One thing related to the SPL handling of the M2s. The tweeter doesn't seem to be as good as the midbass.
https://www.audiopro.de/medias/item/16109/jbl_m2_soundandrecording_1214.pdf
https://www.audiopro.de/medias/item/16109/jbl_m2_soundandrecording_1214.pdf
I think it's three things:
1) The JBL D2415K is something like half the size of the D2430K from the M2, so it needs a higher xover
2) The "image control waveguide" series uses some trickery to widen the beamwidth. Basically the ICWs have two diffraction slots in the horn. The more aggressive the slots are, the lower you can move the xover point. But that probably comes at a price, as all diffractions slots do. If you look at all of the ICWs that came AFTER the M2, the diffraction slots got smaller and smaller and smaller. On the GDI speakers the slots are barely there at all.
3) The 4349 may have a larger exit angle than the M2.
From a Vietnamese article:
"JBL 4349 is the first pair of speakers to use a newly designed HDI horn throat, slightly square with a huge opening angle of about 100 degrees both horizontally and vertically if measured at a maximum high range of 10kHz. At 20kHz, the new HDI's opening angle still has a large coverage equivalent to 80 degrees horizontal x 70 degrees vertical."
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Keep in mind that a limiter setting of 50 Watts (I guess refering to 2.83 Volts into 8 Ohms) was used for the tweeter channel during these measurements. When you take the 32 Ohm impedance and the voltage divider between amp and tweeter into account one does not wonder it didn't get louder. The woofer was limited to 400 Watts BTW. Therefore the peak SPL capabilities would be even higher than shown by these measurements.
OTOH 110 dB is already quite unnerving at frequencies >1kHz and therefore sufficient for most cases.
Regards
Charles
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Ah ok. Thx !
Thats true. 90 dB itself is very loud for me. I was just looking at it comparatively (which anyways is due the reason you gave above)
They have any measurements?? That 2415 has a 3/4" throat and I would like to know what the directivity curve looks like in the last octave to see if or how much it decreases compared to the 1.5" M2 waveguide.
Rob
Here is a paper with info on the 2415
White Paper on Dual Diaphragm Drivers 2430 2415 2420
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Though one strange thing about the C211 is, it claims freq resp of only 77Hz - 14kHz +/-3dB even though it uses same HF as 705/708
The higher ones like C222 claim upto 20kHz but the FR plot in it's spec sheet indicates lower FR range.
Instead of one 1.5" CD going down till 800 Hz, this one uses 1.75" CD from 800Hz to 7kHz
and and a 0.75" CD from 7kHz
And a 12" woofer.
Should allow for wider dispersion ?
4429 | 12” (300mm) 3-way, compression-driver monitor loudspeaker
I had not come across such design using CD, though there a quite a few of dome based designs using 2" and 0.75" domes
and and a 0.75" CD from 7kHz
And a 12" woofer.
Should allow for wider dispersion ?
4429 | 12” (300mm) 3-way, compression-driver monitor loudspeaker
I had not come across such design using CD, though there a quite a few of dome based designs using 2" and 0.75" domes
That's a Greg Timbers design : Second Annual Lansing Heritage Awards
He's one of the engineers that JBL inauspiciously gave the boot, five years ago:
Saying Goodbye to an American Icon: JBL - Audiophile Nirvana
Greg Timbers describes his design process here:
An Interview with Greg Timbers, Past Designer/Engineer for JBL
In regards to your question, here's my take:
The older JBL designs were often "cost is no object" designs. A lot of the Timbers designs are like that. For instance, the speaker you referenced, they probably could have done it with ONE compression driver. But by using two, they were able to eke out a wider bandwidth.
In interviews, Timbers has been dismissive of the ring radiators. In particular, their maximum output is limited, when compared with a beryllium dome.
The designer for Revel and Snell, Kevin Voecks, he hasn't quite come out and said it, but he's made some statements that imply something similar:
Basically if cost is no object, beryllium is the go-to material.
And to be fair, as much as I've obsessed about Unity horns and Synergy horns and the JBL M2 etc....
When it's all said and done, a beryllium compression driver is a very elegant solution. It costs a LOT of money. You pay a heck of a lot to get that last 1-5% of performance, but beryllium is pretty neat.
