Official Premature Arvo Pärt Picante thread

[JonMarsh]

I'm creating this thread just so I won't continue thread jacking other ones when related topics come up- :roll:


The Arvo Pärt Picante is a very new project (about a couple weeks old!) which has been motivated/inspired by a number of diverse factors.

• Metric Halo LIO-8: my main DAC is capable of a lot more than just two channel audio playback, and with it's fairly powerful DSP front end and 8 main channels, it seems like a natural for an active or partially active speaker system. It's about time I tried that out.
• Earlier this year I bought a full Mamba XDB I/O interface box for the LIO-8, so I've all the physical I/O for the DB25 connectors solved.
• Seas has released the L26RO4Y 10" driver optimized for open baffle- a lot of changes to parameters, spider design, etc. - and at nearly the same price as the original- this represents a new level of performance possible with just a 10" nominal OB woofer.
• I've got a couple of pairs of Scanspeak 18wu-8747t00 that were originally intended just for LF, but some testing has shown they can likely be used up through the mids, say with an LR4 1600 Hz crossover? And their LF performance is phenomenal, due to the underhung motor design and suspension.
• I have three pairs of the Jantzen waveguides, and have gotten nice results with the 6640 in them, but also have a pair of Transducer Labs N26c on the way for testing- SS or Accuton level performance at lowline SS pricing
• I already have a good TMM 2.5 way crossover designed at 1600 Hz with measured data from the 18WU/8747t00 and 6640 - using the Jantzen waveguide on the tweeter
• I have enough Pau Ferro and LBL bamboo and high density birch ply that's phenolic veneered on hand to build something new in an Arvo configuration
• I have been a bit inspired by the web site Eric S put together for the Arvo Part Mk II, made be a little nostaligic for some of the "good old days" stuff (five years ago?!?). The section of Eric's site covering the Arvo was exactly what I would have like to put together, but I usually spend my spare time building speakers, not web sites….

If this doesn't constitute all the planets and stars coming into alignment, then I don't know what does... plus I'm going to have a bit of time off and be spending time in town, as my girlfriend is having a hip replacement surgery, so no travel for us for a while.

I'm cutting wood this afternoon, for the first test article, and some pieces for the final pair. I should probably just lay low on this until we've got hardware and results in hand, but I have a good feeling about it...

Also, I plan to investigate lower cost driver and active crossover solutions with a later test bench build. Possible drivers might be the RSS265HO on the bottom end, and the RS180 for miss; tweeter will likely be the N26c if it pans out regardless; I haven't found anything else of significantly lower cost I'm truly partial to, but this could be a good opportunity for the RS28F, or for me to get to know it!

This has also brought up the topic of lower cost active crossover solutions in digital; the DCX2496 is a known but controversial, perhaps inconsistent solution; a new interesting contender is the MiniDSP products, which seem to be easy to work with and well suited to a DIY approach. Lots to investigate and talk about.

The general outline of the cabinet structure is forming fairly clearly, and I have early sketches and some cut wood (a dangerous combination, I know... a little more simulation work remains to be done).

So, in the spirit of sharing, the basic sketches for front and side profile:





As mentioned, I have simulated the crossover concept from some measured data box mount data, using the SS aluminum Illuminator woofers and the SS 9130 tweeter with waveguide as a "proof of concept". This seems satisfactory in a first pass to establish the passive crossover concept for midrange to highs.





This should by NO means be taken as the finished passive part of the crossover, just a way of verifying the network structure and proof of concept using SS waveguide mounted tweeter with the Illuminator woofers at the desired crossover range (LR4 at 1600 Hz, in TMM 2.5 way)

[dlneubec]

Interesting approach on the bass section. I've been thinking of doing something similar, but with a vertical slot(s), perhaps reduced in size to provide some low end boost as well as the dipole presentation. The good thing about the vertical slot(s) is that the drivers can mount in the normal orientation, rather than up or down firing. Also, if you do a vertical slot, you can stack drivers on each side of the slot (or centered with two slots, one on each edge of the baffle, and easily end up with 4-10"woofers/subwoofers in a bass section that is still under 2' tall. Something you might want to look at. See:

http://www.enjoythemusic.com/diy/0911/slot_loaded_open_baffle_speaker.htm

http://www.visaton.com/en/bauvorschlaege/new_products/grandorgue/index.html

There was a discussion thread here:

http://techtalk.parts-express.com/showthread.php?t=226610&highlight=Nelson+Pass

I assume you are thinking of using the N26C in a waveguide as well? They are pretty big and heavy beasts, but that recatngular face plate, which is flat, may be easier to mount to supporting structure on each side of the waveguide than the more typical round faceplate.

