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My Synergy Corner Horn and Bass Bins
My Synergy Corner Horn and Bass Bins
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Old 12th May 2016, 02:44 AM   #1
nc535 is offline nc535
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Default My Synergy Corner Horn and Bass Bins

For some time I've been working at stuffing a waveguide and woofer tightly into a corner so as to not have to worry about boundary reflection nulls, to take advantage of the corner gain, and to achieve a wide sweet spot. Midway through this research and design process I discovered Synergy horns and started moving in that direction. Now I'm on 2nd generation cabinets and third generation horn hoping these will finish well enough to be considered done.

The attachment shows the concept and the look I'm trying to achieve. Its implemented as a sandwich of a Synergy horn cabinet between two triangular bass bins that each contain a 15" slot loaded woofer and horn flares that direct the bass out vertical slots on the sides. These are hidden behind black perforated metal grills. The Synergy is 90H x 45V and is 12" tall at the mouth. The stack is 66" tall and 29" wide. The vertical horn wall will end up 3.5" from the room wall.

The attached photo shows my status. I've got two bass bins and one horn built and sufficient measurements done to know they will work. My plan is to finish these (i.e. apply veneer) , get help moving them upstairs into my media room, and then fix up my CAD files for another trip to my local CNC shop for the next set.

I will post more details tomorrow.
Attached Images
File Type: jpg oak flat cut veneered horn.jpg (331.9 KB, 2695 views)
File Type: jpg test setup in garage.jpg (968.7 KB, 2669 views)
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Old 12th May 2016, 03:19 AM   #2
dreadnoughtstrength is offline dreadnoughtstrength  Australia
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Absolutely interested in how this ends up!
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Old 12th May 2016, 03:48 AM   #3
bwaslo is offline bwaslo  United States
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My Synergy Corner Horn and Bass Bins
Looks like a neat concept. I think you'll still get boundary nulls from ceiling and floor, though. The lower vertical pattern control frequency for the rectangular horn will be much higher than for horizontal propagation, so there will be reflections off the floor (causing a null at I'm guessing around 150-230Hz) and one from the ceiling also. I have that issue on my Synergy clones, too. Allison effect is a bitch.

It wouldn't be as nice cosmetically, but have you considered making a square rather than rectangular horn so the vertical is controlled better? The vertical angle would be wider but would extend down to more useful frequencies. To make a narrower angle to a given frequency, the horn has to be (against intuition) larger in dimension, so the narrower angle causing a smaller dimension hurts quickly.
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Last edited by bwaslo; 12th May 2016 at 03:50 AM.
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Old 12th May 2016, 04:12 AM   #4
HIPCHECK is offline HIPCHECK  United States
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Nice Carolina Hurricanes poster. I lived in NC when the Canes still played in Winston Salem/Greensboro.
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Old 12th May 2016, 09:53 AM   #5
onni is offline onni  Sweden
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Very interesting! Subscribed!
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Old 12th May 2016, 10:47 AM   #6
TBTL is offline TBTL  Germany
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Looks good. Maybe you can improve the horn termination on the mouth side. That would prevent the sound from reflecting back into the horn. It would also prevent beaming around the lower frequencies, where the horn loses pattern control. A second flare with a larger angle or a huge rollover would work.
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Old 12th May 2016, 11:56 AM   #7
wesayso is offline wesayso  Netherlands
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Very nice! Sort of like a MTM with proper C to C distances tucked away in a corner...

Quote:
Originally Posted by bwaslo View Post
Looks like a neat concept. I think you'll still get boundary nulls from ceiling and floor, though. The lower vertical pattern control frequency for the rectangular horn will be much higher than for horizontal propagation, so there will be reflections off the floor (causing a null at I'm guessing around 150-230Hz) and one from the ceiling also. I have that issue on my Synergy clones, too. Allison effect is a bitch.

