Newbie help with MTM and Morel Tweeter project please

[stevecuss]

Hello,

I bought someone's left over MTM project today and would greatly appreciate any guidance with my first DIY speaker build.

I bought 3/4" MDF cabinets (17.5" tall, 8" wide and 14.5" deep) with pre-routed MTM layout on the front and a rear port hole 2" in diameter.

With the cabinets came some Morel MTD33 tweeters and a pair of Audax HM130Z0 5.25" aerogel drivers.

I'd like to build a speaker based on the morel tweeters (I doubt I'll keep the Audax drivers - it looks like they are mostly midrange, not midbass.)

My goal is to make a speaker that is significantly better than my current Boston CR77 bookshelf speakers. I'll be driving them with Rotel separates from the mid 90's - 120 watts per channel at 8ohms. I don't plan on using a subwoofer for now (maybe I'll try to build one later.)

My favorite speaker tone is the B&W line - I really like the CM and the 805s, so if I can get in that ballpark, I'd be thrilled. I like all kinds of musical styles, but I am most drawn to singer/songwriters like Knopfler, Lovett and Emmylou, as well as blues and newgrass (Nickel Creek stuff.)

I've spent $120 so far on this equipment (I'm grateful for such a great deal) and I'm willing to spend $300 - $400 more on the remaining drivers and crossovers, back plate, acoustic treatment etc.

here are some quick questions:

can anyone recommend a design or kit that features these morel tweeters?

How large a driver can I put on an 8" width cabinet face? (currently routed for 5.25" but I assume I can increase the route hole size.)

If 5.25" is the largest size I can use, does any driver that small go low enough to get away with no sub? I'm not expecting earth shattering bass, just don't want all mids and highs.

can I turn this cabinet into anything other than an MTM? So could I make it a TM bookshelf in a larger cab or a 2.5 or even 3 way?

thanks for any help you can provide. I'm excited to get going on my first project!

Steve Cuss

EDIT BY MODERATOR Two threads about this same project have been merged

[ThomasW]

can I turn this cabinet into anything other than an MTM? So could I make it a TM bookshelf in a larger cab or a 2.5 or even 3 way?

You have the makings of a very nice 3-way. Use your existing drivers and box as the upper module, add a bass bin to take the workload off the midwoofers.

[stevecuss]

Hi Thomas,

thanks for replying. so much choice for a new guy to navigate, as well as a steep learning curve.

I think I'll stick with the MTM design for now and maybe down the road build a subwoofer.


currently shopping for good drivers to pair with the mdt33s, then I'll likely ask Parts express or Madisound to design a crossover.

I'd appreciate any suggestions for good mid/low drivers of 5.25 - 6.5" variety

thanks

Steve

[Curt C]

I'd appreciate any suggestions for good mid/low drivers of 5.25 - 6.5" variety

thanks

Steve

I agree with Thomas.
You've got some top shelf drivers in those Audax, who have had something of a cult following from the beginning. I wouldn't be so quick to remove them from consideration. I'd suggest you build your MTM with them and add a woofer (not a sub) at some later date.

If you want to make them MT's, try the Usher 8945P. It will 'just' fit on an 8" baffle, and will provide a reasonably satisfying low end and decent midrange.
Use a 2" x 8" port.
C

[ThomasW]

Use the Audax drivers they're very good.

No you don't want Madisound to design your crossovers, instead use Meniscus. They will design based on measurements taken from your drivers mounted in you baffles. So plan on sending them an MTM section with drivers. (yes it very much worth the hassle to do this)

As Curt indicated these MTM modules are too small to integrate with a sub. So you'll need a separate bass cabinet containing 8"-10" woofers.

[stevecuss]

Guys,

thanks for taking time to reply and giving me some pointers.

To clarify, the project only came with two Audax drivers, so either way, I'll either have to buy two more or two of something that would complement them or 4 matching other drivers.

My goal with these speakers is to have them stand alone as audiophile music speakers without sub or bass bin, so my intent is to build them out the gate with great bass response for their size. (I'm not looking for earth shattering bass, but great bass for a bookshelf, if that makes sense.)

Also, I'll call Meniscus tomorrow - thanks for that tip as I'd not heard of them before. The cabinets I bought don't have removable baffles, so I'd have to send the whole cabinets in then, I assume?

Curt, is your suggestion of adding the usher 7" driver make the project a three way then? That sure sounds enticing to me at this point.

also, this may be insignificant, but do I flush mount the tweeter, but top mount the woofer?

