For $200, can anything beat Pyle PH612 + JBL 2408H-1?

A few years back I bought a single JBL 2408H-1. To my eyes, it's basically a BMS 4540ND with a different phase plug.

I put it back on the shelf and forgot about it.

This week I've been doing some measurements of various waveguides and compression drivers, and noticing that the 2408H-1 plus the Pyle PH612 just keeps winning. In the words of The Iron Sheik, the JBL takes one look at my compression drivers and tells that "I will humble you."

And then it does.

I'm too lazy to upload all the measurements I made, but here's what I've noticed:

1) The 2408H-1 is insanely efficient. At the low end of the spectrum, it's limited by the diaphragm size, but above 2000Hz? YOWZA. This thing will rip your ears off.

0JBrStx.jpg

Here's a comparison of the JBL versus the Tymphany. Admittedly, a different waveguide. But the extra SPL above 2000Hz is noticeable. In particular, note that it's TWELVE dB more efficient at 20Khz. I think this is due to the new phase plug in there, basically same phase plug that's on the D2430K that costs five times as much. I really do think you're getting 80% of the D2430K performance for 20% of the price.

2ixPaHK.jpg

Here's some unequalized polars on the Pyle PH612. Purty!

Some caveats :

1) it's a screw on compression driver, so good luck finding waveguides that will fit. The Pyle PH612 and it's Dayton clone will work.
2) It won't go as low as the Tymphany or the B&Cs. You lose surface area when you go from a dome to a ring.
3) The PH612 has a nasty gap in the throat, you have to fill it in with Mortite to get curves like I've posted


Long story short: Let's give the 2408H-1 some love! It's a really nice compression driver that nobody is using.
 

ICG

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PH612 isn't in production anymore. Some dealers still have a few but that's not what I call 'available', you really have to search for it.

The Dayton H6512 got the same WG function, IMO even identical there. However, it doesn't have the metal insert thread, only a thread in the plastic. If a driver rattles in it, you have to put a very thin teflon tape (or something similar) into the thread and that stops it immediately from rattling.

Besides that, the APT50 isn't a good choice for that WG, you'd want something with a bigger VC and ability to cross over a lot lower.
 

ICG

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I have a par of econowaves in the shed with d220 and dayton, no horrible noise there.

Well, it's the unprecise thread and badly cleaned casting edges/burrs. Some are better, some are worse.

But the dayton is not exactly a clone, its larger vertically

Dayton H6512: 12x6.5"

Pyle PH612: 11.9x6.4"

The difference in size is minimal and only in the mounting plate.
 

ICG

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Now that you mention it, it was a D220-Ti, not the Eminence. It sounded hopeless so I haven't really worked on it. I think the horn had a zinc insert. No rattling.

That's strange since the D220-Ti and the Dayton are an approved combination. The tolerances of the casting can be corrected though.

Anyway, if you don't want the Dayton, you culd still buy the JBL 338800-001 - which would be the 'original'.
 
Now that you mention it, it was a D220-Ti, not the Eminence. It sounded hopeless so I haven't really worked on it. I think the horn had a zinc insert. No rattling.

Maybe the JBL is a much better driver?

The JBL really seems to be special.

I wish someone at JBL would get the memo that neodymium prices have dropped.

I paid $60 for my 2408h-1; it's now $145.
 
It's perfectly fine to use a waveguide that's larger than the midbass below it.

For instance, a waveguide that's 12" wide with a woofer that's 8" wide below it.

That would dictate a crossover point of around 1500Hz, which is perfectly do-able.

Where you get in trouble is if the waveguide is too SMALL not too BIG.
For instance, if you use a 6" waveguide with a 10" woofer, the waveguide loses pattern control at 2250hz while the woofer starts to beam at 1,350Hz. That means you have to 'push' the woofer to 2250hz to maintain pattern control. (which is tough for a ten.)

I think Geddes is using big waveguides with smaller woofers these days. It also improves the polar response of the compression driver below the xover point.

