In post 495, used "elgray" showed another way of approximating the JBL waveguides.
The way that *I* am doing it, I am taking two diffraction slots, combining them at a 90 degree angle, then blending them together.
Elgray shows a method that might be do-able with a spreadsheet. Basically it's a diffraction slot on the *diagonal* axis, but on the *vertical* and horizontal it's close to an OS waveguide.
As far as I can see, this shape can't be made in my 3D software using 2D shapes, but if you *calculated* the points on the x,y, and z axis it could be plotted.
I did something similar to that to make LeCleach waveguides in 123D. Basically I took the output from hornresp, popped it into a spreadsheet, and then transmogrified each circular slice into an elliptical slice.
The way that *I* am doing it, I am taking two diffraction slots, combining them at a 90 degree angle, then blending them together.
Elgray shows a method that might be do-able with a spreadsheet. Basically it's a diffraction slot on the *diagonal* axis, but on the *vertical* and horizontal it's close to an OS waveguide.
As far as I can see, this shape can't be made in my 3D software using 2D shapes, but if you *calculated* the points on the x,y, and z axis it could be plotted.
I did something similar to that to make LeCleach waveguides in 123D. Basically I took the output from hornresp, popped it into a spreadsheet, and then transmogrified each circular slice into an elliptical slice.
patrick, do you feel that this approach has worked? does it achieve what the M2 is meant to?
In my humble opinion, my experiments have demonstrated that there's probably a middle ground between the JBL M2 and the recording monitors.
The M2 has a 15" woofer and a 15" waveguide
The montiors have an 8" woofer and an 8" waveguide.
There's probably a middle ground that's never been built.
Check out my measurements of the Kali LP6. Charles Sprinke REALLY knows what he's doing. Who knows why there was never a "JBL M1" but maybe someone needs to make it.
Sprinkle's waveguide geometry shows promise. I think the M2 is too "extreme"; it's overkill for a home or a studio. The studio monitors win accolades but I wish they made something bigger...
If it was my money, I'd probably opt for the studio monitors. A lot of the M2's DNA, but less of it's complexity.
Then again, I've never heard any of them lol.
I heard the "passive" version of the M2 (the 4367) back to back with the Revel line. Like the people on AVS Forum, I think the Revels are a teensy bit better. Then again, when I literally told Revel's designer (Kevin Voecks) that his speakers were a little bit better, he looked at me like "you don't know what you're talking about." Too bad Kevin doesn't post here, would love to get his 0.02.
The M2 has a 15" woofer and a 15" waveguide
The montiors have an 8" woofer and an 8" waveguide.
There's probably a middle ground that's never been built.
Check out my measurements of the Kali LP6. Charles Sprinke REALLY knows what he's doing. Who knows why there was never a "JBL M1" but maybe someone needs to make it.
Sprinkle's waveguide geometry shows promise. I think the M2 is too "extreme"; it's overkill for a home or a studio. The studio monitors win accolades but I wish they made something bigger...
If it was my money, I'd probably opt for the studio monitors. A lot of the M2's DNA, but less of it's complexity.
Then again, I've never heard any of them lol.
I heard the "passive" version of the M2 (the 4367) back to back with the Revel line. Like the people on AVS Forum, I think the Revels are a teensy bit better. Then again, when I literally told Revel's designer (Kevin Voecks) that his speakers were a little bit better, he looked at me like "you don't know what you're talking about." Too bad Kevin doesn't post here, would love to get his 0.02.
Hello Patrick
There is it's just not a 2 way its a 3 way with an oblate spheroid waveguide loading the tweeter the LSR 6332. Check out the specs on it. It is a baby M2 but years ahead of it and you do need a sub.
http://www.jblpro.com/ProductAttachments/JBL.LSR6332.pdf
Rob
You seem like a perfect candidate to visit the factory for a blind listening session. IIRC, KV made that offer in his new thread on AVS Forum...
The passive in wall with 3 8” woofers and the latest iteration of that WG design.
Are you sure that look wasn’t for the “little bit” rather than the “better?”
PS you should seek out the 705.
When I heard the Revel and the 4367 back-to-back, the thing that I was discussing specifically was how dynamic the Revel is. This is something I've been noticing a lot in the last five years or so, that a lot of "conventional" two-ways with waveguides are just incredibly dynamic.
I think what's going on here is that you can get yourself about 3-6dB of gain on the low end of a conventional tweeter with a waveguide. So when you combine that with the right crossover and the right tweeter, you can end up with a design that has *significantly* more headroom than a conventional two way.
