Modula MT-XE - You didn't ask for it... it's coming anyway

[JonMarsh]

Just a New Year's Eve teaser- at least the last of the crossover parts (cross fingers) "hit the dock" yesterday, plus those for the TMM version.

Well, here I am today doing all kinds of responsible stuff like cleaning and organizing, instead of working on speakers, so the devil in me decided I had to do a small teaser post....

I will not be doing a long build thread, but am preparing a PDF for download detailing everything- DTP is less hassle and work than posting so much material on a forum.

The heart of this project is mating the SS D2608-9130 to the good ole MCM waveguide. I could tell it would be a bit tricky because of the shape of the tweeter mounting plate.



The solution I chose was to create an RTV seal filling in the bevel gap, and to grind the rib plates on the waveguide appropriately.




The waveguide was milled for the correct opening on my router table to a total height of 1-1/4"- and I mean exactly 1-1/4", to a 1/64" or better tolerance. A backing plate of 1/4" MDF is used on the back of the front baffle; of course, the front baffle rebate is critical, too.



As I had some nice LBL scraps around from another project, I made the tweeter mounting plates from that material- about 20% harder and stiffer than maple, it should provide a solid "launch" platform and secure the rear of the waveguide. These were actually fabricated from two narrower pieces that I had to glue edge on with Titebond 3, roughly down the centerline of the tweeter.

The interior front walls and back are lined with Whispermat 3/4" single layer. Crossovers will be mounted on the back side walls. The system is ported, tuning in the upper 30's, with 7" long 2" Precision port.





The first system is spoken for, I've tested a TMM version that led me to develop a TMWW version. Rock and Roll Hootchie Koo? :B


Updating the first post to include the PDF link since the project has been completed. This thread wandered all over the place- save yourself some time if you wish and download and read the PDF for all the core details.

Note this is now known as the Modula MT XE, to better reflect the nature of what it is and the nature of the build- XE = Xtreme Edition.

Modula MT XE PDF

[numberoneoppa]

Sweet work, Jon. Looking forward to the .pdf.

[parodielin]

Wow, Happy New Year's Eve, subscribed and look forward to it...

[Bear]

Looks great, Jon! Given the increased CTC spacing from the waveguide, will the TMM be an over-under arrangement for the woofers, or a traditionall TMM?

Happy New Year!

[evilskillit]

Figures you would do this literally a week after I order the parts for the Zaph Waveguide TMM. Oh well I have to believe that the WG TMM will be awesome anwyays and that I'm not missing anything, otherwise that $600 hole in my wallet might hurt a bit.

Cant wait to see how this design turns out. Don't know if I'll ever build one having already started on the alternative, but I'll keep the PDF and stare at it wistfully from time to time.

[JonMarsh]

Zaph's is a good design and certainly a big part of the inspiration for this one- that and my older Isiris project from 2-3 years ago. You'll get a lot of pleasure out of it, I'm sure!

[parodielin]

For people without router table (plunge router only) and, of course, limited wood working skill, would you recommend wait for the non-waveguide version or take the challenge?

I read it somewhere that if I screwed the waveguide implementation precision, it will be screwed...

I guess I can always fall back to the non-waveguide version since it's not that expensive to get two waveguides...

Zaph's is a good design and certainly a big part of the inspiration for this one- that and my older Isiris project from 2-3 years ago. You'll get a lot of pleasure out of it, I'm sure!

[JonMarsh]

Looks great, Jon! Given the increased CTC spacing from the waveguide, will the TMM be an over-under arrangement for the woofers, or a traditionall TMM?

Happy New Year!

I think it will work best as a traditional TMM- because of the offset from the waveguide, even the MT should be fine with the waveguide on top (it's just what people are used to looking at, no?) The crossover lobe looks to be very horizontal even with the low order crossover without playing phase tricks in the crossover area.

