[mresseguie]

Hello. I've been thinking about speakers lately - okay, I always think about speakers. Lately though, MTM speakers have been on my mind. Many manufacturers produce MTM speakers using 5", 6", 6.5", and even 7" midwoofers. I've even seen 8" MTMs, but they are much less common.

Now what is all this about? Well, I'm hoping to further my education with input from you, dear reader. What are the goals any given manufacturer seeks by using these different sized midwoofers? I can make a few guesses - smaller midwoofers reduce driver costs and allow for smaller and less expensive cabinets. Additionally, smaller drivers will (may??) produce better midrange. Larger drivers produce deeper bass. Are there disadvantages to using larger midwoofer drivers?

So without my creating too many rules for this discussion, what are your thoughts on the different sized midwoofers in MTM speakers?

After some input, I'll clue you into what has captured my imagination recently. 

[S Clark]

Usually true---The smaller driver is faster, depending on which other compromises the manufacturer decided upon.  The larger driver can play deeper, but with more mass and related speed issues. 

Now, all this can be turned on its head.  A line source speaker with 6" drivers can play into the mid 20 hz range with plenty of volume... if you have a dozen splitting the work.  A large driver can play with incredible speed, detail, and volume.... with a huge magnet or with servo controls.  Bose made a reputation by modifying the signal going to a bunch of 4" drivers playing full range and actually getting pretty deep bass from them- not that they sounded especially good doing it.
So it isn't quite as straight forward as it might seem.  Things usually are that way in our hobby. 
I'd say that in a MTM, somewhere around a 5 1/2" driver has decent abilities to have reasonable bass and still be fast enough to have detailed mids.

[iluzun]

I'll simply add a 'for instance'....  Currently listening to a pr. of Castle Conway IIIs, fed by a Prologue II w/ some Mullard el34s and a Modwright Transporter w/Mullard gz32 and a pr. of oval black glass 6sn7s.  The Conways have two carbon fiber mids and a large 28mm silk dome tweet.  I've 1SCs and LS50s in the room but am looking for a nice 3 way.  The room is large, and a Naim dealer once called it 'dead', but currently the Castles r filling it nicely with a vernieuwd play list.  Everything sounds warm and detailed.  Both male and female vocals are very nice, the mids are so inviting.  Just about perfect, though I'd love to try an integrated 845 set amp.  There is always another green pasture in this hobby, no?  Anyways after looking at builds and searching up three ways all month I have to say that this MTM is really filling the bill, so to say.  Again, the mids are great and the thing has 'bite' or 'punch' dynamics with no compression.  It's a really nice amp speaker match and I think the Conway III is a two way.  The older Conway II was a three way.  The III is downward ported and adjustable which works well in the room.  It's been criticized for its well integrated tweeter,  called an old man's speaker, but I believe that it's only in comparison to many more 'flashy' configs
that eventually draw attention to themselves.   They become 'high maintenance', after all, who do you really want to settle down with?   

[G Georgopoulos]

Hello. I've been thinking about speakers lately - okay, I always think about speakers. Lately though, MTM speakers have been on my mind. Many manufacturers produce MTM speakers using 5", 6", 6.5", and even 7" midwoofers. I've even seen 8" MTMs, but they are much less common.

Now what is all this about? Well, I'm hoping to further my education with input from you, dear reader. What are the goals any given manufacturer seeks by using these different sized midwoofers? I can make a few guesses - smaller midwoofers reduce driver costs and allow for smaller and less expensive cabinets. Additionally, smaller drivers will (may??) produce better midrange. Larger drivers produce deeper bass. Are there disadvantages to using larger midwoofer drivers?

So without my creating too many rules for this discussion, what are your thoughts on the different sized midwoofers in MTM speakers?

