DIY Synergy/Unity spreadsheet

Some measurements. Done outside, I tried to put the speaker near a corner between garage door and side of house, probably not a good idea, seem to get some wall reflections. Here's what I got before stopped for fathers' days festivities:


Looks like I need to do a little work on the crossover to bring things down a few dB around 5kHz, maybe at 2kHz too.

And maybe just measure with the speaker up against the garage door again, seemed to have fewer problems with LF reflections that way.

 

No, not a bass horn, just a shelf ported box. I put the horn up at ear level and extended the box down to the floor. Why waste the space with a stand when it can be bass volume? The volume was right for 4 Aura NS6 to do a butterworth 4 box. Kind of stupid big for 4 little sixers, but it works, and again, it would otherwise just be space occupied by a.stand.

 

In stereo, these things are exceptional. I spent all day listening. Wish I could get Tom D to license the patent for some kits!

 

I have asked Tom about it in a couple of emails, but he doesn't seem to want to discuss it. I think he might hold out interest in doing domestic speakers at his company some day, but his business partners aren't wanting to invest in that right now. I don't think that Red Spade's effort is happening under Danley's license, maybe the Unity/Synergy USA patents don't apply in Australia?

Sound of these compared to the SEOS15/AETD15M set has more similarities than differences (at least when compared to more conventional speaker types). Huge sweet spot with both, effortless sound, plays well both loud and soft. These are both "you are there" rather than "they are hear" systems. In neither does sound seem to be coming from the speakers.

The SEOS speakers I think image a little more precisely with a tighter "scene", though depending on the recording, the Synergies sometimes seem more like a real venue (pinpoint imaging is rare in live sound unless really close up to the musicians). Bass is better with the TD15M setup, but that's at least partly because I was using subs with them. I'm running the Synergies 'barefoot' still for now, so not a fair test. Four of the little Aura6 drivers per channel in a big ported box does pretty impressively at the low end, though! And the Synergies have a passive xover while the SEOS/TD setup is all active and EQ'd to boot. It's probably not fair to compare yet, things are so different and the Synergies still have that new-car feel.

 

It was done with PCD. My implementation isn't linear phase, as the tweeter would need to be delayed to achieve that (would be about 16 more components if done passively), but the phase response is still very smooth. I personally think the 'magic' has little to do with phase, but more about having all the sound effectively originate at a single point while still having directivity.

 

Well, some good news for some of you with ambition and table saws. Tom Danley has given his ok for me to give out details of my "coSyne" build for DIYers to use.

Also, some congratulations are in store for Tom, his Synergy patents have finally been granted by the Patent office! It has been in an "applied for" state for quite a long time, and this week they have finally been given the thumbs up. Good going, Tom!!

Of course we still can't build these for sale (DIY only!) and understand that what I'm presenting here is NOT an actual Danley design (so any faults that may be in it aren't Tom's fault!). It is only based on his patent application details and on some hints I've gotten from other builders and from Tom himself. But if you are wanting to put a set together (and, yes, you do!), here is the crossover I used. I'll post the details on the port locations maybe tomorrow after I find my plans (or failing that, go into one of the horns with a set of calipers).

I'll have the speakers at MWAF next week, so if you are going, you'll have a chance to see if you like them. (The MWAF crowd there hasn't been very fond of horns in the past, so I don't expect any competition wins... but maybe synergies and SEOSes will be able to overcome the visual biases?)

Anyway, here is the crossover. Yes, you can use bigger resistors if you want to, and/or go to air-core for that 6mH inductor. Or go with a MiniDSP and 4-way plugin (I just got some MiniDSP boards in today, which I'll try after MWAF is over).

edit: OOps! There's a typo below on L1 -- that should be 6mH, not 1mH! And keep its DCR down, if you go air-core use heavy gauge!


A few other things to point out -- these aren't made with pro audio stuff, so the power handling won't be huge and they aren't applicable for stadiums and big theaters like DSL Synergies are! They will play plenty loud for most home theater, though, at least for me. (But I'm not big on space battles and explosions, so YMMV!)

 

OK, here are some woodcutting details for the horn. First, a big spreadsheet shot of the basic horn piece dimensions and angles. These are the same as the download of the spreadsheet itself will give you, btw. I used 0.5" MDF for all these pieces. You could try plywood, but cutting some of the very acute angles might be hard to do.



The details for the "#2" type panel, which has all the ports cut into it are here:



Note, the black outline is what you'd cut. The bluish-greyish stuff you see inside is to show how it will meet the "#1" type panels. so you can draw your alignment guidelines. Dimensions are in inches. The green circles are the driver outlines, so you can center them (the picture isn't too great, in actuality the woofers almost touch the midranges). You can see the port cutouts for the midranges (round) and woofers (oblong).

I used a router with a 45degree chamfer bit like this http://www.rockler.com/product.cfm?page=2124 to widen the port openings on the outside (driver's side) l port holes so they make like a funnel, but leave the opening into the horn the same size as shown in the drawing (there are straight walls for maybe 1/8" before the chamfered part starts). Make sure you keep the widened part inside the driver's outline so you don't mess up the seal! (If you do, no big deal, wood filler can fix it).

For the midranges, I used a 2" forstner drill bit to cut down about 0.05" so that the driver surround won't touch the wood -- you could probably use a shim instead to accomplish the same thing (raising the midrange very slightly from the wood panel while still keeping the seal). I cut the port holes with forstners, too, but you could use other wood drill types if you don't have a forstner set.

