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.

 

Hi!
Been trough 3 different horn systems, my synergy horns are the 4rth. Last system had flh from about 250hz and up to 600hz with large JMLC horns for mids.
My synergy horns are a different animal. Very little beaming leaves me with a big sweetspot, one of the best things i like about it. Dynamics are offcource mind blowing(like many other types of horns). After a professional calibration of the system this is the best i have heard of a speaker but i am biased since it is my own. Visitors leave with a big smile every time.
Fjordfunk

 

I’ve said this before but what has convinced me that I simply have to try a MEH is how many of the people who have built them all have the same comment; the best speaker they have ever heard. You will be hard pressed to find a MEH owner who has not publicly made such a comment.

 

There is no “ideal” loudspeaker of course. It’s all about tradeoffs.

+1

 

Gents, would you argue the synergy horn to be -- objectively -- the closest approximation to the ideal loudspeaker? I know there are excellent and compelling examples of speakers of all ilk and at the end of the day, you may prefer the sound of one type of speaker type over another despite measurements to the contrary but it's an interesting discussion nonetheless.

The synergy horn solves some of the most fundamental issues of most speaker topologies, so objectively I would say yes. I believe one of the culprits of most horns, sounding a bit wrong and hornish, is the uneven power response. Another "flaw" is beaming in the high frequencies. Decades ago a solution to that was the use of diffraction slot, which led to other sonic problems. A conical horn behaves different, with a much more even power response and a more convincing disappearing act. The trade off is a bit lower sensitivity, than most other horn types, but we are still talking +100db/1w for a conical synergy (MEH) horn.

 

A conical horn behaves different, with a much more even power response and a more convincing disappearing act. The trade off is a bit lower sensitivity, than most other horn types, but we are still talking +100db/1w for a conical synergy (MEH) horn.

The trick is to find a driver with an exit flare that matches the conical flare you want to use. If you have to use an adapter, it's not going to be a cone anymore, and you end up trying to find a contour that will adapt one flare to the other with minimal artifacts. Ear Geddes and other people following in his footsteps have shown how to get the desired conical performance while dealing with flare adaptation at the throat, and the mouth roundover needed to minimize artifacts from the exit shock. When it's all worked out it still sort of resembles a cone, a rather curvy cone.

 

The MEH and esp Synergy type (coherent phase between 100Hz and 20KHz) are very well balanced and even across the entire rev range.

Before I was listening to really excellent individual performances from each horn.
It was oh wow that clarinet sounds good from the 2" throat mid range drivers or hmm that female vocal is truly amazing mostly in the upper mid horns.
Having phase aligned the crossover regions from the listening position it was all pretty good.

Now it's like listening to a cohesive performance across the whole audible spectrum.

Below 100Hz, phase shifts are not heard in the same way I find. So that's not a problem.

The fact that my MEH/Synergy horns pack twice as much mid base punch driver wise, and go 40Hz deeper is really good too.

Front loaded horns that could compete to 55Hz would be enormous!

The MEH is really quite compact.

Agree on the conical thing.
They do not sound like horns.
Just music.

 

A speaker design with a poor impulse response and floor bounce obviously has definite weaknesses. All speakers have their issues and compromises of course, but I would consider these to be worse than certain other problems.

 

A speaker design with a poor impulse response and floor bounce obviously has definite weaknesses. All speakers have their issues and compromises of course, but I would consider these to be worse than certain other problems.

How do you avoid "floor bounce"? Perhaps I am unclear as to what "floor bounce" is...

 

How do you avoid "floor bounce"? Perhaps I am unclear as to what "floor bounce" is...

The floor bounce is the cancellation/dip speakers get over a reflective floor in the midbass area. One can be lucky to have peaks in the same area to combat it. But normally speakers with floor bounce will lack level in this region which leads to uneven response, a leaner presentation with wrong tonality. It's very common and quite detrimental to sound quality.

In a Danish study conducted several years ago it was considered the most negative of all reflections.

