View Full Version : C50 SM Components Inquiry 375 Driver with 1237-1290 or 1217-1290 Horn-Lens?

12-02-2013, 04:21 PM
Greetings from Atlanta, Ga.

I was privileged to acquire an unmolested pair of C50 SM with Serial numbers in the #52700s range. These studio monitors survived with the Dealer notes defining the compliment of components specified by the original owner. They are the grey painted cabinets with the JBL Los Angeles, USA logo on the sides. They are all the speakers I will ever need, and I am very reluctant to disassemble them for an inspection.

My objective is to purchase the components for spares, or perhaps for a replica build. With Ebay as my sole source, I have gathered the LE15A (8 Ohm) Lo Freq, the 077 Hi Freq. and the 3106 Dividing Networks.
The LX-5 Crossovers, the 375 Drivers, the Horn-Lenses, and the unique hardware has not yet been sourced.

The specific question for the experts is about the 375 Drivers and the Horn-Lenses... It seems that the 375 components were not typically specified due to their high price? The Dealer notes define a 1237-1290 "Voice" Horn and Lens with the 375 Drivers. I have never seen these for sale, though I have seen the 1217-1290 Horn-Lens show up for sale a few times.

I have purchased some factory publications in an effort to identify these components. It is all quite a puzzle for me to understand.

What am I searching for? 1237-1290 or 1217-1290...? Can either be used?
Thanks in advance for the help. Sam

12-03-2013, 06:34 AM
Both horns you are mentioning are the so called "potato masher horns"
I've actually never seen a C50 with these horns, I think the most common combination was a 375/376 on a HL93(2311) horn and 2308 lens :dont-know:

The 376 can be replaced by a 2441 which is the same driver and 375 = 2440.

Mr. Widget
12-03-2013, 08:13 AM
I agree with Martin about the HL93 vs the "potato mashers"... though it is possible that your speakers were originally ordered with the potato mashers as early JBLs were rather custom. Another thing that Martin is indirectly mentioning is about part numbers... if you aren't aware of it, the early JBL Professional products used the same JBL Consumer model drivers and networks, but they soon developed their own numbering system and color schemes for the "Pro" drivers... not sure why they did, it. The two lines of drivers are functionally identical, but in general the pro variants are less sought out by collectors, so you can get a 2215 woofer for less than an LE15A and the same is true for the 2440 vs. the 375.

Personally, I am not a fan of the potato mashers, I think the HL93 or the 2311/2308 combo is definitely superior... and there are others that are superior still, but would not be true to your original monitor.

On a side note, please realize that even though your LE15As may be operational, if they still have the cream colored Lans-a-loy surrounds these will need to be treated or replaced for you to get the bass response the speakers are capable of.