TLDR: In the big scheme of things, the JBL M2 is a relatively "affordable" loud speaker. If they'd truly gone off the deep end, it might have been a three way using a pair of beryllium tweeters... But that would have doubled the price.
Would YOU pay an extra $10,000 for improved treble?
He's one of the engineers that JBL inauspiciously gave the boot, five years ago:
Saying Goodbye to an American Icon: JBL - Audiophile Nirvana
Greg Timbers describes his design process here:
An Interview with Greg Timbers, Past Designer/Engineer for JBL
In regards to your question, here's my take:
The older JBL designs were often "cost is no object" designs. A lot of the Timbers designs are like that. For instance, the speaker you referenced, they probably could have done it with ONE compression driver. But by using two, they were able to eke out a wider bandwidth.
In interviews, Timbers has been dismissive of the ring radiators. In particular, their maximum output is limited, when compared with a beryllium dome.
The designer for Revel and Snell, Kevin Voecks, he hasn't quite come out and said it, but he's made some statements that imply something similar:
Basically if cost is no object, beryllium is the go-to material.
And to be fair, as much as I've obsessed about Unity horns and Synergy horns and the JBL M2 etc....
When it's all said and done, a beryllium compression driver is a very elegant solution. It costs a LOT of money. You pay a heck of a lot to get that last 1-5% of performance, but beryllium is pretty neat.
TLDR: In the big scheme of things, the JBL M2 is a relatively "affordable" loud speaker. If they'd truly gone off the deep end, it might have been a three way using a pair of beryllium tweeters... But that would have doubled the price.
Would YOU pay an extra $10,000 for improved treble?
It's a never ending struggle:
1) ring radiators make a flat wavefront
2) ribbons make a flat wavefront
3) planars make a flat wavefront
Because of this, their high frequencies tend to be extended and clean.
Domes and cones generally do not produce a flat wavefront, or at least they don't when the frequencies are smaller than the radiator. This is simply geometric; the tip of a dome is closer than the surround, this screws up your very high frequency performance.
So it becomes a never ending battle between "high frequency extension" and "low frequency extension."
1) ring radiators make a flat wavefront
2) ribbons make a flat wavefront
3) planars make a flat wavefront
Because of this, their high frequencies tend to be extended and clean.
Domes and cones generally do not produce a flat wavefront, or at least they don't when the frequencies are smaller than the radiator. This is simply geometric; the tip of a dome is closer than the surround, this screws up your very high frequency performance.
So it becomes a never ending battle between "high frequency extension" and "low frequency extension."
I was wondering more from directivity aspect , i.e if it has wider horizontal dispersion than M2s, given the drivers and the crossover freq. Sadly no measurements available to compare.
The other similar Synthesis designs (though much larger floorstanders) with BE seem to have too high a crossover UHF driver
DD67000 : 20 kHz !!! ?
K2 S9900 : 15 kHz !!?
Even the non BE ones are
JBL S4700 and S3900 : 12 kHz !
I very highly doubt A DBT would be interesting though...
Foamboard M2 Waveguide
I am not sure if this was covered in this thread or not. I have been following it but this thread is getting old. I finished my garage so I have a place and some time to test out some of the things that I have been wanting to try. I wanted to prototype an M2 type wave guide out of foamboard. Has anyone tried this? Can this work? I was looking at the Eminence ring radiator for the CD.
I am not sure if this was covered in this thread or not. I have been following it but this thread is getting old. I finished my garage so I have a place and some time to test out some of the things that I have been wanting to try. I wanted to prototype an M2 type wave guide out of foamboard. Has anyone tried this? Can this work? I was looking at the Eminence ring radiator for the CD.
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I hate to be a bummer, but if I was building a waveguide out of foamcore, I'd stick with an oblate spheroidal waveguide.
They work REALLY well.
I started this thread, and the M2 waveguides are fun, but they're not really something you can "guess" at. I tried going that route in the beginning, and it didn't work.
Mabat's software is the way to go, if you want to make them.
They work REALLY well.
I started this thread, and the M2 waveguides are fun, but they're not really something you can "guess" at. I tried going that route in the beginning, and it didn't work.
