Anyone interested in designing some MTM's? (1 Viewer)

[AjayM]

Hey if the group can build a set of bookshelf speakers that can surpass these Link Removed
I'd be interested in helping out, although at this level the amount of help I could offer would be limited at best, although I can maybe help out on the enclosure design side. Although it will probably cost $700-$1000 to do.
I'm with Thomas that I prefer a well designed Focal tweeter setup to just about any soft-dome (I haven't heard them all, but I haven't found one I loved yet), as far as a midrange I don't know what all is out there, I've heard the Focal tweeter with a Focal woofer and a Scan Speak woofer, so those are the limits of my experience with Focal tweeters and mids. Anybody have any experience with the Accuton tweeters? I've heard tons of good things about them, but have never heard them.
So I guess first we should define what it is we are looking for in a system, for me I like to have some SPL, but I wouldn't trade awesome sound just to get max SPL. I want a speaker that when somebody listens to it, their mouth drops open and they can't form a complete sentence for a few minutes.
Possible?
Andrew

 

[Mark Hayenga]

The Focal tweeter interests me, there are certainly some very high end speakers that use it. My vote for the midbass goes for the Seas Excel magnesium cone drivers, namely the W18E001. There is a similar project viewable at http://www.speakerbuilding.com/content/1020/ .
Mark

 

[ThomasW]

Hey Mark
If you think the Eton Hexcones are "fun" to design a XO for, just wait until you try and create one for a metal cone driver.

 

[Mark Hayenga]

I can dig it. How low can that Focal be run? I'm harassing a local friend for some measurements on his W17s so I can see what I can do.
Mark

 

[AjayM]

Well, they have an advertised FS of 1180.8Hz (I think I've seen x-over points in the 2-3khz range) But I think Thomas may be able to answer this one a bit better as he has a lot more practical experience with the tweeter.
Thomas, have you done anything yet with the Eton drivers for your newest project? Maybe just have an X-over design laying around that just may work in a Focal/Eton MTM?
Andrew

 

[ThomasW]

Although the tweeter's Fs is around 1.2Khz, we don't use it much below 2-2.5Khz. We prefer to use XO points an octave or so above the Fs when possible. This keeps the drivers very safe.
AndrewM
I've been a little under the weather for a couple of weeks so no I haven't worked on the line array of Etons. But that should change next week

 

[Hank Frankenberg]

Mark, from what I've read, ThomasW's caution about metal cones is good advice. The best commercial dynamic speakers I've heard all had non-metal cones. I sent a note to ThomasW a year ago saying I was thinking about a pair of Newform Research monopole ribbons integrated with one or two Scan-Speaks per side. He replied that in his (extensive) experience, the Etons are better and less expensive to boot.
Cabinets: IMHO, the cabinet design guidance from North Creek Music in their cabinet design handbook can not be beaten. http://www.northcreekmusic.com/Publications.html What do you think, ThomasW?

 

[ThomasW]

Hank
I've looked at the cabinet .pdfs from North Creek, and yes I'd agree with most of what they say/do.
Probably would not mount the XO directly behind the woofer, not glue down the XO components with liquid nails (hot glue is much easier to remove), probably would asymetrically mount the tweeter in an standard MTM application,(makes for better imaging IMO).
Additionally I've found that "generic" metalized poly film caps (such as the G.E. caps from Madisound) and other such items, are usually sonically as good as the "designer" ones. And they are much less expensive.
Mark
Metal cone woofers have very high "Q" cone break up modes, and the cones themselves aren't inherently self damping. So with a driver like the the Excel you have an antiphase dip prior to the resonance from the cone break up. All this is easily seen in any of the published FR plots. So making a crossover appropriate to this is problematic to say the least.

 

[AjayM]

Hey Thomas,
I'd be interested in getting a copy of the Eton/Focal MTM XO, I'm thinking of instead of building a bookshelf type setup, to throw the MTM unit on a bass box of some sort, most likely a dual Focal 11" setup. How does the X1 clone sound overall, how about compared to the original?
I've been modeling for the 7-350/25 Eton, is that the same one you have been using? It looks like I can get away with an enclosure around 40litres for the 2 of them tuned to around 46Hz and have an F3 in the high 40's (47Hz or so), that volume should also work in a sealed unit (albeit with limited bass) for over a bass unit. So it could work as both a bookshelf/stand speaker and part of a 3-way (well, if the roll-off is good enough to not need a bandpass for the mid, and knowing my luck probably not) just by sealing the port.
Thoughts, ideas, am I completely out of my mind?
Andrew

 

[ThomasW]

Andrew

How does the X1 clone sound overall, how about compared to the original?

All I can say is....

The Eton 7-370/32 drivers we used are discontinued. They are similar, but not identical to the current model 7-372/32. If you want more bass handling, then consider the 7-372/32 LH with the "heatpipe" technology.
But as I said in an earlier post, if midbass "punch" is a desired trait, in a stand alone MTM design, then go with one of the ScanSpeak woven kevlar, or carbon fiber designs.
If you are going to make a bass bin (ala SLAMM), and run a woofer/woofers up to 120Hz or so, then get the Hexcone kevlars.
FYI: our version of the SLAMM has an active XO between the bass bin and the top module.
As far as exotic material pure woofers running at 120Hz or lower, save your money. Get Shivas, Tempests, Stryke/Lambdas, SV-12s, etc. The difference won't be heard, and your wallet will be much happier.