Now, the "cheesy" thing I'm doing to make this easy to throw together quickly, is that I'm mating two of the PE 0.75 cu ft enclosures (the boxy ones, not the MTM ones) to create the TMM- the upper one will have the TM, the lower one the 0.5 woofer located near the top to minimize the CTC spacing of the two midwoofers. I think I have a workable concept for doing that in an esthetically acceptable manner.

In fact, the TM cabinet's shown above will go into that configuration, I think, because the recipient of the MT version wants cherry- of course, we just happen to have a set of pristine NOS 0.75 cu. ft Cherry PE cabs in the warehouse... need to prep those once the final cabinet tests look OK.

For this kind of design, I'm more interested in "rapid prototyping" than building an elaborate custom enclosure- what other constructers want to do, that's up to them.

This same approach will be followed for the Modula Xtreme, if the early LF tests work as expected. I have things I need to be doing with electronics, so I'm trying to figure out how to optimize my design productivity- I don't see having the time for another Ardent level project this year!!!

[chasw98]

I seem to remember when the original Modula MT was conceived, you asked to be taken out back and shot if you ever do another 2 way with a small woofer. Admittedly this is using a waveguide so the judge might grant some leniency for that point but you are walking a fine line!
Chuck

Quote from Modula MT thread in 2005......

Keep in mind, I do consider this to be, in some regards, a collection of compromises. I'd probably rather have the network of the Modula MTM, all things being the same- but this IS markedly less expensive, should fit in the smaller enclosure, etc. Hopefully, it's the right set of tradeoffs.

And Hank, I promise, on a HUGE stack of Bibles, that this will be absolutely the LAST 7" two way I design...


this year.

[JonMarsh]

I seem to remember when the original Modula MT was conceived, you asked to be taken out back and shot if you ever do another 2 way with a small woofer. Admittedly this is using a waveguide so the judge might grant some leniency for that point but you are walking a fine line!
Chuck

Quote from Modula MT thread in 2005......

Keep in mind, I do consider this to be, in some regards, a collection of compromises. I'd probably rather have the network of the Modula MTM, all things being the same- but this IS markedly less expensive, should fit in the smaller enclosure, etc. Hopefully, it's the right set of tradeoffs.

And Hank, I promise, on a HUGE stack of Bibles, that this will be absolutely the LAST 7" two way I design...


this year.

I've been called out on that quote a couple of times already in the last week or so... sigh... some of you guys have long memories!

Unfortunately, not all my friends or "family" can handle line arrays or Ardents or whatever... How about we pretend it's really a waveguide TMM design, somewhat cadged from John Krutke TMM with different drivers, which let's me off the hook for designer responsibilities. Then, I devolved it for a select audience (my ex's oldest sister and her son) to use in their family room system, where a very specific size target existed (the NeoD CC's that Scot has and loves would be too big).

This new version of the Modula TM is lower distortion at the frequency extremes and has a somewhat simpler crossover - (from me- can you imagine? But the TMM isn't simpler, at least not the perfectionist version), compared with the Modula MTM, it's most comparable predecessor in my work.

Because of the complexities of the waveguide aspect of the build, I don't expect these to be popular, and I will publish an MT version intended for inverted positioning (woofer above) with conventional usage of the D2608-9130- that's already designed, though not completely finalized.

So, let's face it- I'm doing these projects more for me, others may find one of the many other variants of this type of thing better suited to their requirements.

So, Hank and Chuck, where's this year's stack of Bibles? I guess it will be time for another oath soon, but this one I'll try to do better keeping - you got to admit staying clean and sober from 7" MT's for 5 years isn't bad...

[JonMarsh]

For people without router table (plunge router only) and, of course, limited wood working skill, would you recommend wait for the non-waveguide version or take the challenge?

I read it somewhere that if I screwed the waveguide implementation precision, it will be screwed...

I guess I can always fall back to the non-waveguide version since it's not that expensive to get two waveguides...

You know, it's not difficult at all, IMO, but it would require having a basic router table, and making a very simple jig that's nothing more than a mounting plate for the waveguide (doesn't need to be rebated) and two rails to space it from the table- I'll include details and pics in the PDF of course.