After some input, I'll clue you into what has captured my imagination recently. 

hi micheal

electrical specs come first
look at Frs , sensitivity,power,impendance,freq range,etc
there are small spks and big spks competing with those
cabinets/baffles come next
for this you have to know some spk design, too complex to talk here
if you google spk design you'll get good info (google is the best)
baffle spks are easiest and simplest
next closed box spks
and the more complex ported spks
the goals?,freq range,flat freq response,sensitivity,power
think of compromising,to get all these is gona be expensive

hope this help

all the best my friend

[UpperCut]

Hi there,

This is a tricky one as you specifically state (Manufactures) and so with that to my own opinion it would be FIRST the costs item for them to make it worse their while!

Putting the electronics to the side at the moment I believe that the design considerations for larger size speaker chassis are not too great as with larger diameter the front baffle width of the standard approach (coffin like panel enclosures) becomes to wide so that other problems are a rising which again would / could cut into the profits Etc. Now to make other baffles involves different enclosure shapes, and again would be a cost factor & so on, but it would also be more difficult to find appropriated drive units when they become larger!

If you would have mention not only manufactures then I would have said that I’m presently myself are working on a couple of projects which incorporate 8 inch speaker chassis, but in a more exotic enclosure type & build method used with or without a MTM configuration. These could be used easily in a normal set up with or without a Passive Radiator as a SEALED unit or in a still much unknown & greatly debated arrangement as a interactive SEALED & VENTED enclosure were the baffle arrangement lends itself to the use of larger type speakers like 7 / 8 inch.

Anyway, if I may say so but I do not believe that the electronics should be so heavily addresses as it has been the common approach of people in audio for many years now, yet more so the type of enclosure, the building method used and with that the elimination of resonance etc. of an enclosure first or at least in some unison with the electronics because developing an enclosure in great detail is of up most important then finding as mentioned before the right drivers which leaves the electronics as the easy part for fine tuning these with or towards the enclosure, but not the other way around trying to tune the enclosure towards the electronics which is unfortunately the way most people have done it for years.

It is like trying to put the Bridle on the wrong end of the Horse!

Rgs UpperCut

[JLM]

Mike has posed two different questions: driver size and MTM design.

MTM - I'm don't care for it.  You have to be centered on the drivers to avoid phasing smearing between the two midrange drivers.  In fact the interference is used to improve THX compliance which tries to reduce floor/ceiling effects.  Note, you don't see MTM in professional studios.  Try moving up and down (by inches) and you should be able to hear when the smearing is gone. 

Driver size - As indicated above you can only generalize, but typically larger drivers are more efficient, go lower, don't go as high, require larger cabinets, and have narrower dispersion of higher frequencies.  To keep cabinets narrow (mostly a marketing issue) manufacturers have gone to using multiple smaller drivers which also allows for higher crossover to tweeters. 

[Letitroll98]

The reason for the MTM configuration is to equalize the lobe tilting relative to non time aligned TM designs.  However this results in a narrower lobe that can create marked tone variations at different listening heights.  One way to mitigate this is to have the mid woofers as close to the tweeter as possible.  This can best be achieved through the use of smaller drivers, thus why we see smaller drivers in MTM designs.  Of course there's the trade off of loss of lower frequency extension.  Various strategies are used to offset this loss, multiple drivers, an additional woofer either on the front or side of the cabinet, using more expensive drivers with lower f3, etc.

[mresseguie]

Hi, all.

Thank you for your replies.

I do not own MTM speakers, but I keep bumping into them at shows and I see them on the Selah, Salk, Vapor, and other brands' websites. Greater sensitivity is achieved in MTM speakers, and I find myself attracted to the higher sensitivity and better midrange clarity. I understand the issues (problems?) associated with MTM designs.

I've considered commissioning a pair of 2.5, MTM, or (high sensitivity) TM speakers. [I've gotten ahead of myself.] I want to take another pair of speakers to Taiwan, but I want to avoid paying the 21% import duty and potentially shipping freight costs. My Fritz LS/5-R speakers were $300 to ship from CA and the import duty was $421! By commissioning a kit, I can have cabinets made there (already located a woodworker). I want speakers in the 89dB to 91dB range, so lower powered amps can drive them to reasonable levels.