Basically it's a nice 'middle ground' between something like the 4367 (which is probably overkill for the home) and something like a Wilson Watt/Puppy (which doesn't have the output capabilities of the Revel.)
Basically the best of both worlds, maybe.
Having said all that, Voecks assured me that the 4367 is definitely way more dynamic than the Revel lol.
One thing that makes these two hard to judge is that the room was tiny. The JBL and the Revel room both had *two* sets of speakers set up, and each set got about half the room. So that's something like 125' per speaker. That's not much room at all, so it could certainly make a direct radiator like the Revel sound more dynamic than it would in an actual home.
I think what's going on here is that you can get yourself about 3-6dB of gain on the low end of a conventional tweeter with a waveguide. So when you combine that with the right crossover and the right tweeter, you can end up with a design that has *significantly* more headroom than a conventional two way.
Basically it's a nice 'middle ground' between something like the 4367 (which is probably overkill for the home) and something like a Wilson Watt/Puppy (which doesn't have the output capabilities of the Revel.)
Basically the best of both worlds, maybe.
Having said all that, Voecks assured me that the 4367 is definitely way more dynamic than the Revel lol.
One thing that makes these two hard to judge is that the room was tiny. The JBL and the Revel room both had *two* sets of speakers set up, and each set got about half the room. So that's something like 125' per speaker. That's not much room at all, so it could certainly make a direct radiator like the Revel sound more dynamic than it would in an actual home.
What are the "desireable" frequencies to crossover from a coaxial-CD controlled directivity horn, to a standard woofer driver on a baffle?
Is a 700Hz crossover "good"?
Is a 500Hz crossover "better"?
Is a 300Hz crossover "best"?
Is a 100Hz crossover "glorious"?
A few coaxial compression drivers can cover from 20kHz down to 500Hz. SO, what sonic improvements are possible with a LARGE 3-way Multiple-Entry-Horn which controls directivity down to 100Hz, where a crossover runs big woofer(s) on a baffle?
========
i.e. What sonic improvements are possible with a BIG 3-way MEH over a 2" 4592Nd coaxial compression driver on a SEOS24 waveguide crossover'ed at 500Hz to on-baffle woofers?
Is a 700Hz crossover "good"?
Is a 500Hz crossover "better"?
Is a 300Hz crossover "best"?
Is a 100Hz crossover "glorious"?
A few coaxial compression drivers can cover from 20kHz down to 500Hz. SO, what sonic improvements are possible with a LARGE 3-way Multiple-Entry-Horn which controls directivity down to 100Hz, where a crossover runs big woofer(s) on a baffle?
========
i.e. What sonic improvements are possible with a BIG 3-way MEH over a 2" 4592Nd coaxial compression driver on a SEOS24 waveguide crossover'ed at 500Hz to on-baffle woofers?
In my opinion, the question isn't "where should I crossover?"
The question is "how low do I need to control directivity?"
For instance, a properly designed loudspeaker that's a meter tall will control directivity down to 340hz.
It doesn't matter if:
it's a big horn
it's a big ESL
it's a big conventional speaker
All the options work on the same principle: low frequency directivity control requires a big ol' speaker.
True, a big horn is efficient, because horns are efficient. And a big conventional speaker is relatively small, because conventional speakers are relatively small. And an ESL arguably gives you the most directivity control in the smallest possible footprint.
But the answer to your question largely boils down to what you want to spend and how big of a speaker you can put up with.
Of course, all of this assumes that the engineering is correct. A big speaker isn't inherently blessed with controlled directivity, you have to get the design correct first.
The question is "how low do I need to control directivity?"
For instance, a properly designed loudspeaker that's a meter tall will control directivity down to 340hz.
It doesn't matter if:
it's a big horn
it's a big ESL
it's a big conventional speaker
All the options work on the same principle: low frequency directivity control requires a big ol' speaker.
True, a big horn is efficient, because horns are efficient. And a big conventional speaker is relatively small, because conventional speakers are relatively small. And an ESL arguably gives you the most directivity control in the smallest possible footprint.
But the answer to your question largely boils down to what you want to spend and how big of a speaker you can put up with.
Of course, all of this assumes that the engineering is correct. A big speaker isn't inherently blessed with controlled directivity, you have to get the design correct first.
Oh definitely. The day that I bought my reference speakers, I listened to them back-to-back with a set of Quad ESLs. The previous owner of my speakers replaced them with Quads. (I believe he started with them also.)
The way that he had the Quads set up, they do that 'giant headphone' thing, where it basically sounds like you're listening to a set of Sennheisers, but the sound is out in the room.
