[JDUBS]

OK, just when I thought I had it down with the Brines FTA-2000s (may still go with them)...I did some checking back in the archives and found a discussion about these speakers initiated by JoshK.

I think the effortlessness of these speakers really gets at what I love about my (old) Oris horns.  I want the ability to reproduce a live (rock concert) event and it sounds like these speakers will get me there.

They're definitely leaps and bounds above the Brines models in terms of $$...but I wouldn't need a new amplifier as the Clari-T should provide plenty with these and their 97db efficiency.

The one thing that concerns me is the lack of bass.  I think Geddes has his own line of subs...anyone have any experience here?

Thanks...once again!!

-Jim

[lonewolfny42]

GedLee Summa Link...... Jim....they always remind me of the SP Tech's.....but I've not heard them. 

[ooheadsoo]

Geddes's subs are new.  I'd love to read some impressions about them, but I get the feeling that they're only for the Summas and have no adjustable xover.  I'd love to audition the summas one day.  The SP Techs don't control directivity as much as the Summas, which seems to be both pro and con, pro in terms that the air compression ratio remains low, according to Bob@SPTech, con in terms of having a bit more room interaction.  AFAIK.

[JDUBS]

From everything I've read, these speakers seem like the real deal...the advantages of horn speakers with few of the disadvantages, in a "relatively" small package. 

The GedLee subs look interesting as well...as I'm assuming the integration with the Summas is flawless.  Seems like Geddes makes a couple of different models of these. 

JoshK (if you're reading this), did you get a chance to hear the subs during your visit with Dr. Geddes?

-Jim

[JoshK]

From everything I've read, these speakers seem like the real deal...the advantages of horn speakers with few of the disadvantages, in a "relatively" small package. 

The GedLee subs look interesting as well...as I'm assuming the integration with the Summas is flawless.  Seems like Geddes makes a couple of different models of these. 

JoshK (if you're reading this), did you get a chance to hear the subs during your visit with Dr. Geddes?

-Jim

Upstairs in the untreating Living room, Dr. Geddes has a pair of Summas, one of his prototype subs, a stereo receiver and an older cd player.   I beleive I heard the system with the sub playing, but I am not 100% sure now.  If it was playing, I'd say it was seemless integration.  If it wasn't playing, I'd say the bass of the Summa's doesn't leave you wanting.

I heard zero honky-ness due to horn loading the tweeter.  His theory does work in practice.  The mid treble on up was impossible to fault from my perspective.  I know it will be uncuthe to the objectivists but I had wished that I got to hear his speakers on better electronics.

Downstairs in his HT room (fully treated), he had two subwoofers hooked up.  He said that one was ported, one was sealed.  That room and system was mind blowing on Phantom of the Opera.  The dynamics of this system are what you expect from a horn system without being aggressive and agitating.  We were listening at times at 120db's C-weighted and it didn't seem that loud.   The less distortion (particularly higher order modes) the more the ear can tolerate (and even enjoy) loudness. 

[JDUBS]

Excellent, thanks JoshK!  I e-mailed Dr. Geddes for more info about the subs and will certainly post what I receive, here.

-Jim

[JDUBS]

OK guys, i've been e-mailing with Dr. Geddes.  He says that the optimal setup utilizes one of each of the subwoofers.  The ULF subwoofer is good up to ~50hz. and the LF subwoofer goes from ~50hz. to ~100hz.

So, a whole GedLee setup is ~$6,400 plus shipping.  The Dr. also mentioned that there is a 3 month lead time...yikes!

Is there anything else comparable that can reproduce the kind of dynamics the Summa is known for??

I need a speaker that can ROCK!

-Jim

[ooheadsoo]

I would see if it would be possible to arrange an audition of either SP Technology's speakers or the new NuForce/SPTech collaboration, the S-9.  They would both require either a decent amplifier or preamp, depending on which path you chose, but these speakers are quite dynamic.  The S-9 plays incredibly large, I couldn't believe my eyes.  These speakers also use waveguide technology but they sacrifice efficiency for lower air compression ratios inside the waveguide, which results in lower distortion.  Flip side, you need some watts, they're of middling efficiency in the high 80's.

