Horn Speakers - Is it me or.......

[jeffaegrim]

I have been lurking this forum for a couple of years now and I might have not contributed anything for a couple more, but the current state of discussion in this thread has piqued my interest. I'd like to preface my post by saying that I have read all 33 pages of this thread and found the contributions by various members incredibly valuable (as usual). Thank you all very much - I love this forum, as it seamlessly blends interactions by laymen as well as industry pioneers. I myself am in my late twenties and bar any technical education, squarely in the former camp - hence the following question (and I apologize in advance if it's slightly OT, though I feel like the information potentially provided could at some point be valuable to somebody else):

which "category" of horn would the JBL-produced asymmetrical horns for the Everest DD55000, S3100/S2600 fall under? JBL speaks of "defined directivity", though I am unsure whether this isn't just a marketing slogan. I am certain that I've read the member @Duke talk about having designed a speaker with a similar asymmetrical coverage in a thread here somewhere. The forum's @GXAlan also owns/owned a pair of JBL S2600.

If someone is unfamiliar, the "gimmick" of these horns was their ability to provide the listener sitting off-axis towards the nearer speaker with a stable center sound image. You can read more about it here: https://www.audioheritage.org/html/profiles/jbl/everest.htm

I own the JBL S3100 MKII. Everything I understand about directivity so far, which is little, leads me to think that these are "wide" - my REW measurements look the same (or very similar) in level and FR-response anywhere on the couch in the horizontal plane in the treble. This in turn makes me believe that I should be able to equalize the treble relatively effectively, especially if I gate the measurements or do MMM. Please correct me if I am wrong in this assumption. The speakers sound great and the offset volume effect works great, mostly, but some of these in situ measurements look pretty rough, let me tell you that (see first image attached; I was testing XO frequencies to subs; 30Hz here I think). A -6db PK filter at 2.9k Hz (Q7) and a -8db filter at 10k Hz (Q1) tidy things up nicely, though, and improve the perceived sound.

This leads me into my next question - what are these horns doing in a room? I don't see a 10db boost at 10k on these admittedly low-res quasi-anechoic measurements from some french magazine (see second image attached). And it's reviewing the S3100, and not the S3100 MKII, which is supposed to have better crossovers and a better compression driver (JBL 275nd). My own measurements however, tend to look like the ones I already posted. I can post any number of them if for whatever reason necessary/interesting, also in .mdat.

Is it alternatively perhaps possible, that this behavior in the area covered by the compression driver + horn (750hz upwards) is due to the modifications to the crossovers that the previous owner has made? I haven't given it much thought until now, but the seller was quite an unsavory character, even if seemingly well informed. Please see third image attached. I should try and make these active one day...

Is it perhaps my VTL tube amps? They are Mb-125 monos and are currently waiting to be sold... Embarrassingly enough, in a year of ownership, I wasn't able to measure the speakers on any other amps...

I will furthermore attach a similar (french) review of the JBL S2600 and a picture of the compression driver+horn for the S3100mk2 that I found online + a picture of my speakers if anybody is curious I have a terrible room and live in an apartment. There are also 3 smaller subs scattered around the living room.

I would greatly appreciate any response/any discussion irt the above

 

[robh36062]

which "category" of horn would the JBL-produced asymmetrical horns for the Everest DD55000, S3100/S2600 fall under? JBL speaks of "defined directivity", though I am unsure whether this isn't just a marketing slogan. I

Marketing sure but the design was specific there is an AES paper for it and was designed to be used as an overhead horn in a rectangular room. It keeps SPL uniform over a large area. System was 4660 with 2225 for speech reinforcement For Everest JBL turned it on it's side to use for enhanced stereo imaging and added an 077/2405 up top angled with adjustable level to help imaging. The later system horns have there roots here. The paper and the white paper go a long way in explaining what they are doing.

DD55000 Everest

... Documents provided by Michael Smith

www.audioheritage.org

 

[Duke]

I have been lurking this forum for a couple of years now and I might have not contributed anything for a couple more,

Welcome!

but the current state of discussion in this thread has piqued my interest. I'd like to preface my post by saying that I have read all 33 pages of this thread and found the contributions by various members incredibly valuable (as usual). Thank you all very much - I love this forum, as it seamlessly blends interactions by laymen as well as industry pioneers. I myself am in my late twenties and bar any technical education, squarely in the former camp - hence the following question (and I apologize in advance if it's slightly OT, though I feel like the information potentially provided could at some point be valuable to somebody else):

which "category" of horn would the JBL-produced asymmetrical horns for the Everest DD55000, S3100/S2600 fall under? JBL speaks of "defined directivity", though I am unsure whether this isn't just a marketing slogan. I am certain that I've read the member @Duke talk about having designed a speaker with a similar asymmetrical coverage in a thread here somewhere. The forum's @GXAlan also owns/owned a pair of JBL S2600.

