vs Raal MTM

I know all of these are seriously top notch drivers and for many it goes down to preference or looks. I have a particular goal in mind though. Ruthlessly revealing (even of electronics in the chain), completely disappears, very low volume soundstage are desired. Any thoughts on these?

AT C-Quenze 18H Polypropylene At Pete's recommendation I am really considering this model. The manufacturers pricelist has a MSRP of $350. Unfortunately the only supplier I can find in North America is Solen.ca which only stocks 7 Audio Technology models and their cheapest model is $598:eek:

Accuton Ceramic 6.5" woofers range from $310 to $350. Very stiff cones but their ferrite models seem to have high Le. I am not familiar with motor design though. Might not be an issue at all. Some time ago Pete attempted a group buy but not sure what became of it or if another will ever occur.

Aurum Cantus Carbon Fiber I really like woven carbon fiber cones for their velocity. The ability to address twin peaks in the crossover is a concern. Also, woofer performance ranges from excellent to just mediocre based on which model.

Usher Carbon fiber/Paper The 8945P looks absolutely phenomenal although I cannot find any other retailer for Usher other than Parts-express. Sadly it seems they took it out of stock long ago for some reason :(

Dayton Esoteric Nomex/Glass Fiber Seems to be well built. Low sensitivity though.

SB Acoustics Satori Paper/Papyrus reed Seems to be well thought of and with a good motor. Jeff Bagby seems to have made the MT Auricle, MTM Empires, and TMM Testarossa with this woofer and a RAAL. Unfortunately I can't find the kits anywhere.

Morel Carbon Fiber or Poly Their Supreme series or the Titanium TiCW 638Nd looks good.

Acoustic Elegance Paper Excellent motor designs. Cost should be on par with most Morel, Accuton, or Audio Technology woofers. Last group buy seems to have been a few years ago.

[chrisn]

Re: 15" 2-way vs Raal MTM

http://meniscusaudio.com/seas-w18ex001-p-528.html I preferred that over the Usher 8945P, although the Usher is still a good choice if you can find them. PE still carries the Usher 8945a and 8948A

[Jeff B.]

Re: 15" 2-way vs Raal MTM

I know all of these are seriously top notch drivers and for many it goes down to preference or looks. I have a particular goal in mind though. Ruthlessly revealing (even of electronics in the chain), completely disappears, very low volume soundstage are desired. Any thoughts on these?

AT C-Quenze 18H Polypropylene At Pete's recommendation I am really considering this model. The manufacturers pricelist has a MSRP of $350. Unfortunately the only supplier I can find in North America is Solen.ca which only stocks 7 Audio Technology models and their cheapest model is $598:eek:

Accuton Ceramic 6.5" woofers range from $310 to $350. Very stiff cones but their ferrite models seem to have high Le. I am not familiar with motor design though. Might not be an issue at all. Some time ago Pete attempted a group buy but not sure what became of it or if another will ever occur.

Aurum Cantus Carbon Fiber I really like woven carbon fiber cones for their velocity. The ability to address twin peaks in the crossover is a concern. Also, woofer performance ranges from excellent to just mediocre based on which model.

Usher Carbon fiber/Paper The 8945P looks absolutely phenomenal although I cannot find any other retailer for Usher other than Parts-express. Sadly it seems they took it out of stock long ago for some reason :(

Dayton Esoteric Nomex/Glass Fiber Seems to be well built. Low sensitivity though.

SB Acoustics Satori Paper/Papyrus reed Seems to be well thought of and with a good motor. Jeff Bagby seems to have made the MT Auricle, MTM Empires, and TMM Testarossa with this woofer and a RAAL. Unfortunately I can't find the kits anywhere.

Morel Carbon Fiber or Poly Their Supreme series or the Titanium TiCW 638Nd looks good.

Acoustic Elegance Paper Excellent motor designs. Cost should be on par with most Morel, Accuton, or Audio Technology woofers. Last group buy seems to have been a few years ago.

The RAAL kits that I did with the Satori woofer are available through Meniscus Audio. There is no webpage at this time, you need to call Meniscus direct for pricing and information.

I believe the AT woofers can be purchased directly through Audio Technology.

No all of the woofers you list have motor designs on the same level. there is a big difference in motor quality and distortion between no shorting rings, shorting rings, and copper sleeves in the motor. Cone material is really secondary to motor design.

[Easylistener]

Re: 15" 2-way vs Raal MTM

I know all of these are seriously top notch drivers and for many it goes down to preference or looks. I have a particular goal in mind though. Ruthlessly revealing (even of electronics in the chain), completely disappears, very low volume soundstage are desired. Any thoughts on these?

AT C-Quenze 18H Polypropylene At Pete's recommendation I am really considering this model. The manufacturers pricelist has a MSRP of $350. Unfortunately the only supplier I can find in North America is Solen.ca which only stocks 7 Audio Technology models and their cheapest model is $598:eek:

Accuton Ceramic 6.5" woofers range from $310 to $350. Very stiff cones but their ferrite models seem to have high Le. I am not familiar with motor design though. Might not be an issue at all. Some time ago Pete attempted a group buy but not sure what became of it or if another will ever occur.

