Someone emailed me asking about the sound of a Gedlee Summa, in comparison to a Unity horn. My reference speakers are Summas, I have DIY unity horns in my car, and I've listened to the Lambda Unity horns.
So here goes...
Considering how similar they are, they actually sound a LOT different. IMHO, the imaging of the Summa is unrivaled. It doesn't sound like a six cubic foot speaker. I have a pair of small Polk monitors that I used to use, and the Summa doesn't sound much bigger. The only clue that it's a large speaker is if you see it. The Summa's cabinet simply disappears.
Unity horns are the most articulate speakers I've ever heard. There is simply no other speaker that's able to extract every last bit of detail in the midrange. You immediately notice details in recordings which are obscured by the average speaker. Keep in mind that the midrange and the tweeter in a unity horn are radiating from a point in space that's the size of a tennis ball! This kind of coupling is unheard of. You would think that a small full range could match this articulation, but I've never heard one that could. IMHO, this is because the conical horn is reducing early reflections.
IMHO, the Summa is a *little* bit cleaner in the midrange. The Unity horn that I've listened to had a $1500 TAD compression driver, and was audibly more extended than the $150 B&C thats in the B&C. But what do you expect for an extra $2300? 🙂 The midbass in the Summa has shorting rings, and no interference issues in the midrange. I believe this is why it's "cleaner" around 1khz.
I haven't noticed an edge in dynamics with either one; both of them have more dynamics than you would ever need in a home environment.
So take your pick. Soundstaging or articulation. I suggest using both 🙂 The Unity works best in the car, because you're listening in the nearfield. Due to the center-to-center spacing in the Summa, I believe it sounds best in a big room.
They're both excellent, and neither one sounds like the other.
So here goes...
Considering how similar they are, they actually sound a LOT different. IMHO, the imaging of the Summa is unrivaled. It doesn't sound like a six cubic foot speaker. I have a pair of small Polk monitors that I used to use, and the Summa doesn't sound much bigger. The only clue that it's a large speaker is if you see it. The Summa's cabinet simply disappears.
Unity horns are the most articulate speakers I've ever heard. There is simply no other speaker that's able to extract every last bit of detail in the midrange. You immediately notice details in recordings which are obscured by the average speaker. Keep in mind that the midrange and the tweeter in a unity horn are radiating from a point in space that's the size of a tennis ball! This kind of coupling is unheard of. You would think that a small full range could match this articulation, but I've never heard one that could. IMHO, this is because the conical horn is reducing early reflections.
IMHO, the Summa is a *little* bit cleaner in the midrange. The Unity horn that I've listened to had a $1500 TAD compression driver, and was audibly more extended than the $150 B&C thats in the B&C. But what do you expect for an extra $2300? 🙂 The midbass in the Summa has shorting rings, and no interference issues in the midrange. I believe this is why it's "cleaner" around 1khz.
I haven't noticed an edge in dynamics with either one; both of them have more dynamics than you would ever need in a home environment.
So take your pick. Soundstaging or articulation. I suggest using both 🙂 The Unity works best in the car, because you're listening in the nearfield. Due to the center-to-center spacing in the Summa, I believe it sounds best in a big room.
They're both excellent, and neither one sounds like the other.
Patrick,
I've never heard the fullblown Unity Horns, but if they're close to the Summas that you brought to the Mercer Island Meet a couple of months ago, they must be pretty special.
Best Regards,
TerryO
I've never heard the fullblown Unity Horns, but if they're close to the Summas that you brought to the Mercer Island Meet a couple of months ago, they must be pretty special.
Best Regards,
TerryO
I haven't heard the Summa's, but I have heard William's Unity system, and to date, nothing has bettered it in any area, and that's with the DE25's, same as mine have. One other system has come close, but they are different enough to be like a Ferrari/Lambo comparison, down to preference, and also there was a large time between listening to the two systems, and I doubt my recall is that accurate for anywhere near that length of time.
I've been experimenting with the round QSC WG's of late for the sides and rears, but am also trying some coaxes as the sides are quite close because of room dimensions.
I've been experimenting with the round QSC WG's of late for the sides and rears, but am also trying some coaxes as the sides are quite close because of room dimensions.