[Russell Dawkins]

1. I wonder if this  is "our" Bob Smith being referred to to on the Geddes website:

http://gedlee.com/patents.htm#Improved%20phase%20plug

(in the "Improved phase plug design" patent description).

2. I don't seem to be able to find any details on the subs other than a simple mention. Also, I am under the impression that Earl Geddes prefers the sound of the sealed version over the ported version. He estimates the ported version goes to about 40 Hz and the sealed, 50 Hz. In February of this year he told me he preferred the sealed with the Summas sub from 25 - 50 Hz, but he didn't mention which sub - the LF or ULF.

3. A friend who should remain nameless had this to say about the Summas:

If my memory serves me (and it often times doesn't), I heard the Summas last year at the RMAF.  Very dark sounding speaker, to my ears.  Subjectively, no highs at all.  I left scratching my head.

From what JoshK says, maybe these were not the Summas, unless "dark" does describe them! I know that Dr Geddes thinks that speaker behaviour above 10 kHz is not worth worrying about or charting, not to say that they drop off above 10 k, necessarily.

[Double Ugly]

1. I wonder if this  is "our" Bob Smith being referred to to on the Geddes website:

http://gedlee.com/patents.htm#Improved%20phase%20plug

(in the "Improved phase plug design" patent description).

Seems reasonable to think so. 

What confuses me, though, is that I don't recall Bob ever using what I would consider a compression driver.  The text you linked specifically mentions phase plugs for compression drivers.   

[JoshK]

The Summas were at RMAF, but a few people I know heard them there thought they were not so great.  I think it was Dr. Geddes insistance on using $200 electronics and a terrible room.   When I heard them in Geddes's room I felt the highs were quite natural sounding, at least to my ears. 

[JoshK]

OK guys, i've been e-mailing with Dr. Geddes.  He says that the optimal setup utilizes one of each of the subwoofers.  The ULF subwoofer is good up to ~50hz. and the LF subwoofer goes from ~50hz. to ~100hz.

So, a whole GedLee setup is ~$6,400 plus shipping.  The Dr. also mentioned that there is a 3 month lead time...yikes!

Is there anything else comparable that can reproduce the kind of dynamics the Summa is known for??

I need a speaker that can ROCK!

-Jim

Jim,

I am of the opinion that it is fairly straight forward (or at least well studied and disected) to build your own subwoofers.  Maybe if you purchased just the Summas and added your own subs, following Dr. G's design principles you would have a more reasonable system cost? 

All that said, I do think you need to hear the Summa's for yourself.   Comparing from memory, Dr. G's HT room to our buddy Richard's uber HT room (all Wilson speakers and uber electronics), I preferred Dr. G's.  I'd easily take Richard's in a heartbeat and it was far from wanting, I just liked the overall sound of Dr. G's.  I would want better electronics in Dr. G's though. 

[Aether Audio]

I wonder if this  is "our" Bob Smith being referred to to on the Geddes website:

Ha!  You guys need to do your homework.  Well...I guess you'd have to be a speaker geek like me to know this stuff.  Anyway - I'm honored to think that you'd even consider me to be the author of the phase-plug technology referred to by Earl, but...my ity-bitty brain ain't that smart.

I've read Bob's paper years ago and based our waveguides on some of the concepts presented in his paper.  Namely - the very need for phase-plugs is best to be avoided.  If one wants to design a true, full-bandwidth horn then one hasn't much choice but to use a phase-plug.  Without it you'll get a huge suck-out somewhere above about 8KHz. 

The phase-plug brings together all the different parts of the wavefront emanating from the diaphragm such that they arrive at the throat of the horn in-phase.  At the high compression ratios experienced by the wavefront in true horns, even very small path length differences (that result from the wave being launched from a curved diaphragm) turn into large phase differences if some type of device isn't used to keep the effective paths equal.