The (apparently) sharp-edged slot in your horn, and JBL using the term "defined directivity", makes me think it's a "rectangular diffraction horn"... but obviously a unique one!

My guess is that your speakers were designed by or under the direction of Greg Timbers, and the horn itself may have been designed by Don Keele. These guys are WAY smarter than me. Like three decimal places smarter than me. I do not understand the reason for the horizontal slot but I'm sure they do, and I'm sure some very advanced thinking and analysis went into it.

I don't use in-room measurements because I think they can be misleading, so I don't have any useful comments to make on your measurements. It looks to me like the frequencies of the response-shaping filters were shifted a little bit but I can't reliably say what the net changes would be. Its a complicated crossover and a lot of small changes to capacitor values were made.

Here's the first of a two-part interview with the great Greg Timbers:

 

[GXAlan]

Cannot add more detail to this, other than the DD55000 white paper. The DD55000 has a super tweeter and is a 3-way instead of 2-way.

https://www.audiosciencereview.com/forum/index.php?attachments/jbl-everest-dd55000-1985-white-paper-english-pdf.72153/

I ended up selling mine to a local collector due to a move but I agree that the JBL S/2600 stereo gimmick actually works well. I think it fell out of favor because of the physical footprint these designs need and the aesthetic considerations of such sized speakers when they don’t dip down deep in the bass.

 

[robh36062]

I do not understand the reason for the horizontal slot but I'm sure they do, and I'm sure some very advanced thinking and analysis went into it.

Take a look at my post the papers explain what's happening. The slot was vertical in the original use and when they rotated in the original Everest it went horizontal in that application.

Rob

 

[GXAlan]

The slot was vertical in the original use and when they rotated in the original Everest it went horizontal in that application.

For the benefit of other readers, instead of using a flown array you have a horn generating the same effect with a ceiling mounted speaker which is much lower profile.

https://jblpro.com/en-US/site_elements/4660-information

For this, the people further away got more of the sound than the people close to the speaker. Then it was balanced for the audience.

When you use this horn horizontally, if you are dead center you get a nice phantom center. Now, the person to the right of you gets a louder left and quieter right experience, so the image of the phantom center is still natural in their mind.

The woofers don’t have this trick, so they will get a little more right woofer because they are closer.

The measurements show that the asymmetry isn’t 100% constant for all frequencies.

Lots of reasons this SHOULDN’T work, but somehow it does!

I used this for a theater with a large 15 ft wide sectional sofa where the people at the edge of the sofa are almost on axis with the left or right speakers. With this layout, it was incredible to have the S2600 work its magic.

In my current theater, the width isn’t as extreme so a more conventional setup works. This is where I use the Meyer Sound Amie.

Note that the bass already starts rolling off as early as 100 Hz for the 12” S/2600. But the actual cabinet has the same horn as the Everest and S/3100 so the footprint is ultra wide (even though it’s not too deep).

The high frequency roll off is fixed by the compression driver in the S/3100 mkII

 

[Paffi]

Maybe Zingali? Or Unison Research?

Thank you, again, nice to have a horn expert here.

Had the chance to listen to unison research a couple of days ago. They sound relatively bright (felt like the opposite of a standard houscourve like the harmon one), but I kind of liked them. The issue is (besides the look, my wife would kill me, has to be something in white or bright wood), that the horizontal sweetspot felt kind of small - I asked Unsion Research already via their contact formular, If they could send me some measurements of frequency response and directivity, but unfortunately they didn´t respond (until now).

Zingali speaker looks really nice, but very hard to audition (found no dealer until now). They´re pretty expensive but maybe sometimes a good second hand deal comes by - but I don´t find any measurements of these?

 

[Duke]

Had the chance to listen to unison research a couple of days ago.

Here are the horns that I think Unison Research uses, so their radiation patterns should be essentially the same.