Long story short:
Better to have a wave guide that's too big than too small.
 
Your frequency response data for the JBL CD look nice but that is just one aspect of its performance.

I would never choose a driver based on frequency response alone and I would very much like to see any comparisons include the HD and IMD profiles for driver+horn combinations. It's "fairest" to do this when they are EQd to have about the same frequency response, and tested at the same SPL, but that is probably asking too much. CD+horn can have rather inferior distortion performance compared to home audio, e.g. dome, radiators...
 

ICG

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@CharlieLaub: Yes, I agree, the response is just one of a bunch of parameters you'd have to look onto.

The Eminence N151M-8 was measured on audioXpress. It was used on the Eminence SST1 horn. The SST1 is identical to the MRH-83 except for the driver mount (screw on vs. bolt). I've used the Monacor one a few times, it opens fast and is not particular critical to different drivers. The measurement on the Eminence SST1 horn show some issues however, the angle measurements show a deep dive of ~17dB above 13kHz under angles. The 120dB harmonics distortion measurement looks very good (medium K2, very low K3, THD got a peak at 3,5kHz though but at 120dB that's still fine), the decay too, so it's likely not a resonance of the ring membrane but an interference on the driver exit horn throat. That hints the driver might be picky regarding the choice of the horn. The driver is reasonable priced, so it might be worth a try nevertheless.

At around the same price you can get the Celestion CDX1-1747, which was also reviewed by audioXpress. The burst decay of the eminence is a tad cleaner, the radiation of the Celestion much more uniform, it's a different horn though. The driver behaves uncritical regarding the choice of the horn and sounds excellent, very detailed. For HiFi it's often used at 1kHz or even 800Hz. For PA use I'd recommend a higher crossover frequency though.
 
I own the N151m and it's mounted on JMLC 2000hz from Autotech

If you want me to do measurement, just ask me what you wish to see and I'll do them.

If any interest, I also own:
Celestion- CDX1-1425 on custom 2000hz JMLC (start with a negative 6degree angle)
BMS 4526 on 2000hz JMLC (still fairly new, is there is such thing of burn-in in CD?)
Celestion CDX1-1445 on FaitalPro short 1" horn
Later
 
Your frequency response data for the JBL CD look nice but that is just one aspect of its performance.

I would never choose a driver based on frequency response alone and I would very much like to see any comparisons include the HD and IMD profiles for driver+horn combinations. It's "fairest" to do this when they are EQd to have about the same frequency response, and tested at the same SPL, but that is probably asking too much. CD+horn can have rather inferior distortion performance compared to home audio, e.g. dome, radiators...

My primary motivation was that the JBL compression driver combined with a clone of the JBL horn just worked so darn well. At the time that I posted the thread, the combo cost about $75.

It was just kinda depressing seeing people use a titanium Selenium compresssion driver on a clone of a JBL horn, when the combo of JBL + JBL just worked so much better.

I'd argue that there are very few compression drivers that can outperform this combo above 10khz, at any price. Even the JBL M2 starts to narrow at ultra high frequency. Voishvillo did really nice work here.

IMG_0089-resized.jpg


HARMAN Innovator Spotlight: Alexander Voishvillo, JBL Loudspeakers – HARMAN Professional Solutions Insights

In the pic, the JBL 2408H-1 is there on his desk, alongside the D2-2430K. They're kissing cousins.

And to clarify:

When I saw "it performs well" I mean "it's directivity is really really good." I'm from The School of Geddes, I'm a lot more concerned about directivity than harmonic distortion. Plus, these are professional compression drivers, it's not like we're going to push them hard when we're playing them in a living room.
 
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One of the issues with a lot of the measurements that I made, particularly before 2017, was that I would move the microphone from left to right as I measured the loudspeaker.

So the *angles* were correct, but the distance from the loudspeaker would grow.

For instance, if you measure a loudspeaker on axis, and then you measure it 45 degrees off axis by moving one meter to the LEFT, you will now be 41.4% further away than the first measurement.