Hi Patrick,
I was the one that asked for the comparison, and I just want to thank you for providing it - thanks!
Best regards
Peter
I was the one that asked for the comparison, and I just want to thank you for providing it - thanks!
Best regards
Peter
I recently had a chance to listen to my U15's against a pair of Abbeys, although the comparison was less interesting than I was hoping since there wasn't a chance to optimize/eq the U15s in this system.
The one thing that I do think was apparent from the session though was that the Abbey did do a great job in the imaging/soundstaging area. IMHO this is to be expected given the care taken with minimizing diffraction, but it's always good to see it pan out in practice.
The U15's did OK, but were flatter and not as expansive. I don't really think this has much to do with the Unity arrangement as such, but rather to do with the lack of care in mouth treatment and diffraction. It would be interesting to revisit after some mods to try to improve this aspect of the Unity.
In terms of voicing the Abbeys were a bit more laid back and warmer than what I have the U15's set to in my system, but not at the expense of percieved detail. In line with what I think could be called a 'musical' presentation.
In terms of dynamics it's not exactly a fair comparison (12" vs 15"), but neither was close to what I experience in my room. The concensus of the other listeners was that the dynamics on the U15 were great, though. Since I don't get out to listen to other systems much I'm not sure whether this is because I have things voiced to exagerate dynamics or not, but 'Tamacun' (Rodrigo Y Gabriella) is one of my 'knock your socks off' tracks in my system and it was decidedly limp over the Abbeys in this setup (didn't play it over the U15's in the comparison). So, I think the takeaway is that system setup and room can have a big impact on this. Yeah, not exactly a stunning insight.
So, I guess this was something of a pointless post. The U15 isn't the Lambda, and the Abbey isn't the Summa, and it was in an unfamiliar system so conclusions are tough. My main interest in the undertaking was to try to determine whether I might choose the Geddes speakers over the U15's if I was deciding today. On that score, I dont think I would. Even the Abbey kits are more expensive than the U15's (although the U15's are best thought of as a project rather than a finished speaker) and the narrower dispersion fits my room better. Still, I didn't hear anything to cause me to question the quality of the Abbeys and they are significantly smaller than the U15 (not to mention significantly less ugly).
Based on some news over at avsforum (not much detail yet), it sounds like Danley is coming out with a "SM60" which is a smaller full-range (~50Hz on up) 3-way synergy horn, with an alleged price target of $2500 per speaker. Given that the Summas are listed at $3500 per, I think that would be a very interesting comparison to do. A pair of SM60's plus a DTS-10 kit for a total of $6k strikes me as being potentially untouchable in terms of value.
The one thing that I do think was apparent from the session though was that the Abbey did do a great job in the imaging/soundstaging area. IMHO this is to be expected given the care taken with minimizing diffraction, but it's always good to see it pan out in practice.
The U15's did OK, but were flatter and not as expansive. I don't really think this has much to do with the Unity arrangement as such, but rather to do with the lack of care in mouth treatment and diffraction. It would be interesting to revisit after some mods to try to improve this aspect of the Unity.
In terms of voicing the Abbeys were a bit more laid back and warmer than what I have the U15's set to in my system, but not at the expense of percieved detail. In line with what I think could be called a 'musical' presentation.
In terms of dynamics it's not exactly a fair comparison (12" vs 15"), but neither was close to what I experience in my room. The concensus of the other listeners was that the dynamics on the U15 were great, though. Since I don't get out to listen to other systems much I'm not sure whether this is because I have things voiced to exagerate dynamics or not, but 'Tamacun' (Rodrigo Y Gabriella) is one of my 'knock your socks off' tracks in my system and it was decidedly limp over the Abbeys in this setup (didn't play it over the U15's in the comparison). So, I think the takeaway is that system setup and room can have a big impact on this. Yeah, not exactly a stunning insight.