Aurum Cantus Carbon Fiber I really like woven carbon fiber cones for their velocity. The ability to address twin peaks in the crossover is a concern. Also, woofer performance ranges from excellent to just mediocre based on which model.

Usher Carbon fiber/Paper The 8945P looks absolutely phenomenal although I cannot find any other retailer for Usher other than Parts-express. Sadly it seems they took it out of stock long ago for some reason :(

Dayton Esoteric Nomex/Glass Fiber Seems to be well built. Low sensitivity though.

SB Acoustics Satori Paper/Papyrus reed Seems to be well thought of and with a good motor. Jeff Bagby seems to have made the MT Auricle, MTM Empires, and TMM Testarossa with this woofer and a RAAL. Unfortunately I can't find the kits anywhere.

Morel Carbon Fiber or Poly Their Supreme series or the Titanium TiCW 638Nd looks good.

Acoustic Elegance Paper Excellent motor designs. Cost should be on par with most Morel, Accuton, or Audio Technology woofers. Last group buy seems to have been a few years ago.

Pete;
I am not any sort of expert but about 8 years ago I was on a similar quest. I wanted to design from scratch and build the most transparent speakers I could for under $1000. I decided a two way crossover would be best/easier and more cost effective than 3 way. In the interest of minimizing distortion and providing good clear mid range I decided to go with the Focal 5W 4252. This small mid-woofer used Focal's sandwich cone construction I believe it was an Aerogel/Kevlar combination. I went with a transmission line design for extended base and I used the Focal TC 90 TD5 B inverted dome tweeter. The woofer has an electrical damping of around 0.300 giving it an excellent attack and decay characteristic for cleaner base. I used True Audio's TrueRTA software for optimizing the crossover and insulation fill of the transmission line. Also experimented with woofer baffle placement. Bottom line nice flat response with base extension down to about 30 hz. Plenty of volume for my open concept living area.

I bought my drivers from Zalytron and cross-over components from Solen (Quebec).

[cptomes]

Re: 15" 2-way vs Raal MTM

...

I am trying to understand why smaller drivers excel in depth of detail, transparency, and disappearing acts? Why would any 15" low distortion motor and a cone which has to move very very little be outperformed by smaller drivers which have to move more for a given SPL which equals higher distortion? You are not the first to have written this as I have searched the forums for days seeking answers.

It seems a larger woofer is highly desirable yet for some reason the smaller ones still outperform them above a certain frequency regardless of the larger woofers distortion measurements and woofer response. Is it somehow related to the woofers decay time at higher frequencies?

...

Because unless you're in the nearfield of the speakers and are in a fairly well damped or large room, the off axis response of the drivers and how it reflects around the room will contribute significantly to how you perceive the sound.

As the wavelength of sound produced by the speaker approaches twice the diameter of the cone, you're going to get very significant off axis nulls and lobes that change in shape depending on frequency. Simply put at lower frequencies the sound radiates in a near perfect sphere, with spl 180 degrees behind the speaker marginally lower than directly in front. At higher frequencies it beams out of the cone like a wide flashlight beam. In between those extremes, weird things happen.

For a 2 way crossed at call it 2000Hz the wavelength will be 1100/2000 ft call it .55 ft or ~6 inches. A 15" driver is more than double that diameter, so at crossover the tweeter will be radiating close to a hemisphere from the baffle and the woofer is going to be beaming like a flashlight.

Linkwitz has an interesting set of web pages, with lots of well thought out discussion of spatial cues, loudspeaker response, and room issues.

http://www.linkwitzlab.com/frontiers_6.htm about halfway down, section Z.

This completely ignores cone breakup and any other nonlinear distortion from the drivers. Which you will definitely see from any lightweight 15" cone.

[natehansen66]

Re: 15" 2-way vs Raal MTM

cptomes - I don't see anyone thinking about or suggesting a 15 be used up to 2khz.

[rkeman]

Re: 15" 2-way vs Raal MTM

[QUOTE=Porthos01;2097655]In that case I will stick with a smaller stand mount speaker and possibly add a high quality sub later down the line.

- How does a MTM stack up against a TM? Hopefully nothing is lost as it appears any time a new direction in audio is taken there is a new compromise. Which will image better and disappear?

Imaging is a function of room acoustics and the loudspeakers. Listening room acoustics can and should be addressed with appropriate use of absorption, diffusion and thoughtful positioning of the source and listener. The loudspeaker should be chosen to take full advantage of the room's acoustic strengths and minimize its weaknesses. What is the size and layout of the listening room?

[badman]

Re: 15" 2-way vs Raal MTM

cptomes - I don't see anyone thinking about or suggesting a 15 be used up to 2khz.

There's not an insurmountable issue with doing this- but it takes a very special 15" to manage it. I use the BD Designs BD15, which is a coated paper cone on a soft suspension with an underhung neo motor, and it's comfortable that high (though beaming pretty badly), and might be appropriate in some systems to match to a narrow directivity horn, if a laserbeam treble is preferred. A handful of other 15"s are comfortable that high, the TD15M is probably one of them.