Is it possible to cover the whole spectrum, high SPL, low distortion with a 2-way?

A pair of 2275H woofers are used for the C222HP:
 

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Japanese observations (badly translated and slightly edited):

"Because it is for small screens, it is not a stacked type but a vertical twin arrangement.
Each 15-inch woofer is equipped with a wave guide called "Acoustic Aperture Technology".
The purpose is to improve the directivity of the same band as the 15-inch high frequency response drop.

The 15-inch high side can usually be seen on the response graph from around 800Hz, but the measurement result is not simply rough, and it is not clean, I'm afraid.

In order to solve this, it is sufficient to use 3 ways and leave this band to a small-diameter unit, but this will make the system large.
This technology has solved this problem with 2 ways.
Of course, I think that the 15-inch mid-range problem may be a little lower, but the tweeter doesn't just have horns stacked. The area is different.
In short, it feels like the high beam and low beam of a car.
There are two drivers in order to secure input resistance, so it seems it required a little ingenuity because there are two drivers.

As for the speaker unit, the woofer is 2275H (the image above) and the driver is 2515XP-J.
The 2275H is mounted on the SRX815, and the spec sheet described the following.
"For Low Frequencies, the SRX815 uses a 15-inch woofer with JBL's patented Differential Drive Technology for reduced weight while maximizing power amp efficiency. 3" voice coils and dual ferrite drivers deliver exceptionally low distortion and ended low frequency response. "
In this way 2275H is that ferrite magnet-based differential drive, that 3 inches voice coil.
It seems to be the successor of the 2226H in cinema speaker systems of JBL.

The size of C222HP is 85.75cm wide, 152.4cm high, and 35.56cm deep.
The volume of the box is 350L assuming the inner dimensions are 80cm wide, 147cm high, and 30cm deep.
Even if about 30L is eaten by the horn, there is 160L per woofer.
The area of ​​four bass reflex openings on each side is also quite large.

The baffle plate is provided with a horn part, a wave guide plate provided in the woofer, and a semicircular recess around each woofer.
I think that it is a very elaborate design for a movie theater or commercial system.
It's a waste to hide behind the screen.

You can imagine a traditional cinema system sounding brightly from a wide baffle plate and a large duct.
The vertical twin unit layout is also cool and shallow, so I think it is easy to install for home use.

By the way, what kind of effect is provided by the waveguide plate installed in the woofer?
Below are response graphs with and without this component.
According to this graph, the effect is recognized in the upper band from around 500Hz.

The graph below showing the directivity also shows that the directivity is aligned from 800Hz to 1.6kHz."
 

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A clear and concise explanation of the design by John van Ommen:

"Arguably, the limiting factor in most prosound loudspeakers is the tweeter. At high frequency, you reach a point where you can't load the tweeter, and then that frequency becomes the limit for the entire loduspeaker. You can see this in the Danley Jericho speakers; above 10khz their treble starts to fall, even when the loudspeaker has as many as sixty four tweeters!

Yes, I said sixty four.

The reason that this happens is because you reach a point where you can't pack the tweeters tight enough for them to sum. For instance, 10khz is 2.5cm long. That means that you need to get two tweeters within about ONE CENTIMETER to get them to sum.

So...

There's a couple ways to solve this riddle. The first way to do this is to use the most powerful motor you can build, and couple it to a very light diaphragm. JBL has a long history of doing this. Arguably, this has culminated with the JBL D2430K dual diaphragm compression driver.

But there's another solution, which is to use a very very small compression driver and array it vertically. If I'm not mistaken, this loudspeaker was designed by Paul Peace from Harman, and he's said as much in Youtube videos. Basically you use a very small compression driver and by packing them tightly you can keep the pathlength differences small.

So it has a similar effect as the JBL D2430K, which has dual diaphragms, but it is much cheaper. The D2430K costs about 10X as much as a very small compression driver like the Celestion CDX1-1425 or the BMS 2408H-1. You still have two diaphragms, but instead of sharing a single waveguide you have two waveguides, and the pathlengths are designed in such a way as to equalize the pathlengths.

So... that's the high frequency section of this loudspeaker.