For the Max 1: https://www.eighteensound.it/media/W1siZiIsIjIwMTkvMDcvMTkvMTBfNTVfNTFfNzQ4X1hUMTA4Ni5QREYiXV0

I've seen both of these horns in different photos of the Max 2, they have similar patterns: https://www.eighteensound.it/media/W1siZiIsIjIwMTkvMDcvMTkvMTBfNTZfMzZfMTY4X1hUMTQ2NC5QREYiXV0

https://faitalpro.com/en/products/HF_Horns/product_details/datasheet.php?id=903020105

They sound relatively bright (felt like the opposite of a standard houscourve like the harmon one), but I kind of liked them.

Ime constant-directivity horn speakers are an exception to the rule of "flat on-axis response" because there ends up being MORE high frequency energy off-axis, relatively speaking, than with conventional speakers. So, flat direct sound + closer-to-flat-than-normal off-axis sound can add up to "bright"... again this is in my experience; I don't claim this has been proven, but apparently it has been Earl Geddes' experience as well:

See the curves for the Gedlee Summa at this link. [See my EDIT just below!] In the top graph the black line is the on-axis curve, and the red line is the curve 20 degrees off-axis, which is the designed-for listening axis. I think the curves have been displaced vertically for clarity. But as you can see, along the designed-for axis, there will be somewhat less top-end energy in the first-arrival sound.

EDIT: I was WRONG in my interpretation of Earl Geddes' graph; THANK YOU VERY MUCH @Newman for catching my error! The black curve in the upper graph is the 20 degree axis response, and the red curve is the power response curve (or maybe the front hemisphere curve, as the second graph only goes out to 90 degrees on each side).

The issue is... that the horizontal sweetspot felt kind of small

Were they set up for time/intensity trading, with axes criss-crossing in front of the listening position? I am not POSITIVE that the horns in Unison Research speakers are well-suited for such, but I think it would be worth a try. The soundstage width would probably shrink so you might want to move them a bit further apart than normal. This is of course assuming it's feasible for you to listen to them again with these changes in set-up, and assuming this is not how they were set up to begin with (in which case you already know it won't work).

Some experimentation with toe-in angle would probably be needed to optimize, but with an equilateral triangle and 45 degrees of toe-in (as a possible starting point) you'd be about 15 degrees off-axis of each speaker when in the sweet spot. This might be enough to remedy the brightness you mentioned, killing two birds with one stone.

 

[jeffaegrim]

Marketing sure but the design was specific there is an AES paper for it and was designed to be used as an overhead horn in a rectangular room. It keeps SPL uniform over a large area. System was 4660 with 2225 for speech reinforcement For Everest JBL turned it on it's side to use for enhanced stereo imaging and added an 077/2405 up top angled with adjustable level to help imaging. The later system horns have there roots here. The paper and the white paper go a long way in explaining what they are doing.

DD55000 Everest

... Documents provided by Michael Smith

www.audioheritage.org

Appreciate the Link, Rob - I wasn't familiar with the original Everest white paper and have read it with great interest. They seem to have figured out the science behind it. It's too bad that mainstream adoption obviously remained absent, because, as @GXAlan wrote, the trick works pretty well. At the same time, while the space constraints for wide baffles he mentioned might account for a lack of adoption, JBL does still produce the 4367 or the M2, which also definitely can't be called "small" or "slender". I wonder why it didn't catch on at all. Perhaps also something to do with Hi-Fi becoming a rather solitary hobby.

For the benefit of other readers, instead of using a flown array you have a horn generating the same effect with a ceiling mounted speaker which is much lower profile...

Thank you for your reply and our conversation last year - I was messing around with speaker position etc. for a better half of this year trying to fix an image shift I was experiencing (& that I was sure was due to room asymmetry), only to find out that I have an ear blockage on one side. Now, with minimal balance correction I get a stable stereo image over a two seater sofa in my terrible, cramped listening space. It's probably only temporary, but I have since lost all interest in buying an AVR and finally upgrading to 5.1, because the "trick" works almost best with TV content, where the voices are pretty centered no matter where I sit. They might not be the most neutral speakers out there but the combination of dynamics + stable image is still impressing me every day.

Welcome!



The (apparently) sharp-edged slot in your horn, and JBL using the term "defined directivity", makes me think it's a "rectangular diffraction horn"... but obviously a unique one!

My guess is that your speakers were designed by or under the direction of Greg Timbers, and the horn itself may have been designed by Don Keele. These guys are WAY smarter than me. Like three decimal places smarter than me. I do not understand the reason for the horizontal slot but I'm sure they do, and I'm sure some very advanced thinking and analysis went into it.

