recommend a DIY synergy design for my living room?

[tommus]

So I'm all read up on Bill Waslo's Small Syns, it's a very impressive design. I like his newer shallow box configuration, it could actually fit into my living room. The issue is getting a suitable waveguide...

I have seen a lot of rectangular, double flare expansions made of plywood. These can be made with a tablesaw, but they are surely a sonic compromise compared to a curved expansion/rounded mouth horn, and you still have to somehow sculpt a smooth throat to mate with the compression driver.

Lukasz in Poland (horns-diy.pl) is offering fiberglass SEOS horns (and many other horn designs too). I can get a pair of 18" or 24" shipped to me in NY for about what it would probably cost to buy a 3D printer and figure out how to make my own. Either way, it's a lot of money and/or time. Then I have to drill a bunch of holes in these exotic beauties and hope I am doing the right thing!

I have not seen anyone building rectangular horns, with a curved flare, from flexible plywood. Four pieces of 1/8" to 1/4" ply, properly shaped, could be bonded along their edges to produce a horn on the scale of the Klipsch 402 with any desired expansion. Mate it to a small 3D printed throat "stub" and anything is possible.

DIY boat builders have a technique called stitch-and-glue where plywood parts are cut from templates, "sewn" together along their edges with copper wire, and bonded with epoxy. The proper curvature and edge bevel of the parts forces a specific complex of 3D curves. Here is an example: Christine DeMerchant builds a stitch and glue Skerry boat
Apparently there are open source computer programs that will calculate the 2D shapes needed to make these constructions. The back of the horn could be sprayed with foam and/or laid up with fiberglass and epoxy to stiffen the structure and damp vibrations.

I suppose the frequency response of the resulting contruction would land somewhere in between the somewhat crude slab-sided double-flare, and the shapely and elegant SEOS.

What can be said in general about the sound of the rectangular horn vs. an elliptical or circular, given the same expansion profile? And does anyone think this stitch-and-glue construction technique is worth pursuing?

 

[Patrick Bateman]

I've mentioned before that I thought the treble on Bill's "small syns" is superior to the SH50 by a little bit. I'd always assumed this was because Bill is using a SEOS waveguide and Danley is using a conical horn.

A couple of weeks ago I 3D printed a BIG image control waveguide, similar to what JBL is using in their 4367. But I found something interesting: it didn't measure as nice as the small JBL PT waveguides.

Maybe it's a fluke, but it had me wondering if waveguide performance degrades as the device gets bigger and bigger.

You see the same thing with the big QSC waveguide. It measures really REALLY well, but the little JBL PT waveguide measures better.

If I'm correct, then it would seem to indicate that the ideal synergy horn would look a bit like this. Basically use a waveguide for directivity control on the mids and tweets, then wrap an array around the thing. Bill did this in his speaker, but there are only two midbasses, not four.



Pseudo-coaxial with narrow directivity (and Horbach-Keele filters)

 

[Cask05]

I've mentioned before that I thought the treble on Bill's "small syns" is superior to the SH50 by a little bit. I'd always assumed this was because Bill is using a SEOS waveguide and Danley is using a conical horn.

Better horns sound better. This is not a fluke in my experience.

A couple of weeks ago I 3D printed a BIG image control waveguide, similar to what JBL is using in their 4367. But I found something interesting: it didn't measure as nice as the small JBL PT waveguides...Maybe it's a fluke...

So you're saying that the loss of horn-controlled directivity below ~2 kHz is offset by "better treble" (something that I've neither measured nor experienced in a well-designed larger horn like a K-402)? Having horn-controlled directivity to a lower frequency and the same or better high frequency performance--like what I hear in the difference between the K-402 vs. K-510 horns--is one that I've found that everyone prefers in the larger horn over smaller (a large sample group of listeners)

The disruption of coverage in the midrange/treble band by using a small horn with multiple surrounding DR array types or horns becomes apparent to the listener. For those that have actually heard a side-by-side comparison of the two horns (402 vs. 510) prefer the K-402 because of the overwhelming effect of constant coverage all the way down to below the room's Schroeder frequency.

As a side note: knowing what the throat of the horn should look like to achieve constant coverage at higher frequency I've found is a big deal--but not talked about how to achieve in audio forums. I think a lot of measurement issues at higher frequencies is due to this lack of knowledge of what works well and what doesn't.

Avoiding coverage mismatches, lobing, or impedance bounces in the horn from a very high to very low frequency, and having a smooth tractrix flare mouth out to at least 90 degrees...produces a huge soundstage, unbelievable clarity and speech intelligence, and a sweet spot the entire width and almost the entire depth of the listening room. This is is something that I've found to be very difficult to be traded away so readily.

Chris

 

[tommus]

If I start another project, it will need to do double duty as my living room system, as well as PA tops for outdoor events and DJ parties. I can fit a 36" tall, 24" wide and 16" deep enclosure with angled backs into the corners of my room. Also (for the first time in quite a while) I have more money than time! So, in trying to keep it somewhat simple, but not necessarily cheap, and in the interest of going as BIG as I can, here is what I have come up with:

- 24" SEOS waveguide (Auto-Tech from Poland) + BMS 4594ND 1.4" coax
- 18" woofer, maybe AE TD18H or some other high-spec pro driver
- 2nd or 4th order crossover circa 500hz
- woofer will be in a sealed enclosure, somewhat direct radiating but angled at about 45 degrees in the vertical plane to fire into a 24" wide x 14-16" very short horn mouth to match the directivity of the SEOS-24 and keep the CTC spacing small. enclosure volume will be 4+ cubic feet.
- active amplification with DSP, phase linearization, etc.

I am thinking I can run these full range in my house and be able to reach quite deep at reasonable SPL, or cut them at 100Hz to subs for PA duty.

It looks like the horn + CD combo is pretty much blameless.

As far as the bottom goes, can I just fire the woofer into a properly dimensioned mouth and get the horizontal and vertical directivity I want, using DSP to flatten any resonances?

I would consider bandpass slots for the woofer - will the benefit be worth the added complexity?

And one more thing, I can definitely see the elegance of porting two 12" woofers into the SEOS-24. Does this have a good chance of working well?(with commensurate investment in development of course)

 

[nc535]

Yes slot loading the woofer will reduce CTC distance, for less lobing or higher XO. I just posted about a slot loaded AE TD15H (4" wide slot) that is usable with EQ to 650 Hz or so which is what you need to play with the BMS CD

Companion Woofers for my Synergy Horns

I don't think you need/want both the external woofer(s) and woofers on the horn, do you? If all you want is to get down to 100 Hz with woofers on the horn, a pair of 8" will do that. I don't think 12" woofers will fit on a SEOS24.

 

[Soldermizer]

Options for the ten-thumbed

Is WAF (wife acceptance factor) an issue? You can buy about five pairs of Danley SH-50 for the cost of an average divorce. I can at least lay claim to having heard a pair ... very briefly ... at the factory.

An older, and about 4x cheaper option is the older Yorkville Unity U15. Not all the way to a Synergy, but cheap and loud and even nearly 20 years later, I doubt you could build anything equivalent for much cheaper. Rather than a few pathetic clones I attempted (I am carpentry-challenged), I lucked onto a pair of used U15 and am quite pleased with them. I don't claim Synergy like performance, but mine are actively EQ-ed so I am fully responsible for how lousy they sound

Good luck on your build(s) and please keep us informed.