Current QSC waveguides are similar to OS waveguides. It's mentioned in this paper, which I don't have on hand at the moment.
Have you ever tried the JBL horn profile with MEH?
Typical MEH has only conical or parabolic expansion for woofer mounting, is 3D printing a way to make JBL type HDI horn with MEH?
Yup they are good, I've used them for a few recones and some drivers over the last many years.
Is a 15 inch woofer an ideal match to the M2 waveguide?
Look at Erins polar measurement:
https://www.audiosciencereview.com/...reference-master-monitor-review.26051/page-16
Look at Erins polar measurement:
https://www.audiosciencereview.com/...reference-master-monitor-review.26051/page-16
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IIRC, Erin took his measurement of the M2 down. I haven't read that ASR thread, but I imagine it's possible that he found some issue with his own measurement.
I know from doing my own measurements that it's pretty easy to come up with two different results using the same speaker, especially in a speaker like the M2 where the center-to-center spacing is so ridiculously huge.
I measured my Gedlee Summas (a 15" two way) before I sold them, and found that there was a huge suckout in the midrange, so bad that I figured the tweeter must be wired out of polarity. Which was a real bummer, considering I never measured them until literally the week that I sold them.
Turned out they WERE wired correctly; it's just that when you have a center-to-center spacing of about eighteen inches, you get one heck of a null if you're mic isn't at the right height. 750Hz is eighteen inches long, so if you're listening off axis you get a big ol' null right in the lower midrange. This is further exacerbated by the fact that the Summa is passive. IE, with an active speaker like the M2, you have the luxury of tweaking the delay on the tweeter to minimize the midrange null. With a passive speaker, you would have to change the entire waveguide to do the same thing.
This is also one of the 'odd' things about Unity horns; yes they are complex, but they're actually harder to screw up, because all of the drivers are so close together. With a plain ol' two way, things get quite a bit trickier, and the complexity becomes increasingly challenging as the woofer gets bigger and bigger. With an 8" two way you have some wiggle room with the xover point, but with a 15" two way you're basically pushing the compression driver to it's limits and you don't have the luxury of lowering the crossover 100hz to improve the vertical polar response.
I know from doing my own measurements that it's pretty easy to come up with two different results using the same speaker, especially in a speaker like the M2 where the center-to-center spacing is so ridiculously huge.
I measured my Gedlee Summas (a 15" two way) before I sold them, and found that there was a huge suckout in the midrange, so bad that I figured the tweeter must be wired out of polarity. Which was a real bummer, considering I never measured them until literally the week that I sold them.
Turned out they WERE wired correctly; it's just that when you have a center-to-center spacing of about eighteen inches, you get one heck of a null if you're mic isn't at the right height. 750Hz is eighteen inches long, so if you're listening off axis you get a big ol' null right in the lower midrange. This is further exacerbated by the fact that the Summa is passive. IE, with an active speaker like the M2, you have the luxury of tweaking the delay on the tweeter to minimize the midrange null. With a passive speaker, you would have to change the entire waveguide to do the same thing.
This is also one of the 'odd' things about Unity horns; yes they are complex, but they're actually harder to screw up, because all of the drivers are so close together. With a plain ol' two way, things get quite a bit trickier, and the complexity becomes increasingly challenging as the woofer gets bigger and bigger. With an 8" two way you have some wiggle room with the xover point, but with a 15" two way you're basically pushing the compression driver to it's limits and you don't have the luxury of lowering the crossover 100hz to improve the vertical polar response.
With a two way, the design axis must be selected such that the major lobe is centered on the listening axis. That minimizes the effect of c-to-c spacing. You can even design it to point the suck out at the floor and somewhat mitigate the floor bounce, assuming other things such as listening distance works in your favor.
Not sure why you'd think that. Results have been on my site since August 2021.
https://www.erinsaudiocorner.com/loudspeakers/jbl_m2/
Its too bad my design is too big for your machine, I'd love to see my loudspeaker in the same light.