The down side is, as Earl points out, that the phase-plug (of the other "Bob Smith's" design) introduces turbulence - hence, distortion.  And the distortion gets worse as the frequency increases.  Now supposedly Earl has a phase-plug design that eliminates the turbulence.  If so, that would be a good thing for horns. 

But Earl's not telling you that distortion also results from the high compression ratios, apart from the phase-plug turbulence issue.  And it isn't just a problem with high frequency horns either. 

Heck, I remember a nomogram in an old speaker design book from years gone by that was to be used to calculate the distortion generated by a given bass horn design.  I forget how it worked but if I remember correctly, you pick an upper frequency cut-off for the horn and a certain low frequency cut-off, then a taper (exponential, etc.) and then a power level, then using a ruler you draw a line through the points and it will tell you what the distortion is at any given frequency between the cut-off points.  ...Or something like that.  The main thing one noticed is that for a given design, the distortion always gets worse as the operating frequency is increased

Anyway, the point is that distortion increases as compression ratios increase and/or power levels increase and/or frequency is increased - assuming the acoustic "gain" is constant (i.e., "broad-band" as in a true horn).  That's why I don't design broad-band horns.  The whole phase-plug issue is very touchy and small variations in geometry makes a huge difference.  Designing ones own phase-plug is no small issue and you'd better have precision manufacturing equipment to make them.  Too much headache for this guy.

And what's the point?  Every engineer knows that the actual power content of music drops off fairly quickly as frequency is increased.  Above about 5KHz there's very little energy (from a dissipated power standpoint), so why engineer in all that gain?  You sure don't need it from a tweeter power handling standpoint.  So unless you NEED a tweeter with a 100dB+ @ 1W/1M sensitivity to begin with, why go through all the heroics and increase HF distortion on top of it?  Our waveguides have high gain at the low frequency end of the tweeter's range - where it's needed for increased power handling.  The gain then gradually decreases as you go up the spectrum until you get to about 5KHz - where then there's no added gain and the tweeter's SPL output level is the same as if it was mounted on a flat baffle.  So right where distortion would start to really become noticeable, we have zero increased compression and therefore the same distortion performance as the tweeter mounted in a conventional box.  Sort of the "best of both worlds" - if you ask me.

Uh...I'm not the Bob Smith Geddes was referring to - sorry about that.

-Bob "the other" Smith

[JDUBS]

Guys

Thanks for all the input...its greatly appreciated!!  JoshK, its especially nice to get your input as you heard these speakers first hand...and I think we're both on the same wavelength in terms of what we're looking for in music reproduction.

This past week has been crazy trying to find a place in NYC.  Finally did, though!!  Will be out there full-time beginning this Saturday.  I can't wait to meet all of the NYC Ravers! 

I did manage to e-mail Dr. Geddes about his subs.  We're going to have a phone conversation upon his return from Hong Kong but he let me know that his subs include plate amps and they accept both low level and high level inputs.

Again, I'll keep everyone in the loop as I learn more about these speakers.  I should be talking with Dr. Geddes within the next couple of weeks.

Thanks again, everyone!!

-Jim

[zybar]

Any updates?

George

[JDUBS]

Any updates?

George

George

Unfortunately, no.  Dr. Geddes was going to try to set me up with a NYC owner to hear the speakers for myself, but I never heard anything back about it.

During that same time, I decided on going with NuForce S-9's.  Their smaller size (relative to the Geddes!) made them a little more "appropriate" for my NYC apartment.  Amplification will hopefully be EVS 500Ms.

I'm really curious to hear a waveguide in action!

-Jim

[Duke]

Dr. Geddes has been out of the country for most of the past month and a half.  Last week he had to return to Hong Kong on short notice for the funeral of his wife's mother.  I don't think he's back yet, as he said he would contact me when he returns.   

I'm a friend of his, and was fortunate enough to be peripherally involved in the project that resulted in the Summas. 

Duke