The rest is just a little work with black RTV, waxpaper, and a small paring knife (using the inside lip of the tweeter plate as a guide- no skilled labor here). If you've ever done any model construction, for example, it's trivial.

I think, considering the difference in effort and cost, it's well worthwhile. But if you don't have a basic router table or table saw that can implement a router table, I can understand one might not want to go the additional expense. That said, I think making the extra effort will definitely have rewards. :W

[evilskillit]

Hrm, I'd be curious to know how you routed the waveguide down since I still have to do mine. I bought 4 since they're only $11, just incase I screw up 1 or 2

I'm planning on hacking off the brass threads with a hack saw. Then screwing the waveguide face down to a board. Then I'm going to glue together a little jig that will look kind of like a barbie kitchen table with a big hole in the middle of it. I'll put that over the WG, drop the router cutting bit through the hole and move it around till I've milled off enough.

Just like Collo shows us on his web page.

http://www.subwoofer-builder.com/milling/index.htm

Did you have an easier or better method? And FWIW if I messed up the first 2 I was just going to take the second 2 to a machine shop and ask them to do it for me.

Oh, and finally, you say you're doing this more for you than for the community but from what I've heard from people who built the WG design and from the measurements I've seen if this design doesn't end up being very popular I think it'll be a bit sad. Granted when trying to pick my next upgrade I overlooked the WGs a lot as a 5 year old, sort of bland looking design that didn't attract me at all. Then I realized that they're relatively insensitive to room issues, which is great since my listening room is too small. I couldn't use Statements or the ZDT3.5 because my room just isn't long enough. But I did want something a lot bigger and more dynamic than the bookshelves I had right now. Then given the super low distortion in the mid range, the sensitivity and the forgiving room placement issues I think the WGs will be my perfect speaker for a while. I bet they would be for other people if anybody would give em a chance.

I wonder if anybody on here with access to a CNC machine would be interested in doing a buy on those WGs, machining them down and then reselling them for a small markup + shipping or something... anywas, awesome design, can't wait to see how it ends.

[JonMarsh]

NOT the way I do it!!

Any kind of small router table and a simple fixture looks a LOT easier to do than the pictures at that link! :W

I'll post pictures in the PDF, it's really pretty simple as long as you have a basic router table of almost any kind.

And I do think the waveguide has some significant benefits- up to 10-12 dB dynamic range extension and distortion reduction, plus some dispersion control...

It's just been something I've wanted to do for the last couple of years, and the confluence of available drivers and a family need just made it the right time to do it- the waveguides have been sitting around milled for a couple of years!!

[frascati]

It's really a shame that difficulty of waveguide implementation for prosective builders limits the incorporation of these in projects available on the web. When Zaph first posted his TMM five years ago I remember being very very impressed with the look and the write-up. His commentary on the benefits of waveguiides in that project seemed to signal the beginning of a fertile branch of projects. But even Zaph never revisited the concept. I was always hoping that a TM waveguide design would come along using really nice drivers. I can only assume that it was that difficulty in the build for the average diy'er that explains the scarcity.

I'm much more confident in my woodworking skills than my electronic skills, so I my enthusiasm for this may differ from the average member here. The waveguide mounting poses no obstacle for me, but I could never dream of doing any of the crossover design on my own. Thank you so much Jon, and Zaph, and all others for contributing such wealth to diy audio.

I'm VERY much looking forward to this design. The preliminary choice of drivers and the waveguide design seem to be the answer to a few of my prayers. You mentioned that the TM might actually end up with a relatively simple crossover. Is it possible to roughly estimate the cost of this project? (I hope that question is not inappropriate here. I'm new here. But I'd hate to fall too in love with this particular design if it's going to end up out of my reach)

And to address that problem of builders using waveguides... I saw this question come up some time back in another waveguide thread but don't recall what the answer was. There is plenty of comment, documentation, and measurement that supports a benefit to utilizing waveguides. Why haven't any of the tweeter manufacturers by now offered waveguides as accessories to fit at least a few of their more popular lines? I don't mean this as a 'wouldn't it be nice if" question, but more to understand if SEAS, Vifa, SS, Peerless, Morel, et al, believe that there is any merit to waveguide mounted domes. Seems like a bit of disconnect somewhere.

