JBL PA 13075

[Zilch]

Pretty sure someone will move this to DIY soon..

Your DIY design development facilities are better looking than mine, but the wires are very much the same....

[Anthony L100]

Very nice Fangio, there's something cool about having a "fiddle" with this old gear. Shall we call you "Filch" or "Zilchio"???

[Fangio]

Thanks Tony. I'm far away from Zilchs expertise, but learning.

[Anthony L100]

These look like a very nice unit to hang on to for general use, especially as they were a "steal" It's amazing how efficient they are compared to the real "hi fi" units, but I guess you have to make sacrifices in other areas to get the real low bass. I feel the same about my L200As, far more efficient than the 4430s but lacking LF extension. While i'm at it, you have a fine pair of drivers in the 2420s, those old ali' diaphrams are soooo nice and smooth. When are we going to see your 4 ways??. Tony.

[Fangio]

Yup, the 2420s are great, dias like new, and after a bit fine justage absolutely faultless at a tone generator. I'm happy with that find.

I had to realize, probably like most others going down this road, that the HF/UHF section kinda grows on trees even in europe, is much easier to gather than the LF drivers. Will update the accordant thread soon.. have better news about the 3143 section, and there is one more thing..


Edit, more topic: I agree with the effiency thing, these oldies are astonishing. Have the feeling though the K130 doesn't lack much bass anymore since he's crossed over at 3.5kHz now. It still doesn't go as deep as a 15" with foam surround, but the xover improved his LF extension quite a lot, maybe since the aluminium cap isn't used for the mids anymore..

[maro]

Hi Fangio and other forum people!
First of all my apologies of such a long exile from the forum. I need a little advice. As you remember I wrote about having 4 JBL PA13075 boxes. Well, in two of them (grey pair) I put 2404H tweeter instead of stolen 2402 (or 075). First of all I want to know if they are compatible with K130, or can they replace 2402 without degrading the sound of the original box? I try to compare their features and the only thing I found was a little bit diferent range of frequencies. Second, anyone have the idea which type of xover will be ok for that combination? I put inside some copy of xover which were in the originally box with 2404H but the bas speaker was 12" JBL. So the thing works but not even close the sound of original pair (black pair-K130 with 2402/075,original xover). Is it maybe better to copy xover from that original box even it is a little different tweeter (2402-2404H)?
Thanks in advance!
Maro

[Zilch]

I put 2404H tweeter instead of stolen 2402 (or 075). First of all I want to know if they are compatible with K130, or can they replace 2402 without degrading the sound of the original box? I try to compare their features and the only thing I found was a little bit diferent range of frequencies.

What you missed is that 2402 is 5 dB more efficient than 2404, and the drive level will have to be adjusted accordingly.

Also, the 2402 "beams" the high frequencies in a 30° conical pattern, whereas the 2404 is 100° x 100° constant directivity, providing substantially more beamwidth (that's where the 5 dB goes). Even properly balanced, the two different driver configurations will not "sound" the same.

The 2404 has more extended UHF response, as you've observed. In my experience, the 2404 is very much preferred, but you must get the driver levels properly balanced.

JBL recommended minimum crossover frequency for 2404 is 3 kHz, with minimum 12 dB/octave slope, whereas 2402 is minimum 2.5 kHz, no minimum slope specified. You've gotta pay attention to this stuff to make it work well....

[GordonW]

Though JBL spec'd the 2404 tweeter as crossover'ed at 3KHz on several designs, if you "run the numbers" on the component values on, for example, the 4612... you find it's effectively a 5KHz ELECTRICAL crossover, which seems to give an effective ACOUSTIC crossover somewhere near 3KHz.

So, if you use an electrical crossover at 3KHz, you'll overload the unit with low end, and the diaphragm will likely fail... word to the wise!

Regards,
Gordon.

[Mr. Widget]

What you missed is that 2402 is 5 dB more efficient than 2404, and the drive level will have to be adjusted accordingly.