 

[Mark Hayenga]

Thanks for the lessons on cone resonances guys, I'll be sure to go back and read that section in the LDC [/sarcasm]. Let's not kid ourselves, the Eton kevlars aren't a real treat to work with either. Just read the LDSG entries on the Etons and Excels and compare:
Link Removed
Link Removed
To quote Mr. Stout, "...the waterfall plots indicate some potential resonance problems only slightly less severe than the Seas magnesium cone drivers."
Or instead, examine the available data on each. Playing the 'metal cone card' on the Excels isn't fair without acknowledging the ring-like-a-bell act the Etons pull in the 2-4kHz range (depending on model). The Excels at least wait til 5k before they get real nasty.
Even then, I'll grant that the 7-372-32 is likely a little easier work with than the Excels - but not by any amount that I'd let affect my choice. I feel the more advanced motor structure of the Excels and their published ultra-low distortion figures are enough to warrant their use.
Going by the data and what I've heard firsthand from the W17s, the Excel still get my vote. But in the end, this is all up to Bob.
Mark

 

[ThomasW]

Hi Mark,
Well as they say "to each their own".
Although I certainly respect Bob Stout for the astounding amount of data he's collected and organized, much of it is based on word of mouth.
I was a Seas dealer for almost a decade, so my statements about their products are from hands on experience. As a result I'd certainly differ with Bob's characterization of the Etons. They are considerably easier to work with compared to the Excels.

 

[Noel G]

I think your initial driver choices are excellent: Scanspeak 5" and Revelator Tweeter. Since Scanspeak and Vifa are now one and the same, I don't know if the 5" driver you selected is better or an equivalent of the famous Vifa P13WH-00. You have mentioned some new cone materials so it appears you are interested in the new generation of drivers. In this case, I would suggest checking out the Seas line of magnesium drivers.
I've also heard of some people not liking the Revelator because of the absence of ferrofluid cooling but I think its design has a lot or merits. I am also currently selecting drivers for DIY fronts and am considering the tested and proven Vifa P13WH-00 and Scanspeak 9500 tweeter, also in an MTM configuration.
As a speaker DIY-er, have you used exotic caps and inductors in your projects? I am interested in NorthCreekMusic's offerings.
I will obviously be following this thread. Thanks for starting it.
Noel

 

[AjayM]

Well, I guess the question is really which one will sound the best, the Seas or the Eton. This originally started out as building a world class bookshelf speaker system, to me that means that a little or even a lot more work on the x-over is basically trivial. Because once you have it done you can then reap the rewards of having something truly special. This is obviously true if the Seas will give you better performance.
I think one of the reasons we have talked about the P13MH Vifa is that the goal is to get as much bass response as possible, definately under 80Hz, and lower is better.
Thomas, I can't find the Eton's you are talking about, Madisound carries 7-350, 7-360, and 7-372 (with the Heat Pipe). Solen is the same. For me I'm looking for more midrange accuracy, not so much punch. Also, about the Bass bin idea, I'm still throwing around some ideas, one idea was to go with two Stryke SB10's, one Focal 11V7511, maybe 2 Focal 11V7511's (need a BIG box though), without doing any measuring just some modeling it looks like I'll need to x-over the woofers to the mids in the 150-200Hz range, which is why I ruled out the Shiva, as I think the Focal or Stryke would give me better results for not much more money (don't get me wrong, I think the Shiva is an awesome sub-bass driver). What was the reason John went Active between the bass drives and the mid/hi's? Worried about having to use big inductor values for the x-over, had an extra amp around? I'd love nothing more than to have an all active system, it's just not very practical for me at the moment.
So Bob what do you think so far?
Andrew

 

[ThomasW]

Andrew
I emailed you a link where we can discuss the Eton drivers, SLAMM clones, whatever, without hijacking Bob's thread, or offending the Seas loyalists.
Hasta
Tomas'

 

[Bob Sorel]

Hi guys,
I've been loaded with work for the last day and a half, so I am going to have to play catch up tomorrow (hopefully). Between now and then, could someone please make up a summary of the actual model numbers of the drivers that are on the short list right now? And then maybe provide me with a link or links where I can read up on them to familiarize myself with their construction and properties? This is going to be my first speaker project that is built from scratch, rather than just building someone's preconceived kit, so I am going to have to take things slowly and get educated as I go along. I hope this will not be too slow and painful for you guys, as I don't want to rush into buying drivers, just to find out next week that I made a bad choice So please come up with that short list for me and I'll be back tomorrow for more reading. Thanks, guys!
Bob
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STOP DVI/HDCP (the DIVX of HDTV)...DO NOT SUPPORT COMPANIES WHO PROPOSE THIS

 

[Mark Hayenga]