[evilskillit]

Well seas does offer the DXT which is a sort of waveguide loaded tweeter. But the WG isn't very big and its got diffraction points, which is a bit weird.

I think the main reasons are mostly cosmetic, most people won't care for the look of the big WG. Also you can't fit it on a real small narrow speaker like The Blades or a little desktop computer speaker. I think those are the main reasons. That and theres no prescident set, nobody else has done it first to show that its a safe, money making proposition. It would be nice to see more tho. Especially with flat backs so you could just screw the tweeter right into them without having to do all of these woodworking sommersaults to get the tweeter stuck to the WG.

[frascati]

No accounting for tastes eh? I actually think the waveguide in Zaph's WG TMM
contributes to one of the sleekest looking speaker designs I've ever seen. It actually brings a sophistication to the look; an aesthetic detail beyond what most would expect from a DIY speaker. Professional? Thumbs up from me anyway.

[Kidsrapain]

Me to Zaph's wgtmm my next speaker just wish I could upgrade the woofers to something more modern I don't have what it takes to do it myself.

[evilskillit]

Everybody says that, to which Zaph always says "Feel free to do so, if you know how" However I think I would say don't under estimate the CA18RNX, it isn't new and cutting edge but for $75 it still kicks a lot of butt in its price point. Other than maybe the reed cone, which isn't THAT much better, I'm not sure what else you'd want to use in the price point. You can't use metal cone drivers like the Dayton Reference drivers with the 2nd order crossover, and unless you needed to save money I don't know why you'd want to, the CA18RNX seems like a better driver.

[Kidsrapain]

I've done two of Zaphs and a lot of others and Zaphs is the ones I use the most, so I have no doubt in that I will be totally happy with it (as is).I guess it was my attempt to put my 2 cents in LOL I read a post where you could substitute CA18RNX (H1215) for the P18RNX/P (H1350) but I would not if not in-less passed by him first.

[Mark K]

Hey Jon,

What xover slopes and Fc are you shooting for?

[Mark K]

It's really a shame that difficulty of waveguide implementation for prosective builders limits the incorporation of these in projects available on the web. When Zaph first posted his TMM five years ago I remember being very very impressed with the look and the write-up. His commentary on the benefits of waveguiides in that project seemed to signal the beginning of a fertile branch of projects. But even Zaph never revisited the concept. I was always hoping that a TM waveguide design would come along using really nice drivers. I can only assume that it was that difficulty in the build for the average diy'er that explains the scarcity.

I'm much more confident in my woodworking skills than my electronic skills, so I my enthusiasm for this may differ from the average member here. The waveguide mounting poses no obstacle for me, but I could never dream of doing any of the crossover design on my own. Thank you so much Jon, and Zaph, and all others for contributing such wealth to diy audio.

I'm VERY much looking forward to this design. The preliminary choice of drivers and the waveguide design seem to be the answer to a few of my prayers. You mentioned that the TM might actually end up with a relatively simple crossover. Is it possible to roughly estimate the cost of this project? (I hope that question is not inappropriate here. I'm new here. But I'd hate to fall too in love with this particular design if it's going to end up out of my reach)

And to address that problem of builders using waveguides... I saw this question come up some time back in another waveguide thread but don't recall what the answer was. There is plenty of comment, documentation, and measurement that supports a benefit to utilizing waveguides. Why haven't any of the tweeter manufacturers by now offered waveguides as accessories to fit at least a few of their more popular lines? I don't mean this as a 'wouldn't it be nice if" question, but more to understand if SEAS, Vifa, SS, Peerless, Morel, et al, believe that there is any merit to waveguide mounted domes. Seems like a bit of disconnect somewhere.