From personal experience and from our measurements on the "Ring Radiator" thread, I'd submit the 2404 is more in the -10dB range relative to the 2402... at least if you are on or nearly on axis. The 2404 does produce a better polar plot but at the cost of overall sensitivity and especially at frequencies above 12KHz... usually not a problem in PA applications.

http://audioheritage.org/vbulletin/s...ead.php?t=6368


Widget

[maro]

Hi! Thanks for helping me guys, Zilch, GordonW and Mr.Widget ! I apreciate it very much . I can follow the ideas of your opinions but I must be honest and say that I do not understand all you are saying (because of my low level of understanding acoustic laws). So I go further more with, maybe, stupid questions and hope someone of you, experts, will have patience to follow.
First I will tell what I did understand: the better effitiency of 2402, more beamwidth of 2404, better VHF response of 2404, because I could hear it walking in front of speakers and listening to reproduction of fine jazz songs.
But I dont understand how to "accordingly adjust the drive level of 2404"? This could be done with adding different values of xover components or? Furthermore, "Even properly balanced, the two different driver configurations will not "sound" the same"...this means that it is not ok to use the 2 types of drivers(boxes) at the same time?! Or if I do adjustment of the 2404 driver then is possible? "2404 is very much preferred, but you must get the driver levels properly balanced"-how to do this?
If I adjust xover frequency for 2404 at 3 kHz, will bas speaker K130 reproduce missing frequencies(from 2.5 to 3 kHz)?
What means to "run the numbers" on the component values? Electrical-acoustical xover freq.-this means that the xover frequency must be adjusted higher than 3 kHz to protect HF driver of low end freq.? I already blow one diaphragm of 2404(shame on me), maybe this was a reason?
I think it is enaugh misunderstanding for this level of forum,but please do not throw me out of it!! Thanks again to follow me to this sentence...best regards...and good night! maro

[Zilch]

There's also the 2404H-1 variant, used in several SR products, which incorparates the thicker (and presumably more rugged) 2402 diaphragm (in lieu of 2405 diaphragm). The ring radiator studies show the concomitantly reduced VHF extension of that configuration (Post #6).

[It ain't just the horn.]

I have a pair of 2404H-2. Nobody seems to know WHAT they are....

But I dont understand how to "accordingly adjust the drive level of 2404"? This could be done with adding different values of xover components or?

You are doing fine.

If there's a HF level adjustment control, it means you'll probably have to turn it up to supply more drive to the 2404H to balance it with the bass. However, as discussed above, that may be risky, depending upon the crossover frequency and slope. You may have already discovered this to be a problem in blowing one of the diaphragms, though that's not necessarily the case.

We really need to know the circuit and component values of the present crossovers. (N2600?)

Yes, the K130's will "fill in" the frequencies we're talking about here.

Furthermore, "Even properly balanced, the two different driver configurations will not "sound" the same"...this means that it is not ok to use the 2 types of drivers(boxes) at the same time?

You've already heard the difference, it appears, for the most part.

It's not O.K. to play the same program material on more than one stereo pair in the same listening space at the same time in any case, let alone multiple pairs with different drivers.

[Unless we're talking party time, of course, in which case, other factors predominate.... ]

[maro]

What a speed Zilch! Thanks. There is a hope for ignorants...I thought everybody is sleeping but I forget that the world is still round (isnt it?) Ok I will try to put some pictures and features of present xover so maybe the things become even more clearer (to me) with such a great support....so, for those in dark part of globe, sleep well, and for the others, enjoy the cosmic light! bye bye Zilch

[maro]

Hi guys! too long in exile...I hope you remember me... I was thinking to add some low end sub woofer to existing PA13075 speakers which will than take a role of sattelites only...any ideas what (existing) bass speakers would be good for this combination? I will use this combination for sound reinforcement of small acoustic/light electric concerts Thanks in advance for any suggestion!!

[maro]

Hi guys! too long in exile...I hope you remember me... I was thinking to add some low end sub woofer to existing PA13075 speakers which will than take a role of sattelites only...any ideas what (existing) bass speakers would be good for this combination? I will use this combination for sound reinforcement of small acoustic/light electric concerts Thanks in advance for any suggestion!!

No one interested in suggestions? come on boys, please share your precious knowledge with ignorants

[maro]

Hi guys,

I came to an idea to make LF PA cabinets from existing PA13075 cabinets by replacing the K130 with K140 and removing HF driver 2402. I intend to use them together with original PA13075 cabinets (as mid/high units) and power them with two amps via active crossover (two basses and two satellites). Any ideas about how it might sound this little PA "system"?

Offcourse, I will not use it for heavy metal bands but small acoustic ensembles or school bands. The idea is to add more bass audio spectrum so that e.g. double bass or low kick drum could work apropriate without obstructing satellites sound with unwanted LF signals.

Any thoughts & ideas are welcome, thanks a lot in advance!

Maro