I wouldn't want to go onto the record saying that the midrange entry ports have "zero" effect on the compression driver's output. It is more like, it doesn't have a "significant" effect. The effect would be very diminished if the construction of the speaker followed all the rules found in the Synergy horn patent application. I would say that there are bigger fish to fry at this point.
I think I know what you are getting at. I don't see your question as redundant. It is a question that needs to be asked and understood. I believe you want to understand the effects of the midrange's port entries on the creation of HOMs. You believe that the odd shapes used to introduce the midrange's output into the horn will cause HOMs. I'm I correct in understanding your question?
If I understand you question correctly, then the following is how I see it. The introduction method for the midranges is not conventional. We have compression ratios around 10:1 . This changes the mode of sound transmission. We are no longer "radiating" into the midrange port as much as we are "injecting" pressure into it. (Radiating sound allows for scatter, pressure follows laminar flow) The pressure enters into the horn and travels toward the mouth. Provided the mouth has sufficient termination, there should not be a significant amount of HOMs due to mouth deffraction. You will not get significant HOMs due to the ports themselves, mostly from the mouth termination.
P.S. I found this cool Laminar flow clip. It is a great example how either high pressure or high viscosity can be used to reconstruct something.
YouTube - Laminar Flow
I think I know what you are getting at. I don't see your question as redundant. It is a question that needs to be asked and understood. I believe you want to understand the effects of the midrange's port entries on the creation of HOMs. You believe that the odd shapes used to introduce the midrange's output into the horn will cause HOMs. I'm I correct in understanding your question?
If I understand you question correctly, then the following is how I see it. The introduction method for the midranges is not conventional. We have compression ratios around 10:1 . This changes the mode of sound transmission. We are no longer "radiating" into the midrange port as much as we are "injecting" pressure into it. (Radiating sound allows for scatter, pressure follows laminar flow) The pressure enters into the horn and travels toward the mouth. Provided the mouth has sufficient termination, there should not be a significant amount of HOMs due to mouth deffraction. You will not get significant HOMs due to the ports themselves, mostly from the mouth termination.
P.S. I found this cool Laminar flow clip. It is a great example how either high pressure or high viscosity can be used to reconstruct something.
YouTube - Laminar Flow
What you could do is to test the device with only the midrange drivers and connect the compression driver as a microphone and look at its output.
The structure of a compression driver makes it a Helmholtz resonator, and the holes and slots for the midrange are also, so in this part we have three coupled Helmholtz resonators.
I would guess that the best results are given when the compression driver resonance is out of phase with the others.
rcw.
The structure of a compression driver makes it a Helmholtz resonator, and the holes and slots for the midrange are also, so in this part we have three coupled Helmholtz resonators.
I would guess that the best results are given when the compression driver resonance is out of phase with the others.
rcw.
Hi John,
I would also like to thank you very much for your thorough explanation of some of the key principles behind the Unity and Synergy Horns.
Now, the Synergy horns seems like a real masterpiece - at least from a technical point of view. I can't help asking whether you have had a chance to hear the Danley SH-50s or any of its sister models, and if "yes" I would really love to hear your impressions of these.🙂
For us on the other side of the Atlantic, it is unfortunately difficult to get close to hearing a pair.
Thanks a lot!
Best regards
Peter
The nulls in the midrange response are caused by the reflections off the diaphragm of the compression driver. The low pass function is caused by the midrange front chamber. There could be additional nulls at higher frequencies caused by the geometry of the midrange front chamber when that becomes large relative to the wavelengths under consideration.
Related to something else that was said, the midrange holes will mess up the compression driver's output if they're too big (in my experience). Alternatively you could say they'll have an effect if their impedance is not high enough.
I've heard the SH-50, SH-95, and SH46 models. All were very good at what they were designed to do. The SH-95 doesn't go as low as the SH-50 or SH-46. You would really need something starting at around 200Hz to work with the SH-95. The tonal balance was a bit hot in the high frequencies too. We must remember these are designed as P.A. speakers and the high frequencies are required to cut through some distance in most cases. Of course a little bit of EQ would take care of this. I think of the SH-95 as the best center channel speaker I have ever heard.
