Why Synergy horns?

In another thread I was asked, if I would provide more details about my speakers, so I thought why not?

I have played on active 4 way horn systems since 2016. First iteration was front loaded bass horn, midbass horn, tractrix midrange horn and tractrix tweeter horn. I worked nicely, with all the attributes associated with well implemented horns. Clarity, dynamics, realistic live sound etc.

However some problems will arise, with such horns. First of all, the center to center distance between the different horns is big, compared to the crossover frequencies. We need to be within 1/4 wave in distance at x-over for a seamless transition. For instance if you x-over from the midrange horn to the tweeter horn at 3 KHz the c-to-c distance would have to be 340/3000/4= 2.83 cm (1.11 inch). This is virtually impossible with "normal" horn configurations. This problem rears its ugly head, at every x-over throughout the audio frequency range. As frequency decreases, the wavelengths gets bigger, but so does the horns in the specific bandpass and then c-t-c also increases. It is a linear problem, that can't be solved with the regular approach, aka stacking horns on top of each other. This creates interference problems and lobing in the vertical response curves, that will color the reflection from floor and ceiling. Secondly a large column of vertically stacked horns, will push the sweet spot (SS) further back, for the horns to be perceived as more coherent and integrated, with one another.

But the biggest problem is that almost all horns beam with increasing frequency, it's their way of nature so to speak. What that means, is that the off-axis FR will not be similar to the on-axis FR. This translate into a poor power response, which is not considered a good thing, in terms of best sound quality.

Luckily we can circumvent all these problems with clever engineering and have our cake and eat it too, so to speak. Enter the Synergy horn.synergy.jpg
 
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Finally the synergy horns and subs are measured and adjusted. He found something odd in the measurement of the right channel. It turned out that one of the 12" drivers had a reversed phase. After correcting that and with some more tuning it measures so smooth. Never had or heard sound and capacity like this. We played a lot of music and some at/above concert level and it was crystal clear with a lot of punch and details. Just love it!
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Nice Fjordfunk, a good example of how important measurements are, if not, then just for checking that everything is in order. It is not that easy to hear faults in the frequency response, unless you know what to listen for and are aware of it.
A little story to back it up. Some time ago I had a bunch of people coming in for a listen to the JBL copy setup. It wasn't until after the session, that I found out that the left JBL midbass, for some reason, was muted in the Minidsp. Definitely my (rookie) mistake, but the funny thing is, that nobody discovered or mentioned it. They all, actually, liked what they heard, at least, that was what they said :D
 
@schlager did you have the chance to participate in Stemholjm's latest review (Radiant speakers)? If so, I would be curious to hear your thoughts. I found the speaker comparisons he made were interesting.
 
Finally the synergy horns and subs are measured and adjusted. He found something odd in the measurement of the right channel. It turned out that one of the 12" drivers had a reversed phase. After correcting that and with some more tuning it measures so smooth. Never had or heard sound and capacity like this. We played a lot of music and some at/above concert level and it was crystal clear with a lot of punch and details. Just love it!
View attachment 136546
Do you want to share some measurements, if you are okay with that? Frequency response, phase, waterfall but impulse is also interesting to see the room interaction.
 
Do you want to share some measurements, if you are okay with that? Frequency response, phase, waterfall but impulse is also interesting to see the room interaction.
I would love to but we used his PC for measuring and my PC for programming so i dont have access to it, i am sorry.
But the response was straight, slightly falling against the top. Since this is point sources from 150hz and up the phase was excellent. The subˋs, JBL2242 is mounted more in front of the rest so i believed he had to make a delay but he told me that the inductance of the drivers is making a delay naturally so very little had to be done.
Cheers
Espen
 
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@schlager did you have the chance to participate in Stemholjm's latest review (Radiant speakers)? If so, I would be curious to hear your thoughts. I found the speaker comparisons he made were interesting.
Hi hopkins, no I haven't heard Radient, but I'll probably get the chance at some point, because I think that Morten is going to keep the speakers:)
I can post measurements, if I get the chance.
 
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I have finished the second ribbon horn for stereo listening. It sounds good to my ears, so I have decided to keep them for now. I might even get around of buffing up the finish on them. Working as a dipole the sound is less dry, than from the synergy horns, so it's a nice supplement to the system.
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Purple no horn.
Blue with horn, it actually flattens the response pretty nicely and bump up the low end with up to 8 dB, so the horn works as intended. As a bonus it also raises the tweeter response from 5- 12 KHz, pretty awesome.

