I have a pair of 2445 driver with 2446 ribbed membrane. measuring freq.response i have realized that both have deep notch "hole" about 3kHz ( about 15dB deep and say width about 1kHz/-15dB ). The picture is the same with an other driver too.
Is there any explanation or experience about such bad behavior of 2445?
It was 2311 JBL horn mounted on the drivers.
Hi ivica;
Was it mouted in a baffle or free standing in open air?
With the 2308 lense or without?
Without a baffle and lense it may not be well behaved.
If we knew what the hell we were doing, we wouldn't call it research would we.
Well hmmm;
I just measured one of my 2445's (with a 2445 diaphragm) with no horn at all, then with a 2311, and then with a 2311 and a 2308, standing up on the bench with no baffle.
With no horn at all I get an 11dB dip at 1328Hz but nothing like you are seeing.
Tomorrow I will baffle it and see what it looks like.
If we knew what the hell we were doing, we wouldn't call it research would we.
Audiohack..a 2445 with an aluminum diaphragm correct?
Integra DHC80.1,3x 4636LF, 2360-2446J 2404H,12 x 8340 Surrounds, 2 x4645B, BGW 250D's,250E's,& 750B's 16 amps...7600 watts
Nope, the stock D16R2445 made from Ti with diamond surround.
ivica if it would help I have a pair of 2226's that I could measure if you think it will help you. I will have to pull them out of another system to do it, and I belive they would sweep the same as the 2445's however.
If we knew what the hell we were doing, we wouldn't call it research would we.
I have measured with baffle with almost the same results. I have not measure with lenses, I will do in next days, but I do not expect anything much difference. What is interesting is that I have done measurements with another not JBL horns, but the behavior around 3kHz is almost the same. I wonder that may be interaction of the 2445 internal horn-mouth (49mm- what corresponds to Lambda/2 of around 3kHz) as a kind of cancellation around Lambda/2.Originally Posted by 1audiohack
My experience with 2420/21 (mouth around 25mm) has notch deep -6~8dB around 5kHz, but here with 2445 deep is too much.
I have put 2446/2450 Ti membrane (ribbed), because original had gone out, but as have seen from other experiences they have not any problem about.
Mine 2445 original membrane had gone out, so I put new original JBL 2446/2450
(16 Ohms) Ti "ribbed" membrane.
As I understand 2226 is BASS, I believe that you think about 2426 ( 1 inch mouth). I have done the same measurements with mine 2420 with Ti membrane ( similar to 2421Ti). It has noticeable notch around 5kHz ( about 6~8 dB deep), but not 15dB as I have for 2445
I have done with and without baffle, but without 2308 lenses. I will do the measurements with lenses too one in next days, but I do not expect large improvement.
I assume the measurement is on-axis, but what distance from the horn (baffle surface) is
the measurement made?
Sorry I meant to say I also have a pair of 2446's (with the original diaphragms), I could measure one of them also, they are in service so I would have to pull one out to measure it. I believe it will measure the same as the 2445 however.As I understand 2226 is BASS, I believe that you think about 2426 ( 1 inch mouth).
If we knew what the hell we were doing, we wouldn't call it research would we.
Yes, on axis measurements. I Did on about 1.2m and about 0.4m, but with almost the same results
Nice if you can measure it and send the measurements: [email protected]
Finally I have measured it with "lens" but unfortunately with almost same result
If ant help.
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
Reply With Quote