Modula Xtreme follow up

[JonMarsh]

Thanks for the kind words! The owners are pretty happy with them...

[JonMarsh]

Though this is supposed to be Ardent Speaker Camp

The Modula Xtreme is getting a bit more loving for now... completed the CAD models so I can start cutting final front panels.

I wish there was just a magic wand to wave and have this directly translated from my head- I do prefer to be making sawdust to pushing pixels.



But you what they say about planning/measuring three time and cutting once.

And no, I'm not finishing these in weird automotive colors- they were just basic colors that came close to emulating LBL and maple. OK, not very close...

[spadez]

Looks good, the drivers are a very tight fit on the front face

[JonMarsh]

Looks good, the drivers are a very tight fit on the front face

You bet they are, as this inadvertently leaked spy photo of the Xtreme head unit from the Ardent thread shows....




Cut front panel and sub panel blanks yesterday for the LBL baffles for the head units and bass cabinets.

[JonMarsh]

Front panels in fabrication, CAD model essentially completed. Not high end industrial design, but this is a "Modula" system, which means PE cabs, or derived from PE cabs. This one is a bit more like derived from PE cabs via the Borg.



Fast to build is the point- at least one should be together by Friday.

[Brian Bunge]

Jon,

I haven't been around these parts for awhile so can you share with me what drivers these will use? Life has been crazy for me lately so I'm hoping to get back into building speakers by the end of the year. Well...assuming I'm back in FL then, which very well may happen!

[savage25xtreme]

Jon, do you have the part numbers for the correct PE cabinets to use?

[bbcmp1979]

Jon, that is looking mighty good.

[JonMarsh]

Hi Brian!

Jon,

I haven't been around these parts for awhile so can you share with me what drivers these will use? Life has been crazy for me lately so I'm hoping to get back into building speakers by the end of the year. Well...assuming I'm back in FL then, which very well may happen!

Good to hear from you again! I hope getting back to FL works out for you if it means being able to build speakers again!

This is kind of my "cop out" project, because after spending the last 13 months working on the Ardent's, I knew I didn't have the time and energy to do an Isis inspired speaker anytime soon, but I wanted to use some of the drivers I'd acquired, and come up with something not too large, either, in proportion to SPL. Plus, ThomasW is building a "rock and roll" speaker, his Whisper 2, so I figured I'd build a rock and roll speaker, too.


Cabinets start as basic PE models, but have upgraded front panels and are put together like a project from the Borg. The head unit is the Dayton Audio 0.5 cu. Ft cabinet, in this case, maple ones, part number is 302-726. It's a snug fit, but I've already built a proto with the Accuton C173N-T6-C90 midrange in it, with a modified MCM H-65 waveguide that's coupled to a Scanspeak D26008/9130 tweeter. The waveguide/tweeter is the same setup as for the Modula MT XE; there's another combination I've been playing with, but so far it's not working as well.

The bass cabinets are the Dayton SWC1-MA 1 cu ft "Subwoofer" cabinet, again in this case in Maple, part number 302-838. Of course, a person could build their own cabinets using the Parts Express Spec PDF, which is quite detailed on dimensions. These also have custom front panels and modified baffles, and are joined with a spacer plate. Each cabinet has a Scanspeak 26W12867T0, though they could be done easily with the 26W8867T0, I just got a good deal on the former from Madisound.

Why the 10" Scanspeaks? Well, they're the lowest distortion drivers in their size class I've come across so far (of course, I don't get around all that much...)



Normally that would be too small a cabinet for this driver and it's actual Q, so we fix that using Flux Capacitors™. It's another Duelund style crossover, roughly at 400 Hz and 2400 Hz.



With the right tuning on the Flux Capacitor™, you wind up with the response curve of the blue trace. With the wrong tuning, if you overload the low end, you wind up in 1955.

I have to be batsh*t crazy, because I'm trying/hoping to have them built by the Northern CA DIY the end of April. Of course, that's why I'm on vacation this week to work on that and wrapping up wood finishing on the Ardents. Wish me luck- I must be out of my mind.

Did I say these should go together fast? And I have a big grab bag of crossover parts lying around- hope I have what I need in it! Gonna start working on the network design tonight- I already have measurements using the "stock" front panels.

[ultrakaz]

Plus, ThomasW is building a "rock and roll" speaker, his Whisper 2, so I figured I'd build a rock and roll speaker, too.

