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Multi-Way Conventional loudspeakers with crossovers

Synergy horn for 135 dB+
Synergy horn for 135 dB+
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Old 28th March 2017, 11:34 AM   #1
Thijs666 is offline Thijs666  Netherlands
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Join Date: Nov 2003
Location: Maastricht
Default Synergy horn for 135 dB+

Synergy horn for >135 dB

Since I first saw (and heard) Synergy horns on YouTube I was intrigued. This coherent sound image was nothing I had ever seen before. And after building a 3-way Synergy with a half passive crossover I was sold. A small 2-way for my living room followed quickly and I wanted another pair that would easily endure a rock band in a small to medium sized space, replacing my 4 Bill Fitzmaurice DR200 cabs; less lugging, better quality, if possible even more balls (more dB’s and a bit better low end), but still a one man transport. That meant > 133 dB, extension < 120 Hz, preferably down to 90-100 Hz, to couple better with subs, and not too big or heavy. It should be pole mountable and (thus) be a one man lift.

With this in mind, more than a year ago I purchased the Beyma CP850ND compression driver, a 2” beast with a 4” voice coil, for a good 2nd hand price, with the intention to design a 2-way Synergy top. Why 2-way? I wanted a passive crossover and to design a 3-way crossover for a Synergy horn that also accounts for the phase curve is a bridge to far for me right now. A 2-way crossover I think I can manage. Than I ran into an offer on 12” B&C 12NDL76 lightweight neodymium woofers. Before I pulled the trigger on them, I quickly threw together some simulations and it looked like it would be a good candidate. So I bought 4 of them. Time passed by and life happened, as many of you undoubtedly know, and the project got put on hold.

On and off I had some time to think about the project and I started reading again for inspiration where I always start, right here on diyaudio . That is when I read about Art Welter’s SynTripP(C). What a marvellous idea he had with that horn extender. Also, it gave me some confidence that a proper 2-way Synergy could be feasible. I was never 100% satisfied with my small 2-way living room Synergy horns…

Before I continue I’d like to thank Bill Waslo for his SynCalc spreadsheet, which is immensely helpful for designing and constructing a Synergy horn, Art Welter for sharing his SynTripP design, David McBean for offering his HornResp software, Tom Danley for his Synergy concept and everyone else here on diyaudio and on the world wide web for sharing his/her knowledge on this topic!

Let’s start with some simulations:

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Note: 80V @ 4 ohms = 1600W, the program power of two 12NDL76s combined.
Note 2: Hornresp 39.40 is, as far as I know, not able to simulate this horn combined with a vented chamber for the woofers. I figured I could get about 6dB from adding vented ports tuned to 100 Hz and even out the bottom response.

Lately I have had some time to turn my thoughts and simulations into sawdust and this happened:

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Not much room left...
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Then some measurements:

Tweeter:

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Woofer:

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Then a passive crossover design:

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Which resulted in:

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Note: this is @ 2m, my calibrated measurement ‘system’ is limited to 110 dB input. So add 6dB for a 2.83V/1m figure.
Note 2: the dip at 140 Hz is a room dip, as can be seen from the measurement below, which I did right in front of the horn mouth (“0 cm”):

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*all measurements without any EQ, just the crossover (when applicable).

The strange phase jump around 760 Hz, that’s where the crossover frequency is, I find a bit odd. Look what happens when I put the mic about 10 cm off axis:

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So what I want to do is try out REW’s Impulse Response Calculation. It’s set to “No timing reference”. I’d like to try the “Use loopback as timing reference” but I have to make a special cable for it…

What do you guys think so far?

Cheers!

Edit: Btw, the last three measurements are with four 65-mm bass reflex ports (not in photo's)

Last edited by Thijs666; 28th March 2017 at 11:39 AM.
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Old 28th March 2017, 12:12 PM   #2
anji12305 is offline anji12305  United States
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This is an epic in the making.

Kudos.

Sent from my Nexus 6 using Tapatalk
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Old 28th March 2017, 01:53 PM   #3
fluid is offline fluid  Australia
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Thijs666,

I like that you used better plywood this time and they look a much sturdier build than your other's

How did you smooth the compression driver entrance it looks to be nicely done.

Did you reflex port it yet?

Edit: Just saw your edit, makes sense now!
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Old 28th March 2017, 03:15 PM   #4
nc535 is offline nc535
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Hi Thijs666:
HornResp is now up to version 40.30. You can simulate vented woofers as offset drivers on the horn without issue. You might not be able to do this when simulating it as a multiple entry horn but simulating woofers alone is not a problem

You should take a look and see how closely your CD and woofers are time aligned. The best indication is probably the step response of the full range measurement but you should also look at an overlay of separate driver measurment IRs.

Jack
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Old 28th March 2017, 09:07 PM   #5
fotsinijts is offline fotsinijts
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Really nice! After building two unity horns for home use, I'm looking for a couple of horns for pa use, this may be it!

Following this

Groetjes
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Old 29th March 2017, 01:44 AM   #6
weltersys is online now weltersys  United States
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Location: Florida
Quote:
Originally Posted by Thijs666 View Post
Synergy horn for >135 dB

What do you guys think so far?

Cheers!

Edit: Btw, the last three measurements are with four 65-mm bass reflex ports (not in photo's)
Thijs666,

Looks somewhat familiar...
Nice work!

Art
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Old 29th March 2017, 08:56 AM   #7
David McBean is offline David McBean  Australia
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Quote:
Originally Posted by nc535 View Post
HornResp is now up to version 40.30.
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Old 29th March 2017, 09:49 PM   #8
zettairyouiki is offline zettairyouiki  United States
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Very nice! I was thinking about doing something almost exactly the same. I've got 4 12ndl76s and 2 Faital HF14ATs. My only concern is that the Faital CDs don't have enough low extension to meet the 12s at a reasonable point for a synergy design.
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Old 30th March 2017, 02:48 AM   #9
msibilia is offline msibilia  United States
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Quote:
Originally Posted by zettairyouiki View Post
Very nice! I was thinking about doing something almost exactly the same. I've got 4 12ndl76s and 2 Faital HF14ATs. My only concern is that the Faital CDs don't have enough low extension to meet the 12s at a reasonable point for a synergy design.
If you can't get a synergy to go high enough, you might follow my thread A 12 inch horn loaded MTM top: 12NDL76 and N314T-8. It will probably work really well with your drivers.

Last edited by msibilia; 30th March 2017 at 02:52 AM. Reason: Removed graph to not clutter up this thread
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Old 30th March 2017, 05:22 AM   #10
zettairyouiki is offline zettairyouiki  United States
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Join Date: Apr 2014
I did see that before. Nice project. My plan is to go big or go home. I know I'm going to need mids, and I'm mostly just whining about it because doing a 2 way and ditching an amp sounds nice but impractical to me.

I'm more than likely going to go "whole hog" on this one and do a proper 3 way with 4 4" Celestion mids to keep up with 2 12s.

My other idea that I'm still floating is doing Peter Morris' mid-top design with a 2way synergy center instead of the prescribed BMS coax. Just need some time to agonize over the choices haha.
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