"Unitized" Image Control Waveguide

So standard. I'm interested in printers capable of 400 mm/s. Today I printed 12" STH biradial flat front for Aurum Cantus AST25120. Each part is 8-9 hours.
 

Attachments

  • 58E3B782-B6A7-4211-86D4-45794C033194.jpg
    58E3B782-B6A7-4211-86D4-45794C033194.jpg
    231.7 KB · Views: 742
Yes, these prints take nearly a day to complete, depending on how my printer is cooperating. That's part of the reason I'm letting people have the "Tier 3" prints instead of tossing them, there's a significant amount of time sunk into each print.

K6TQESS.jpg


bl8cqLF.jpg


Here's a comparison of how the tiers look these days. Tier 3 on the left, Tier One on the right.

vDGCPm5.jpg


jYjGfNY.jpg


zbnRUIV.jpg


Here's a new filament that I like a lot. It's called "ABS+."

I like plain ol' ABS a lot, but it is by far the most difficult to work with. It warps badly and it cracks. The reason that I continue experimenting with ABS is that the surface looks really good, it is strong, and most importantly it doesn't jam. ABS has a tough time sticking to anything, which is why it cracks, but it also doesn't stick to the nozzle, which is really nice! I am so sick of PETG prints that jam.

The ABS+ seems to make a dramatic reduction in cracking and shrinking. It is noticeably heavier, so I'm guessing it's denser somehow?

The only bad thing about ABS+, from what I can see, is availability. For instance, this off-white ABS+ filament is unobtanium now.

One thing that's promising about this ABS+ print is that I think this might be one of my first prints that's (almost) exceeding the quality you get from injection molding. It's a REALLY nice print. Note how the top and bottom are almost perfectly flat, and how the surface is really well behaved.

9N6mryg.jpg


Here's a Tier Two waveguide for comparison. This particular waveguide, I started out with PETG so that it would stick to the bed, then switched to ABS because ABS doesn't jam. This particular set of waveguides is headed to a member in Australia.

vvTLoE4.jpg


nyTdneV.jpg


Here's a "Tier Three" PETG waveguide. I had to glue this one together because the print died when the print head gummed up, due to the stickness of PETG.
 
Excellent! That's my best PETG print. I have one running as we speak, in grey, we'll see how it turns out later today.

DfEtMxWV4AAe2Y-.jpg


As I understand it, PETG isn't as easy to sand as ABS, but it *is* sandable. The pic above is from ESUN, showing a PETG print, then sanded, then painted.

IMG_0661.JPG


My Gedlee Summas were bright blue when I purchased them, and I painted them black. Pictured above. To get them black, I simply used black plastidip from Home Depot. I went this route because it can be peeled off if you don't like how it looks.

IMG_20131223_152747.jpg


Here's how my Summas looked before I painted them.

As I understand it, the blue color of the Summas was actually vinyl paint! Which is kind of shocking, considering that it looks like an oil based paint.

Since your waveguides are plastic and the Summas are plastic*, painting them should be similar.

If you really wanted to go all-out, I think the ideal finish would be to sand them, cover them in bondo, sand that, and then go to an automotive supply store and purchase paint intended for automobiles. I used to do that for my car audio projects back in the day. It is a LOT of work, but it comes out looking about as good as an automotive finish.

If you want something quick and dirty, just spray paint them.

* My Summas had a carbon fiber skin which was bonded to a foam core using epoxy. Very much like surfboard construction.
 
With ABS you need closed chamber and ABS+Acetone (glue) if you use perforated table. Quality extruder is essential. For instance I use Microswiss on Zortrax (I do not reccomend these printers). From time to time replace PTFE tube or drill/clean if without. I like PLA because look very cool (pearl type), perfect dimensions, price, cold table etc. But requires fine tune raft to table gap so that supports removal is easy. PETG is even nicer. Best ABS I had is this: Compositum ABS EX™

I would like try two things:

1) Print outside skin with brittle material like PETG and inside rubber type material (TPU).

2) Print very thin shell (0.5mm, fast printing) and use expanding foam inside - require special design. For thin printing I would test material with carbon fibres - expensive 60-80$ per kg.
 
One "weird" thing about ABS is that the quality of filament seems to vary much more.

That is part of the reason that I used clear PETG and "natural" ABS: my hunch is that the quality of vendors may vary based on color.

That might seem nutty, but I've *definitely* noticed that certain colors print better than others. I'm guessing this is because vendors have to keep the purity of clear and light colors very high. IE, if you have a dark filament, it's easier to get away with impurities or even recycled material. Again, rampant speculation on my part. My best PETG print of all time is that one that Brinkman has, and it used clear PETG filament. I can barely get black PETG to print at all.

