JBL 2397 Curves

[Mr. Widget]

I recently bought an electro-acoustic measurement system called Clio. I still have a lot to learn about using it to do fancier measurements like THD, Polar Plots, etc., but I have been using it to do some basic frequency plots for the Project May effort and tonight I thought I'd give it a whirl on the popular JBL 2397 "Smith" horns.

Here is a plot of the JBL 2441 driver on the 2397 horn. The Blue plot is on axis and the Red plot is 30 degrees off axis. These plots have what is called 1/12th Octave smoothing. With smoothing it averages the response within the specified octave rate. The overall response is pretty flat (no speaker really measures flat at this resolution), and the 30 degree off axis response is surprisingly good. Realize that this horn is not really meant to be used below 800Hz.

Widget

[Mr. Widget]

Here is a comparison between the JBL 2397 and one of my Westlake clones. It is interesting how the the wider lips of the Westlake do seem to improve the lower response, but at a sacrifice at the top end. This explains why I always feel the need to EQ up a bit around 6-10KHz.

[Mr. Widget]

These plots are from the same measurements as above but with half octave smoothing. This is frequently the way we see response plots in catalogs as it looks better.

Widget

[Steve Gonzales]

Lovely piece of equipment there,Sir. Very interesting data too. With all due respect, I think you should be named Mr "Wizard". I've shown the drawings to some craftsmen I know and I'll be cookin' some test runs off those drawings you so kindly posted very soon. I love this new data because I really didn't know if there was truely a difference between the 2397's and the Westlake's . Can you plot spatially or is that a bad question? Also, when you say EQing, do you use an EQ in your main system (music). I have always got such a negative response when I tell friends that I use an EQ, but to my ears, when I use the EQ, the response is pleasing . I use both parametric and fixed band- subtlely . I am curious to know if you do too and to what extent, notch filter, full fixed band or parametric?

[Alex Lancaster]

That´s neat Widget!; Do You plan to compare the 2311/08 combo sometime?.

[paragon]

This is measured 12 years ago by "Audio-Technik" (Lowther Dist.) with a prof.
measure system.

[paragon]

This is my 2441 with the 2397. May use this from 800-10000 Hz.

Eckhard

[Earl K]

Yes indeed ,

- Nice stuff there Mr. Widget

FWIW - For General consumption; I'd go with 1/3 octave smoothing , along with 3db vertical scale increments . The reasoning ??? It was determined decades ago, that this is the most typical change in power and/or musical division ("resolution") that the majority of the population can sense ( hence the common adoption of the 1/3 octave RTA ) . Of course everyone has different personal calibrations. For Instance : I'm quite "aware" of broadlybased level-changes as small as .5 db when implementing a balance between components .

regards <> Earl K

[Mr. Widget]

Can you plot spatially or is that a bad question? Also, when you say EQing, do you use an EQ in your main system (music).

I do plan to do polar plots and waterfall plots at some point. I will need to get a turntable and a bit more experience using the system.

As for EQ. I have found the White 4400 1/3 octaves to sound pretty much invisible. I have tried a variety of other EQs and felt they did more harm than good. I obviously haven't tried all of the EQs out there, only a handful really, but anecdotally there seems to be a consensus that the rotary pot Whites which have recently been discontinued are among the very best if not the very best.

Widget

[Mr. Widget]

That´s neat Widget!; Do You plan to compare the 2311/08 combo sometime?.

I don't currently have one or any 1" drivers. If someone brings one by, I'd be curious to check it out with this objective measurement gear. Subjectively, I prefer the 2397/2441. A while back I had both and did AB comparisons and to my ears there was no competition. I suppose THD measurements comparing the big 2" 2441 vs. the 1" driver should be made too as that is likely a contributing factor.

Widget

[Zilch]

I don't currently have one or any 1" drivers. If someone brings one by, I'd be curious to check it out with this objective measurement gear.

Now, you KNOW I have a nasty 'ol LE85 and a "special" horn for you to test.

Hang on. A coupla 2426's are on their way here on 2370A horns.

I'll strike while the toys are "hot," if you'd like to check them out....

[Mr. Widget]

Now, you KNOW I have a nasty 'ol LE85 and a "special" horn for you to test.

Hang on. A coupla 2426's are on their way here on 2370A horns.

I'll strike while the toys are "hot," if you'd like to check them out....

To quote the fearless leader, "Bring it on."

Widget

[4313B]

I recently bought an electro-acoustic measurement system called Clio.

Very exciting!

[scott fitlin]

Impressive piece of electronics. Use it well.

[lfh]

I do plan to do polar plots and waterfall plots at some point.

Thanks for posting those curves! It's most interesting to see the difference between the two flavours. I really look forward to see the polars and waterfalls later on.

Do You plan to compare the 2311/08 combo sometime?

As a matter of fact a 2441/2311/2308 vs 2441/2328/2397 shootout is on my to-do list, but it'll take a while since the 2308 lenses will ride in a '68 El Camino from LA to Stockholm. (Yes, I do have a pair of 2397s now - bought them yesterday! I'm sooo happy! )