The SH-50 and SH-46 sounded almost the same. I liked the SH-46 better because it has a nice falling high frequency response that is easier to listen to. The SH-50 was not as hot as the SH-95 in the high frequencies, but was still a bit much for me. Once again, a little bit of EQ would fix this. I really like the SH-46 and think it would make for a killer home theater speaker. The controlled directivity helps remove the room from the listening experience.
The thing that all three shared was the point source image. The imaging and sound stage depth was ridiculous. The coherence through the entire audio band was the best I've heard. The intelligibility of voices and nuances was also the best I've heard. The Synergy horn's ability to flesh out detail and to place it correctly in the sound stage was uncanny. When listening to 2 channel stereo, it sounded like there was a center channel in play. That's how well the Synergy horn resolves fine detail.
To me the Synergy does everything a single driver setup does, but with none of the weaknesses. The Synergy is actually more coherent than a single driver. In addition, it has high sensitivity, high power handling, high SPL capability, no hint of Doppler distortion, low harmonic distortion, and can pass a square wave over most of its bandwidth. No single driver can do those things.
Hi JLH,
Thanks a lot for very elaborated reply regarding the sound quality of the SH-50 and its sister models, I really appreciate it!
The SH-50 sure seem to excell in many areas. You are a very experienced DIY'er and I would like to ask: Besides the 'hotness' in the highs, was there any other areas where you would prefer your own setup relative to the SH-50's - well maybe besides price?
One final question: Do you have any idea about the crossover components used in the SH-50s?
Once again many thanks!
Best regards
Peter
A traditional horn stack has higher sensitivity. Most of the Synergy horns are 95dB to 100dB with 1W/1M. Most of the horns I’ve made are more like 106dB 1W/1M. This allows me to use very low power tube amplifiers. My previous horns only required about 2 watts. I would say you would really need something more like 10 watts or more with the Synergy horns. The combination I’d love to hear is the SH-46 powered with one of Allen Wright’s DPA-300B amplifiers. With 25W on tap I’m sure it would really be something to hear.
I’ve done enough modeling and simulations to get a general idea what crossover hides inside the Synergy horns. They are not conventional crossover orders or slopes. You must think about the crossover components more as transfer function modifiers. You use whatever is required to get things phase aligned and frequency response reasonably flat. The crossover works in conjunction with the physical construction of the horn. The throat transition, midrange ports, mouth termination, etc. all will affect what the final crossover looks like. I would forget trying to clone a SH-50. You are better off just rolling your own. Even if you had the crossover schematic of the SH-50 in hand, unless you copied the rest of the horn and drivers it would be useless.
I have a working model of a 3-way Synergy horn in Akabak. I will build it once things slow down around me. It will be interesting to see how close the simulation is to the real world result.
Hi John,
Thanks a lot again for another thorough answer! My question concerning the crossover was not about the filter topology as such, but rather regarding whether you knew anything about the quality of the components involved (e.g., polypropylene caps, air coils, or???). My initial guess would be that that components used are of good quality although not 'exotic' at all. I find it genuinely thought provoking that such sound quality can be reached with fairly conventional drivers and components!
Please do report back to us in case you succeed making a Synergy Horn! I am very far from having the necessary skills required in order to model and make a Synergy Horn myself. Thus, I can't help thinking that quite a few people would be very interested if Tom Danley came up with a DIY 'home' version of the SH-50 or equivalent🙂 On the other, hand I somehow understand if Tom Danley hesitates launching such a project!
Thanks once again!
Best regards
Peter
From the attached picture, it looks like Tom uses poly caps and air core inductors where he can. For larger values he uses Bi-polar electrolytic caps and iron core inductors. I would agree that the parts are not "Exotic", but are of decent quality. When/if I complete my project I will be using better quality parts. Probably Mills resistors, Auricaps, and ERSE coils. I'm also throwing around the idea of battery biasing any caps that appear in series with the compression driver, or mids.
