PDA

View Full Version : Jbl 2447 with aquapas dia?



greg32
01-11-2017, 04:17 PM
As the title says, I have mint 2447 drivers and was reading about the aquaplas damped diaphragms, does anyone have any links to info or response graphs or first hand experience with the d16r2451 in a 2447 core? regards Greg

JeffW
01-11-2017, 04:30 PM
Here's a fellow who recently went to aquaplas coated diaphragms in a pair of 2446, so similar:

http://www.audioheritage.org/vbulletin/showthread.php?39033-JBL-2360-Compression-Driver&p=399991&viewfull=1#post399991

greg32
01-11-2017, 11:36 PM
Thanks Jeff, i hadn't seen that thread. I have searched up lots of info on the aquaplas diagraphams but was hoping someone had first hand experience with the 2447 core and maybe even some comparative measurements. As I understand the aquaplas will be slightly more detailed less bright and more natural and slightly less sensitive. The thing im not sure about is if i will loose significant hf extension and require a uhf driver. mind you my hearing runs out at 15k now. Greg

JeffW
01-12-2017, 09:23 AM
The 2447 looks like a ferrite 2451 to me, I would take a wild guess and say the 2451 diaphragm should be OK in the 2447. I bet you could find some comparisons of the different diaphragms in a 2451 and use that as a starting point.

http://www.audioheritage.org/vbulletin/showthread.php?39185-2447j-2381-2168x-2169x-2251x-info-and-suggestions-please

AlexanderZ
01-19-2017, 11:57 AM
Hi Greg,

I've had 2447j with both titanium and -SL diaphragms and 2447 with -SL diaphragm sounds much better than with titanium ones. I also have 2450SL and in its turn it sounds (not so much) better than 2447 with -SL diaphragm.

No response graphs only listening impressions sorry.

greg32
01-19-2017, 10:45 PM
Hi Alexander, thanks for the reply, if i may ask did you notice any difference in the hf extension between the ti and aquaplas diaphragms. regards Greg

ivica
01-20-2017, 10:01 AM
Hi Alexander, thanks for the reply, if i may ask did you notice any difference in the hf extension between the ti and aquaplas diaphragms. regards Greg

Hi Greg,

What kind of horn You would to apply with 2447 driver?
The influence of the horn can not be neglected.
Regards
Ivica

greg32
01-20-2017, 03:04 PM
Hi ivica, I am using the 2381 at the moment from 1200hz Greg

greg32
01-20-2017, 11:01 PM
I have just ordered a pair of d16r2451sl diaphragms. for the record i will measure and post the response graphs for the std ti and sl diaphragms in the 2447 cores. Greg

ivica
01-21-2017, 02:09 AM
Hi ivica, I am using the 2381 at the moment from 1200hz Greg

Hi Greg,
Nice to show us off-axis response too, with the 2381 horn and 2447 core.
Good luck!

Just some of my experience with SL diaphragms
http://www.audioheritage.org/vbulletin/showthread.php?36528-Is-PT-F95HF-a-meaningful-sonic-upgrade-from-2332&highlight=2332

http://www.audioheritage.org/vbulletin/showthread.php?36686-New-JBL-waveguides-5006812-90x50-vs-PT-F95HF/page2


Ivica

greg32
01-21-2017, 05:08 AM
Ivica a pleasure to do so. i have not measured off axis before but can make a protractor and measure.
what are the standards for off axis? 10deg? 20deg? etc
Greg

ivica
01-21-2017, 11:00 AM
Ivica a pleasure to do so. i have not measured off axis before but can make a protractor and measure.
what are the standards for off axis? 10deg? 20deg? etc
Greg

Hi Greg,
I think only horizontal 15, 30 and 45 degs offaxis would be enough, and I would suggest to EQ 15 deg. Off-axis response....as a reference.