Why the 10" Scanspeaks? Well, they're the lowest distortion drivers in their size class I've come across so far (of course, I don't get around all that much...)

Normally that would be too small a cabinet for this driver and it's actual Q, so we fix that using Flux Capacitors™. It's another Duelund style crossover, roughly at 400 Hz and 2400 Hz.

With the right tuning on the Flux Capacitor™, you wind up with the response curve of the blue trace. With the wrong tuning, if you overload the low end, you wind up in 1955.

Yes! Rock and Roll forever.

Pardon the intrusion, but what are the "Flux Capacitors"? (Yes, I'm old enought to recognize your avatar Or if you could point me to a thread/document that explains how it allows a smaller cabinet to be used with the Scan Speaks. Thanks.

[Brian Bunge]

Jon,

Sounds awesome! I assume the "flux capacitor" is one of those alignments with a cap in series with the woofer for a 3rd order rolloff, giving you a little more low end extension in a smaller box, all with the tradeoff of slightly lower sensitivity?

Yes, moving back to FL would allow me to get back to building some speakers. Right now we are in a townhouse and all my tools are at my dad's house...an hour away. I'd take my routers and various hand tools and buy a new table saw and Workmate once I'm down there. I've been looking at those Craftsman contractor saws that are supposedly like saw you have. The one with the sliding table and built-in router table. Is it Ryobi? Don't remember the brand for sure...

[JonMarsh]

Jon,

Sounds awesome! I assume the "flux capacitor" is one of those alignments with a cap in series with the woofer for a 3rd order rolloff, giving you a little more low end extension in a smaller box, all with the tradeoff of slightly lower sensitivity?

Yes, moving back to FL would allow me to get back to building some speakers. Right now we are in a townhouse and all my tools are at my dad's house...an hour away. I'd take my routers and various hand tools and buy a new table saw and Workmate once I'm down there. I've been looking at those Craftsman contractor saws that are supposedly like saw you have. The one with the sliding table and built-in router table. Is it Ryobi? Don't remember the brand for sure...

Yeah, that's how it works, though actually the overall sensitivity isn't really changed; it works well with drivers in the Qts range of 0.5 or a bit above. It can knock down the Qts hump fairly well, and the tradeoff is a 3rd order roll off (slower than bass reflex, but faster than a normal sealed). A side benefit is DC protection for the woofers.

You're thinking of Ryobi, all right- like this one



I've also picked up a DeWalt DW745 contractor's saw that I really like for smaller pieces; rack and pinion fence, sets up quite accurate, only real drawback is gear drive is kind of noisy, no soft start, and being as small as it is, won't handle larger project. I looked at a lot of smaller saws, this one is pretty much in a class by it self, must have been designed by the guy who did the DeWalt DW621K router.



I slapped a good 80 tooth blade in it, and have been having lots of fun with it on some smaller projects (like the Modiula MT XE, and the Modula Xtreme).

[---k---]

Yes! Rock and Roll forever.

Pardon the intrusion, but what are the "Flux Capacitors"? (Yes, I'm old enought to recognize your avatar Or if you could point me to a thread/document that explains how it allows a smaller cabinet to be used with the Scan Speaks. Thanks.

Tony Gee has a good build that explains it also.

http://www.humblehomemadehifi.com/Black%20Box.html

[ultrakaz]

Yeah, that's how it works, though actually the overall sensitivity isn't really changed; it works well with drivers in the Qts range of 0.5 or a bit above. It can knock down the Qts hump fairly well, and the tradeoff is a 3rd order roll off (slower than bass reflex, but faster than a normal sealed). A side benefit is DC protection for the woofers.

Why is a 3rd order roll off a "tradeoff"? Is it because the speaker will be more difficult to cross over to a sub? Thanks.

[JonMarsh]

Why is a 3rd order roll off a "tradeoff"? Is it because the speaker will be more difficult to cross over to a sub? Thanks.

Well, for starters, there's no getting around Hoffman's Iron law regarding sensitivity and LF extension and the size of the box.

But with this approach you're making trade-offs that give what may be more desirable characteristics in the main part of the pass band, and as regards overall performance.

This LspCAD graph I prepared high lights what is theoretically possible as an example, using the 26W12867T0 as a modeling example, in a 28 liter enclosure. Modeling this behavior doesn't appear to be done very easily with standard programs- probably something they're not taking into account. But it comes close enough to what's going on below 100-200 Hz.