[JonMarsh]

I assume you are thinking of using the N26C in a waveguide as well? They are pretty big and heavy beasts, but that recatngular face plate, which is flat, may be easier to mount to supporting structure on each side of the waveguide than the more typical round faceplate.

Yes Dan, that's the idea. that N26c has a monster faceplate as you note, the mounting holes actually extend past the circle of the waveguide backside. I'm pretty sure this will be an easier job than some of the other waveguide mounts I've attempted. Just have to see how well it actually works; so far the only hard dome tweeter I've been able to get good results, relatively, has been the 6640, duplicating sdl2112's method.

[dlneubec]

Jon,

I believe you've used or tested several different small waveguides and this information is probably available scattered around. I think it would be beneficial to list them here all in one place, along their sources, costs, etc. Your impressions of them would be valuable as well.

Dan

[JonMarsh]

Why a Waveguide?

Great idea Dan, I'll update/edit this to include waveguide background and my thinking in using it in this project; how it should work out, and why.

Probably won't get finished until later this week- getting ready for business travel today.

Why a waveguide?

I've used waveguides and drivers in some other projects and experimented with them individually- why in this one? Why trying the Jantzen? *(which are hard to get hold of- had to order direct from Jantzen in Europe- shipped from their warehouse in Poland). These inputs are not offered as any "absolutes", just as my preferences and directions for hoping to achieve some specific things. Many of you long time DIY'ers are quite familiar with these ideas, but there are always new folks around, and after all, this is just my opinion and direction for this experiment.

• Use waveguide to increase sensitivity and lower distortion in the lower part of the tweeter's range- particularly useful for low crossover points to midwoofers
• Provide increased and more uniform dispersion above 10 kHz, with a gradual uniform drop in level off axis which somewhat mimics the off axis fall of of the frontal response of a dipole speaker. This way some of the tweeter flare can be avoided or reduced, without having a "micro baffle" for the tweeter.
• Provide some acoustic center offset from the front panel, with "luck" coming close to matching the time origin of the midwoofer without additional delay circuits or playing games with the phase response in the crossover region
• The ability to get a near ideal 2nd order roll off with just a series cap facilitiates a simpler crossover AND the use of LCR contouring networks for SPL magnitude correction/flattening
• The Jantzen waveguide is similar in profile to the H64 from MCM. VERY similar. It may be that different developers come to the same conclusions by similar paths.
• Troells has this to say about the Jantzen Waveguide: The waveguide was a new problem, as no existing waveguide would fit the TW034 tweeter. Thus I had to engage a factory dealing with CNC fabrication of everything that can possibly be made on a lathe. A huge 180 mm diameter rod of black POM plastic is stuck into the lathe and in a few minutes turned into nice looking, solid waveguides. No need to fill cavities here with damping material.
  I developed the waveguide for Jantzen Audio, thus proprietary to Jantzen Audio, so please do not ask for drawings or specifications. A waveguide developed for a 34 mm dome is unlikely to perform with other (smaller) domes. To my esperience every dome will require its own waveguide made to suit the dome's shape, diameter, suspension, etc. In short: A waveguide is not just a waveguide.
• I'm not going to specifically take issues with these comments, just saying that it seems the Jantzen waveguide can be adapted to other tweeters successfully; the TW034 requires SUBSTANTIAL modification to it's motor to eliminate resonances, and "as-is" is a less than optimal solution. I speak from both information on Troels site as well as my own measurements of the TW034, with and without the Jantzen waveguide.
• The materials and workmanship of the milled Jantzen waveguide are first class in my opinion- haven't come across anything comparable. Troell's references to filling cavities with damping material is clearly aimed (I think) at the MCM H64. And justified- been there, done that.

Dampened and milled MCM H64


Jantzen Waveguide


My experience is that the Jantzen benefits from a slight backside milling, opening the entry throat by 1 mm and removing the ~1mm vertical wall, so that it's a sharp clean edge. Photo's of that later.