So, I guess this was something of a pointless post. The U15 isn't the Lambda, and the Abbey isn't the Summa, and it was in an unfamiliar system so conclusions are tough. My main interest in the undertaking was to try to determine whether I might choose the Geddes speakers over the U15's if I was deciding today. On that score, I dont think I would. Even the Abbey kits are more expensive than the U15's (although the U15's are best thought of as a project rather than a finished speaker) and the narrower dispersion fits my room better. Still, I didn't hear anything to cause me to question the quality of the Abbeys and they are significantly smaller than the U15 (not to mention significantly less ugly).
Based on some news over at avsforum (not much detail yet), it sounds like Danley is coming out with a "SM60" which is a smaller full-range (~50Hz on up) 3-way synergy horn, with an alleged price target of $2500 per speaker. Given that the Summas are listed at $3500 per, I think that would be a very interesting comparison to do. A pair of SM60's plus a DTS-10 kit for a total of $6k strikes me as being potentially untouchable in terms of value.
Based on what I know about the Unity technology, I have a hunch that the U15 would sound superior to the Lambda unity. It has a series of improvements over the original:
- Conical horn should have more consistent directivity
- The horn is terminated better. This is a biggie - I think a PVC roundover would go a long way in the Lambda
- The BMS compression driver in the U15 is a better match for the horn than the TAD, because the throat on the TAD is very long. Of course this doesn't mean there's anything wrong with TAD; it's just not the best match for that horn. If you modified the throat it would improve things; there really should be a different throat depending on what compression driver is used. In fact, that's one of the reasons the oblate spheroidal waveguides work so well. The OS curve is more tolerant of variations in the length of compression drivers. (The BMS is much shorter than the TAD.)
- In my experiments, the slot ports of the U15 work better than the cylindrical ports of the Lambda. The shape of the ports in a Unity makes a humongous difference in the midrange response. Literally ten dB or more!
Anyways, long story short, the U15 is a heck of deal. I'd love to see more people use them at home. They even look pretty decent.
It's too bad Danley wasn't at the 2005 RMAF. The discussions that you, Geddes, Lynn Olson and I had in the Gedlee room inspired a lot of my projects. And I believe they influenced Lynn's projects too. It was definitely the most interesting room at the whole show.
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Hello,
Thank you for this comparative review! Much appreciated!
It also sparked my interest in the technology behind Unity. Maybe a large 22" OS wave-guide with a nice round termination and a throat designed to accept 4 midrange units as Unity does could be the best of both worlds?
Thank you for this comparative review! Much appreciated!
It also sparked my interest in the technology behind Unity. Maybe a large 22" OS wave-guide with a nice round termination and a throat designed to accept 4 midrange units as Unity does could be the best of both worlds?
dwk123,
Could you please elaborate on this a bit. Would you mind sharing what you have done to adapt them to the domestic environment?
Why go to all the trouble?
In the pic above, you can see the two curves are virtually identical once you get past the throat.
To mod the SH-50, you would do the same thing I did, but just use A LOT more of it. Basically line the first three inches of the throat, smoothing out any discontinuity between the exit of the BMS compression driver and the throat of the Synergy Horn.
An externally hosted image should be here but it was not working when we last tested it.
- It's full range. My unities only go down to 300hz, and the articulation is breathtaking. I can only imagine what a Synergy Horn sounds like. (I've never heard one.) The Lambda Unities have a cutoff that's somewhere around 300hz IIRC.
- Based on my understanding of higher order modes, there are a lot generated at the mouth of a horn. Because of this, the time delay will be greater with a Synergy Horn than with a Unity horn. (The pathlength is longer.) From what we know about psychoacoustics, a greater delay should be less offensive.
- If Geddes sold a foam plug for the Synergy Horn the attenuation of HOMs would be quite dramatic, because the volume of the Synergy Horn is more than twice as much as the Summa. On the downside, you'd have a greater reduction in SPL. Of course you could do a partial plug like Sheldon has.
- The Synergy Horn uses a coaxial compression driver with much greater high frequency extension than the Lambda Unity or the Summa. Whether this is audible is debatable, but the extension is there if you want it. The BMS goes out to 24khz. I'm running BMS on my Unity and I like them a lot.
To make a long story short, instead of reinventing the wheel, I'd probably take a long hard look at modding the SH-50.