Is it a problem that my cabs don't have removable baffles?

thanks for all your guidance so far

Steve

[Curt C]

My goal with these speakers is to have them stand alone as audiophile music speakers without sub or bass bin, so my intent is to build them out the gate with great bass response for their size. (I'm not looking for earth shattering bass, but great bass for a bookshelf, if that makes sense.)

Curt, is your suggestion of adding the usher 7" driver make the project a three way then? That sure sounds enticing to me at this point.

The Usher was suggested for a 2 way design in the volume of the existing enclosure, similar to PE's Usher kit (but with the morel tweeter, likely sounding much better) I'd recommend this as a possible solution to attain your goal.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-950

Certainly the Usher driver would also work as a 3 way with your existing drivers, although many other drivers would also be suitable candidates, and some much more cost effective. For example: PE's RS225-8 will provide a very deep f3 of 33 Hz in 50 liters tuned to 25 Hz. Since this would be a TMW, new purpose built enclosures would be likely be the best choice.

also, this may be insignificant, but do I flush mount the tweeter, but top mount the woofer?

Flush mounting all drivers is always the preferred method.

Is it a problem that my cabs don't have removable baffles?

Not for me. You may find it problematic though...:rofl:

Since the baffles are already cut for drivers that are no longer available, it seems you will need to remove the existing baffles. Perhaps a little work with a router or table saw will make the enclosures 'baffleless'. -Or simply start over with an enclosure optimized for your intended drivers. ....

C

[ThomasW]

Steve I'm answering your email here...

" I have a couple of questions about a bass bin and how to integrate it:

-- I assume then that you're recommending I purchase two more Audax 5.25" drivers (mine are discontinued, so I'd buy two of the newer version) and finish out the MTM project as is.

-- then start a bass bin project, with an 8" or 10" driver?
-- I assume then that I'd have meniscus design a 3 way crossover to include the bassbin from day 1.
so if I go this route, would the MTM speaker sit on top of the bass bin? My current plan is to have the MTMs sitting on isolation pads on my end tables about 24" off the ground. I suppose I could wire them to bass bins that could then sit on the floor under the end tables? I've got a SAF I have to deal with...."

----------------------------------------------------------------------------

I misunderstood and was under the impression you had 4 of the little Audax mids...my bad....

Curt covered most of it, but I'll throw out the options I see.

1) 3-way using your existing drivers the someones 6.5"-8" woofer
2) 2-way using only the Morel tweets and a woofer.

The 3-way would probably sound somewhat better, but the crossover cost would double, and you'd have less bass output since the midrange enclosure would occupy space in the box.

Regarding bass bins (aka woofer bins). These need to be immediately adjacent to the upper speaker. This means for all intents and purposes the upper module needs to sit on the bin.

If you go with either option above, you should have enough bass from your existing boxes that you can forget about the bass bins and use a sub.

[stevecuss]

Thomas and Curt,

thanks for your feedback - I'm getting closer to resolution here based on your replies and my research.

Ok, so I really want to work with these cabinets if possible. Bottom line is I'm a cheapskate with expensive taste (yeah, I know...get in line, right?) But I paid $120 for this whole package with a goal to outdo my current Bostons and get closer to the $2000 B&Ws I heard two weeks back. (B&W: metal dome, killer crossovers, but also killer price.)

-- so, if I keep the morels and cabs, then it sounds like a 3 way is out. no worries - that appeals nicely to cheapskate boy here....

-- I'll shelve the audax pair for a future center channel project or something...

meanwhile, to complete an MTM two way with good bass response on a budget, it looks like the best option is to go for 6.5" woofers, flush mounted.

7" is getting very close to the edge of the cab for a flush mount (coming close to the 3/4" sides, if that makes sense.) perhaps this isn't a problem at all?

So if I go with 6.5" drivers that go down to, say, 40 - 45hz at -3bd, then I'd just have to re route the very permanent baffle and seek help designing a crossover?

Am I on the right track here?

If so, then based on research (Zaph tests, other responses on forums) my choices balancing budget, sensitivity and bass response seems to be:

Tang Band W6-789S 6-1/2" Woofer – reputation for going low. $43 per driver.

Tang Band W5-704D 5-1/4" Woofer – 5.25” woofer. Apparently goes to 40 hz $24.70 per driver. No need to reroute cabs.

Seas CA15RLY's ($66 each) pricier, but better.

