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  »  New  Adding one more non-spherical to Macondo...  Horn suggestions for 300Hz-1000Hz channel...  Horn-Loaded Speakers Forum     23  123404  12-15-2010
01-01-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 1
Post ID: 15335
Reply to: 15335
JBL 2490 mid-range driver
fiogf49gjkf0d

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.

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-01-2011 Post does not mapped to Knowledge Tree
AOK_Farmer


Marlboro NY USA
Posts 63
Joined on 07-08-2004

Post #: 2
Post ID: 15336
Reply to: 15335
Fundamental Channel
fiogf49gjkf0d
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?


Happy 2011 I think it's gunna be a good one.


Steve
01-01-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 3
Post ID: 15337
Reply to: 15336
Melody
fiogf49gjkf0d
You dont know much about music do you,,,?...   Its a musical phrase...  Check melody in your dictionary..
01-01-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 4
Post ID: 15338
Reply to: 15337
It is not well defined or relevant
fiogf49gjkf0d

 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.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-01-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 5
Post ID: 15341
Reply to: 15338
2490 compression driver
fiogf49gjkf0d
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,,
01-01-2011 Post does not mapped to Knowledge Tree
zako
Posts 85
Joined on 05-25-2008

Post #: 6
Post ID: 15342
Reply to: 15341
Melody reducks
fiogf49gjkf0d

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!!!!!!!!!

01-01-2011 Post does not mapped to Knowledge Tree
eduardo
Posts 9
Joined on 04-17-2009

Post #: 7
Post ID: 15343
Reply to: 15335
One more option
fiogf49gjkf0d
Romy, may be the alnico jbl 2482 + aluminium diaphragm (plastic surround) would suit for your application here. I tested such driver on 200 hz tractrix horn and worked fine. Went down well under 200 hz and is 2" throat. It is heavy but I would be using it again anytime if not using the japanese YL 55000 that I
posted at:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=5&postID=11591#11591


I thought it worked diferently but was very good indeed on that range 200 up to 5k  .
01-01-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 8
Post ID: 15344
Reply to: 15341
So far it is not bad.
fiogf49gjkf0d

 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.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-01-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 9
Post ID: 15345
Reply to: 15344
Thoughts about the 2490 testing
fiogf49gjkf0d
 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 will probably put my experiment with 2490 on hold.  The infrastructure that I meant above is the environment in which the 2490 can be objectively evaluated. I do not have it now. The ability of a driver to provide saturated tonal reaction to very minor current irritations is a very fine characteristic. I would not excaudate if I say that 95% of audio people out do not understand the concept and even higher percentage of them do not know how to test the driver for this quality. To do it properly I need a fully broken in driver, for this type of suspension it might take a long time. Also, I need a good electricity to get colors. The dams PP2000 is still not fixed and the next fight with Purepower it looks like to get my colors back. The PP2000 that I have at my disposal now are eating all fine tonal ensignations that render my playback to nothing that was proud before. Not the last thing is that I need to have an adapter made from 3” driver to entrance of my Multicell. The adapter will be a bit complex and I would like to have buffering front chamber and perhaps eventually strip down the driver from it’s phase plug. I did not open the driver yet and I do not know how it is made. I do not have my own driver and use a borrowed for now, so I do not want to open up somebody else driver. Then - the making of the adapter. I have wood, glue and the table saw to do it myself but I am kind of get spoiled with my former carpenter. I feel it is easy to form the task, go to work, return and to have the things done. Instead of cutting the wood and making the things myself I would like to pay it off and to get it ready. I was not thrilled how my carpenter behaved in the end, so I would like do not employ him again. I would feel better if I find another guy, as I have some other ideas that I need to render.
 
So, I will put the things on hold: will talk to different handy men, will trying to get sound out of Pure Power… When all things “click” I will pit the 2490 for test and will see if I will work with Macondo. The alternative option would be to use 2490, it is can sound OK, with 180Hz multi-cell with my Ledom Cetla 91 loudspeker. If I get the 200-1000Hz from 2490, than I know how I will convert the Altec 19 into a very nice sounding machine and it will be relatively easy.
 
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-20-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,301
Joined on 05-28-2004

Post #: 10
Post ID: 15813
Reply to: 15335
A Russian implementation of JBL-2490
fiogf49gjkf0d

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.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
08-15-2015 Post does not mapped to Knowledge Tree
Murataltuev


Moscow
Posts 98
Joined on 05-21-2010

Post #: 11
Post ID: 21881
Reply to: 15813
Any result of your experiments ?
fiogf49gjkf0d
Romy, can you share more thoughts about 2490 ?You've suspended your experiments with it, but have you had a chance to continue ?Is it worth to try this driver for 200-300+ range ?
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  »  New  Adding one more non-spherical to Macondo...  Horn suggestions for 300Hz-1000Hz channel...  Horn-Loaded Speakers Forum     23  123404  12-15-2010
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