I don‘t care to listen to the first major lobe when it’s centered between 800hz and 4K…..to much phase interference……a dedicated midrange driver performs MUCH BETTER here when the recording is excellent. Poor recordings do better with a two way which mask those shortcomings…….vocals that were poorly recorded or produced sit better in the mix when the mix is confused and overcrowded in the above mentioned passband…..liken it to spray paint when a detail brush should have been used. The two way has garnished much favor since the recording industry has been streamlined to reduce costs and turn out endless streams mediocre content.
Mayhem, you are saying that you can hear the hole in the power response. While that may be true, generally power response holes are benign compared to peaks. In a 15” plus large horn type speaker, you can minimize the hole by crossing over where both drivers are near 90 deg radiation. This typically means 1” drivers are out. If the phase overlap is good, then it is not so audible.
Not sure why you'd think that. Results have been on my site since August 2021.
https://www.erinsaudiocorner.com/loudspeakers/jbl_m2/
Ah OK. There's a lot of misinformation about the Klippel drama on ASR
And I prefer as you mention 1.4”-2” CDs crossover over below 800hz and playing to 8-10k……I prefer the super tweeter tradeoff. Somehow the industry has been beholden to the the audiophools and that last octave from 10-20k…..that fwd lobe is FAR less destructive IMO since there’s nearly no fundamentals present.
But I digress, large systems like the M2 don’t fit modern lifestyles and IME narrow baffle systems image much better. If I were to build a high output speaker today, it would be a Synthesis 1400 type with 8” woofers instead of the 14” they used.
That computer is long gone
Here are the measurements: https://www.diyaudio.com/community/threads/monster-massive.244508/page-11
Probably the most interesting measurement of the Summas, in the context of this discussion, is this one:
It's been nine years, but if memory serves, I measured them at various listening heights. This wasn't a rigorous scientific method, I was simply trying to determine what listening height offered the flattest response. So I literally just did some gated measurements at various microphone heights, nothing very scientific.
Things I notice:
1) The Summas, despite being humongous, are quite light on the bass. The used a B&C 15TBX1000 that has a QTS of 0.27 so they're slooooowly rolling off, as early as 95Hz. Mine likely look worse because I measured mine in my living room and I had to set the gate to do what I could to gate out reflections in my tiny condo. I wish you guys could've seen how tiny my place was; I live in Nevada know and even my guest bedroom dwarfs the living room of the living room of the condo where I measured these. I had an upstairs loft there and I probably should have dragged them up there to measure (since there's nothing behind the loft, just empty space and vaulted ceilings) but I was already wiped out from moving two SH50s and two Summas three times in one weekend with no assistance. So these measurements are admittedly rough.
2) Earl made some posts on here alluding to the fact that a compression driver with the proper phase plug can control beamwidth above 13.5khz. (One inch is 13.5khz.) I wonder if that's one of the reasons he switched compression drivers later? We see in the O.G. Summa measurement here, that there's a fair bit of oxx axis rolloff here, above 13.5khz. I'm kinda glad that you inspired me to revisit these measurements, because to a great extent I'd lost interest in compression drivers over the last ten years or so, and part of that was because I thought that the Summa didn't have that "sparkle" above 10khz that you get with a good aluminum dome or a ribbon tweeter. But it might have been "curable" with just a bit of EQ. I spent my 40s living in tiny homes in California, and I'd argue that the Summa might be overkill for a tiny room, AND it's also very difficult to arrange things to make them work. I bought the Summas when I was 36 years old, lived in a ginormous house in Oregon, lived alone, and could basically devote entire FLOORS of my home to audio-video noodling. That wasn't an option at my CA homes and I struggled to come up with any setup that included the Summas and didn't dominate the entire room. I offered to buy the SH50s that I rented, and one of my ideas was to erect a false wall, similar to what William Cowan did with his Lambda Unity horns. I think that's a pretty awesome solution to the WAF factor.
I loved my Summas and I hope this post doesn't sound overly critical. I didn't really appreciate them fully until I bought my Yamaha DXR12s, which sound so bass-heavy (out-of-the-box) that they're basically unusable without equalization. But it was that experience of taking the DXR12 and equalizing them flat, which made me wonder: what if I'd done the same to the Summa?