One of the big reasons that I purchased the Gedlee Summas is because of their resale value. A modified SH-50 would be a challenge to sell - the prosound guys wouldn't want it, and finding someone who'd purchase a modified one for home use might be tricky. With the Summa, there's really no good reason to modify it, so if I ever get tired of it, it would be easy to recoup my investment.
I believe that applies to the entire Gedlee line, and I think it's one of the best reasons to purchase a set. In five or ten years I'm certain they will be very collectable.
Intrigued to know how much difference the soffit mounting made to the sound quality of William's unity horns. Whether this is similar in effect to the diffraction minimizing techniques Patrick Bateman has suggested...
Would be good to have a demo pair of Summa's in Oz to compare. Any offers? 😉
From my rough calculations you should get the best results if you join the conical inner section, (just after the midrange ports), to a circular arc that meets both the baffle and the inner flare at right angles.
rcw.
rcw.
I only heard them as they are built in, not the prior free standing boxes. IIRC William's comment about building them in was that they were a large improvement, but didn't go into the details.
Are there any in Oz?
That would be a lot of work, unfortunately. I guess you *could* use a whole lot of clay?
I would expect that a significant reduction in HOMs would be found by smoothing the transition from the exit of the compression driver to the conical horn. If you don't do this, there's an abrupt change in directivity. Basically I would prefer to see a gradual increase in the coverage angle, from about six degrees at the compression driver's exit to 25 degrees about four inches forward of the exit.
These changes would also improve the polar response.
It's certainly not the most time-effective tweak, but it's inexpensive and measurably better. Possibly overkill for a commercial venue, but for the home, it would be worthwhile.
You could also modify the ports to some degree; the port shape affects the midrange response.
Thank you for the reply, it's very informative.
My only problem against tackling a Unity-clone (or even buying a Synergy) is all this discussion regarding diffraction effects. I guess Beyond Ariel thread is the main guilty here 🙂
While I believe the midrange slits, due to the fact they are quite small, won't significantly affect the tweeters time-domain response, I can't resist thinking that the slits themselves are sub-optimal for the midrange behaviour in the time domain.
And that's because those ports or holes are essentially phase-plugs at the exit of a small compression chamber. Probably the unbeliever in me wants to see something more complicated 🙂).
Nevertheless the overwhelming positive feedback from various people keeps making me reconsider this design.
Regarding phase-plugs for cones, please find below: Phase Plugs
My only problem against tackling a Unity-clone (or even buying a Synergy) is all this discussion regarding diffraction effects. I guess Beyond Ariel thread is the main guilty here 🙂
While I believe the midrange slits, due to the fact they are quite small, won't significantly affect the tweeters time-domain response, I can't resist thinking that the slits themselves are sub-optimal for the midrange behaviour in the time domain.
And that's because those ports or holes are essentially phase-plugs at the exit of a small compression chamber. Probably the unbeliever in me wants to see something more complicated 🙂).
Nevertheless the overwhelming positive feedback from various people keeps making me reconsider this design.
Regarding phase-plugs for cones, please find below: Phase Plugs
You're right on the money. That was my "eureka" moment with the design, realizing that the volume of air under the midrange cone, the depth of the holes, how far they are from the throat, and their geometry all play a part.
Even after years of screwing around with this stuff, I still learn new things about it all the time.
I never could figure out why the Danley horns place the holes at the edge of the woofer diaphragm, and I just figured that one out tonight.*
And this is after studying it for half a decade, and building half a dozen!
It's a crazy complex design.
* If anyone's curious, I believe the ports are located at the edge of the cone because that extends the port length. You can't model this behavior easily, but a set of measurements that I did tonight indicate that you can get away with a shallower port if the holes are spaced further apart. Which seems to indicate that the cavity under the cone itself is lengthening the port. (Theoretically the cavity should simply function as a low pass filter. I use a deeply flared port, like on the Synergy Horn.)
I'll post some pics if anyone is curious.
By the way, the article you posted is an excellent one.
Yes, sure, some pics would be great!
In fact, I haven't seen many pictures with the cone side of the ports. Just one set, where there was a carved shape for every hole, somehow increasing the volume of the compression chamber and maybe having a positive effect on the diffraction effects.