It wouldn't be as nice cosmetically, but have you considered making a square rather than rectangular horn so the vertical is controlled better? The vertical angle would be wider but would extend down to more useful frequencies. To make a narrower angle to a given frequency, the horn has to be (against intuition) larger in dimension, so the narrower angle causing a smaller dimension hurts quickly.
As the bass bins are closed above and below in the mid sections, couldn't one extend the synergy horn shape in the middle? I believe I once saw a proposal from you to do something like that. The front panels of the bass bins would no longer be flat but bulging in the middle (half round) to accommodate the larger horn shape, more of an extending lip actually.
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Old 12th May 2016, 01:51 PM   #8
Cask05 is offline Cask05  United States
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To OP: What you are describing and showing is very similar to the split Jubilee corner horn bass bin design by Tom B. He is using a K-402 from 400 Hz on up, not needing a multiple entry horn for that band. Tom puts his K-402 between the two bass bins. Here is a link to the half-height bass bins: https://community.klipsch.com/index....nnel-or-rears/

They work very well. Floor and ceiling bounce (...Roy Allison wasn't the first to describe the effect...neither was Klipsch...) isn't an issue with these like you see with direct radiating bass bins.

Yours is a nice implementation - congrats. That's what I'd do if using folded bass horns since it reduces the acoustic vertical offset to a minimum for the bass bins vs. the multiple-entry horn. The improvement in imaging and midbass performance is significant over a typical Khorn or Jubilee setup.

Chris

Last edited by Cask05; 12th May 2016 at 02:00 PM.
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Old 12th May 2016, 03:07 PM   #9
nc535 is offline nc535
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Thanks to all. I'm gratified by the responses.

Bwaslo: you are right re' ceiling and floor reflections. That is why I added the 2nd woofer which should control vertical from a 200 down more than an octave. I see a big floor bounce null in my hard floored garage but hardly noticeable upstairs in my carpeted media room. Throw rugs are my friend. I hope I can do without ceiling treatment.

I've drawn up a secondary flare to slide onto the sides of the horn (like the SynTrip); I doubt my wife will like how it looks but an engineer certainly would. I would blend it into the walls on the sides and use large roundovers top and bottom. Since I went sealed instead of ported for the woofers, I don't need the extra woofer volume that would allow. First I want to see how well it does without a secondary flare. We can all discuss that more later; its an interesting topic.

HIPCHECK: I was wondering what a hockey player was doing in Arkansas. I just retired from the Hillsborough Adult leagues two years ago due to a worn out back and age.

Cask: Very impressed with the Jubilee and your Synergization of it. Thanks for the link.

Jack
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Old 12th May 2016, 04:35 PM   #10
nc535 is offline nc535
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Default about the bass bins

When I started aiming for the corners I researched classical corner horns, focusing on Khorn and Jubilee. They had impressive sensitivity but not as much extension as I wanted. Following Wayne Parham, I built a ported prototype - same approach as I ended up with but taller and deeper; about twice the volume - using an AE TD12X I picked up in the infamous group buy a several years ago. This is the first attached photo.

The design tune was 35 Hz but I ignored vent proximity effects and ended up with a 29 Hz tune. When I hauled it upstairs I found a huge room mode peak right at 40 Hz. The quick fix was to close off the vent. It was still -3 db at 25 Hz. It was then I knew I should go sealed.

Going sealed though called for more extension so I upgraded to TD15Hs. This time they only took about a month to arrive. I shrunk the box height to 26" for a volume of 65L and a Qtc stuffed of .65 or so.

These boxes have 3" deep slot with flares to direct the sound out to the sides. I modeled them in HornResp and simulated in 4pi space then included a room gain profile exported from Jeff Bagby's Diffraction and Boundary Simulator. This models a side slot as a radiator and includes the reflection from the opposite side wall, which limits the high end extension (although not as much as does the split horn path when you get off axis). This model is optimistic on the high side because it includes a V shaped reflector in the baffle hole (where a phase plug might go) that reduced the Vtc. I dropped that deflector in the interest of simplicity when measurements showed it bought me only 50 Hz, which I didn't need. You can see the acoustic impedance taking off from the horn gain at 200 Hz, delaying the response fall off due to the bandpass chamber effect of the slot.

In the sim I'm modelling two drivers in twice the volume, ignoring their physical separation. Equalized flat to 20 Hz, I get 123 db SPL at Xmax. I don't listen nearly that loud so I'm confident I have a low distortion solution.

I'll post some build photos and measurement results shortly.

Jack
Attached Images
File Type: jpg ported proto.JPG (227.6 KB, 2643 views)
File Type: jpg HR sim.jpg (298.1 KB, 2258 views)
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