ZfcSwJA.jpg


vonhhwe.jpg


This was the first and last black PETG print I ever did. It jammed up three times before it finished. There were something like three or four failed prints that went into the trash. I think I spent about four hours tinkering with my printer until realizing the problem was the filament. (Note the ugly 'stitching' where I welded two prints together using a soldering iron.

9klmtsm.jpg


And with white filament, it wasn't perfect, but it didn't jam. (Note some shrinkage on the bottom right.)

My ABS+ prints are coming out quite well, I might go that route 100% of the time if I can find some more filament in natural or white. I am using a MicroSwiss nozzle and a DIY enclosure. I think I may add some kind of insulating blanket to my enclosure, because I've noticed the walls get warm, which indicates that the enclosure itself is radiating heat. I have to find some kind of insulator that isn't flammable. I'd use foam insulation but that's too risky I think. (3D printers have been known to catch on fire!)

TLDR: ESUN ABS+ seems to work quite nicely, but is unobtanium in 'natural'. Monoprice ABS hates me. Clear PETG from Amazon works really nice too, when it's not jamming up the nozzle.
 
Last edited:
Thanks for the info John.
I’ll probably sand it to 150 grit, fill any dips & dings with woodfiller and then coat them with black rustoleum paint & primer from a rattle can. After that, a clear gloss topcoat. That’s essentially how I got made some black EOS plastic waveguides white (see below). Coincidentally, the Fusion 8 speakers as pictured below are what I’m replacing with whatever fruits are borne from this project.
 

Attachments

  • 03BDF9C1-76D4-494C-9E00-495E4EFEC954.jpg
    03BDF9C1-76D4-494C-9E00-495E4EFEC954.jpg
    926.2 KB · Views: 186
Progress

After giving the waveguides a couple quick passes with a propane torch, I deburred both with 80 grit sand paper. After rinsing them off, I covered both waveguide interiors with Elmer’s wood filler (I am familiar with it and like the sandability) and am in the process of removing the excess filler with 100 grit sandpaper.

I’m leaving around lunch to spend the holiday weekend in the mountains and do a little repair work at the in-laws cabin so I won’t get to priming and painting until next week.
 

Attachments

  • 0EB84749-0993-43C1-B724-43D41785151D.jpg
    0EB84749-0993-43C1-B724-43D41785151D.jpg
    1 MB · Views: 859
I know that it's a bit of a hassle to email me to buy these waveguides, so I put some up on eBay. The cost on eBay is $10 higher to cover my fees, but otherwise, they're the same you'd get on here.

I also input the weight and the dimensions of the box, so if you live anywhere from Germany to Thailand, you can figure out the shipping cost.

I'm not sure if I can post links to eBay, but you can find it by searching for "Compact Unity Waveguide."
 
I've been suffering from a bad case of "analysis paralysis."

Basically I evaluated over a dozen different enclosures for the low frequencies. Everything from conventional boxes, to various wedge shapes, using midbasses as diverse as the Exodus Audio Anarchy to the MCM 55-1870 to the B&C 8NDL51. I was really keen on doing a QB5 alignment (Satellites and Subwoofers) because of the insane power handling.

But after a lot of tinkering, I think I'm going to go the Geddes route, and do a plain ol' sealed box.

QP41VH3.jpg

M7RaxSr.jpg


Here's the response and the excursion of four MCM 55-1870 woofers in a vented QB5 alignment, versus *one* Cerwin Vega 12" in an undersized sealed box. This is with 200 watts into 8ohms.

The sims show that the sealed twelve is simpler to build, has a slower rolloff, takes about the same space, and has more displacement. There's a lot to like.

I think that it *might* be possible to squeeze a little bit more output out of the MCMs if I juggled high pass filters and tuned the enclosure perfectly, but the bottom line is that the twelve inch woofer is just way less work for comparable and possibly superior performance.

The headroom of the twelve is quite insane also; I was aiming for output of about 110dB, but it looks like the CV can do quite a bit more, if you have the power.

CV12inTN.jpg


If you're in SoCal, go visit Steve at Apex Jr and buy lots of stuff. He has a great warehouse. If you're not in SoCal, get the woofers off eBay or his website. Here's the link:

Speaker Stuff

If you don't want to use the CVs, this is a plain ol' sealed box, I imagine that nearly any woofer with similar Thiele Small specs will work. The nice thing about the CVs is that they're practically free, there isn't anything even close at this price range.

Here's what the cost of the speakers looks like, as of 5/30/2019:

1) a stereo set of waveguides and midranges is $150
2) a stereo set of CV woofers is $44
3) the speaker requires miniDSP or the like for EQ, at a cost of approximately $80
4) The passive crossover is about $40 for a stereo pair, at the moment
5) The enclosure cost is about $30, depending on how you finish it.

So about $344 for a stereo pair of Unity horns.