Dayton RS150S-4 6" Reference Shielded Woofer 4 Ohm in series. $30 each. 92db efficient! Is the 4ohm thing an issue?

if 7" flush mounted, almost touching sides isn't an issue, then the suggested Ushers ($98) become an option if budget allows.

I had a great chat to Chad at Meniscus - very helpful. His crossover design is $200, so I think I'll have to pass at this point due to budget constraints. On top of my $120 invested, I'd like to add another $400 in max if I can manage it.

feel free to tell me if I'm wearing out my welcome, but also feel free to offer feedback on this too. I'm learning a ton and I appreciate people's help

Steve

[ThomasW]

You have recommendations from Curt and I.

Recommendations from other forums are best discussed with the people making them. But understand any system using a pair of 5-1/4" drivers isn't going to have much bass.

[stevecuss]

Thomas,

I hear you. I'm leaning toward either MTM with Dayton 6" or cutting off the baffles, buying new baffles and going with a single 7" usher with the morel tweeter.

Flushmounting the 7" on an 8" width still seems problematic, but I'm digging into it

thanks and I'll post an update when I've chosen a direction.

Steve

thanks for all your help

[ThomasW]

You didn't bother to post your pictures here, but I'll comment anyway.

Looks like the cabinet was built by Zalytron (if it wasn't it's stereotypic of their designs).

Given the nature of the construction unless you want to butcher the baffle, you'd probably be better off staying with 5-1/4" drivers and live with the minimal bass output.

[fjhuerta]

Audax Aerogel woofers and a Morel tweeter.

Sounds suspiciously like Vance Dickason's MTM on his loudspeaker cookbook . Only difference is, he used 6.5" woofers, if I remember correctly.

[Deward Hastings]

Sounds suspiciously like Vance Dickason's MTM on his loudspeaker cookbook . Only difference is, he used 6.5" woofers, if I remember correctly.

Close. Dickason used AP130Z0 and MDT40, but in a smaller box. Someone was looking to get a bit more bass, maybe?

[stevecuss]

Here are photos of the cabinets. I'm deciding between two options:

keep the baffles as is and drop in some Dayton rs150s or Focal 6" for MTM design. They will fit in existing holes, top mounted.

remove the baffle or add new baffle on top and route it for TM design with Usher 7".

The usher TM approach better reaches my audio goal, the MTM approach leaves me with less tonal range, but surely a cleaner looking finished product.

I'm gone for two weeks starting Sunday and will re engage when I return. Thanks again for everyone's help here. In a short week I've gone from wishing I could afford $$$ B&W speakers to buying some DIY products and jumping into the DIY community. Its been a blast so far.

Steve

[Deward Hastings]

What you seem to be doing is letting the existing box constrain your design. Which is fine, but you have to live with the constraint. If you don’t want to do any woodworking then there it is . . . find some mid-bass drivers that fit the cutouts and go with it. The box would be fine closed using RS150s if used with a subwoofer below 80 Hz. And there’s the Aurum Cantus AC-130F1 as another option:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-400

OTOH if you’re up to doing some woodworking then just cut off the existing baffle and fit a new one. You can cut it off easily with the same router you’ll have to have to make the driver cutouts in the new one. While the box is open add the side panel bracing that should have been there. Seal and paint your new baffle a nice black to match your drivers . . . it’s not a bad look, and many prefer it to black blobs on a wood background. You can probably fit the grill you’ve got if you want.

That leaves the size of the box as the remaining constraint but still substantially increases your choice of drivers. Any nominally 7” driver is going to lap into the roundover . . . (there you go, constrained by the box again). The Usher 8945P is a nice driver except for the cost . . . there are others, including the RS180, which suit your box volume well (40 Hz. F3 ported) if not the width at a third the price, and will sound quite good if used with a suitable crossover to avoid cone breakup (also a problem with soft or composite cones, just expressed differently).

[stevecuss]

Hi Deward,

You're right - I am letting the box constrain me, for better or worse. Unfortunately, I have to pause the project for a couple of weeks while I'm gone, but I'm definitely considering cutting off the baffles and making new ones for a design based on my tweeter and a 7" driver.

I like the idea of simply painting it black - saves trying to salvage the current veneer and match it with the new baffle.

I'll be back in a couple of weeks with a direction

Steve

[JJones]

You have recommendations from Curt and I.

Recommendations from other forums are best discussed with the people making them. But understand any system using a pair of 5-1/4" drivers isn't going to have much bass.

