I'm kinda beginning to wonder why care about out of band nulls, if contained ...
Cause I really like steep xovers, which make out-of-band nulls less problematic.
If I want to cross higher it seems worth addressing, but otherwise i think it makes sense to just tame the null with enough EQ , so that a steep xoxer renders the null completely inconsequential.....
Whatcha think?
Thanks, Bwaslo! Our wives have to put up with all of the rest of our gear already 
I am lucky in that I have an audio lab in the basement which is totally messy and filled with gear, amps, speakers all under construction. I don’t get hassled as long as it stays there. If the speaker is finished and presentable it makes it to the upstairs.
I am lucky in that I have an audio lab in the basement which is totally messy and filled with gear, amps, speakers all under construction. I don’t get hassled as long as it stays there. If the speaker is finished and presentable it makes it to the upstairs.
My call is that the mid tap placement improved mid response, and did not hurt coax response any more than corner ports did.
All the testing that led to those conclusions was done at fairly close range indoors...within 1m.
(It was about all i could do while letting shoulder surgery heal....)
This morning i was able to quickly measure some syn 7 polars at about 3m outdoors.
Worst waistbanding I've seen yet ! lol
So there are a few main possibilities to explore i think.
One is that the mid ports are causing it, (don't think so, but a possibility for sure)
or the lack of a secondary flare is causing it, (no doubt)
and/or the wider the dispersion pattern va any previous attempt is a factor. (good chance maybe).
I did notice before, on syns of 60x60 and 60x40 without secondary flares, that the tighter the pattern and the larger the horn, the less was the waistbanding.
That's why I suspect the wider 90x60 may be a contributing factor.
Meaurement conditions were very noisy this morning, so I didn't try to get driver section-by-section polars. That will help determine whats going on i think.
Frankly, the increased waistbanding was a surprise, because it's been the smoothest sounding synergy attempt 'out of the box' yet. (indoors)
I'm really beginning to think wider dispersion is simply easier to get right than narrow dispersion, in terms of overall sound and room integration.
The big 60x40 syn with secondary flare has an almost magic sound to it, but indoors it begs for sweet spot listening and too much fiddling with the tonality of individual tracks.
The new 90x60 syn7 has glorious clarity but not quite the magic sound. And pleasantly, i find i don't feel the need to make nearly as many track by track adjustments.
It's more livable really, especially at 45lbs !
Now, i just have to get to work on a detachable secondary flare, be it conical or tractrix.
With your SPL requirements? I doubt it
LoL Wesayso ! You're right
I did notice some of the Klipsch guys are double stacking the Heils to get the SPL bump.
Supersweet project, and great to see the other Heil projects underway...
Hey, if i want to add a tractrix secondary flare to this syn 7, do you have any pointers how to start?
I've considered foam board, but will probably go with bendy ply for strength...
I guess the first thing i need is to find a way how to lay out the tractrix curves and cuts...know of any some layout software ?...
I'm really 3D challenged...like i keep thanking Bill W...i simply could not do a syn without his program..or at least not without making a scrap pile of plywood as high as my house
Download the tractrix horn spreadsheet from Volvotreter’s website.
I made a scale plot of the tractrix function (XY graphing software). I put that jpg image into CAD software as a template background. I then used a spline segment and hand fitted that to the jpg background. Then extruded that to get the curved wall. I intersected that with the top and bottom flat walls. Then I used the sheet metal unroll function to get a flat plan for cutting.
There is probably an easier way somewhere else but that’s what I did.
I recall seeing an horn designer package called ATH4 in the Multi-way forum. Maybe Hornresp May even do this automatically.
You can also scale my pdf design.
Presenting the Trynergy - a full range tractrix synergy.
I made a scale plot of the tractrix function (XY graphing software). I put that jpg image into CAD software as a template background. I then used a spline segment and hand fitted that to the jpg background. Then extruded that to get the curved wall. I intersected that with the top and bottom flat walls. Then I used the sheet metal unroll function to get a flat plan for cutting.
There is probably an easier way somewhere else but that’s what I did.
I recall seeing an horn designer package called ATH4 in the Multi-way forum. Maybe Hornresp May even do this automatically.
You can also scale my pdf design.
Presenting the Trynergy - a full range tractrix synergy.
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I've never got around to using foam core, but I'd expect that you'd be fine with it for secondary flares (unless you plan to support all the weight via the secondary flares that is). There'd be no drivers attached directly to it after all and the weight difference should be significant. If it gives you any trouble transmitting vibration, a layer of rubber or foam on the back of it might take care of that.
A big plus of it is that it would take little time to try out compared to messing with wood.
A big plus of it is that it would take little time to try out compared to messing with wood.
Unless it has any impact on your crossover then it probably can be left alone.
If it is a real null rather than a dip then EQ won't fix it in any case.
The waistbanding pattern/flip comes from the asymmetry of the waveguide, the more asymmetric you make it the worse it will get. The secondary flare will help, but it will always be worse than a square one.
Almost everyone that has tried 60 and 90 degree waveguides of the same type seem to prefer the wider pattern in room.
I have had some EQ schemes on my own speakers that have been really awesome on some tracks but don't work across the board. When I find something that sounds good on almost everything I know I'm heading in the right direction even if it is not quite so awesome on some tracks. I haven't been able to get both together yet which is why I am still tweaking it
Thanks a bunch ! Very helpful info to get going.
I've definitely decided to try a tractrix-like secondary flare, not conical.
Think i'll start with bendy board, wiggle board, whatever the local name for bendable ply.
