Gedlee Summa vs Lambda Unity Horn

[Patrick Bateman]

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.

[TerryO]

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

[Brett]

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.

[pk]

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

[dwk123]

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.

[Patrick Bateman]

Originally Posted by dwk123

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.

[SunRa]

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?

[musical noise]

Originally Posted by dwk123

although the U15's are best thought of as a project rather than a finished speaker

dwk123,

Could you please elaborate on this a bit. Would you mind sharing what you have done to adapt them to the domestic environment?

[Patrick Bateman]

Originally Posted by SunRa

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?

Why go to all the trouble?

The difference between an oblate spheroidal waveguide and a conical horn is at the throat. Because of that, you can turn a conical horn into an oblate spheroidal waveguide. Just go to Home Depot and buy two packages of "Frost King" clay. It's used to seal doors and windows. But it's pliable, tacky, and works great for modifying horns and waveguides.

In the pic above, you can see the two curves are virtually identical once you get past the throat.

Here's my oblate spheroidal waveguides that are in my car. They're a Unity. See that white stuff in the throat? That's the Frost King clay that I'm talking about. I'm using it to smooth out the throat of the waveguide.

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.

Here's the Danley SH-50 Synergy Horn. I believe the Danley horn has a few advantages over what you are proposing:

• 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.

[Antripodean]

Originally Posted by Brett

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

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?