There are tons of horn and waveguide projects out there. Unfortunately, they fall mostly into two camps, pro audio, and cr*ppy honky diy attempts. Sometimes a bit of overlap :

So horns and WG's have gotten a bit of a bad rap in the audiophile community, or, at least some elements of the audio community anyway. The problem is a bit compounded by the horn cause being taken up by the hi efficiency, 1 watt, western electric, 12ax7 rotary phone crowd...

As far as the major manufacturers-horns add manufacturing complexity and cost, as well as size, and the general public is not clamoring for them-they don't quite get the benefits. Hard to fit a dxt into a B*se cube...

Still, I do see a market for a 6-8" waveguide that could fit standard Seas, SS, and Usher motors with the appropriate shim.

Zaph, instead of another driver, how about designing a waveguide as your next project!!!

[JonMarsh]

Hey Jon,

What xover slopes and Fc are you shooting for?

Roughly LR2 at 1700-1800 Hz.

[Mark K]

Roughly LR2 at 1700-1800 Hz.

That should be nice. With a larger lens and lower xover point, it has the potential to have even a smoother power response that the ER18DXT.

[JonMarsh]

That should be nice. With a larger lens and lower xover point, it has the potential to have even a smoother power response that the ER18DXT.

I do have my fingers crossed on this one- should have final test measurements today for the crossover design. Slow work takes time with two sets of cabinets in progress, one for TM, one for TMM.

Plus this season is when I do my "spring cleaning", as I never have time in the spring!

[JoshK]

I wouldn't be that hard for someone who took the time to set up a jig to make a lot of the milled waveguides and then offer them for such projects. Maybe 5 bucks for their time.

[JonMarsh]

I wouldn't be that hard for someone who took the time to set up a jig to make a lot of the milled waveguides and then offer them for such projects. Maybe 5 bucks for their time.

Is that a hint Josh? I suppose it could be done- plus shipping.

We'll look into that possibility after the project is done- I could turn these out pretty quickly... might need to be $10, considering the time involved. Inflation, you know!

[---k---]

Jon,
Based on your availability and the number of projects you have in the hopper, I suggest you sell your jig to Josh. He can then make a killing selling the waveguides for $5.

[frascati]

Is there enough meat left in the throat of the waveguide to support the weight of the tweeter?

Use the tweeter's (unattached) face plate as a template along with a centering guide of some sort. I am assuming, just by the picture, that the 1.25 height on the guide results in a exactly the ID at the throat to match the tweeter faceplate aperture.

Cut two aluminum discs matching the OD of the tweeter's faceplate and each approx half its thickness. Cut holes in the centers matching the throat ID. Perfect diameter or concentricity of the plates is not a worry at this point... just an accurate ID hole in the middle.

You have a milled waveguide, the tweeter faceplate, and two aluminum discs with apertures of identical ID. Now we need a dowel, tube, pipe, whatever, with OD to match that ID to use as an alignment guide. Let's just say we got very lucky and found one off the shelf at the hardware store.

Using the alignment guide, center one of the discs on the milled face of that waveguide and (forgot this step... this disc should by now have six counter sunk holes circling the aperture, and four more holes outbound to match the mounting holes of the tweeter faceplate) score the plastic though the screw holes. Remove alum plate and drill pilot holes in the waveguide for tiny coarse thread deck screws or appropriate.

Now use the alignment tool/tube to center the other alum disc under the tweeter faceplate and score all eight mounting holes in the alum. Centering punches are really handy for this but if you don't have a set, just be very very exacting.

mount one disc with six screws to the waveguide, and then mount the other disc to the tweeter in place of the original faceplate. Now they just mate together.

I know I've overexplained this. It's only about an hour's worth of labor. Pics would have shown that it would be a very simple method of mounting the tweeter if the waveguide is robust enough to support it.

