Insider news...
"I had a nice conversation with G.T.{Greg Timbers} over the New Years weekend and he mentioned something that those of you who actually still care about what JBL is doing might find interesting.
The latest generation of waveguides/horns are "prefect". They don't pinch at the top end like the "almost perfect" M2 and 4367 do.
I would imagine they will be thoroughly "protected" and "patented". I believe the first examples will be coming out in some in-wall systems"
Quoted from this thread.
"I had a nice conversation with G.T.{Greg Timbers} over the New Years weekend and he mentioned something that those of you who actually still care about what JBL is doing might find interesting.
The latest generation of waveguides/horns are "prefect". They don't pinch at the top end like the "almost perfect" M2 and 4367 do.
Quoted from this thread.
You probably know this already, but in case anyone is wondering what Timbers meant my "perfect:"
All waveguides lose directivity control at two points. The first point is on the low end, and is dictated by the mouth of the waveguide. The second point is on the high end and is dictated by the throat of a waveguide. Loudspeaker designers typically deal with the low end by handing off to a woofer of similar size. For instance, the waveguide in the M2 hands off to a woofer that's about the same width as the mouth of the waveguide. And loudspeaker designers have done this for decades; you see similar designs from Meyer Sound, Gedlee, Klipsch, etc.
We lose directivity control at the high end due to the dimensions of the throat. For instance, if you look at the polars in the 'great waveguide list' here at diyaudio, most of them start to narrow at 13,500hz... Which is the dimensions of the throat.
In order to push that all the way up to 20,000hz, you'd need to use a smaller throat. Which is exactly what JBL has done in their newer speakers. According to the buzz over at Avsforum, the newer speakers in the JBL line may give the M2 a run for it's money.
I'm doing all of this off the top of my head, but if memory serves, JBL is now offering *two* compression drivers with throats that are smaller than one inch in diameter. One of the compression drivers is a dual-diaphragm unit, the first addition to the dual diaphragm line since the debut of the D2430K. The other unit has a single diaphragm. Both are ring radiators.
The fact that they're ring radiators also plays a part here. I'm not an expert on phase plug design, but as I understand it, a ring radiator is a bit special because you can make a phase plug that expands constantly, all the way from the surface of the diaphragm. Conventional compression drivers (generally) can't do this, because conventional compression drivers have diaphragms which are larger than the throat. If you look at the phase plug on the BMS 4540ND, the JBL D2430K, and the JBL 2408H-1, all of them are expanding constantly.
I just checked all the usual suspects to see if there's a way to buy a JBL 2409H, and I don't see one yet. It's not in the JBL part list, isn't for sale on eBay, Google Products, Amazon, etc. 🙁
IMHO there's three things you'd want:
1) a throat that's 19mm or less
2) a phase plug with no compression ratio, like what you see in the JBL ring radiators
3) a matched waveguide
Methinks JBL has been reading those Geddes patents
1) a throat that's 19mm or less
2) a phase plug with no compression ratio, like what you see in the JBL ring radiators
3) a matched waveguide
Methinks JBL has been reading those Geddes patents
Those JBLhorn are just wave guide without spl amplification if I understood the M2 thread from AudioHeritage?
Motors of those classic line dome tweeters (0.75") from ScanSpeak have a 550 Hz Fs but have a poor sensivity : Scan-Speak (look at the bottom the classic line)
A passive M2 for domestic use will need less résistors attenuator than the genuine 94 db M2 to match the vented standalone bass/mid-woof !
Certainly the BL of those ScanSpeak are not strong enough ! A good opportunity to those non-compressions brands to make classic driver with strong BL for horn/wave-guide uses ?
Motors of those classic line dome tweeters (0.75") from ScanSpeak have a 550 Hz Fs but have a poor sensivity : Scan-Speak (look at the bottom the classic line)
A passive M2 for domestic use will need less résistors attenuator than the genuine 94 db M2 to match the vented standalone bass/mid-woof !
Certainly the BL of those ScanSpeak are not strong enough ! A good opportunity to those non-compressions brands to make classic driver with strong BL for horn/wave-guide uses ?
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+1
An interesting dream;
JBL for spec #1&2, Geddes, and Danley for #3 collaborate...😴
Any sightings of a D2415k in the wild? I believe it has a 21mm/0.8 inch exit with a 1.5" throat? Should get pattern control up just past 17KHz ish I think ish? Which would be an improvement if not more than sufficient?
I've been getting better results with 3/4" domes and SAW lenses than I was getting with compression drivers and waveguides, so that's what I've doing lately.
Here's the frequency response of the lens, the distortion, and a pic of it. I'll concede that the QSC waveguide is smoother, but I am willing to bet that if mine was symmetrical and larger, it could give the QSC a run for it's money. And the QSC is arguably the best waveguide I've ever measured. (And measurements by others, in the "best waveguide list", echo this opinion.)
I'm not 100% ready to write off compression drivers, but those SAW lenses work really nicely. I can't figure out why I'm the only one building them. They work.
An externally hosted image should be here but it was not working when we last tested it.
To smooth out the response curve, you want to make the waveguide bigger. Which is exactly what the inventor did when he debuted his new speaker last year. (Pictured above.) To improve the distortion curve you might want to use a different tweeter; I am using an SB Acoustics 3/4". In many aspects it performs better than my compression drivers. The main reason I opted for a 3/4" unit is because you need a really small diaphragm to get to 16khz on one of these lenses. The 1" units I tried couldn't go up high enough.
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When seeing this picture:
Can't help but think what a couple of mid injection ports would do placed in the back flat area 🙂.
Can't help but think what a couple of mid injection ports would do placed in the back flat area 🙂.
Yeah, check out my car project, that's basically what I'm doing :
One Horn to Rule Them All - Car Audio | DiyMobileAudio.com | Car Stereo Forum
Once that's done, I'm hoping to do something that looks like this, but as a Synergy horn, with a saw lens at the apex :
One Horn to Rule Them All - Car Audio | DiyMobileAudio.com | Car Stereo Forum
Once that's done, I'm hoping to do something that looks like this, but as a Synergy horn, with a saw lens at the apex :
An externally hosted image should be here but it was not working when we last tested it.
Wow, really interesting stuff show here, what are the speakers shown in post #151 and #153?
I would like to read the specs and reviews.
I would like to read the specs and reviews.
ZERO 1 by Avantgarde Acoustic
EISA Award 2014-15
http://www.theabsolutesound.com/articles/avantgarde-acoustic-zero-1-pro-loudspeaker/
EISA Award 2014-15
http://www.theabsolutesound.com/articles/avantgarde-acoustic-zero-1-pro-loudspeaker/
An externally hosted image should be here but it was not working when we last tested it.
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A Start
From the attached file, with some scaling, you should arrive at a first approximation. WHG
From the attached file, with some scaling, you should arrive at a first approximation. WHG
Patrick, have you ever sat still long enough between building speakers to listen to one for a while 🙂