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To find out how low I can go with the horn, I did a distortion measurement with horns. This is with a highpass at 100 hz and sweep start at 200 hz. From that it seems tha 350 hz will be a safe x-over.
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Highpass at 350 hz and distortion is under control.
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Horizontal direction 0-90 degrees
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Vertical response 0-30 degrees
vertical response.jpg

With EQ

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RCanelas I took the idea from Joseph Crowe and used it for inspiration.


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Luckily he also provided some drawings so I could guesstimate how to build it. My horn is build of straight sided panels, whereas Crowes horn is CNC machined. The first section is 18 cm deep and tilts in an outward angle of 15 degrees. The next section is 15 cm and has an angle of 30 degrees, so in total I end up with 90 degree horizontal and vertical 2 x (15+30). I have finished the horn with cardboard tubes cut in half. Size of the horn is 83x46 cm. I used Crowes horn as inspiration, his horn is less angled and a bit smaller, but here in the garage I like everything to be big :D
 
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Spectrogram, decay and burst decay plot looks pretty clean, so the horn should be free of resonances and diffraction from the horn mouth and result in clean sound. I will probably try to damp the horn, to see if things improve.
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With MEH, is there really no price to pay for drilling a set of holes in the sides of a horn flare? Seems it would set off high frequency diffractions/reflections inside the horn.
 
Hi Tim, the short answer is no. Measurements with and without holes, shows an insignificant difference. At least the advantage of the MEH idea itself, far out weights this insignificant difference.
 
Hi Tim, the short answer is no. Measurements with and without holes, shows an insignificant difference. At least the advantage of the MEH idea itself, far out weights this insignificant difference.
Thanks. I just a got a reply on another forum from someone who is testing and building them, and he measured more ragged response with the holes than when he taped them over. He's now working on different positioning of the holes to minimize the effect. I'd expect from a pragmatic perspective that the audible effect of the holes would be minimal. But when we're talking high end audio, pragmatism is way down the list. If someone is paying tens of thousands for a dac, it would surprise me that they'd accept any rough response from the tweeter. It seems that it may be possible to use a membrane over the holes that will dramatically cut back on any effects on the tweeter response while still letting the lower frequencies pass through. Specialized drivers for this use case might be appropriate.

I haven't had a chance to hear an MEH design yet. I'm intrigued with the idea.
 
Hi Tim, could you provide a link for that discussion?

In general, placing the entry holes at or near the corners of the horn, where the pressure is lowest, the compression driver doesn't really "see" the holes, thus ensuring minimal impact on the tweeter response. The holes for bass drivers are of course bigger, but at the same time also placed further out the horn, where pressure is even lower, from the tweeters perspective.

One could experiment with foam with PPI 10-30 and plug the holes, but I think it is safe to say that the entry holes, will have none to a benign effect on the quality of the tweeter, perceived by the listener.

Hopefully, anyone clever enough to go with this type of horn, will also be clever enough, not to go with a 10K DAC :D
 
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Hi Tim, could you provide a link for that discussion?

In general, placing the entry holes at or near the corners of the horn, where the pressure is lowest, the compression driver doesn't really "see" the holes, thus ensuring minimal impact on the tweeter response. The holes for bass drivers are of course bigger, but at the same time also placed further out the horn, where pressure is even lower, from the tweeters perspective.

One could experiment with foam with PPI 10-30 and plug the holes, but I think it is safe to say that the entry holes, will have none to a benign effect on the quality of the tweeter, perceived by the listener.

Hopefully, anyone clever enough to go with this type of horn, will also be clever enough, not to go with a 10K DAC :D
 
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Placing a ring of holes around the tweeter at the apex, is of course not without consequences.

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Looks like he redid the horn with less and more appropriate locations of the entry holes. What he did on the modified horn seems much more appropriate. Less, but slightly bigger holes and placed in the corners of the horn walls.

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Subs are now crossed at 180hz 24db/LR. Then the 18Sound 12"ˋs are taking over. The mid/high i am not quite sure of where it starts since the crossover is pretty advanced with so many settings. I guess the mid/high comes in about 600hz or so?
What is the benefit for this relative high crossover point to the bass section and not 60 or 100hz for example?
 

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