Coming next - waveguides I have used and abused- MCM H65, DDS-ENG-1


BMS 4540 on DDS ENG-1 waveguide - promise and problems






And the problem... a wicked impedance curve. But this is largely a function of the driver, I think....

Interestingly, the DDS-ENG1 is on the current DDSHORN web site, and is one the US Speakers website, with a "NEW" red flag (new version, back in production, or? ) Milling the throat mouth of a fiberglass waveguide would likely be a b*tch, but it is an intriguing thought, considering how low that waveguide works. Hmmmm. Not an expensive experiment to make, compared to some I've done.





And a massive zobel network to match.



Success with H64 and SS 9130











SS 9130 With and without waveguide unequalized



Note constant directivity with consistent drop off sort of tanks in the 2,000-2700 area.


Distortion is very satisfactory in the upper midrange to highs. Might well be better with the right tweeter- SS 9139 was chosen for cost.

[5th element]

I always look forward to your build threads Jon as they tend to be a great lot of fun from all angles. You might want to alter the part number from the L26RO47 to the L26RO4Y in the opening of the thread, just to avoid any possible confusion.

I see you're planning on a W frame woofer section, just like Linkwitz has swapped to in his latest Orion version. I can't really see why you'd want to go with anything else as the opposing woofer motion is quite important imo. Open baffles tend to be quite light and a vertically mounted H baffle with two high excursion drivers can cause the entire rig to shake about quite a bit. Of course, horizontally mounting the drivers should help a lot with that, but having an opposing motion going on too should really cut that down to a minimum.

As the SS drivers are quite capable in their own right, it would be interesting to see how an all OB system would compare to a similar thing, only using multiple subs for the <100hz region. This would of course allow you to minimise the main panel width too for added benefits, but would of course be a completely different loudspeaker!

[JonMarsh]

I always look forward to your build threads Jon as they tend to be a great lot of fun from all angles. You might want to alter the part number from the L26RO47 to the L26RO4Y in the opening of the thread, just to avoid any possible confusion.

I see you're planning on a W frame woofer section, just like Linkwitz has swapped to in his latest Orion version. I can't really see why you'd want to go with anything else as the opposing woofer motion is quite important imo. Open baffles tend to be quite light and a vertically mounted H baffle with two high excursion drivers can cause the entire rig to shake about quite a bit. Of course, horizontally mounting the drivers should help a lot with that, but having an opposing motion going on too should really cut that down to a minimum.

As the SS drivers are quite capable in their own right, it would be interesting to see how an all OB system would compare to a similar thing, only using multiple subs for the <100hz region. This would of course allow you to minimise the main panel width too for added benefits, but would of course be a completely different loudspeaker!

Thanks for the catch on the woof typo- it's updated.

Yeah, there are a lot of different things that could be compared and benchmarked even before a build- in this case, I'm flying half way on intuition and experience, and figuring I can work things out as I go along.

The new version of the Seas woofer has a significantly higher moving mass, so I think the force canceling arrangement is pretty mandatory- no original thought on my part here, just stealing from the best. Because I'm using an active crossover this time, the added complexity in the network is not a problem... I hope!

Might be an interesting read, if embarrassing for me if I pull a real boner! :lol:

Rather than be ultra-methodical this time, it's going to be a race to the holiday to get something up and playing!

[---k---]

Jon, have you see the waveguide that cjd won at diy chicago? Ed is willing to see them for $70and can probably cut what ever profile you want. They seemed to be able to mount an rs28 quickly.

[Bear]

Jon, have you see the waveguide that cjd won at diy chicago? Ed is willing to see them for $70and can probably cut what ever profile you want. They seemed to be able to mount an rs28 quickly.

I thought the RadarCarve they were using was copying an existing profile, not machining a fresh profile from scratch (computer file)? Wouldn't a new waveguide profile need to be created first, and then replicated with Ed's RadarCarve?

[JonMarsh]

Hadn't seen that- is it on HtGuide somewhere, or elsewhere? I saw the write up about the meet on Tech Talk- looks like a very successful meet and a lot of fun for the participants.