I remember that the location of the holes intrigued me as well. I initially thought that they are positioned that way in order to fire closer to the HF unit exit.
I really hope sometimes in the future I'll try a Unity, sounds to be one of the few systems with so many pros (CD, point-source radiation down to 300Hz, really high efficiency), the only difficult problem to overcome / predict being the diffraction effects at the throat for the midranges.
In fact, I haven't seen many pictures with the cone side of the ports. Just one set, where there was a carved shape for every hole, somehow increasing the volume of the compression chamber and maybe having a positive effect on the diffraction effects.
I remember that the location of the holes intrigued me as well. I initially thought that they are positioned that way in order to fire closer to the HF unit exit.
I really hope sometimes in the future I'll try a Unity, sounds to be one of the few systems with so many pros (CD, point-source radiation down to 300Hz, really high efficiency), the only difficult problem to overcome / predict being the diffraction effects at the throat for the midranges.
You guys are putting way too much into the midrange port diffraction effects. If you read the Synergy horn patent application you will see the way Tom eliminates that problem. One of the key features of the Synergy over that of the Unity is it specifically calls out where and how to place the midrange entry ports.
1.) The distance between the compression driver’s and midrange’s acoustic centers is between ¼ and ½ wavelength. The highest frequency played by the midranges is below that of the first acoustic null caused by the low pass function of the midrange entry port.
2.) The entry point of the midrange is such that the circumference of the horn at the midrange entry point is 1 wavelength of the crossover point between the compression driver and midranges.
What this means is by the time the output of the compression driver reaches the midrange ports, it is so attenuated by the crossover that the wavelengths in play can’t be affected by the midrange ports. It is a seamless handoff between midrange and compression driver and everything is phase coherent.
Rgs, JLH
1.) The distance between the compression driver’s and midrange’s acoustic centers is between ¼ and ½ wavelength. The highest frequency played by the midranges is below that of the first acoustic null caused by the low pass function of the midrange entry port.
2.) The entry point of the midrange is such that the circumference of the horn at the midrange entry point is 1 wavelength of the crossover point between the compression driver and midranges.
What this means is by the time the output of the compression driver reaches the midrange ports, it is so attenuated by the crossover that the wavelengths in play can’t be affected by the midrange ports. It is a seamless handoff between midrange and compression driver and everything is phase coherent.
Rgs, JLH
Hello JLH,
Indeed these are valid point you brought up. This is one reason I find Unity/Synergy to be very appealing.
However I believe that both Mr. Bateman and me understand by diffraction effects the phenomena occurring at the exit point of the midrange ports, caused by the discontinuities in the throat and the peripheral placement of the slots relative to the horns axis.
Dr. Geddes has over and over again emphasized the importance of a smooth transit between the CD exit and the horn/wave-guide. And, as I've said in the previous posts, what actually is bugging me with this design is the impression that the midrange "phase-plugs" and the transit to the horn is sub-optimal. This occurs independently of the crossover point to the HF unit.
Whether this is a real issue or not, I can't tell, but the variables indicated by Mr. Bateman regarding the response of the midrange depending on the port design should be considered.
Indeed these are valid point you brought up. This is one reason I find Unity/Synergy to be very appealing.
However I believe that both Mr. Bateman and me understand by diffraction effects the phenomena occurring at the exit point of the midrange ports, caused by the discontinuities in the throat and the peripheral placement of the slots relative to the horns axis.
Dr. Geddes has over and over again emphasized the importance of a smooth transit between the CD exit and the horn/wave-guide. And, as I've said in the previous posts, what actually is bugging me with this design is the impression that the midrange "phase-plugs" and the transit to the horn is sub-optimal. This occurs independently of the crossover point to the HF unit.
Whether this is a real issue or not, I can't tell, but the variables indicated by Mr. Bateman regarding the response of the midrange depending on the port design should be considered.
Everything is relative. You must look at the length of the waves we are talking about. Let’s look at an example where the midranges cover up to 1.5KHz. This is a very common crossover point for a Unity or Synergy horn.