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THIS is why I am so obsessive about getting the Unity horn working in a car. At home I can listen to my Summas, but in the car the center-to-center spacing of a Unity horn is basically the perfect setup.
The coherence is something you really have to hear to believe.
On a side note, I've been toying with the idea of Unity computer speakers. Because we listen to speakers in the extreme nearfield, and we sit in front of our PCs for hours every day, it seems like an interesting project.
Also, why are half the guys building DIY unities named John? (I didn't realize JLH's first name was John, and I'm John too... (PB is a pseudonym.))
Nice to know you John 🙂
So, in the end, if you'd be doing a home-setup, kind of your first project, what would you choose? A two way, oblate-spheroid waveguide + 15" woofer, or an Unity?
Hi Brett,
As you know DIY'ers can at times have really long discussions about differences between single components. It was just my 2 cent comment that achieving excellent results with good, but not exotic, parts put such discussions in perspective...
Best regards
Peter
Are you still planning on using the KCN5FD?
I've auditioned about ten different options, and the Misco was exceeded by quite a few. Peerless offers models with lower distortion, and are less expensive. (They're on closeout, so quantities are limited.) An array of Tang Band W2-852SH drivers has comparable distortion, but is easier to work with due to the small size. This improves the high frequency output in the Unity.
It's a real oddball unit - it has a motor that's big enough for a twelve attached to a four inch cone. That motor in the pic above is neodymium, not ferrite! It's one brutal midbass.
Also, this is subjective, but it seems like the stiff-coned drivers sound better than the paper coned drivers in the Unities I've built. The distortion is measurably lower. Perhaps this has something to do with the compression ratio? The cone on the Misco and TB is very delicate paper, while the Peerless uses aluminum and JBL uses carbon fiber.
To my ears, the JBL and the Peerless midbasses sound cleaner than the Misco and the Tang Band on a Unity.
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Definitely a Summa. The resale value on a DIY unity is basically nothing. Believe me, the Gedlee speakers are going to be collectible. You could buy a Summa and be listening to music this week... Or spend half a decade obsessing over the Unity.
Besides the time investment, I've also had to buy a bunch of tools. For instance, I had to buy a drill press to get the holes perfectly straight and centered, and a bunch of router bits to chamfer the ports.
I agree about the perspective part, and that was the crux of my comment too. William's Unitys are exceptional and use, for the most part, modest components.
Endless discussions about a cap brand when there are major issues with another part of the design is like putting racing stripes on a Hyundai Excel and calling it a high performance car.
I do agree that arguing over capacitors can be a distraction from solving the bigger issues. But I'm not the only that's heard an improvement by replacing the midbasses in the Unity. Sheldon has Lambda Unities, and mentioned that he sometimes runs them as a two-way, bypassing the Misco midbasses entirely.
Replacing them with a more advanced driver can yield gains of 10-20dB in distortion performance. Sheldon's Lambdas use lots of copper in the woofer, which might explain what he heard. And the woofer in the Summa costs $350 because it's about as exotic as you can get, without resorting to something hand-built like the Lambda.
I'm still determining which mid to use. One that looks good is the Misco JC4C-8. The Tang Band W2-852 is indeed much easier to work with. I’ve found that treating the paper cones with one coat of high gloss spar urethane quiets the cone cry of the less expensive mids. I'm of the opinion that for home use, you really don't need a mid any larger than a 4" or 3". Due to the falling high frequency response of a CD wave guide, by the time you get the compression driver EQ'ed flat your sensitivity is around 100dB or less. This results in having to attenuate the mids quite a bit. I'd like to avoid attenuating the mids as much as possible because excessive attenuation drowns out the dynamics. Three of the Tand Band W2-852 can do over 100dB on a 60 degree round OS wave guide. So, even 2" mids are enough for home use.
That JBL 4” mid does look like a beast. However, I’m avoiding expensive mids. Faital makes a very nice 5” mid, but they are $100 a piece. There is no way I am willing to drop $600-$800 just on mids. Whatever the final choice is, be rest assured it will be affordable.