The black trace is the natural response of the woofer in the 1 cu ft enclosure, which is a "too small" box in classic terms, resulting in a relatively high box Q, and an Fb around 75 Hz.

The green and red traces show two predicted response curves with different size series caps. What is significant about both is that the current phase shift form the caps, interacting with the driver resonance (which itself phase shifts the current) is modified, and even in the case of the green trace, it can "kill" the the Qtc bump, and extend the low end in the transition region. The red trace uses a smaller cap and produces a further damped response (one that may work better if proximity to the walls is needed without a strong bass lift in the 50-60 Hz area), and has a few dB more output in the mid 30's.

This alignment has a fast roll off than the conventional sealed alignment, so at some point between 15 and 20 dB down, the curves cross over with the box curve without the "flux capacitor™"

If one was intending to use this with an HT crossover, it would be best to have the crossover a bit higher up than the box roll off; then whether it was 2nd order or 3rd order roll off would be of no importance. OTOH, I'm not concerned about HT processors and subs; this is a more or less full range music speaker, and the trick here was to get solid bass and very low distortion (through the 26W drivers) in about half the size of a "normal" enclosure for them. Where the LF roll off rate is picked at 12/db per octave is where an HT crossover is assuming you've got a small box speaker with a 80 Hz Fb sealed and it puts the crossover frequency with an electrical 12 dB/octave on the high pass to net an acoustic transfer function of 24 dB/octave. How well that works in the real world is sometimes problematical, given that variations in the driver Qts and box Qtc can throw off the behavior at box Fb from the ideal acoustic target (under damped or over damped- one reason crossover "Q" controls are provided in some cases)>

For example, a relatively "normal/optimal" ported enclosure for a single 26W8867 works out (using the real, not factory T/S parameters) to be in the range of 65-85 liters. For greater voltage sensitivity, you could use the 4 ohm version. But you'd just have a single driver, so while a well designed ported enclosure will up the bass extension an the output at the LF corner frequency by 3-6 dB, it doesn't help the upper bass or midrange output.

Dual drivers does help those parameters- but at a cost- you've got to buy the second driver! And in a conventional alignment with two drivers, you'd have a ginormous box for the both of them.

This is an experiment to try something a bit different, see if we can't get a satisfactory bottom end with a much smaller net enclosure. The 26W12867 were a special at Madisound at half price, so while the experiment is expensive, it's not hideously expensive. Total net LF enclosure volume per side is just 56 liters.

[Russ_L]

Via the Borg

Jon- I'm not quite up on all the terminology. "Parts Express cabinets via the Borg". Borg??

Looks like a real nice design. :T

Thanks.

Russ

[JonMarsh]

It's just my lame attempt to be funny. :W By "Borg", I mean Star Trek Borg, which would assemble things out of existing bits and pieces that were once other things-

in this case, we're making a full range speaker cabinet from a small bookshelf cabinet,

Image not available


two "baby" 1 cu ft subwoofer "cubes",

Image not available

and some miscellaneous wood and hardware to tie it all together.

Sort of a "rapid prototyping" kind of approach.

[ultrakaz]

Tony Gee has a good build that explains it also.
http://www.humblehomemadehifi.com/Black%20Box.html

Thanks for the link. Never thought of that, but I get the idea. A super high pass filter? 600uF. Perhaps, if one can accommodate biamping, you can line level the thing for a lower value.

[ultrakaz]

But with this approach you're making trade-offs that give what may be more desirable characteristics in the main part of the pass band, and as regards overall performance.

The green and red traces show two predicted response curves with different size series caps. What is significant about both is that the current phase shift form the caps, interacting with the driver resonance (which itself phase shifts the current) is modified, and even in the case of the green trace, it can "kill" the the Qtc bump, and extend the low end in the transition region. The red trace uses a smaller cap and produces a further damped response (one that may work better if proximity to the walls is needed without a strong bass lift in the 50-60 Hz area), and has a few dB more output in the mid 30's.

For example, a relatively "normal/optimal" ported enclosure for a single 26W8867 works out (using the real, not factory T/S parameters) to be in the range of 65-85 liters. For greater voltage sensitivity, you could use the 4 ohm version. But you'd just have a single driver, so while a well designed ported enclosure will up the bass extension an the output at the LF corner frequency by 3-6 dB, it doesn't help the upper bass or midrange output.

This is an experiment to try something a bit different, see if we can't get a satisfactory bottom end with a much smaller net enclosure. The 26W12867 were a special at Madisound at half price, so while the experiment is expensive, it's not hideously expensive. Total net LF enclosure volume per side is just 56 liters.