Regards
Ivica

AlexanderZ
01-23-2017, 11:02 PM
Hi Alexander, thanks for the reply, if i may ask did you notice any difference in the hf extension between the ti and aquaplas diaphragms. regards Greg
Greg, HF extension has the biggest difference: Ti diaphragm sounds obviously harsh.

emilime75
01-25-2017, 04:28 PM
Hey, Greg, curious if you've successully swapped your 2447 - SL diaphragms yet? I have to do the same thing and was wondering if there were any tricks involved or any special precautions.

gibber
01-25-2017, 04:43 PM
Hey, Greg, curious if you've successully swapped your 2447 - SL diaphragms yet? I have to do the same thing and was wondering if there were any tricks involved or any special precautions.


No need to observe much if your cores are marked close to "0" after opening the back lid. If you see a felt pen marking like +3 or -3, you would need to take care that your diaphragms have a simlar value written into the inside of the coil former. The markings on the magnet pole plate describe the "height" of the phase plug over the mounting plane of the dome ass'y.

If the deviation from design standard (= "0") was high, JBL took care to put frams in that deviated from standard correspondingly.
Sounds almost as unlikely as the story about the lady with the ball pen correcting 075 fram suspensions. Craft is art sometimes.

Ralph

greg32
01-25-2017, 05:16 PM
Hey, Greg, curious if you've successully swapped your 2447 - SL diaphragms yet? I have to do the same thing and was wondering if there were any tricks involved or any special precautions.
I have only changed some 2426 diaphragms sofar, I used a 1khz test tone to help with the alignment during the tightening process, you can hear a rub instantly and adjust. also make sure the gap is clean. my sl diaphragms are on order from speaker exchange and they are waiting for jbl to deliver any day now. Greg

greg32
03-11-2017, 04:54 AM
Still waiting on jbl to deliver to speaker exchange. Hopefully any day soon.

greg32
04-08-2017, 07:50 PM
Diaphragms have arrived. I have installed both and have been listening to them for a few days now. I will try and do some measurements shortly. But wanted to give them some run time first. They are currently in a pair of sp215-9
Cabinets. Greg

emilime75
11-24-2017, 11:19 AM
Hey, Greg. Curious as to how all of this went for you. I'm using the 2447Js on 2384 guides for my front L+R and center channel. I've also purchased 3 SL diaphragms, but so far only installed 1 in the center.

Haven't done any real precise measurements yet, but I've found that I have to boost the HF significantly on the SL center to match the extension of the Ti L+R channels...I should point out that the L+R channels are using different woofers and crossed differently than the center. L+R are over dual SP215-9 cabinets with 2226H woofers in each. It's a .5 alignment, where 1 woofer is low passed at 150 and the other at 500, where the 2447J takes over. The center, currently, is a single 261F and it's high passed at 1200Hz.

greg32
12-25-2017, 07:05 PM
Hi emilime, I dont have the best measuring set up and only have REW to work with. i did some measurements today on axis, horn in cabinet, with the ti diaphragm and then the sl dia, there was not much difference visible. the red is the ti and the green is the sl, the blue is with the sp215 hf crossover sl dia. my listening impressions are that the sl dia has a much more natural sound. both need augmentation with 2404 on top.

emilime75
10-06-2018, 10:31 AM
...both need augmentation with 2404 on top.

A bit of an older thread...but, I find it interesting you think VHF needs augmenting. I'm now running 3x 2447s with the 2451SL diaphragms on 2384 waveguides for my LCR and find them to be excellent, as is. Hearing tests show I'm good to about 16k, and I never feel I'm missing anything.

greg32
10-08-2018, 01:01 AM
Hi emilime, my thoughts were based on listening with the sp215 passive crossover, the aquaplas diaphragm is slightly less bright sounding than the titanium and sounded better with 2404 on top. I have since biamped the sp215s and equalised the top end and I'm now very happy with the top end. Greg

greg32
10-08-2018, 02:30 AM
This is a rough measurement with my active biamp setup, mic was on axis with the horn. 82493