JBL 123-A1 TS parameters

[AlexanderS]

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]

http://www.jblproservice.com/pdf/Thi...Parameters.pdf

Welcome !

pdf file. Handy as a pocket on a shirt

[ilya]

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]

Anyone with a measurement system AND a 123A-1?

[ilya]

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]

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]

Hi!

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

[AlexanderS]

This is Xover network with 123-A1
http://www.audioheritage.org/vbullet...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]

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]

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]

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]

See attached

[ratitifb]

attached

[badman]

See attached

Dang!