Thanks for the detailed explanation. So, there are some other advantages other than just a smaller box. Looking forward to reading how the whole speaker comes together. Since this is and "Extreme" project, 2x SS 26W per side is not prohibitive (especially when you consider the deal you got) as you could have used Accutons. Or even 4x SS per side.

[Mark K]

Jon- I'm not quite up on all the terminology. "Parts Express cabinets via the Borg". Borg??

Looks like a real nice design. :T

Thanks.

Russ

Oh, you're so assimilated...

[mkc]

Hi Jon,

Sorry if it's a bit off-topic and dragging you away from speaker-camp. I have a question regarding your distortion measurements. Judging from the the plot, you measure quite close or at least with a long gating time. Is that correct?


Best regards,
Mogens (who has a DW744XP, which about the only thing you can get around here)

[JonMarsh]

Distortion measurements are done several ways; the software I use can (Fuzzmeasure) take any speaker measurement and turn it into a distortion measurement.

The plots for the Scanspeak W26 were done relatively nearfield (4-6 inches, as I do when doing a "dedicated" distortion measurement (keep in mind I have an ACO Pacific instrumentation mic with 200V power supply; it has a lot of headroom). This sort of measurement I do with a relatively slow sine chirp sweep and in the convolution to impulse response, a long gating window (200 msec). Because of the nearfield measurement point, there is almost no impact of baffle step, and the result is very similar to an IB measurement, though with some affect on the response above 2 kHz (which for 10" woofers is not too important... )

The measurements of completed systems, not just drivers, are done using the system measurements, which are typically done at 1 or 2 meter (small two ways at 1 meter, larger systems at 2 meter) and using a 100 msec window in most cases. Same SPL measurement for a completed system (Ardent, for example) can be used for distortion plot.

[CraigJ]

By "Borg", I mean Star Trek Borg, which would assemble things out of existing bits and pieces that were once other things-

I thought you meant BORG, as in Big Orang Retail Giant. No wonder I couldn't find the cabinet at Home Depot.

Hope camp is going well and happy birthday to the Arvos.

Craig

[benchtester]

I thought you meant BORG, as in Big Orang Retail Giant. No wonder I couldn't find the cabinet at Home Depot.

Hope camp is going well and happy birthday to the Arvos.

Craig

That name will stick. I will just have to explain to the wife what I mean when I say I going to do battle with the BORG.

(At checkout time, in particular, I always ask myself "why, why do I come here"?

[Russ_L]

[QUOTE=JonMarsh]It's just my lame attempt to be funny. :W By "Borg", I mean Star Trek Borg, which would assemble things out of existing bits and pieces that were once other things-

Thanks Jon. I guess I'm not up on Star Trek either but I loved Back to the Future. :W

Russ (hoping to retire this year and start making sawdust)
:T

[JonMarsh]

Not up on Star Trek? Well, you have some fun movie watching ahead of you, should you chose to go down that path when you retire and start making sawdust! I'm jealous of those retired or retiring, all the time they have for stuff like this.

[JimS]

Hope camp is going well and happy birthday to the Arvos.

Craig

Good excuse for some cake!

Craig - you must be up to v12 or 13 by now . . .

[CraigJ]

Good excuse for some cake!

Craig - you must be up to v12 or 13 by now . . .

Close, but let's just say the Arvo and I share a special day in life so it's easy to remember.

I may just take the tweeter/waveguide from my Phoenix clone, add the midrange from the Isiris Jr. and try your Modula Xtreme "active". How's that for an April Fool's speaker.

Craig

[JonMarsh]

Cake? That's a good idea! Less calories than Margarita's... easier on the liver

OK, I haven't been sitting around twiddling my thumbs, UNFORTUNATELY, I made the mistake of looking at my personal emails and got some urgent support requests from work that tied me up most of yesterday. But still things are moving forward- now it's time to see if I can whip up a junk box crossover quickly to test out the LspCAD design I've put together- I've been out to my off site storage and gone through my parts collections, it's looking good, as long as I setup CLIO to be my computerized LCR meter.




The big dip at 175 Hz is a low frequency room issue at that measurement position, but I didn't want to pull the mic all the way back to my normal listening spot, as that would allow even more reflections in other parts of the band, which for the purposes of design wouldn't be addressed at this point.