[dlneubec]

Somewhere, I've seen Pete's published response profiles for the RS28F in the waveguide they used. They were, if memory serves, easily the best looking I've seen for a dome tweeter. I believe it is about 3" deep and around 8.5" in diameter.

Edit: I was wrong about the 3" depth, that was a different DIY waqveguide. The 8.5" dia. was accurate.

[peepaj]

Jon, you might want to check here for some info on the waveguides.

http://techtalk.parts-express.com/showthread.php?t=226733

and here

http://techtalk.parts-express.com/showthread.php?t=224110

[cjd]

I might be convinced to try some different tweeters in the ones I have along the way, if I can get them smoothed and at least finish-ready. ... Thinking I may target a net 92dB@2.83v with the waveguide...

Dipole, for me, will be dipole all the way up. Got some stuff to make a better frame to mount the drivers together in so I can get more data through the long winter months.

[---k---]

Jon, no post over here yet about them. Just the pe links above.


Bear, I think you are right. I should have said any shape could be copied.


Cud, maybe start with some minwax wood hardener. I think that would work well to seal the surface for anything on top.


J love hijacking a these intended to prevent hijacking of other threads.

[JonMarsh]

J love hijacking a these intended to prevent hijacking of other threads.

Stuff happens...

BTW, wasn't that speaker with the machined front panel at Chiago DIY the one that is becoming a commercial design? I recall a little bit of ruckus about that in the thread at PE.

Heading out to Minneapolis this AM. Last biz trip of the year unless something really bizarre happens during the week. Originally I was supposed to be in Villach Austria this week, but that got cancelled at the last minute, and trip to Minneapolis was moved up. Yay, makes an easier week following!

BTW, Dan, enjoyed your Raal inspired speaker shown at Chicago! I had some similar ideas and a bunch of drivers in boxes and some aluminum tube- no time, and nothing otherwise to show for it!

[dlneubec]

Stuff happens...

BTW, wasn't that speaker with the machined front panel at Chiago DIY the one that is becoming a commercial design? I recall a little bit of ruckus about that in the thread at PE.

Heading out to Minneapolis this AM. Last biz trip of the year unless something really bizarre happens during the week. Originally I was supposed to be in Villach Austria this week, but that got cancelled at the last minute, and trip to Minneapolis was moved up. Yay, makes an easier week following!

BTW, Dan, enjoyed your Raal inspired speaker shown at Chicago! I had some similar ideas and a bunch of drivers in boxes and some aluminum tube- no time, and nothing otherwise to show for it!

Yeah, there was a bit of a ruckus about that design going commercial.

The funny thing about the Contrappeso's (Raal inspired design) is that they started out as a minimalist prototype. built from PCV couplings, that was basically intended as a proof of concept with regard to using the dome tweeter working in that configuration and it just progressed from prototype to a finished design.

I do want revisit that design with some nicer drivers, smaller aluminum mid tubes and maybe something other than a tube for the bass bin. I was playing with the bass bin design and looking at the slotted multiple driver concept sort of like what you are using here, but as a bipole instead of dipole. I'd use something like through slots, front to rear that the drivers fired into, similar to the midrange congifuration. It should be fun!

[---k---]

Stuff happens...

BTW, wasn't that speaker with the machined front panel at Chiago DIY the one that is becoming a commercial design? I recall a little bit of ruckus about that in the thread at PE.

Yeah. Here: http://www.vaporsound.com/ The Aurora.

I didn't get caught up in the ruckus...

[JonMarsh]

Weekly update

Been traveling on business again this week, so just a little time to work on things this weekend-

Have ripped all the Pau ferro for various side panels and other pieces, and started gluing up stuff (epoxy only- Pau Ferro can be a bit oily and hard to glue with normal wood glues).

Pau Ferro dust is irritating and rippling with a mask with good dust control is more than just a good idea! 8O

So far I'm doing all the work on my DeWalt 745 -



It's a very compact 10" table/job site saw, with an excellent fence. It's a rack and pinion system for setting cut width; quite accurate, and dead on 90 degrees. Noisy motor, no soft start. You get used to it. Very accurate cuts, even the pusher stick that comes with it is pretty decent.

HOWEVER, the STOCK blade MUST GO! Mine now has an 80 tooth blade designed for hard woods and smooth cutting. Feed it reasonably slow, and it works like a dream.