Mabat's software is the way to go, if you want to make them.
please excuse, but what would happen if you were to clamshell two normal compression drivers, and limit the exit aperture to 180 degrees, with asymmetrical curves, in a car audio application?
Ideally you could keep the expansion rate from interfering with the compression, which would reduce "yaw" in a perpendicular exit, and make the Sausalito spray without the need for a huge platter...
705P/708P
So after watching this thread and others related a question came to mind well searching for new Nearfields for my studio. Reading the Audio Science forums they measured the 705p and there is a deviation in the higher frequencies with a large notch/cut.
Wouldn't this be of concern is terms of accuracy and a perhaps a trade off in design. It really had me look at the Neumann 310s but size might be an issue.
Big JBL fan here and I have the 305s and some JBL SVA 2100. The 2100s in some ways I prefer.
So after watching this thread and others related a question came to mind well searching for new Nearfields for my studio. Reading the Audio Science forums they measured the 705p and there is a deviation in the higher frequencies with a large notch/cut.
Wouldn't this be of concern is terms of accuracy and a perhaps a trade off in design. It really had me look at the Neumann 310s but size might be an issue.
Big JBL fan here and I have the 305s and some JBL SVA 2100. The 2100s in some ways I prefer.
It's kinda the thing I've been agonizing over for about two years now.
Basically after listening to a JBL 4367 and a Revel back-to-back, I think the Revel was quite competitive. I was surprised by how loud and dynamic conventional speakers can be these days.
I spent a ton of time evaluating why the Revel performed as well as it did, and for me the big takeways were:
1) Enclosures are waveguides. I have a thread named this; in a nutshell, you can manipulate the width and the depth of a loudspeaker enclosure to control directivity much lower than what the waveguide on the baffle would lead you to expect. For instance, the Revel M106 has a waveguide that's about 15cm in diameter (2267Hz) but it offers directivity control down to about 500Hz. I believe this is due to a synergistic combination of enclosure and waveguide. IE, we don't need 40cm wide waveguides, we just need to factor the enclosure shape into the overall design.
2) Yes, compression drivers can hit 120dB. But do we need all that? 110dB is a good number I think, and that can be achieved with a good dome tweeter. This particular factor is particularly influenced by the 'house curve' that Samsung uses. In particular, you may only need 110dB at 100Hz, 105dB at 1khz, and 100dB at 10khz. (Because the house curve is sloped down.)
I've attached measurements of the Revel M106 and the JBL 705P. I think what you'll notice is that the JBL has really well controlled polars (because it has a compression driver) but that the M106 has smoother response overall.
Basically after listening to a JBL 4367 and a Revel back-to-back, I think the Revel was quite competitive. I was surprised by how loud and dynamic conventional speakers can be these days.
I spent a ton of time evaluating why the Revel performed as well as it did, and for me the big takeways were:
1) Enclosures are waveguides. I have a thread named this; in a nutshell, you can manipulate the width and the depth of a loudspeaker enclosure to control directivity much lower than what the waveguide on the baffle would lead you to expect. For instance, the Revel M106 has a waveguide that's about 15cm in diameter (2267Hz) but it offers directivity control down to about 500Hz. I believe this is due to a synergistic combination of enclosure and waveguide. IE, we don't need 40cm wide waveguides, we just need to factor the enclosure shape into the overall design.
2) Yes, compression drivers can hit 120dB. But do we need all that? 110dB is a good number I think, and that can be achieved with a good dome tweeter. This particular factor is particularly influenced by the 'house curve' that Samsung uses. In particular, you may only need 110dB at 100Hz, 105dB at 1khz, and 100dB at 10khz. (Because the house curve is sloped down.)
I've attached measurements of the Revel M106 and the JBL 705P. I think what you'll notice is that the JBL has really well controlled polars (because it has a compression driver) but that the M106 has smoother response overall.
Attachments
Then you look at the Neumann or Genelec which I also think plays loud enough and they also have really good directivity and smooth responses. The Kiii speakers also go for narrow cabinets and domes and with their cardioid DSP system have what many say subjectivity are the best sound. Cost and size does not equate for me though.
Either way hard to get meaningful information these days as it is all just subjective overhyped opinions.
Either way hard to get meaningful information these days as it is all just subjective overhyped opinions.