The idea is to get something roughed out and do measurements with the crossovers in place on one system ASAP, see what fine tuning may be necessary to the concept. Also to listen to it. :yesnod: I expect to need to do some tweaking because the mids won't hold up that well off axis above 5 kHz, and this will impact the overall level off axis; I may need to bump the tweeter a little bit on axis in the 4-7 kHz area to smooth out the power response.

Funny, I just noticed now that the tweeter and woofer alignment seem just about perfect with the midrange- the target functions was a Duelund with 900 Hz center frequency, and that's exactly where the tweeter and woofer are crossing over with each other. I should have been checking that when working on the network and looking at the final SPL response, but I was more fixated on the midrange curve and the overall voicing with a slight down tilt. The phase stack up worked out well for all drivers; having the tweeter offset by the waveguide helps nicely.

[Face]

What do you estimate for their efficiency? 90db w/o BSC?

[JonMarsh]

Estimating the sensitivity might not be easy to do- one reason I measured both woofers separately is because one is boundary loaded at low frequencies to a greater extent (due to the proximity to the floor). That one has less sensitivity to the room interaction and floor bounce.

I expect the sensitivity before BSC to be somewhere around 89-90 dB, just how much BSC is really dialed in is not clear- the mid, for example, has a fair amount of amplitude cut, but it's 94 dB/2.83 VRMS in the upper midrange. I'm wacking it down a bit, but not as much as you might think because the Duelund response profile is partly taken care of by baffle step and diffraction effects- the electrical XFR function feed is pretty flat between 300 Hz and 2 kHz.

I've got a "special" set of back panels made up so I can work the midrange and treble crossovers external during development; then once everything is wired up and finalized, the "normal" panels will be bolted in, probably epoxied, too. The permanent ones are reinforced a bit more also.

[spadez]

Sorry for bumping an old thread, but I thought it was more fitting to put this here rather than hijack one of your newer threads.

Are the Modula XESO TMWW's at a stage where you are certain of the drivers that will be used, or would further testing be necessary?

Absolutely no rush, I was just wondering since you seem to have done a variety of tests recently and wondered how they came out.

[JonMarsh]

Your answer is in post #329 in this thread, posted March 14. :W

[spadez]

Sorry, I did read that, but I just wanted to make sure. Without trying to beat a dead horse here, can I just confirm that these are the key driver components needed for the Modula Xtreme SO and it is at a point where I could go forward and purchase these parts?

For a left and right channel I would need:

2x ScanSpeak D2608s
2x Vifa NE180W Mids
4x Dayton RS270 Woofers
2x MCM H65 Waveguides

[JonMarsh]

That is correct. I'm going to finish construction and testing on the Xtreme version before the SO, but based on driver measurements I see no problem- in fact for now I'm using the D2608 in the Xtreme version.

[Juhazi]

Easter thoughts,
Jon, thank you for your contributions to the art of speaker diy. But I'm a bit worrid about how do you feel about your disciples? Some are already buying parts for XE versions when even you haven't heard more than tone bursts and pink noise coming from them! Hope that you can manage with that better than the guy 'bout 2k years ago...

Juha
(Not meant to offend anyone)

[Russ_L]

Wow

Just looked at the cost of the drivers alone - $1,385 per side using the 4867 woofers. I could not find the cost for the 12867 woofers or the waveguide for the tweeter.

Now I know where the Xtreme part of the name comes from.

Still looking good though as the design does not require a lot of sawdust. The Modula part of the name is certainly a big help in that regard. :T

Still looking good Jon.

Russ

[JonMarsh]

Actually, he's talking about buying parts for the SO version of the Modula Xtreme. The Modula MT XE is the small two way in it's own thead- for which I removed these off topic posts and put them where they should be, in the Modula Xtreme thread.

But of course, you have a point- though I've published a preliminary network diagram for the "standard" version of the Modula Xtreme, as well as pictures of a CAD model, that's not enough for someone to build the SO version (different lower cost drivers) unless they're reasonably capable at DIY and have some measurement capabilities.

And I could be hit by a car while riding my motorcycle at any time, or I could be in a plane that goes down on business travel (unfortunately I do fly regional jets frequently- some of their pilots have pulled some real boners and that's why we've had some of the accidents we have like the one near Buffalo NY)- or I could drop dead of a heart attack next week when my boss tells me he wants me to move to the East Coast to be in the same office as he is- who knows?