The low frequency section is fairly traditional, just a big ol' woofer for high output. The design includes JBL's "RBI" technology. The "RBI" technology is basically designed to widen the beamwidth, as Bill Fitzmaurice correctly observed. The RBI allows you to use a LARGE woofer while attaining the beamwidth of a SMALL woofer.

This technology has been utilized by a few designers:

1) Nexo uses this

2) Charles Sprinkle, formerly of JBL, used this technology

3) Paul Peace used it in this design

4) Way back in the day, Doug Button was the first person I've seen use it.

Arguably, these enhancements allow you to build a two way speaker that can perform a lot like a three way. The dual tweeters allow you to lower the tweeter xover point, and the RBI allows you to RAISE the low frequency xover point. Basically eliminating the need for a dedicated midrange."
 
The design(concept) of the C222HP is all nice and dandy, but I'm under the impression the drivers are nothing to write home about.
A pair of C222-TOP's is for sale at less then 30% of the list price.

The 2275H has been largely ignored by the JBL community.
It's basically the cheaper brother of the 2265H Differential Drive® and used in JBL's mass market products like the PRX series.
This doesn't imply it's bad, but, much like the tiny comp. drivers, not comparable to JBL's higher end offerings.
 
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If someone in the UK would like to experiment with some oldskool JBL 2360 type of horns...
For less than the price of 1 driver at the shops, you could buy the biggest Beyma horns ever, CP800Ti drivers included, as well as some spare diaphragms.

This could work with a Beyma CP-25 smoothly blended in from about 8 kHz, crossed first-order with a single cap.



Note: image 2, 3 & 4 are my own.
 

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what an impressive FR plot. Makes developing crossovers seemingly more straight forward I would assume? More simplistic crossovers (ie. less components) = better sound quality?

The big beyma 2" CDs all have amazing FR plots. Not cheap new though.

I want those big horns. Hard to get in Australia.

PS. Have a pair of Faital HF108R + 18Sound XT1086 horns enroute. Still to get pair of Faital 15PR400 and will setup 'simple' 2-way. Excited :D
 
How does one go about matching woofer directivity to these large narrow dispersion horns?

For instance if you were to cross the XT1464 at ~500 Hz you would need an extremely large woofer to match the 50 degree dispersion :scratch2:

At 500Hz that thing is probably closer to 100 deg. It start loosing pattern control at before 800Hz already.

Personally I'm looking at the PH-3520 right now. It's still on the small side of things, but it 12 euro's, so might be worth a first try..
 
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"Arguably, the limiting factor in most prosound loudspeakers is the tweeter. At high frequency, you reach a point where you can't load the tweeter, and then that frequency becomes the limit for the entire loduspeaker.

I've seen this in every one of my designs. The upper end of the tweeter sets the limit of system SPL.

This is why I couldn't use a DE500 in my NS-15. Because the DE500 had a few dB lower output at 10k I could not match it to the higher efficiency 15" woofer. In the NA-12 the match was fine, but not the larger woofer.

However, simple solution arrived. Pad out the woofer instead of the usual tweeter. Not a common solution, but it does work just fine (especially in a closed-box system.)
 
The low frequency section is fairly traditional, just a big ol' woofer for high output. The design includes JBL's "RBI" technology. The "RBI" technology is basically designed to widen the beamwidth, as Bill Fitzmaurice correctly observed. The RBI allows you to use a LARGE woofer while attaining the beamwidth of a SMALL woofer.

All techniques of this type will widen the directivity, nothing can really narrow it without a large waveguide. Wider directivity is NOT what I want, so these techniques are not really a solution in that case. Using a very large woofer in my designs is to get narrower directivity, not higher output.
 
All techniques of this type will widen the directivity, nothing can really narrow it without a large waveguide. Wider directivity is NOT what I want, so these techniques are not really a solution in that case. Using a very large woofer in my designs is to get narrower directivity, not higher output.


There's no substitute for a big horn.
This also applies to OSWGs, as illustrated by Marcel Batik in the sims below of a 52cm (diameter) OSWG.


Now that he has released his tool to the public, I guess it's permitted to show some sample waveguides.
 

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