[JonMarsh]

There are probably many ways to skin the cat. I've been sticking to wood based solutions instead of going to aluminum, as though I have means to work on aluminum just fine, including carbide metal blades, that raises the bar a bit for most folks.

The thing is, once the basic design is published, anyone interested is free to innovate on the construction method as long as the acoustic properties aren't disturbed.

Note that because of the VC assembly and machining of the back of the SS tweeter plate, replacing it with a flat plate piece of aluminum is most likely not an option.

You can see that from this pic here, where I'm forming the RTV gasket to the waveguide using wax paper as a separator.... KISS.




Remember, it's the other moderator that is putting the "No" in "InNovation". :W

[jkrutke]

Zaph, instead of another driver, how about designing a waveguide as your next project!!!

I've already looked into it. I didn't have to look very deep to see that new tooling for injection molding would cost so much that I would never get a return on the investment unless I sold a few thousand of them. (not likely)

The other option is one-off lathe machining, basically what Troels did with his waveguide design. Still too expensive though - while there is some setup time savings for manufacturing a batch of these at one time, it's still primarily a slow operation. As far as production speed, time=money.

There was another waveguide kit manufacturer in Europe somewhere making bolt-on waveguides. I have not been able to contact them for an order of them and I've since lost the link. I am not talking about the Monacor WG300, which generally only fits the WT300 tweeter due to the extended lip on the inside.

So, continuing to hack up MCM waveguides seems the way to go. It's not too hard to hack off the threads and make a milling table from scrap wood.

[CraigJ]

Jon,

I see the future and this is going to be a popular build. Milling the waveguide is fairly easy. I even used a drill press and Forstner bit (after the metal threads were hacked off).

This question could be a little too late, but have you seen the QSC HPR122 waveguide that Josh said is similar to the DDS model? The QSC waveguide is in the center. Thanks for the pic Josh, and can't beat the price either.

Oh, and if you take the back off the box, you get something like this :

[Face]

Another interesting waveguide: http://www.peerlessaudio.com/products_details.asp?id=50

[benchtester]

I've played around a bit with waveguides. I found the most immediately gratifying method is to back-mount the tweeter and fill the step with modeling clay. Then take a chirp measurement and rework the clay.

Significantly, I found that my AirCirc 6600 was best with a shallow waveguide like the MCM. But a Dynaudio D260 (nearly hemispherical dome) was better with a steeper throat, more like Gedlee's waveguides.

So my note of caution is that the waveguide shape may be significantly different for various dome designs. I am cautiously optimistic that the MCM is a good match for the HDS.

[JonMarsh]

Jon,

I see the future and this is going to be a popular build. Milling the waveguide is fairly easy. I even used a drill press and Fostner bit (after the metal threads were hacked off).

This question could be a little too late, but have you seen the QSC HPR122 waveguide that Josh said is similar to the DDS model? The QSC waveguide is in the center. Thanks for the pic Josh, and can't beat the price either.

Oh, and if you take the back off the box, you get something like this :

I've seen the QSC and considered it as a possibility for 1.4" drivers, but haven't been working further in that direction. 10" diameter is too big for this kind of project, probably unneeded.

To some extent, it's about trade-offs, I've got to see how this bunch works out. I've done the MCM with the Accuton C13N, it might have been usable, though the tweeter construction made that a real PITA, and it was ultimately discarded partly for that reason.



Certainly ole Willie the Shake was right when he said there's many a slip twixt the cup and the lip- we'll see how this works out.

[JonMarsh]

Jon,
Based on your availability and the number of projects you have in the hopper, I suggest you sell your jig to Josh. He can then make a killing selling the waveguides for $5.

Well, the jig's no big deal- anyone can make that from a little bit of scrap. Just a small MDF plate and two rib spars to lift it off the table.

It's possibly the router table and Woodpecker Quick Lift with dedicated router (mine is with a Bosch that's compatible with a Porter-Cable 7518, don't remember the number) that might be a stumbling block.





