2216Nd(-1) / M2 / 4367 measurements

[sebackman]

I have questions that you may be able to help me sort out.

The 2216 does show a raising FR response from about 100Hz up to 2kHz with about 6-8db (dependent on range). In the M2 this is addressed with a DSP point (among others) with a high shelving @ -8db from 135Hz (6db/oct) which makes sense.

4367 uses the 2216nd-1 which in my measurements in my 4367M clone cabinets show a similar raising level curve. The passive filter in the 4367 is just a "basic" charge coupled 18db filter with no tweaks och conjugate links.

Yet, the official JBL 4367 curve it is more or flat up to the driver XO. Same in the measurements from Erin.
https://www.erinsaudiocorner.com/loudspeakers/jbl_4367/

That is puzzling. The baffle step (unless included in the curve) would make it worse albeit the XO would reduce from maybe 500Hz (XO approx. 700Hz 18db/oct)).

Is this due to how they measure or why would you need -8db in M2 and not in 4367? Is it different measures including room curves and all of that? The Harman curves dos not specify.

Attached is my cheap-and-dirty 2216Nd-1 curve that shows the same trend. Disregard the jaggedness as it is measurement artifacts. Up to about 300Hz is NF, above is gated 10ms FF (resolution down to about 250Hz) and baffle step comp is introduced from 200Hz.

An additional question is did JBL use different slopes in M2 (32db woofer and 6+6 db for driver) to get the phase where they wanted them at XO? The FR would be easy to fix in the DSP regardless of slope.

I note that they have no phase compensation in the official XO DSP settings albeit BSS does have that option. Maybe the Crown amps does not? Any input on that?

Thank you
//Rob

[Earl K]

The 4367 uses the 2216nd-1 which in my measurements in my 4367M clone cabinets show a similar raising level curve. The passive filter in the 4367 is just a "basic" charge coupled 18db filter with no tweaks och
conjugate links.

Your observational mistake is underscored, colorized and enlarged in the above quote.

The 4367 or S4700 LowPass networks are not just simple 18db "text-book" filters.

The "rising" responses of the 2216nd woofers ( in both systems ) is taken care of ( levelled ) with an up-valued inductor-coil at positions L1. that starts "steering the LF response downwards, at just over 100hz.
- Ignore the coil values that JBL published for the S4700 >> they were an obvious case of dis-information from my perspective ( though 4.2mH and 1.5mH will work very well in the lowpass section for the 4700 ) .

Here's a simulation using JBL's own published response curves ( with appropriate impedance file ) for the 2216nd working in the S4700.

Study the transfer function ( Electrical Response ) to see what I'm referring to.

[Robh3606]

Hello Rob

I had a hard time getting a good measurement of my 2216nd where I showed a rising response. Once I did I finalized my passive network.

Here is the schematic and voltage drive. I used the basic 4700/4367 network as a guide. Attached is also the crossover zone measurement actual crossover at 700Hz.

It worked out just fine using an 18dB electrical network on both drivers. And as Earl said there is some "Magic" in there. Earls sims line up with my actual build network.

Rob

[Ian Mackenzie]

Earl and Rob are correct based on my own prior Leap crossover for this driver.

The same is true for an active equivalent crossover network.

The 2216nd and the 2216nd-1 are Not diy friendly drivers to work with without the means of measuring and curve fitting a voltage drive to meet the appropriate acoustic response.

The 2235H extended bass woofer is a more user friendly diy woofer to start off with for its relative flat response and extended bass response in 5 cu ft enclosures.

The 4367 sort to improve on JbL previous attempts at using the 2216nd in the 4700 passive system.

The reality is the 2216nd driver is not a straight forward woofer to implement in the diy space.

In the diy space l prefer to tell it as it really is than sugar coast diy folks with the belief they can get a good result straioff the bat when they won’t.

This is why JBL developed passive crossover for their Enclosure Series of designs in the 1970’s.

Note you could graft the 4700 schematic for a diy project but it’s only relevant for that shape front baffle and the relent horn in use. The same applies to the 4367 and the 2216-1. If you plan to invest in $1200 in top flight woofer it makes sense to have a working design so it will go properly first time than spend months or years tweaking.

Cheers

Ian

[sebackman]

Brilliant!

Great feedback, thank you Earl K and Robh3606. That just highlights my limited knowledge of passive filters since getting lost in the DSP world 20 years ago.

The curves clearly show the compensation in the passive link at about the same level as the active settings. Good news for me. I can easily mimic that in the DSP. I stand corrected, not "Basic" :-) .

I will do some more measurements this weekend and try some settings close to the curves you supplied. Thank you, much appreciated.

As my 4367 clones, will be DSP, the plan is to start with the basic M2 settings and work from there, albeit 2216Nd-1 is slightly different. In the M2, JBL has introduced many small corrections for the 2216 and I'm not sure they are all audible in a home environment. I will have to look at my curve once XO is set and major EQ points made. I thought the "naked" curve looked quite good above.

I plan to XO around 650-700Hz but maybe opt for steeper filters (probably LR24) as I probably can correct the phase at the XO point with the DSP. Even with IRR filters.

I find passive filters hard as I clearly do not have the same insights to the "Magic" as you do. I find the beauty of DSP being that you can adress all findings in real time and instantly see the resultat in FR and phase. -That is if one can stand having an extra "pre-amp" and additional power amps.

I also hope to get some help from member POS to translate my findings into FIR filters that can be made phase linear, at a later stage. That is an exciting prospect.

Ian, my 2216Nd-1 are mounted in my 4367 clone enclosures which I believe are rather faithful the originals. In the best of worlds I hope to be able to marry the M2 active advantage with the 4367 horn and a 4" driver.

As you pointed out in a different thread, I hope that the 4367 waveguide may be easier to integrate in a residential setting compared to the M2. It took forever to get the M2 wave guides in my other system to work in my room and some of that may pertain to the 100x100 dispersion. Or the room. Or the construction. Or SBK. Or...

That is really the driver for the 4367M project. We already knew that the 2216Ns(-1) are great woofers in the right setting.

This will be interesting.

Thank you
//Rob