I’ve done a lot of testing on the effects of reflections in rooms, and there was a big, big project in Denmark about twelve years ago, with a lot of companies involved in investigating effects of reflections in rooms. I had the pleasure of being a test person, where we could actually simulate the audible effect of the floor reflection, sidewall reflection, ceiling reflection, and so on independently. The single most disturbing reflection in the room is the floor reflection. That is what makes the speaker sound like a radio and not like the actual event. ... The floor reflection absolutely must be handled

There are several ways to either minimize it or avoid it. It's done this in all speaker designs I've been involved in. I have done a lot of AB testing with and without it. I very much agree with the statement above. For high quality sound, it must be dealt with and that's not the case with a synergy/MEH horn.

 

The floor bounce is the cancelation/dip speakers get over a reflective floor in the midbass area. One can be lucky to have peaks in the same area to combat it. But normally speakers with floor bounce will lack level in this region which leads to uneven response, a leaner presentation with wrong tonality. It's very common and quite detrimental to sound quality.

In a Danish study conducted several years ago it was considered the most negative of all reflections.

At least one acoustician I asked about this told me the opposite: our brain seems to be more "used" to floor bounce, at least when it comes to reflections. Maybe if you have large cancellations, that's more of an issue, but my question was, "how do you avoid it" by "design"?

 

At least one acoustician I asked about this told me the opposite: our brain seems to be more "used" to floor bounce...

My question was, "how do you avoid it" by "design"?

I think certain people say this because it's seems reasonable, but not because they have actually done a study or a good AB test. We must also remember that with most speakers and rooms there are also cancellations in the same region on top. So the level can end up being very low.

Besides, playback is something else than real life or the recording. Another wrong assumption here would be that since we hear some live music with a lot of reflections, we shouild listen with a lot of high gain specular energy as well. But that's not the case if one wants accuracy. We don't get closer to the live event by adding more strong reflections on top what's in the recording.

I don''t necessarily share how it can be dealt with in a design since it's something I work with.

 

I think certain people say this because it's seems reasonable, but not because they have actually done a study or a good AB test.

Maybe they have, maybe the have not, I have no idea.

Besides, playback is something else than real life or the recording. Another wrong assumption here would be that since we hear some live music with a lot of reflections, we shouild listen with a lot of high gain specular energy as well. But that's not the case if one wants accuracy. We don't get closer to the live event by adding more strong reflections on top what's in the recording.

I never said that.

I don''t necessarily share how it can be dealt with in a design since it's something I work with.

Easy way out
I would be curious to know how a speaker's design could avoid reflections from nearby surfaces, unless it is "highly" directive. That would be a first, especially in lower frequencies... Good luck with your work.

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The trick is to find a driver with an exit flare that matches the conical flare you want to use. If you have to use an adapter, it's not going to be a cone anymore, and you end up trying to find a contour that will adapt one flare to the other with minimal artifacts. Ear Geddes and other people following in his footsteps have shown how to get the desired conical performance while dealing with flare adaptation at the throat, and the mouth roundover needed to minimize artifacts from the exit shock. When it's all worked out it still sort of resembles a cone, a rather curvy cone.

Sure and then design the horn throat from scratch. Here 3D printing comes in handy. Geddes is using Oblate Spheroid horn and all my synergy horns use the OS profile at the horn apex.

Over the years I have gathered a list of drivers exit angle.
Most have less than 30 degree exit and I think it's safe to say, that going from a small CD exit angle into a horn with bigger flare angle, is much better than the other way around.

B & C
DE250 14.6°
DE10 7.7°
DE12 24°
DE400TN 20.7°
DE400 31°
DE500 17°
DE200 9.9°
DE85TN 34.5°
DE750TN 22°
DE950TN 17°

JBL
2450 10+°

2445 exit to 5 degs

Radian
950 20.3°

Celestion
CDX1-1745 20.16°
CDX1-1730 20.16°
CDX1-1731 20.16°
CDX1-1746 7.6°

Beyma
CP750Nd – 24º
CP850Nd – 7º
CP755Nd – 12º60’
SMC65Nd – 15º
CP385Nd – 16º30’
SMC225Nd – 13º1’



CP750Nd – 24º
CP850Nd – 7º
CP755Nd – 12º60’
SMC65Nd – 15º
CP385Nd – 16º30’
cd10 - 16º30’
SMC225Nd – 13º1’

B&C

1"
DE250 14.6°
DE10 7.7°
DE12 24°
DE400TN 20.7°
DE400 31°
DE500 17°
DE200 9.9°

2"
DE85TN 34.5°
DE750TN 22°
DE950TN 17°

BMS

4524 20º
4538 21.8º
4544 20.6º
4550 14º
4552 – 24°
4554 26.7º
4555 30º
4590/4590p 1º
4591 1º
4540nd 14º
4552nd 24º
4592nd 10º
4594nd 3º
4595nd 10.8º

 

How do you avoid "floor bounce"? Perhaps I am unclear as to what "floor bounce" is...