Nothing mandatory about the quicklift, but it sure makes changing router bits a LOT faster, and the control over the router bit height for the Woodpecker lifts has to be seen to be appreciated.

[JonMarsh]

More pics, showing assembly details

OK, a few more this morning, these will all go in the PDF in the appropriate places, but it gives some idea of the construction concept.



Rear of baffle, showing 1/4" MDF spacer board glued to baffle and tweeter mount board screwed to baffle.


Same, at an angle. Angle cuts are necessary to clear Dayton cabinet plates with nuts for mounting baffles.


Front Baffle view of drivers.

[Bear]

Looking good, jon! It looks like you are using ordinary wood screws to hold the driver in place with no rear chamfer. Is this not necessary for the ER18s, or is this still WIP?

[JonMarsh]

WIP, evaluating what's necessary- based on the measured nearfield response, the ER18 with this opening size doesn't have any "choke" issues, the frame is pretty open, fortunately. The attachment screws are fine thread drywall screws, "technically", which I prefer to wood screws. They get a decent bite in MDF with the right pilot size. In the LBL material, the combination is excellent- they tighten down to a certain point then "lock" like you were putting a threaded bolt into a metal plate. Love that LBL...

This is not intended to be an unobtanium class build, the TMM build may veer slightly more that direction just for fun with a completely custom front baffle, back fiberglass layup of the waveguide, and some crossover tricks, but I'm trying to be reasonable... sort of. :W

For those curious, the D2608 and waveguide seem to be mating up acceptably well, about what I'd hoped for.



These are curves at 0 deg, 10 deg, 20 deg, 30 deg, and 45 deg. Even the 45 degree sweeps sound pretty good off axis. This is a 50 msec window, so the lack of too much off axis exitation is a positive factor, I think.

[villastrangiato]

Pretty sweet setup on the waveguide mounting - looks really professional! ;x( Probly want to insist in the instructional pdf on wearing a 3M 6800 during the grinding operation if the waveguide is plastic though.....otherwise, the builder will probably get a little more than his daily dose of dioxin intake..... 8O

[JonMarsh]

That's a good point, but then even MDF is an issue-

I use one of the 3M 6300 masks with various filters, they have ones for particulates as well as for volatiles (like lacquer).



OTOH, I don't enjoy doing lots of detailed safety cautionary statements- most of this stuff should be second nature, but I realize in many cases it isn't.

The milling for the waveguide goes pretty easy, and only some touch up with the hand grinder on the spars is needed- very little material involved. Probably more harm potentially from the volatiles from forming the RTV gasket! :W

[LING GOWA]

Jon, isn't that block of wood taking up allot of internal box volume?

[dlneubec]

Jon,

The waveguide results look very good. I'm not surprised, however, since they looked good in the much smaller DIY waveguide in the BaSSlines. Based on my experience, I bet your gonna love this tweeter with that waveguide mount.

If you could post a meaurement of the tweeter flush mounted, sans wavegide, superimposed over these plots, that would really give a more complete picture of what the waveguide is accomplishing.

[JonMarsh]

Jon,

The waveguide results look very good. I'm not surprised, however, since they looked good in the much smaller DIY waveguide in the BaSSlines. Based on my experience, I bet your gonna love this tweeter with that waveguide mount.

If you could post a meaurement of the tweeter flush mounted, sans wavegide, superimposed over these plots, that would really give a more complete picture of what the waveguide is accomplishing.

Something like this?

[Curly Woods]

Something like this?

Which is which John :smackbutt:

[benchtester]

The blue curve is with the waveguide, the "crimson" curve is without the waveguide.

Over all it looks very good. There is a little "waveguide dip" at ~13 khz; but it is modest and would be less noticeable (for me and my old ears) than usual (my dips were often around 9 khz). Also looking at the off-axis curves above, one can see that the dip goes away quickly.

These curves appear to be either raw without a crossover or just one blocking cap for protection. This that a good assumption?