Depends on your perspective. Plenty of people have heard 2-way speakers with just one 5.25" driver (and a tweeter) on each and said "wow, impressive bass for such a small speaker", etc. Such speakers could particularly do fine playing female vocals and guitar, and, I bet with 4 5.25" drivers you could get a design that can crossover nicely to a sub at ~ 80 Hz (sealed MTM).

This woofer: http://www.partsexpress.com/pe/pshow...TOKEN=90810488 ($16.50 ea for 4) doesn't have the easiest top end to work with, and the spec is only 2.5mm x-max, but, I've heard it tuned to about ~ 45 - 50 Hz and play suprisingly loud without sounding too bad. Now, of course it's not going to compare to a ScanSpeak 15W... How low can you cross the MDT-33?

Here's another good cheap woofer: http://www.madisound.com/catalog/pro...oducts_id=1757 at ~ $10 each

EDIT: Oh, that Aurum Cantus driver looks NICE! I don't know why I'd overlooked it, all those times I've looked at Zaph's driver roundups... Hmm... Almost looks too good to be true, that combination of sensitivity, low FS, X-max, smooth response, and price, all in one neat little driver...

[stevecuss]

Hi Guys,

I'm back from my trip and decided to choose a project without having to change the cabinet or baffle. So I'm saving the audax drivers for a future center channel and I'll buy 4 Dayton 150 drivers - the 6" truncated version. They'll fit into the existing holes and being truncated, won't invade the tweeter space like another 6".

I'll begin a fresh thread requesting crossover design assistance

thanks for everyone's guidance and patience as I sorted this out

Steve

[stevecuss]

crossover design request for morel/dayton mtm project

Hello,

I sought advice in the "newbie MTM project" thread and have benefited greatly from everyone's suggestions. Basically, I own a pair of mtm cabinets and morel mdt33 tweeters and I need to buy 4 drivers and accessories to round out the project.

It has been suggested to me to seek a crossover design from people on the forum rather than from the parts houses. Would anyone be willing to do one, or does anyone live in the Denver area who would be interested in designing a crossover?

The cabinets are 14.5" deep, 17.5" tall and 8" wide. Built with 3/4" mdf and with a 2" rear port hole.

I'll use the morel tweeters listed above and add Dayton rs150T 8ohm drivers. (these are truncated, so they'll fit in the existing cutouts.) I'm looking to get the best possibly frequency range out of this setup and have no current plans to add a sub, although I could down the road if need be.

the speakers will be primarily for 2 channel music reproduction and I favor folk, acoustic and classical music. They'll be running through older Rotel separates - power amp is 130 watts per channel in 8ohm and rotel confirmed that it will drive 4 ohm speakers no problem.

thanks

Steve

[norcad]

IMO this enclosure is a little to small for the Dayton drivers, and you will get little (low)bass out of them. Without losing to much sensitivity.

I know it will cost some more, but still I will suggest the Seas CA15RLY.
The Fs are lower, xmax higher, it can handle twice the power.
And they will fit the volum of your enclosure better.

My simulations tells me that you will get -3db@67hz with the Dayton's, and with Seas -3db@50hz.

I dont know the Dayton drivers, but the Seas has a very good midrange and very low diffraction from the frame.

[stevecuss]

Hi Norcad,

I looked at Zaph's tests on his site and it seemed that the Dayton fared very well against the Seas for less money, hence I was heading in that direction. Seas was/is on my short list, but the Daytons are truncated and less $$.

Steve

[norcad]

Dayton is very good, for its price. And maybe you will be very happy with them. The problem with a low cost project, is all the money you spend in the future before you get the sound you want!
With the Dayton you will probebly need a sub, with more expensive drivers, you may not need it.
Of course, if you use the Seas drivers, and still find out the need for a sub, then it will be expensive

[augerpro]

PM sent

[stevecuss]

Hi Folks,

I've pulled the trigger on some commercial drivers from a company that offers DIY kits. The designer is also offering crossover design with the sale of his drivers and parts. I believe this forum discourages naming brands.

thanks to everyone for your input and I believe these will be the first of many DIY speakers I attempt. if it is permitted, I'll post pictures and a review when they are completed.

[ThomasW]

I'll post pictures and a review when they are completed.

As a matter of routine we don't limit discussion about companies, kits, designs or projects. But there are exceptions..... You might want to read #2 in our New Rules thread.

https://www.htguide.com/forum/showthread.php?t=28354