I talked about that subject under my description of the Dali Epikore 11. They are coupling 2 pairs of bass drivers, placed at different positions vertically. By using different crossovers aka different frequency x-over and different order of x-over, they mitigate the floor bounce, often found in the 200-300 hz, sucking life and energy out of most of musics fundamentals. A more simple way is to place the bass driver at floor level and use it up til +300 hz. Look at the famous classic AR9 speaker, a lot of clever engineering went into that speaker and this was in the 70's.

 

I talked about that subject under my description of the Dali Epikore 11. They are coupling 2 pairs of bass drivers, placed at different positions vertically. By using different crossovers aka different frequency x-over and different order of x-over, they mitigate the floor bounce, often found in the 200-300 hz, sucking life and energy out of most of musics fundamentals. A more simple way is to place the bass driver at floor level and use it up til +300 hz. Look at the famous classic AR9 speaker, a lot of clever engineering went into that speaker and this was in the 70's.

Thanks!

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I talked about that subject under my description of the Dali Epikore 11. They are coupling 2 pairs of bass drivers, placed at different positions vertically. By using different crossovers aka different frequency x-over and different order of x-over, they mitigate the floor bounce, often found in the 200-300 hz, sucking life and energy out of most of musics fundamentals. A more simple way is to place the bass driver at floor level and use it up til +300 hz. Look at the famous classic AR9 speaker, a lot of clever engineering went into that speaker and this was in the 70's.

P.S. if there are "simple", known solutions, why don't more speaker manufactures adopt them? (and at a reasonable cost...).

 

P.S. if there are "simple", known solutions, why don't more speaker manufactures adopt them? (and at a reasonable cost...).

That is what I would call a good question. One can only speculate, but maybe the loudspeaker industry as a whole, don't have the knowledge, maybe they simply don't give it any weight in the design phase or maybe they simply don't care. We see all kinds of loudspeaker designs and most are greatly flawed, so we have market of products that performs the same task, but do it differently and thus the saying goes "there is a loudspeaker for everyone, you just have to find it". I don't buy into that at all.

 

Here's a FR curve for my speaker (Teufel Ultima 40, modded crossovers) with a nice dip around 300Hz (among other irregularities), which I assume illustrates what we are talking about here. I do want to measure the speakers with the woofers only to confirm that it is not an issue with the crossover to the other drivers (I will also check how it behaves with some thick basotect absorption panels on the floor at the first reflection point). I do really enjoy the sound, but of course everything can be improved...



Those Teufel speakers, by the way, are now sold for 300€...

 

Here's a FR curve for my speaker (Teufel Ultima 40, modded crossovers) with a nice dip around 300Hz (among other irregularities), which I assume illustrates what we are talking about here. I do want to measure the speakers with the woofers only to confirm that it is not an issue with the crossover to the other drivers (I will also check how it behaves with some thick basotect absorption panels on the floor at the first reflection point). I do really enjoy the sound, but of course everything can be improved...

View attachment 141186

Those Teufel speakers, by the way, are now sold for 300€...

For the money they seem like a great buy. Try to place a madras or other absorbing material between the speaker and mic and see if that suck out goes away and double check with a near field measurement of the bass drivers (10 cm).

 

It's time for a change.

This has been on my "to do list" for a while and now with the winter kicking in here in Scandinavia, the down time in the garage is increasing. So I thought it would be a good time to do some changes on the big synergy horn. I'm swapping the EVM 15" to 4 x 10" for a more even input into the horn. That will get me 3 things, a better defined notch around 500 hz and thus, a better transition to the midrange drivers and lastly a more even sound dispersion out of the horn.