I don't use in-room measurements because I think they can be misleading, so I don't have any useful comments to make on your measurements. It looks to me like the frequencies of the response-shaping filters were shifted a little bit but I can't reliably say what the net changes would be. Its a complicated crossover and a lot of small changes to capacitor values were made.

Here's the first of a two-part interview with the great Greg Timbers:

Thanks a lot! Watching right now. AFAIK you're correct and it was GT who designed the S2600/S3100 systems. I also understand the vague nature of my questions - and I don't really EQ anything upwards of 750Hz - I was just confused about some rather large aberrations in FR that I measured in my room and that don't show up in quasi-anechoic measurements (of pretty much the same speakers) from the 90's. Possibly some part of the horn's geometry accounts for that. Either way - your contribution is, as always on this forum, very welcome

 

[Duke]

... I get a stable stereo image over a two seater sofa in my terrible, cramped listening space. It's probably only temporary, but I have since lost all interest in buying an AVR and finally upgrading to 5.1, because the "trick" works almost best with TV content, where the voices are pretty centered no matter where I sit. They might not be the most neutral speakers out there but the combination of dynamics + stable image is still impressing me every day.

Very interesting! Thanks for posting your experience with these speakers, which arguably have time/intensity trading (for the horns anyway) built into the design.

 

[GXAlan]

And just to be clear, the other reason I sold my s2600 is that I have occasionally seen the DD55000 Everest at sub $10k pricing which I have had to pass on each time the opportunity arose.

 

[jeffaegrim]

And just to be clear, the other reason I sold my s2600 is that I have occasionally seen the DD55000 Everest at sub $10k pricing which I have had to pass on each time the opportunity arose.

Well… those weren’t small, after all. Your current setup has superior transducers, too, I strongly assume. And the DD55000 does have a very special pedigree - incredible piece of industrial design.

Maybe the asymmetrical horn will make a comeback one day. Until then I hope none of the unobtainium compression drivers in the 3100mkII fail on me.

 

[jeffaegrim]

Welcome!



The (apparently) sharp-edged slot in your horn, and JBL using the term "defined directivity", makes me think it's a "rectangular diffraction horn"... but obviously a unique one!

My guess is that your speakers were designed by or under the direction of Greg Timbers, and the horn itself may have been designed by Don Keele. These guys are WAY smarter than me. Like three decimal places smarter than me. I do not understand the reason for the horizontal slot but I'm sure they do, and I'm sure some very advanced thinking and analysis went into it.

I don't use in-room measurements because I think they can be misleading, so I don't have any useful comments to make on your measurements. It looks to me like the frequencies of the response-shaping filters were shifted a little bit but I can't reliably say what the net changes would be. Its a complicated crossover and a lot of small changes to capacitor values were made.

Here's the first of a two-part interview with the great Greg Timbers:

Thanks again for the video link, @Duke - at the 59 minute mark or so GT talks about the Everest design, which really helped understand some of the concepts that were implemented (I.e. how the directivity was controlled ranging from wide on one side of the horn to narrow on the other, but it wasn’t constant, etc)

 

[Duke]

Thanks again for the video link, @Duke - at the 59 minute mark or so GT talks about the Everest design, which really helped understand some of the concepts that were implemented (I.e. how the directivity was controlled ranging from wide on one side of the horn to narrow on the other, but it wasn’t constant, etc)

Yes! That's a solution I never would have thought of.

 

[bmc0]

I'm doing something similar. On a 12" diameter OSWG I'm getting a measured on-axis ripple of about 2 dB. I expect to have less on larger waveguides.

Sounds like you're on the right track then. In my experience, simply making the device larger doesn't substantially reduce the ripple; it mostly just shifts the peak and dip down in frequency.

 

[Duke]

Sounds like you're on the right track then. In my experience, simply making the device larger doesn't substantially reduce the ripple; it mostly just shifts the peak and dip down in frequency.

It's less ripple than I had with a 10" waveguide, and I figured that was because the round-over was a bit more gradual, but even if the 2 dB ripple persists in larger waveguides imo it's not a significant problem in this application.

 

[bmc0]

It's less ripple than I had with a 10" waveguide, and I figured that was because the round-over was a bit more gradual

A more gradual termination relative to the size of the device will certainly reduce the ripple.
In my waveguide generation script, the start of the Euler spiral termination is specified as a percentage of the total depth. If I recall my past simulation results correctly, I believe that increasing the total depth (leaving all other parameters alone) resulted in the dip shifting down in frequency but not changing much in magnitude. I'd have to revisit this to be absolutely sure though.