This has become the saw I would recommend for those on a budget and with space limitations like me. I still have to use a long out feed table to handle long pieces, like the panels on these speakers, but that comes with the territory.

[Bear]

Retired the BT3k?

[JonMarsh]

Retired the BT3k?

In storage for future requirements. This one is much easier to store and get out, I also did all of the Modula HE and Extreme with this 'un. Just figured it deserved a little credit. The more I use it, the more I like it, especially the rack and pinion fence.

[---k---]

!warning, threadjacking!

Jon,
Don't know if you saw this, but I immediately thought of you, especially since you're currently working on an Active.

http://techtalk.parts-express.com/showthread.php?t=228491

Need Testers/Developers for open-source Excel based Crossover Design Tools

Over the past 6 months I have been developing and testing an Excel-based active loudspeaker crossover design tool. I am at the point that I would like to open up testing and development to other DIYers and create an open source development group. When the tools look like they are ready to go, I will open it up to everyone.

I am looking for a few people with the following:
experience measuring driver frequency responses (and current capability for doing measurements)
general knowledge of active crossovers
DIY loudspeaker design experience
access to a MiniDSP, Behringer DCX2496, or other configurable crossover/delay unit
general knowledge of transfer functions (in s and z^-1) for various types of audio filters is helpful but not absolutely necessary ....
.......
Charlie's Audio Pages: http://audio.claub.net

Of course, you'll likely need to find a windows machine.

[JonMarsh]

!warning, threadjacking!



Of course, you'll likely need to find a windows machine.

A windows machine? Is that something to open up windows in my apartment? What is it, electric driven? Computer controlled?

:roll:

I have Excel, of course. Might not support all the programming stuff equivalently, though Office 2011 is mighty compatible. I do have Windows partitions, otherwise I couldn't run LspCAD.

Currently there are three Windows programs I regularly run- LspCAD, Altium Designer, and SIMetrix. Can't think of any others...

Seriously, thanks for the link and I'll check it out. It could be fairly interesting. I was planning on using LspCAD for working out the combination of active and passive crossovers, though- it supports that kind of stuff fairly well, and I plan to make the transfer function requirements on the active side available in case anyone else wants to go down that path but with different tools.

Christmas is coming, the goose is getting fat, please put a Seas in the old man's hat... :B

[JonMarsh]

Got Woofers?

Man, these are packed very carefully, and I can see why- pretty serious construction for 10" nominal drivers! They make the NS10 Aurasound look pretty light weight in comparison, but that's what Neodumium did for Aurasound.

Beefy....

[5th element]

Now you're getting me excited, I can't wait to see how they measure + speaker porn

[JonMarsh]

'Tis the season to be jolly

And what makes you more jolly than new drivers in house? :B

[Face]

Purdy!

[Dean100]

Wow. Those are some nice looking drivers!

[JonMarsh]

And these are the "new, improved" version, the L26R04Y; four layer voice coil, higher MMS and stiffer suspension, and redesigned spider. Look very similar to the naked eye.

I'm very hopeful, too, about how the illuminator mid woofers are going to work out in this dipole application.





Got some work done on front baffle lay up and the putting the dual 45 degree bevels in the pau ferro side strips yesterday, also a little CAD work.





These cuts with the Pau Ferro are critical only because of my esthetic design choices (possibly questionable!) for the project- as a note to any others, using Maple or some other less expensive and less toxic hardwood would likely be the smart thing to do, but I had the Pau Ferro on hand, purchased at a good price a few years ago, and I have hopes this will turn out interesting looking when it's done. Somewhat dangerous cuts to make, but with a high grade 80 tooth blade and slow steady feed, quite uneventful and completely with out any burn marks or other issues. The DeWalt saw works very well for this, but as I'll have some big cross cuts to make soon, it will be time to bring out the Craftsman/Ryobi saw soon.

Still have things going on at work while I'm on "vacation" and an early morning conference call with HQ. Ugh! Last day for anything work related until after the 2nd!

[Bear]

Last day for anything work related until after the 2nd!

And that may be your best single sentence posted in a while! You've earned the break.

(Now build some speakers for daddy!)