Possibly the first thing you notice, when comparing the two, is that the treble on the Unity horns sounds "rolled off." The Quads have that "sparkle."
I listen at fairly ridiculous levels, and I would certainly destroy a set of Quads. When I was auditioning them a few months ago (when I bought the Unities) I could hear a little bit of 'cracking' on some loud passages.
Though the Quads image really well, I also noticed some 'liveliness' to the sound that I generally think is due to 2nd harmonic distortion. This isn't a knock on the Quads; there's a ton of speakers where you can hear distortion even at fairly modest levels. Full-range speakers in particular. But if you're accustomed to something like Gedlee Summas, you get used to noticing distortion pretty quickly.
On a side note, I honestly think that the Summa's *lack* of distortion was one of the things that turned people off when they were at RMAF. That 'laidback' presentation that you get from a really low distortion speaker can sound "boring" to a lot of people. I think it takes a few weeks to adjust your brain to low distortion constant directivity loudspeakers.
I've never heard an M2, but I *have* heard a JBL 4367, and the sound of the JBL is closer to the Quads than my Unity, at least in respect to the treble. I need to dig out my measurements, but IIRC, the compression driver on my Unities rolls off around 16 or 18khz, while the 4367 goes past 20khz. Ring radiators are good for that.
I am acutely aware of this shortcoming in conventional compression drivers, and it's one of the reasons that I am using a 3/4" dome in my current project, which is intended to replace my Unity horns. Naturally, that will probably never happen because I never finish a project.
Basically I love my Cosynes, but the cabinet is obnoxiously large and I wish the treble went a little higher.
Naturally, this is splitting hairs in a huge way, because the Cosynes are fantastic.
I am feeling pretty silly today:
For literally five years I've invested easily 100+ hours trying to figure out how to make these waveguides. I've come up with three or four different ways to 'get in the ballpark', but none of them are a 100% match for The Real Thing. Complicating matters further, JBL doesn't even use the same curve on all the speakers with an "Image Control Waveguide." For instance, the ICW in the JBL 4367 is dramatically different than the JBL M2.
To cut to the chase, the answer was out there all along. JBL patented the waveguide. It's patent US20160173975A1. It never even crossed my mind that there might be a patent, because I've never heard of someone patenting a waveguide.
It turns out that the waveguide shape is constructed using a series of curves, and each curves is at different angles.
Picture the spokes on a wheel. Then make a curve and assign it to each spoke. The 'trick' is that each curve is slightly different.
Imagine if you had a waveguide that was an oblate spheroidal curve on the X axis, but a diffraction horn on the Y axis. The ICW is a bit like that.
For literally five years I've invested easily 100+ hours trying to figure out how to make these waveguides. I've come up with three or four different ways to 'get in the ballpark', but none of them are a 100% match for The Real Thing. Complicating matters further, JBL doesn't even use the same curve on all the speakers with an "Image Control Waveguide." For instance, the ICW in the JBL 4367 is dramatically different than the JBL M2.
To cut to the chase, the answer was out there all along. JBL patented the waveguide. It's patent US20160173975A1. It never even crossed my mind that there might be a patent, because I've never heard of someone patenting a waveguide.
It turns out that the waveguide shape is constructed using a series of curves, and each curves is at different angles.
Picture the spokes on a wheel. Then make a curve and assign it to each spoke. The 'trick' is that each curve is slightly different.
Imagine if you had a waveguide that was an oblate spheroidal curve on the X axis, but a diffraction horn on the Y axis. The ICW is a bit like that.
Crossing over right in the heart of the midrange, 300-500Hz, may not be the best thing to do. Splitting a female vocal up so that half of her voice is coming from the woofer and half from the horn, with all their differences, is very difficult to get right. This is what you would do with e.g. a BMS 4594 on a SEOS-24 (or the typical 3-way with cross between M-T floor bounces).
It is probably more optimal to cross above the midrange in the 850Hz or higher range (4550 on SEOS-18) or below it in the 200Hz range or less (Synergy horn). Out of those, the Synergy would obviously offer an advantageous in terms of directivity and perceived point source - IOW “glorious”!
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it's a big conventional speaker
I have listened to the Mk1 and Mk2 Evidence on several occasions...
and found those remarkably bad.
I have owned 6 pairs of Dynaudio speakers, all from the Contour range as well as the Crafft with Esotar 330, so I am familiar with the brand.
With a few exceptions, the smaller monitors are their best products. That is, if you like the sound of low sensitivity monitors.
No doubt, the Revel Salon2 will give the Evidence a run for its money.
These JBL's were not bad either:
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