You should probably discuss that with Spadez- I would worry for him and particularly be concerned if I were running a business and compensated in some way, and didn't follow through or wasn't able to follow through- but this is just a hobby affair here- everything is done at one's own risk, isn't it?

That's why we don't usually recommend people diving in until a design is fully published, and preferably reviewed by others- note that my Modula MT XE design is not in Ryan's list of recommended designs yet- it may never be, if no one else hears a set somewhere, and so far there's only one pair in existence.

And actually, no tone bursts or pink noise were used in the testing of those drivers- far too crude! :naughty: :W

[JonMarsh]

Just looked at the cost of the drivers alone - $1,034 per side using the 4867 woofers. I could not find the cost for the 12867 woofers or the waveguide for the tweeter.

Now I know where the Xtreme part of the name comes from.

Still looking good though as the design does not require a lot of sawdust. The Modula part of the name is certainly a big help in that regard. :T

Still looking good Jon.

Russ

Well, for a "normal" build you'd use the 26W/8867; the 26W/12867 means the impedance isn't quite as low in the mid bass. But I agree that doesn't help the price any... that's why the SO version as a option with RS270's and the Vifa NE180W-04 makes sense on a budget. Though the change in the drivers won't change the crossover topology appreciably; of course, that's some thing that can be addressed to some extent by component selection, skip the boutique caps, but inductors there's not really any way to save.

[Bear]

Jon - I'd love to hear more details on your thoughts in switching somewhat mid-stream from the ER18NX to the NE180. Looking to give the new kids a chance or did you find the distortion and/or FR to be significantly superior? I saw your measurements in the Vifa thread, and they were impressive, but the ER18 isn't too shabby either, so I'm curious what, if anything, drove the change.

[JonMarsh]

IMO, the NE180W has the edge considered as a pure midrange- a more extended top end (less phase shift in the region of interest, though we deal with that in the Modula MT crossover), and lower distortion in the midrange and presence region. So, for a pure three way, not a 2.5 way, I think it makes some sense, and since I bought a pair and they actually test out OK for the intended application, then for an SO variant for those on more of a budget, I think it makes sense.

Additionally, the NE180W has more sensitivity, which means more freedom in crossover design.





Very low distortion for this type of driver in the upper end, due to the low inductance and low inductivity modulation- that's more important I think for a midrange used above 300 Hz.

[Bear]

Thanks! Looking at the curves on the same scale, the superiority in the 300Hz and up range is definitely evident.

[Russ_L]

Well, for a "normal" build you'd use the 26W/8867; the 26W/12867 means the impedance isn't quite as low in the mid bass. But I agree that doesn't help the price any... that's why the SO version as a option with RS270's and the Vifa NE180W-04 makes sense on a budget. Though the change in the drivers won't change the crossover topology appreciably; of course, that's some thing that can be addressed to some extent by component selection, skip the boutique caps, but inductors there's not really any way to save.

Hi Jon- well I was trying to get a heads-up on cost. I have an extensive multichannel SACD collection so I’m looking at five :roll: Modula Extremes. I was thinking about five Statement Monitors and an infinite baffle sub prior to your thread about the Extremes.

I even considered Jed's Tombstones at one point. Wish the basement was finished already (13 x 22 x 7.5) so I can just pick a speaker design and go with it! But like everything else in life, things get in the way.

Russ

PS- your Modula MT MKII pdf file was excellent reading and gave insight into the superb effort that went into the tweeter / midrange head design. You're to be commended for your fine work.

[JonMarsh]

Hi Jon- well I was trying to get a heads-up on cost. I have an extensive multichannel SACD collection so I’m looking at five :roll: Modula Extremes. I was thinking about five Statement Monitors and an infinite baffle sub prior to your thread about the Extremes.

I even considered Jed's Tombstones at one point. Wish the basement was finished already (13 x 22 x 7.5) so I can just pick a speaker design and go with it! But like everything else in life, things get in the way.

Russ

PS- your Modula MT MKII pdf file was excellent reading and gave insight into the superb effort that went into the tweeter / midrange head design. You're to be commended for your fine work.

Thanks for your very kind words- glad you enjoyed the read! Part of my "day job" as an engineer is writing technical papers and magazine articles, so it was fun to take that approach for a DIY project. Expect to see more like this soon.

[BeerParty]

...or I could drop dead of a heart attack next week when my boss tells me he wants me to move to the East Coast to be in the same office as he is...

Ouch! I think us East Coast readers just got slammed! :W