:T


Alright, to contribute vaguely to the topic (or at least to my own knowledge base): it looks like the L26RO4Y aren't just good for dipole applications, but also model really, really well in a standard vented enclosure of relatively modest size (at least in Unibox). It looks like a 1cf box in an EBS-type alignment can get down to an F3 at 30Hz or below. The step response is a pretty terrible looking graph, but then so is the "standard design" -- at least how Unibox calculates it. Any thoughts on using this driver in a more conventional application vs. the original?

[JonMarsh]

And that may be your best single sentence posted in a while! You've earned the break.

(Now build some speakers for daddy!)

:T


Alright, to contribute vaguely to the topic (or at least to my own knowledge base): it looks like the L26RO4Y aren't just good for dipole applications, but also model really, really well in a standard vented enclosure of relatively modest size (at least in Unibox). It looks like a 1cf box in an EBS-type alignment can get down to an F3 at 30Hz or below. The step response is a pretty terrible looking graph, but then so is the "standard design" -- at least how Unibox calculates it. Any thoughts on using this driver in a more conventional application vs. the original?

We're thinking along the same lines- I'm even pondering looking at force cancellation sealed alignments with dual drivers in each cabinet for my baby HT in the bedroom. This would have pretty decent time domain behavior. Haven't run out all the model possibilities yet. A little shelving EQ perhaps, or perhaps not, given room gain. Would be dinky, and that's a big selling point. One for my girl friend's , too. You wouldn't believe what she has that she calls her sub woofer, which technically is a subwoofer with amp built in- she bought it at a garage sale or thrift shop, I can't remember which. Of course, she feels it meets her needs- :rofl:

Now I'm curious what the NAD M51 DAC will sound like with HT input from Blu-Ray, but I'm having so much fun with it in the living room this week, we may have a conflict of interest here...

(Madisound gives a discount for buying four, they assume you're upgrading your Orions. Let's see how often I can get away with that...)

Hope you're up to some fun for the holidays!

[CraigJ]

Jon,

No more answering the work phone as its allowed me to get way ahead of you.



I decided to use a pair of these;



Happy Holidays!

Craig

[JonMarsh]

Geez, Craig, you're practically all done! Amazing how you've recycled the picture from me, though you need to fine tune your photoshop skills just a little bit more for the demo speaker!

Still, you've clearly got it down- I'll expect to see SPL plots and distortion figures soon!

Happy Holidays Craig!

[JonMarsh]

Another hot flash idea...

While showering this morning I was thinking about way to implement the active part of this project, and it (finally) occurred to me that the requirements are pretty similar in some ways to what I did for the old X1- Klone project from the 90's, as regards a two way active crossover with EQ.







Considering I have all the files for this, my original CAD and Gerbers, and possibly some more bare boards, as well as the original unit, this might be a reasonable platform for an ASP version (Analog Signal Processor, as per SL). The opamps are very high grade and outputs are buffered with ultra high speed, high current video power drivers, with balanced transformer isolation all around (not shown in schematic). The schematic shown is for one channel.

Better dig up those schematics and review them. Oh, and yes, the power supplies are dual mono. Had the bare PCBs done at Advanced Circuits in Colorado. I think I still have some of them in storage.

[Johnloudb]

Hi Jon,

Very interesting project you got going here! :T

So, you're doing the mid/high crossover passively and the woofer to mid/high actively ... is that right?

[JonMarsh]

That's basically right- how I'll do it actively, I'll probably document at least a couple of approaches, using a common transfer function target- DSP on the MH LIO-8, and analog possibly on the old X1 Klone crossover. I also have a set of MiniDSP boards and software modules ordered.

Hang up at the moment is tweeters- back ordered.

[JimS]

Great minds think alike Craig . . . coincidentally, I am also planning to cleverly disguise mine as a grandfather clock to increase WAF

[Johnloudb]

I am also planning to cleverly disguise mine as a grandfather clock to increase WAF

Two grandfather clocks in the same room is going to look a bit suspect ... :W

[JonMarsh]

while you're playing with Grandfather clocks...

I'm updating/finalizing the front panel design for driver cut outs and setting up the cross cut saw... hey, it's a balmy 55 out, probably peaking right now.



Main laminated LBL panel is 33" long, actual width about 11-7/8".