I'm trying to determine if MTM speakers will satisfy my wants. They have greater sensitivity and better midrange - I want these characteristics. I auditioned the new Evoke Eddie three-way speakers. They sound fantastic, but they are 60 pounds each, so shipping alone would kill me. The manufacturer won't sell them as a kit.

Anyway, I've been wondering if sealed MTM speakers using the SB Acoustics Satori 7.5" drivers "MW19P" would give me not only the high sensitivity, but also excellent midrange quality. I'm a bit stumped on which tweeter to use, but I'm attracted to the Seas Crescendo "Excel T29CF-002" fabric dome tweeter. Sure, I consider the Be domes and ribbons, but I know I suffer some hearing loss in the 8k and above range, so do I really need Be or RAAL tweeters? [I doubt it.] I generally prefer dome tweeters over ribbon tweeters based on two-plus years of listening.

Why sealed? Well, I'll get either bass cabinet kits (dual 8", dual 10", or single 10") or Rythmik Audio's dual 8" subwoofers. I'd have to pay import duty on Rythmik subs, but they would ship from HK, so shipping would be lower.

Sigh. I'm doing it again. I'm getting carried away, I think.

Edit: I knew I'd forget something...Rather than using the 7.5" midwoofer and cutting it off at 120Hz, I could just as easily use the Satori 6.5" midwoofer.

Man, I wish I had $50k to spend on speakers so I could (maybe) figure out which speakers and which driver combinations make me happiest.

[hdspeakerman]

http://www.diysoundgroup.com/
Look here for systems with higher sensitivity. 

[JLM]

Please do audition those tweeters and good examples of MTM before purchase.

I don't associate MTM with improved clarity, in fact doubling the budget for a single midrange should gain more improvement.

By 2.5 MTM are you saying a tweeter, midrange, and a 2nd midrange/woofer?  I've never heard of that but I'm not intrigued with the idea.

What do you mean by TM speakers?

A couple of months ago I had a chance to hear Vapor Audio Nimbus Whites in a private home.  Unfortunately they were set up in a far too small room, but the vertical ribbon with the MTM configuration combined with near-field listening was highly problematic.  We kept sliding down, moving to higher/lower seats (based on our heights) to try correcting for the MTM (and vertical ribbon) effect.

I like the idea of sealed.  Bass will be reduced, but matches room gain better and integrates better with a sub.

[mresseguie]

I have considered buying 2.5-way speakers; I have considered buying MTM speakers, and I have considered buying 2-way speakers. Two-way speakers are sometimes referred to as "TM" speakers because there is one Tweeter and one Midwoofer.

It is difficult to find speakers using the Seas Crescendo tweeter to audition. I have heard the Exotic and the Millenium tweeters and liked them. The Exotic seems overpriced, so I am betting the Crescendo will deliver most of the Exotic's sound for $100 less per tweeter. Likewise, I like the Seas Exotic midwoofer, but I refuse to pay $740 per driver. I'm willing to bet the Satori 7.5" drivers will deliver much of what the Exotic woofer delivers - especially if the low end is cut off at approximately 120Hz. [If I do this, it would be in a two-way design supported by subs, or bass cabinets (3-way).] The Satori 7.5" driver is just $175. This is very attractive to me.

[OzarkTom]

Check out the Glow DIY speakers for$248 a pair. A lot of glowing reviews out there and they have no crossovers. I have been a huge fan of  speakers with no crossovers since early 80's.

http://www.glow-audio.com/voiceone.html

[mresseguie]

hdspeakerman,

Thank you. I poke around there fairly often, but I can never seem to decide what fits me. That's often my problem when I must decide on new equipment.

OzarkTom,

I did not know about Glow. Thanks!

[Letitroll98]

Why buy a 7 1/2" driver if you only want to get to 120 Hz?  A smaller driver would be ostensibly be better as a midrange speaker and still get as low.  Not trying to derail your project, but it struck me as a odd choice for an MTM design.

