A few months ago a reader of my site contacted me and informed about that he found a very interesting driver, that his is using and he is very excited about it. The driver is JBL 2490.

http://www.jblpro.com/pub/components/2490.pdf

http://www.jblpro.com/pages/pub/components/2490.pdf

It was mentioned at this site a few times but I never seen/used it and I decided to look what it is. My objective was to have a compression driver, useable in my Fundamental Channel,  that will be able to go down to 200Hz.

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=15201

There are not a lot of suitable drivers around. The large Elmar and Community drivers are out of questions. The Goto/Ale/WE have very small throat that would lead to a long time non-align horn, also it is not know if I like their sound and there is no options to try it. The RCA MI-95XX might be an interesting driver but I do not know them and whoever use them are not credible. Cogent would cover the range but they are too soft sounding for my taste and they are physically too long. The JBL 2" 248X series are unusable as they have too soft diaphragms. The 4592ND-mid is excellent theoretical choose but I had it and it sounds like crap.

From all analyses the JBL 2490 sound like a very interesting candidate. Take a look: It has 3” exit and in order to properly load 183Hz hour it would need just 20” horn. The driver has very low depth, which will be excellent for my Macondo frame.  The JBL 2490 wants “200 watts continuous program above 250 Hz”, which means that with my 1-2W it shall be able to handle down to 100Hz-150Hz. So, it looks wonderful. There is negative moment however. The 3” exit makes short horn that minimizes the horn equalization. As the result the lower knee of the Fundamental Channel will be contributively more produce by the efforts of the driver instead of the efforts of horn equalization. That is not good. Well, the 2490 is still compression driver, it is not the idiotic Kharma Ceramic drivers where more bass mean more excursion. The compression drivers are underhang by nature and the extra excursion that this JBL 4” diaphragm will care shall not be too much problem.

Now, JBL 2490 has reportedly fully titanium diaphragm with I presume the titanium suspension. Usually those type of diaphragms sound like shit and only plastic imbedded titanium diaphragms sound acceptably. However, my hope is that since JBL 2490 is only lower MF driver then the HF ringing that is so annoying with fully titanium diaphragms will not be there.

Since JBL 2490 is very much not know I did some searching and reading what people say about it online. There is not a lot of there. There is a Sound African gat with his 5-channals GOTO/Altec playback use 2490 for a number of years and he is hugely pleased.  You can find his comment at AA and at Audio Heritage sites.  I did not listen his playback and he hardly ever talks about Sound, so I do not know what he is listening and what he is looking in Sound. I made a few phone calls and find a guy that know who use to have JBL 2490. He passed extremely negative feedback about it sound. He found that the driver had a lot of typical titanium coloration and strong lock of colors in lower MF range. It is important to get that this comment came from the guy who I know very much, have good grip about his reference points and he is in my books is a very much “trusted source”. There were a few more comments that I found but they are less relevant or indicative. So, the stage was set for me to try the JBL 2490 and to see if it would be worthy performer.

The JBL 2490 retail price is $960 per driver, the diaphragm replacement is $250. I would call it expensive. Still, I got the JBL 2490 and I will be playing with it, with a naked driver and in various horns I have, probably driving it from my full-range Melquiades.  Let see what the JBL 2490 will show up.

Meanwhile if any of you have any experience with JBL 2490, I mean USE the driver, then raise your voice.

AOK_Farmer wrote:

Is that the same as the melody range? Defined per this discussion: http://www.goodsoundclub.com/Forums/ShowPost.aspx?postID=1421#1421 Where is the fundamental range in relation to the melody range? Low C is 128 Hz. and it seems to me low C is in the melody range. I guess I think of the melody range from 100 - 400... is this where you place the fundamental channel?

It is not well defined and I do not think that a specific definition is ever necessary. What is the difference how one or another channel is related to melody range? Melody range is definition of Sound, the layout of the drivers is absolutely irrelevant from it and wary from given characteristic of driver, horn, crossover and loading pattern. So, I feel that the question is very much irrelevant.

Saying it I also disagree with Zako that for sound reproduction the musical definition of melody range is valuable.   In music theory the melody range defined as 10 tones up from middle C. However, we do not have universal middle C. The middle for a flute and for bass clarinet would be very different. Then we do not deal with live sound but with sound reproduction by artificial means and therefore, in my view, the melody range for playback shall include second harmonic.

If we pretend that middle C for whole orchestra would be at 262Hz then the melody range for playback I would defend as from 120Hz to 500-700Hz. The point is, however, that there is no point to define it firmly for a playback and there is absolutely no reason to think about melody range when we try to assess drivers. I understand that somebody would like to talk about melody ranges but let to keep this thread dedicated to JBL 2490 driver.

ROMY,,,As far as MELODY,,I again disagree,,,You talking about frequency bandwidth of musicle instruments,,,NOT THE COMPOSITIONAL line of musicle phrases,,... HELL I studied that in collage..  SO lets not cross swords with me on that subject..  I,ll end on that a souer NOTE!!!!!!!!!

zako wrote:

I did not like the two slit configuration of the phase plug..but the five to one compression ratio produced low distortion,,,but i was not impressed with its bandwidth,,,JBL also used a eight inch speaker assembled to a special phase plug,,  You will find it in there TECHNICLE PAPERS... I found it more musicle,,in theaters with out stress,,, the 2490 needs to be coupled to a 2393 type horn,,,another product long throw horn with its own polor problems,,

Zako, I do not expect to be “impressed with its bandwidth”. I do not feel that this diver might be use over 1.5kHz. I am planning to low-pass it at 1000Hz. The way how JBL intended to use it has no relevancy to me. My major concern is how it will react to low signal. It will be driven by one single stage of a tube that has 7W on plate and grossly attenuated. So, it will not see more that 1/2W and it will be very low currant. The reactance to the the low currents is the key as this type of suspension is more suitable for endurance at high power levels. I do not particularly case able it phase plug as the phase plug works at upper knee – or where I do not care.

I plug it for a first time today. It looks like it is sensitive like hell and I did not hear any titanium problems on it even without low pass filter. I do not have infrastructure now to look into it further.

Romy the Cat wrote:

I plug it for a first time today. It looks like it is sensitive like hell and I did not hear any titanium problems on it even without low pass filter. I do not have infrastructure now to look into it further.

I saw today link of a Russian guy who was trying to make set a playback around JBL-2490.

http://photofile.ru/users/yras/3860502/all/?mode=xlarge

The speaker turn out to be a ridicules – 2490 in upperbass shorted version of WE horn and a tweeter in the upperbass mouth.  Poor Russkies – they discovered the word of horns but can’t “get” that horns are a narrow bandwidth devise. It is no surprised that all Russian horns idea are ether open idiocy or slavish imitation.

The guy on the picture who employed 2490 used it in right horn for this driver but this type of seashell horn is a great illustration that if it used then there is practically impossible to add to this type of horn other channels. I have no idea why this two way setup was built. If it was just to test the 2490 driver then it is very right attempt but from the picture it looks like that it is some kind of complete solution. If so then it is an unfortunate foolishness in my view.