The backs of the midranges are sealed by gluing them onto 2" mailing tubes cut to 3" long and capped with the mailing tube caps. Glue was a silicone sealer/adhesive. I wired the drivers with light gauge wire, cut a slit in the tube at the cap end and slid the wire into the slit to get it out of the tube. Then stuffed the tube with a polyester fiber and stuck the caps on.

The sets of 4 woofers (or midranges) are wired series-parallel -- wire sets of two with a + connected to a -, then parallel the remaining + and - to the other set and from there to the crossover.

The tweeter's compression driver is mounted on a piece of 0.187" plywood (or what have you), glued to the throat end of the horn assembly.

GEV asked how to hold the weird angles while gluing... good question. Earlier in this thread I showed some photos and talked about it. For the pieces that make the throat, I predrilled the #2 mdf pieces' faces to clear #4 wood screws, then marked and predrilled holes in the edges of the #1 mdf pieces with a drill size big enough to minimize splitting when the screws are used, but small enough so the screws still grab some. Then dry-fit with the screws (1" long), then pull one of the #2 pieces off, apply glue and screw it back on. Repeat for the other #2 piece. This is kind of a pain to do, get another pair of hands to help if you can.

For the mouth pieces, the angles are too wide to use screws. I just put the throat section down on the bench, throat down, and then roughly built the mouth section on top using duct tape and lots of Titebond glue. It was a mess, but it worked. Make sure you have guide lines drawn on all #2 mdf pieces so you know where to position the intersections with the #1 mdf pieces! If you have small gaps or overlaps, don't get upset, you can clean them up with a wood rasp and wood filler.

I think that covers the horn. See the photos in the thread to see how the boxes were built. I used half inch ply (oak pre-veneered) and lots of internal window braces every 6 inches or so. The top and sides of the box are made from 3/4 inch ply, mostly for appearance. The box volume is about 6.2 cubic feet, tuned to about 40Hz. You put it in a lot smaller sealed box (though bass won't go much below 90Hz then - with the big box and slot port, it has f3 of about 38Hz and does remarkably well down there!).

FWIW, the box was harder to make than the horn (but I'd made a number of wood horns previously, so I'm getting good at it). Just take your time and remember that most of your time should go into making setups and jigs, don't rush ahead into any cuts till you are sure about how you are doing them.

Bill

 

Ok, reading that, I see some stuff I forgot.

To glue the CD mount plywood piece, you will probably have to flatten out the throat surface a little -- don't overdo that, you want to avoid making the mount sit crooked, like I did on one of mine. And don't forget to drill the bolt holes for the driver first, and the 1" diameter hole in the center of the CD mount. The holes go between the midrange drivers' positions, otherwise you won't be able to get them in! (and get screws that are short enough to get them into the holes, there won't be much room there to do it in).

Here's a picture of the insides of the box right before the back gets put on:

 

The rear path in the lower half is just off the back of the drivers and down through all the brace windows, the ports on the way down. There's no transmission line or folded horn or anything. Really, it's just a ported box.

Not that it couldn't maybe be done better. I just did it that way because I had made some ported boxes of the same height before using one of the Aura NS6 woofers, and the port at that height and I liked the way the bass turned out in those. I was in a bit of a hurry to get an enclosure around the synergy horn so I could see how it all sounded (without the woofers enclosed the low end was nonexistent, as you might imagine. If I do it again, I might invest in Martin King's transmission line program and see if a tapped horn or something could be done instead. Or maybe not, bass sounded pretty good.

I didn't want the port too close to the drivers, to avoid any midrange getting out the port.

BTW, they were at DIY, so everyone there got to hear them.... for three minutes (playing tracks with little low end and nowhere near loud enough!).

 

No, sorry, no Sketchup drawings, all there is at present is the design spreadsheet and the not-to-scale sketches in that. Those are what I used to make them from. To do it with a CNC you'll need a pretty fancy multiaxis machine for all the weird multidimensional angles. I used a tablesaw, less equipment needed but a lot more labor intensive, of course!

I can put together more box details and maybe pictures if you want, but it's not magic. It's just a box, very well braced. You could make a sealed one, or a ported one of different shape, or maybe a tline or something instead with the same horn. The overall outside dimensions of mine are 47" high, 25.5" wide, 12" deep. Sides and top are 3/4" ply (oak pre-veneered). Front, back, bottom and internal window (matrix) braces (every 6" or so) are all 1/2" ply. The vent is 1" high, about 6" long, 24" wide (this didn't come out as modeled, I don't know if that's because of the compression chambers in front of the woofers or because of the oddities of a shelf port)-- but if you make the shelf port higher (I started with 2" high) it's easy to narrow it down or make it longer by gluing in ply inserts while watching the woofer impedance when tuning -- just adjust till the minimum between the impedance peaks is at 40 Hz.

 

They actually are part of the bracing, but I ended up putting some more ply inside the ones built into the bracing to narrow the port, as the tuning came in higher than I expected.

Saw some neat 6" drivers at MWAF that Dayton will be coming out with soon, 95dB sensitivity and neo. If I put those into a Synergy, would get the sensitivity up near 100dB SPL. Not cheap though. Particularly when compared to the $9 each for these Aura NS6 drivers!

Sensitivity now is in the low 90s, but the bass does go way down. I'm fighting the impulse to try some 48" wide Synergies. I don't think I've ever had speakers I wanted to spend so much time listening to.

 

Sorry, I don't know the eta.

 

Yeah. Maybe I can scale back and do only 36 inches. "experimental" only, of course!