Edit: Just for clarity, the "other parameters" mentioned above are the throat radius, throat angle, and coverage angle. It's more mathematically convenient to specify the total depth of the device and leave the mouth radius as a dependent variable.

 

[Newman]

If someone is unfamiliar, the "gimmick" of these horns was their ability to provide the listener sitting off-axis towards the nearer speaker with a stable center sound image. You can read more about it here: https://www.audioheritage.org/html/profiles/jbl/everest.htm

Hi, I don't see anywhere in that article claiming a stable centre sound image when seated off-centre. I do see the words, "someone walking a horizontal line between the speakers would be exposed to a constant sound level", but that is not the same thing.

...When you use this horn horizontally, if you are dead center you get a nice phantom center. Now, the person to the right of you gets a louder left and quieter right experience, so the image of the phantom center is still natural in their mind.

OK...if the two of you are conflating equal sound level from left and right speaker when sitting off-centre, as meaning the phantom centre is maintained, then I don't think it is right to make that claim.

It is (probably slightly) better than nothing, but it would be overreach to say the phantom centre is stabilised when moving from centre seat to an off-centre seat.

cheers

 

[Newman]

Ime constant-directivity horn speakers are an exception to the rule of "flat on-axis response" because there ends up being MORE high frequency energy off-axis, relatively speaking, than with conventional speakers. So, flat direct sound + closer-to-flat-than-normal off-axis sound can add up to "bright"... again this is in my experience; I don't claim this has been proven, but apparently it has been Earl Geddes' experience as well:

Interesting...although "bright" could mean (a) "brighter than normal speakers" (after all, you do mention normal speakers as a reference), or could mean (b) "brighter than neutral sounding". I agree with you that (a) could be true, but note that (b) could simultaneously be untrue. It would need to be separately tested.

I mean, look at the ASR reviews of Genelec speakers. They are generally dead flat right out to 20 kHz, and yet have a slightly wider beam (say ± 50-60° vs ± 45°) and maintain that width right out to 20 Khz, whereas the Geddes collapses above 12-13 kHz. As a result, Genelecs have even more HF energy off-axis than the Geddes horns. Do we see a pattern of complaints about excessively bright highs with Genelecs? I haven't noticed it.

See the curves for the Gedlee Summa at this link.

I am going to replicate them here, because I have a couple of comments.

© Gedlee LLC, fair use claimed​

In the top graph the black line is the on-axis curve,

The black line is the 20 degree off-axis curve.

and the red line is the curve 20 degrees off-axis, which is the designed-for listening axis.

That is actually the black line. The red line is the sound power curve.

I think the curves have been displaced vertically for clarity.

I think not, otherwise the red would be above the black at 20 Hz.

But as you can see, along the designed-for axis, there will be somewhat less top-end energy in the first-arrival sound.

Those kinds of rolloffs, in the top octave or so, are very common in the measurements (I don't mean ASR measurements, I mean taking a variety of real-world examples) seen from all kinds of speakers, including conventional. I tend to grit my teeth and say, "I'm not going to interpret that, because it could be almost anything: microphone performance, microphone positioning, anti-aliasing filter, air absorption, or the tweeter itself." I would want to be intimately familiar with every detail of the measurement test itself, before drawing conclusions.

Having raised all my caveats, my best guess is that Earl is ceasing to equalise for the top octave, and allowing the horn's natural rolloff to occur. You can see from the polar plot that the horn's directivity control is collapsing above 12-13 kHz, and we all know that makes it less amenable to EQ in that range without audible negative consequences. Earl would be aware of that.

cheers

 

[jhaider]

They are generally dead flat right out to 20 kHz, and yet have a slightly wider beam (say ± 50-60° vs ± 45°) and maintain that width right out to 20 Khz, whereas the Geddes collapses above 12-13 kHz. As a result, Genelecs have even more HF energy off-axis than the Geddes horns. Do we see a pattern of complaints about excessively bright highs with Genelecs? I haven't noticed it.

I haven't noticed that either. The biggest difference I've experienced between speakers with uniform response out to as high as one can hear vs a collapsing polar is that the former sound tonally correct over a wider area. The latter quickly lose that sense of air outside the sweet spot.