Syn7 has about a 4" unencumbered band around the mouth to make secondary attachment easier. Probably looking at about a 10" secondary expansion.
Unless it has any impact on your crossover then it probably can be left alone.
If it is a real null rather than a dip then EQ won't fix it in any case.
The waistbanding pattern/flip comes from the asymmetry of the waveguide, the more asymmetric you make it the worse it will get. The secondary flare will help, but it will always be worse than a square one.
Almost everyone that has tried 60 and 90 degree waveguides of the same type seem to prefer the wider pattern in room.
I have had some EQ schemes on my own speakers that have been really awesome on some tracks but don't work across the board. When I find something that sounds good on almost everything I know I'm heading in the right direction even if it is not quite so awesome on some tracks. I haven't been able to get both together yet which is why I am still tweaking it
Yep re nulls, and I guess most of the auto-eqs being used that match response to a target curve which include xover slope, are likely applying out of band EQ to the nulls anyway. Or at least attempting to...i know FirD does..
I think i've read Tom D say that a 1.6X aspect ratio limit is a good rule of thumb to avoid major pattern flip.
I was hoping the 90x60 syn7, at 1.5X would show less than it did.
The 60x40 I built had less waistbanding.
So I'm thinking the rule of thumb may need adjusting according to how wide or narrow pattern control is...just spit-balling here...
I've consistently liked the sound of 60 degree horns over 90 degrees using the bms coax CD, both inside and out, ...when everything is just right...particular spot, particular track, EQ. volume, etc, etc ect.
The latest syn is a 90 degree-er, to overcome the need for everything to be just right...well that, and maybe more importantly I saw how to build it to weigh less than my 60 ...
At any rate, the waistbanding is not a setback at all...i almost view it as a blessing in that it motivates me to go ahead and try to add a tractrix secondary flare ...which has been part of the eventual design goal all along.
Syn7 is sounding so good indoors I would be tempted to be lazy and skip the secondary if measurements were better ...well, skip for a while that is lol
Syn7 got part of its start from wanting to replicate the K-402 in wood.
A clever build from Oohms
Klipsch K402 replica build - DIY Audio Projects - StereoNET
shows how he used foam board for the secondary flare.
I've built the conical section to be able to attach such foam flares in the same way he did.
If i go that way....and probably should, as i already have the foam board from other projects..
I'm waffling re bendy board haha
Update:
Definitely a work in progress still, but I'm committed to finishing it as my 'go to' all around compromise,....between super sounding, portable, and usable indoor and out... system.
With stand as shown below, weighs 47 lbs.
Stand includes speakon NL8 for feeding the synergy along with a NL2 passthru for a sub. Final version will not need speakon connections on horn cover.
Stand includes an adjustable tilt top hap for pole mount, outdoor use. Round base plate quickly comes off for pole mounting.
There's a strong handle in the top of the speaker.
I've gone with foamboard for the secondary flares, which are detachable and in the process of being glass-clothed with epoxy for durability. (thx for help diyuser2010)
The flares are curved ala tractrix, although I'm sure they wouldn't hold up to true tractrix math. It's been a heck of an effort learning how to cut them smoothly, 48" wide, with a hot wire.
Mouth size ended up at 48" x 29", for horizontal control down to about 200Hz.
On axis measurements rock; polar measurements still need to be taken.
But frankly it doesn't matter how they turn out. The box sounds too good on and off axis, gets loud enough, and is too light, for me to care.
Much work to do still, including building the second speaker, and figuring out finishing aesthetics.
But I'm psyched on seeing this one thru !
Definitely a work in progress still, but I'm committed to finishing it as my 'go to' all around compromise,....between super sounding, portable, and usable indoor and out... system.
With stand as shown below, weighs 47 lbs.
Stand includes speakon NL8 for feeding the synergy along with a NL2 passthru for a sub. Final version will not need speakon connections on horn cover.
Stand includes an adjustable tilt top hap for pole mount, outdoor use. Round base plate quickly comes off for pole mounting.
There's a strong handle in the top of the speaker.
I've gone with foamboard for the secondary flares, which are detachable and in the process of being glass-clothed with epoxy for durability. (thx for help diyuser2010)
The flares are curved ala tractrix, although I'm sure they wouldn't hold up to true tractrix math. It's been a heck of an effort learning how to cut them smoothly, 48" wide, with a hot wire.
Mouth size ended up at 48" x 29", for horizontal control down to about 200Hz.
On axis measurements rock; polar measurements still need to be taken.
But frankly it doesn't matter how they turn out. The box sounds too good on and off axis, gets loud enough, and is too light, for me to care.
Much work to do still, including building the second speaker, and figuring out finishing aesthetics.
But I'm psyched on seeing this one thru !
You make me wish I had room for such a large horn. I agree re' polars. Even my single segment conical Synergy sounded great throughout the house, despite its imperfect polars. On axis it was even better and I suspect yours is better still. It will be interesting to see how well it fills its nominal pattern when you do get around to doing the polars.
Yep, you know, i think we put too much emphasis into polars, because of all of the Harman literature.
Not that i think it's wrong, on the contrary i think it's right.
Right as in a best fit for whatever the room.
It's just....we still have these damn rooms to contend with...and each room has it's own particular best solution.
Sometimes bad directivity might fix/fit the room ????
Which btw, your work and sims on your line array thread continue to blow me away..
I've started to post so many times in the thread.
I've decided you are going to figure out the perfect indoor speaker...
so i just watch and learn, wondering if you will finally compel me in to the world of sims, and maybe another line array ...
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