List of drivers, official websites, and LDSG entries for ease of navigation. I tossed in some 'late entries' and I might have missed some drivers mentioned, so I'll come back and edit as necessary.
For tweeters:
Accuton C2-12
Accuton C2-23
Official Website: Link Removed
LDSG entry: Link Removed
Focal TC 120 TdX2
Official Website: Link Removed
LDSG entry: Link Removed
Scan Speak D2905/9900 Revelator
Scan Speak D2904/9800 (the new metal dome)
Official Website: http://www.vifa-speak.com/scs_prod/tweeters.htm
LDSG entry: Link Removed
Seas Excel Millenium
Official Website: http://www.seas.no
LDSG entry: Link Removed
For Midwoofers:
Eton 7-372/32, 7-372/32LH
Official Website: Link Removed
LDSG entry: Link Removed
Scan-Speak 15W/8530K
Scan-Speak 18W/8545
Official Website: http://www.vifa-speak.com/scs_prod/midwoofers.htm
LDSG entry: Link Removed
Seas Excel W18E001
Official Website: http://www.seas.no
LDSG entry: Link Removed
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Lemme know if I forgot anything. I have no strong preference on tweeters so long as they can be crossed over low (2kHz) in case any of the more difficult to work with midwoofers is selected. Also, does Focal have any midwoofs we should be looking at? I hated their Polykevlar 7", but some of their stuff might work.
Mark

 

[Bob Sorel]

Hi guys!
I've been playing catch up for the last couple of hours, and I am now here:
1. I think I would like to go with the Focal tweeter, as Thomas's comments about how "revealing" it is has really piqued my curiosity. It sounds to me as if this tweeter has incredible potential, as long as the XO is done right I just want to make sure that we don't end up with a "harsh" tweeter, as I like to spend a lot of time listening to music at pretty high SPL's, so a harsh tweeter would put an end to those long listening sessions. Also, a harsh tweeter would make extended movie watching become grating, especially with action movies with a lot of glass breaking and such. If everyone agrees that this tweeter has the most potential, we can consider this decided. If not, then please make another recommendation with an explanation of why you consider it a better choice than the Focal.
2. I'm still undecided about the mid-bass driver. I have a few questions that might help out with this decision:
A. Since you guys know that I will be building 2 HE 15 subs, where should I be crossing over to the mid-bass units? THX recommends 80 hz for home theater, so that is my current setting, and I want to have just one setting for both music and HT. Will 80 hz be ok with any and all of the above drivers?
B. I would like smooth sounding drivers, again avoiding any harshness or distortion. Which drivers can and will remain clean when driven to high SPL's?
C. Accuracy is the number one concern. I want drivers that will make human voices sound as if they are in my room, live and in person. I want drivers that don't sound like speakers at all, but rather like I am live at the concert or I am part of the movie (rather than watching it). Human male dialog seems to be one of the toughest sounds for any speaker to get right. It is easy for a speaker to be "musical", since nobody knows exactly what the instrument sounds like, but I have heard very few speakers that can recreate male dialog accurately. Which drivers win that contest?
D. We have to assume that my measuring capabilities will be limited for fine tuning the XO, so which drivers will require less "fine tuning"? In other words, which drivers will most likely sound great even if the XO can't be tweaked to death?
Remember, guys, that this is my first complete DIY from scratch project, and it is probably going to cost some pretty big bucks, so I would really like to end up with something of which I can be proud. I have decided to invest in a decent table saw (which I didn't need for the Sonotube projects), in order to do a good job at cabinet building. I have also ordered the Loudspeaker Design Cookbook to start educating myself with design concepts, but I will be depending on the knowledge and experience from you guys to make this project work, so before I start spending the money, please assure me that you will stick it out to the end. If anyone wants to bow out, now is the time to do it with no hard feelings, as I haven't invested much money or time to date.
That being said, in the words of the immortal referee Mills Lane "Let's get it on!"
Ok, so now that I've made all these crazy requests, let's discuss the pros and cons of each driver
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STOP DVI/HDCP (the DIVX of HDTV)...DO NOT SUPPORT COMPANIES WHO PROPOSE THIS

 

[Mark Hayenga]

so before I start spending the money, please assure me that you will stick it out to the end. If anyone wants to bow out, now is the time to do it with no hard feelings, as I haven't invested much money or time to date.

I do this for fun. No matter what drivers are picked, I will be here - assuming you can get me some Laud/Clio measurements (otherwise I don't really have anything to work with). BUT, I would recommend starting with a single test cabinet and only enough drivers for it. Then by emulation with LspCAD pro make sure we can get em to where you like the sound before putting any more money in them. If things just don't work, I'd prefer if we found it out before you bought a full complement of $100+ dollar woofers and tweeters.
Mark

 

[ThomasW]

Just a couple quick notes,
Bob, you'd better chose the highest efficiency tweeter in the group, given your propensity for things LOUD
Mark, the Legacy roadshow unfortunately won't let you hear the potential of the Eton drivers. Legacy uses electrolytic caps and ferrite core inductors in their XO's.(we toured the factory and saw the XO's being built)