An externally hosted image should be here but it was not working when we last tested it.


This measurement was made that way. You can see it in the measurement; as the wavefronts become spherical because the waveguide can no longer control directivity, the SPL level starts to fall off with distance. (See what's going on below 2khz?)

An externally hosted image should be here but it was not working when we last tested it.


Today I re-ran that measurement with the following improvements:

1) measurement distance is two meters instead of one

2) The distance from microphone to speaker is equidistant at every measurement point. IE, the mic is like spokes on a bicycle wheel, each measurement changes in angle but not in distance.

3) I made a half-assed attempt to EQ the speaker flat

Anyways, hope that helps. I still think the combo of JBL 2408H-1 plus a PT waveguide or one of it's clones is pretty darn special. This performance is very good; note how the shape of the response doesn't change as you move around, it just gets quieter as you get off-axis. Very nice if you're setting up a system like Geddes recommends, with the loudspeakers cross-fired. The response curve isn't *perfectly* flat, but I didn't even put this waveguide on a baffle, this is a naked waveguide measured two meters above the ground. On a baffle, it will perform even better.
 
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Someone would have to ask Voishvillo that question (he designed them) but here's my guess:

1) the original ring radiators from the Voishvillo patent were drivers like the BMS 4550. A ferrite ring radiator, used on the Danley SH50, came out something like fifteen years ago. As legend has it, there was a designer at Yorkville who selected the BMS 4550 for his Unity horn, and Danley was impressed with it's performance, and then used it in the Sound Physics Labs "SPL Runt." IIRC, that was the 2nd Unity horn with a ring radiator, the Yorkville U15 was first. I am not aware of any Cerwin Vega speakers that use a ring radiator, even though it's their patent. I have no idea if Voishvillo designed the 4550. The technology is definitely from the same patent, I don't know if BMS owns or licenses it.

2) JBL then licensed the ring radiator patent. That led to a flurry of ring radiators, about twelve years back, from JBL. Of the top of my head, I recall that some of the JBL drivers were made in Germany. Do the math, and it's fairly clear that JBL was simply selling BMS ring radiators with JBL labels on them. The BMS 4540ND is an obvious example of this, there's a JBL model that's practically the same thing. I'm too lazy to look up which one.

3) Fourteen years ago, Voishvillo went to work for JBL, and that's when we started to see a bunch of innovations in the ring radiator design. In particular, new phase plugs and the dual ring radiator used in the Vertec line and the JBL M2.

There's been a consistent series of innovations in these drivers. If I take apart my 4540NDs, *externally* they look similar to my JBL 2408H-1, but internally they're very different.

At the same time, there's been obvious cost-cutting. The 2408H-1 is made in Mexico.

They've been shrinking it down; the 2409H is about half the volume of the 2408H-1.

This is a really long winded way of saying "I don't know what the specific differences are between a 2408H-1 and 2408H-2." They're definitely different.

To me, it looks like a cost cutting measure. There's a LOT of neodymium in a 2408H-1. I paid something like $80 for my 2408H-2, but it's about as big and complex as my BMS 4552, which retail for $250.

Obviously, Samsung is a bean counter, there's going to be an effort to get the cost of these things down. But they're also an innovator. It's safe to say that the two are different.

But all of them are very very good, it really just boils down to "how high and how low do I want to play, how much can I afford, and how loud do I need to get."

If the build quality on the Eminence ring radiators is acceptable, those are CLEARLY the screaming deal right now. They appear to be very much like the BMS 4552 for less than half the cost. BMS is made in Germany, I'm assuming the N151M is made at Eminence Dongguan in China.

Side note : the Peerless is a completely different animal than any of these ring radiators. The Peerless is basically the "goto" compression driver if you need wide bandwidth for a reasonable price. Ring radiators generally can't play as low, but they excel at playing out to 16khz and beyond. To my ears, the Peerless sounds comparable to a DE250.
 
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