A 1.5KHz wave is approximately 9 inches in length. To get cancellation you need a reflective surface that is 4.5 inches away from the cone. Now take a look at the shape and size of any of the midrange drivers used in a Unity or Synergy horn. The depth of the cone from the basket edge to the deepest point is well under 4.5 inches. In fact it is at most 2.5 inches. Due to the fact our distance is significantly shorter than the half wavelength cancellation distance, no phasing plug is required. The extra machining seen where the midranges mount is to contour the low pass filter of the front air chamber compliance. (SEE ATTACHED PICTURE OF SH-25)
Additionally, if the crossover is made correctly the midrange ports will not significantly contribute to HOMs. In the Synergy horn the midrange ports are located along the horn where the crossover frequency of the compression driver is equal to or shorter than the circumference of the horn at the midrange entry point. Once you get near this physical point in the horn, the compression driver’s output wavelengths are too acoustically small to be significantly affected by the midrange ports. The horn has become too acoustically large to have any loading or much effect on the compression driver’s output. Near the midrange ports the compression driver’s output does not “see” the horn anymore. The compression driver’s output is beaming out at the angle set by the throat region of the horn.
Rgs, JLH
A 1.5KHz wave is approximately 9 inches in length. To get cancellation you need a reflective surface that is 4.5 inches away from the cone. Now take a look at the shape and size of any of the midrange drivers used in a Unity or Synergy horn. The depth of the cone from the basket edge to the deepest point is well under 4.5 inches. In fact it is at most 2.5 inches. Due to the fact our distance is significantly shorter than the half wavelength cancellation distance, no phasing plug is required. The extra machining seen where the midranges mount is to contour the low pass filter of the front air chamber compliance. (SEE ATTACHED PICTURE OF SH-25)
Additionally, if the crossover is made correctly the midrange ports will not significantly contribute to HOMs. In the Synergy horn the midrange ports are located along the horn where the crossover frequency of the compression driver is equal to or shorter than the circumference of the horn at the midrange entry point. Once you get near this physical point in the horn, the compression driver’s output wavelengths are too acoustically small to be significantly affected by the midrange ports. The horn has become too acoustically large to have any loading or much effect on the compression driver’s output. Near the midrange ports the compression driver’s output does not “see” the horn anymore. The compression driver’s output is beaming out at the angle set by the throat region of the horn.
Rgs, JLH
Attachments
Thank you so much for the in-depth explanation! I find it really useful!
If I understood well, your second paragraph explains why the midrange drivers need no phase plug. The construction ensures no early reflections between the cone and the hole edges of the exit point. I found this explanation especially useful as it illuminates some of the design choices we where trying to understand a couple of posts earlier.
Your third paragraph argues that the midrange holes will not affect the HF driver output in any way. I already had an intuition about this but your argument actually makes sense of the matter.
What I still don't get is how the ex-centric placement of the midrange holes relative to the horn axis are influential to HOM and other diffraction effects. If I remember correctly I've read Dr. Geddes arguing that even the slightest misalignment between the exit of the CD and the entry of the horn will create HOM. The same is valid for any abrupt change in the horn contour (diffraction slot horns are given as example).
To conclude, what I don't get with this design is if the slots placement in the throat of the horn satisfies the diffraction free design principle I was referring above.
I apologise if I am getting to redundant with these questions 🙂.
If I understood well, your second paragraph explains why the midrange drivers need no phase plug. The construction ensures no early reflections between the cone and the hole edges of the exit point. I found this explanation especially useful as it illuminates some of the design choices we where trying to understand a couple of posts earlier.
Your third paragraph argues that the midrange holes will not affect the HF driver output in any way. I already had an intuition about this but your argument actually makes sense of the matter.
What I still don't get is how the ex-centric placement of the midrange holes relative to the horn axis are influential to HOM and other diffraction effects. If I remember correctly I've read Dr. Geddes arguing that even the slightest misalignment between the exit of the CD and the entry of the horn will create HOM. The same is valid for any abrupt change in the horn contour (diffraction slot horns are given as example).
To conclude, what I don't get with this design is if the slots placement in the throat of the horn satisfies the diffraction free design principle I was referring above.
I apologise if I am getting to redundant with these questions 🙂.