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AlexanderS
03-01-2005, 07:28 AM
Hello, friends,

I am new to this forum.

I am looking for TS parameters of this driver. I guess this is 8 ohm version of JBL 123A. Can anybody help?

Thanks,

Alexander

DONALD G
03-01-2005, 07:42 AM
http://www.jblproservice.com/pdf/Thiele%20Small%20Parameters/Theile%20Parameters.pdf

Welcome !

pdf file. Handy as a pocket on a shirt

ilya
03-01-2005, 08:35 AM
Donald,

123A-1 does not appear in this list. Classified military product? :-)

As Alexander told me - this driver has different DC resistance so Q's may be also different or...

4313B
03-01-2005, 08:40 AM
Anyone with a measurement system AND a 123A-1?

ilya
03-02-2005, 03:52 AM
Yes, Giskard! You're hundredpercent right.
Anyone - means Alexander won the lot on e-bay,
measurement instruments - he has PC with sound card and I may give him Signal generator and AC milliviltmeter/ impedance measurement tool. He lives 5 km from me, just 20 minutes driving through bloody Moscow traffic.

Anyway it's interesting fact - there is JBL driver which JBL did not list. And it looks totally different from 123A.

AlexanderS
03-02-2005, 05:12 AM
This stands for 8 ohm version:

http://www.bassreflex.de/index/JBL/jbl.htm

Strange is that they wrote 8 ohm, but again 123A (without 1), while the original pdf says 123A has Re=4.4 ohm.

ilya
03-02-2005, 05:22 AM
Hi!

Most strange - 123A-1 mentioned here in zillions of threads, as very common thing; but nobody knows the specs.

AlexanderS
03-02-2005, 06:17 AM
This is Xover network with 123-A1
http://www.audioheritage.org/vbulletin/images/attach/pdf.gif

It says Re of 123A-1 is in the range of 4.4 to 5.5 Ohm, while this is 8 ohm impedance driver! Maybe I was wrong?

GordonW
03-02-2005, 05:20 PM
AFAIK, the 123A and 123A-1 are completely interchangable? As in, the same cone mass, same impedence, same Bl product. Should be able to use the specs for the 123A to build a box for a 123A-1, without problem. JBL certainly did, and it worked fine for them!

Regards,
Gordon.

spkrman57
08-28-2005, 08:34 AM
Disclaimer: I am not a professional, take the specs with a grain of salt!

Between a pair of 123A1's, I averaged the pair and came up with these values:

fs - 23hz
Qts - .5
Le - .8mh
Vas - 7.5 ft
Revc - 5.3 ohm
Sensitivity - 87.8db and 91db (WT2 has sensitivity at 1 watt and 2.83v)

I did these in my living room, used "yellow pages" phone book to place driver upright and keep the vent open. This was measured on the ground. I know there are more exacting ways to accomplish this, but I had the drivers handy and wanted a quick peek.

Ron

Lancer
08-28-2005, 08:54 AM
Disclaimer: I am not a professional, take the specs with a grain of salt!

Yeah, well, we need more folks to do these measurements so don't fret about not being a professional.
Please post individual specs though as opposed to any averages.

badman
04-09-2009, 02:38 PM
See attached

ratitifb
04-10-2009, 06:53 AM
attached :blink:

badman
04-10-2009, 10:25 AM
See attached

Dang!