[Rocket]

Hi,

I know you weren't considering a 3 ways speaker but I thought I would recommend the Selah Audio Tempesta kit for $2295USD.  I understand that you wanted a more efficient speaker but this is a high reviewed and rated speaker.  Just buy a more powerful amplifier.

http://www.selahaudio.com/lineup/#/tempesta/

Cheers Rod

[JLM]

I'm a single driver fan/owner too, but they have their limitations.  No efficiency specified for the Glow Voice One (most 3 inch drivers can only handle a few watts and are around 83 dB/w/m efficient - severely limiting output) and by the frequency response graph begins to show roll off at 100 Hz (being ported, no doubt at a 24 dB/octave slope).  Might be OK if you're using them in a very small room or with subwoofer(s).  We're all subject to "proud papa syndrome" but it's spooky how small amp/small single driver fans learn to live without bass, even forget what its like.  There is no perfect speaker.  In fact, not sure you could even find consensus on what would be the theoretical perfect speaker.

Don't recall ever hearing 2-ways referred to as 'TM'.  Nevertheless recommend you settle on a budget and design type, based on what fits your tastes and life.  Single drivers are great for small ensembles and near-field listening.  2-way monitors expand on that in terms of genres, frequency range, and sound pressure levels.  Both can also provide great soundstage specificity.  Active 2-ways can be a very good compromise between the coherence of smaller speakers and the dynamics/bass capabilities of larger speakers.  (I've recently been most pleasantly exposed to JBL LSR305 in "average" sized rooms: $300/pair small active 2-ways that have F3 = 41 Hz.)  Beyond that I recommend developing a "good room", looking into how bass propagates in-room, and adding multiple subwoofers.

Picking drivers and then coming up with a concept/crossover/cabinet design, sounds like you want to become a DIYer or a manufacturer (who has to fit a parts budget into a product).  Guessing how particular drivers might sound like together in a given configuration is a recipe for lots of sawdust and/or disillusionment even if you're familiar with the drivers and crossover components.  Figure out what you want (basic design and budget) then look for pre-built options.  Or you might try finding a cottage industry designer that works in that arena to talk with and see what he can come up with if you want something custom.

[opnly bafld]

There is no perfect speaker. 

"There is no perfect speaker for everyone."   Fixed it for you.

[S Clark]

.
.  Figure out what you want (basic design and budget) then look for pre-built options. 

JLM is on target here.  I'd only add that there is a set of plans or a kit already out there that covers nearly every option.  Don't try to reinvent the wheel- you're not likely to succeed and definitely not likely to improve on what's already available. 

[opnly bafld]

mresseguie,

I also prefer dome tweeters (with cone midrange drivers), ribbons from midbass up (like VMPS) can work for me depending upon the design. Ribbon tweeters used as "super tweeters" don't seem to bother me.

[mresseguie]

Guys, guys. I promise that I won't rush out to spend gobs of money on drivers and XO components to 'reinvent the wheel'. At least in regards to DIY speaker builds, I really understand my limits. I can glue precut MDF boards together. I can either paint, or hire someone to veneer the cabinets. I think I mentioned in my first (second?) post that I was thinking of commissioning a pair. That means calling a reputable (and reliable) manufacturer and asking him to make me a kit that closely reflects my 'ideal wheel'. The manufacturers have the knowledge and experience to be able to tell me if drivers A and B will work together harmoniously. 

If drivers A and B won't work harmoniously, I will buy a kit that already exists - this is plan B. Plan B is (probably) either the Jeff Bagby designed Kairos speakers with upgraded XO components or (possibly) the Seas Bifrost kit. Both are two-way stand-mount designs that work well sealed.

I began this thread to attempt to suss out in my mind whether an MTM design was in my future. I'm pretty sure I will stick to a sealed two-way design supported by subs or bass cabinet. Again, I wish to take these to Taiwan, so a kit allows me to avoid onerous shipping fees and 21% import duties.

Thank you, all, for your enthusiasm. I really appreciate everyone's thoughts.