To put that in perspective, the Lambda Unity Horns were $1590 per pair when you could purchase them, seventeen years ago. That price was for two wood horns, eight 5" midranges, and two B&C DE250 compression drivers.
 
Last edited:
Hmmm, just ran into an unexpected problem.

Af2fkIS.jpg


In order to achieve these beautiful polars, I used the LeCleach crossover described here : Car Audio | DiyMobileAudio.com | Car Stereo Forum - View Single Post - Crossovers, a Step Further

The way that this crossover works is fairly straightforward. It uses third order Butterworth filters. A 3rd order filter introduces approximately 270 degrees of phase shift. (90 degrees for each order.)

So the LeCleach filter fixes the phase response with two steps:

1) it moves the midranges *closer* by a bit less than one quarter of a wavelength (90 degrees)

2) and then LeCleach flips the phase on the tweeter, to compensate for the other 180 degrees of phase shift.

So here's the dilemna:

When I add the 12" woofer into the mix, it needs to be quite a bit forward of the waveguide. About eight inches.

Now the obvious solutions would be to use DSP delay from the MiniDSP to simply put the two wavefronts into phase. A brute force approach.

But personally, I really like the nebulous depth of my Waslo Cosynes:

Juovg3w.jpg

The Cosynes *also* place the woofers forward of the midranges, like LeCleach does. I have no idea what type of xover is in the Cosynes, but it's purely passive, so there must be some type of compensation for phase if it's producing a wavefront that's in-phase.


BTW, here is the current crossover:

RNEnrxy.png


That diagram is from this post from a few weeks ago:

"Unitized" Image Control Waveguide

Anyways, long story short, if I want to maintain good phase behavior below 1000Hz, I will likely need to do one of three things:

1) Bring the woofer forward of the waveguide by about 8". That would be ideal I think, it helps achieve that nebulous depth which is so neat about Unity horns.

2) Fix the phase via DSP. Boring but workable solution.

3) Use a shallower slope. For instance, I think that if I used a 2nd order filter I might be OK, and a 1st order filter would definitely be no problem.
 
PB -- for reference, this is the final crossover (or very nearly what it is anyway) for the Cosynes:
attachment.php
All that craziness on the tweeter is an all-pass filter to get to linear phase. DSP is a whole lot easier and more sensible, except that the "filters" are spread around in different components rather than just in a speaker.
L9, C12, R5, R8 are to level the impedance curve if used with a tube amp (I think there was a wire link in by the terminals that could be used to detach those parts).
 

Attachments

  • Fancy Xover.png
    Fancy Xover.png
    39.2 KB · Views: 923
Basically I evaluated over a dozen different enclosures for the low frequencies. Everything from conventional boxes, to various wedge shapes, using midbasses as diverse as the Exodus Audio Anarchy to the MCM 55-1870 to the B&C 8NDL51. I was really keen on doing a QB5 alignment (Satellites and Subwoofers) because of the insane power handling.

I was thinking of using the B&C 8PS21 in a sealed cabinet, sitting atop a the 12” midbass module from DIYSG, tuned to about 35Hz.

Below is one of the waveguides from a page back after a sanding of 150 grit and a primer “tattletale” coat. This coat exposes how much my hands lie to me and tells me I need to go back to about 100 grit and do more smoothing. I might even try bondo, despite pain it will cause my shoulder to manually sand it off. My goal is a glossy black finish.
 

Attachments

  • 78449F66-89E2-42D4-9248-A2DA2475021D.jpeg
    78449F66-89E2-42D4-9248-A2DA2475021D.jpeg
    368.5 KB · Views: 238
Where to buy poweramps for active speakers. Hifimediy.com is a good choice If you prefere diy and want to get by on a budget. I have emailed Nick who is behind the site and he is as much a Hifi freek as all of us.
I have the T1 x 4 board and it works well for my JBL 4waysetup. You can also buy Connexelectronics powersupplyes that are well documented and specially designed for hifi use.
On Connexelectronics.com site is also wery interesting LM3886 amplifier with smps on the same board.
 
So starting over on the sanding didn’t have the intended result; restarting at 50 grit and continuing on with a 80 grit wet sanding followed by a 150 grit wet sanding still left unsatisfactory results after a primer coat. So I dry-sanded the primer coat back with 150 grit and wiped it down with naptha. It’s overall smoothness *has* improved but a fresh container of Elmer’s wood filler applied with a shop towel should fill in most of the remaining crevices. I’ll sand that back down with 150 grit, respray primer and decide from there whether to go back a step or smooth with 220 grit before topcoating with flat black.
 

Attachments

  • CF046879-448D-4CF7-ABAA-D3EAD429F976.jpg
    CF046879-448D-4CF7-ABAA-D3EAD429F976.jpg
    1,007.7 KB · Views: 244