Waveguide holes will be cut first, and waveguide mounted; then rebates for mid woofers made and cut- yeah, copying Troell's TQWT to keep the mounting centers close, but I'm not overlapping as much as he did for the 8" MT.

[JonMarsh]

Side View, LF module details



Cutting parts for LF modules and routing front panels today. Will take some pics and include some build stuff later if folks are interested. More concerned making sawdust than pictures right now.

If this turns out well, I'll do the typical PDF package with all piece item details and dimensions.

[Bear]

Looks good, Jon. I'll be curious how all of this compares to your prior OB efforts.

[JonMarsh]

Yeah, me too. But then, I may have learned a few things since 2005. Here's hoping!

Had a gut bug the last day and a half, so not all that much progress yesterday, apart from the posted LF module sketch update and getting the Pau Ferro side rails cut to final length, and the internal woofer baffle boards ripped to width.

Today should be much better... I'm ready to route the main front panels, cross cut the woofer baffle pieces, biscuit them for assembly, and take a stab at LF side panels, which are currently planned to be made from phenolic veneered tooling grade plywood (basically, high layer density baltic birch ply).

We'll see how that goes, many a slip twixt the cup and the lip and all. The motivation level is pretty high at the moment!

I realize there are some arbitrary design decisions made partly for esthetics which some dipole designers wouldn't follow (like the guys who like to use really small baffles and shape the width to each driver. and prefer dipole tweeters). Well, we'll see if I can come up with something I can live with.

[CraigJ]

I realize there are some arbitrary design decisions made partly for esthetics which some dipole designers wouldn't follow (like the guys who like to use really small baffles and shape the width to each driver. and prefer dipole tweeters). Well, we'll see if I can come up with something I can live with.

Glad you feel better today. Funny you should mention the baffle width shaping, as I am hoping to test that theory later today. Oh, and it doesn't have anything to do with stereo clocks....

[JonMarsh]

Be curious to see what you think, Craig!

Me, I'm going for a Genesis retro look, and that required straight baffles with rosewood edges.

Staggering bafffle sizes could have some benefits in controlling the dipole dispersion and making power response more uniform. I'm cheating by hoping to get some of that with the waveguide approach. I know, apostasy. Just makes me human and eccentric, right?

[CraigJ]

Kids, cousins, and soccer got the best of my time today, so no speaker building for me. Besides, it was only 10 degrees above normal, as opposed to the 20+ above average we're getting used to here; too cold outside.

Hey, I thought retro, or V8 engine type speakers were more like the M12ta, not this Arvo Part Type 2 dipole design.



On a more serious note, while you are waiting for the Transducer Labs N26c, have you thought about using Thomas's Raals in your current design? I would think than any Delorian driving eccentric would give it a whirl only to be scratching their head wondering why they hadn't tried it before. That MiniDsp will make it oh so super easy and enjoyable. Gotta send a note to that Evil Twin guy.

Cj

[JonMarsh]

Of wood cutting and saw dust making

Been fairly busy today, and have some slightly sore muscles to prove it! Oh, also have some pics and wood bits, too!

I've mostly been working on the main top front panel. I'd decided to slightly overlap the mid woofers on the wave-guide in order to minimize the center to center distance, which meant needing to route with the waveguide in place, also.

Getting the waveguide rebate and hole was straight forward...




Next, one of the mid woofer hole rebates is routed, with the wave-guide in place and screwed done.



Of course, I'm trying to keep the fitment fairly snug, but you've got to make sure it actually goes in- I've had to use rabbeting bits on a few occasions to hog out a rebate or through hole that wasn't quite right.



Both basic mid/tweeter panels were rebated and through-holed, and the woofer baffle panels cut to size also. Last step today was some forming on the Pau Ferro rail edges with a 1/4" round over bit on my baby hand held Porter Cable.




Re the tweeters, given the form factor issues, if the N26c's don't show up for a while, I'll use a pair of SS 6640 I have around.

Though I hear there's a brand new pair of B&W diamond tweeters on eBay right now, from a vendor in Poland... and they're priced sort of reasonably, which is not to say cheaply! Alas, I just won/bought another Pentax 645 lens on auction, so no B&W diamond tweeters for me unless they hang around a while.

Tomorrow should see some biscuiting and joining up most of the front pieces, and cutting the rest of the LF module- hoping for assembly, too, may be too much!