JBL Cinetron and the origin of the 2397

[lfh]

Reflecting the importance and popularity of the 2397 horn, I'm curious about its origin. It's clear that the concept can be traced back to Bob Smith's DSH (Distributed Source Horn) of the 50:s - but who within JBL designed this particular version? Who designed the 2328 and 2329 throats (also used on other horns)?

In the library (http://audioheritage.org/html/history/jbl-pro/1960s.htm) we find the following info:

"The attempt [at competing with Altec's VOTT] was the Cinetron system of 1969. It used direct radiator bass enclosures with a high frequency horn. It introduced the 2397 "Smith" horn that had very wide dispersion, even at high frequency extremes. After extensive development work, JBL sold exactly one installation. The VOTT standard was as impenetrable as ever."

What did the Cinetron look like? What bass driver, LF cabinet and x-over was used? Does JBL still have the blueprints, tech sheets - or even a prototype or production unit in the vault?

Why didn't the 2397 appear as a component (AFAICT) until the 1976 model year? Furthermore, it soon became popular in custom monitor designs, and it didn't take long until Westlake did an enhanced version of its own, but it never made it into a JBL studio monitor. Why?

Questions, questions...

Any and all info would be highly appreciated!

Fredrik

[Mr. Widget]

If it was a really old system that required field coils we could count on a full history from Steve Schell... :D Are there any late '60s early '70s JBL experts who would like to enlighten us?

I'd love to know more too... Ken, maybe you could ask your friends at Westlake how they got into the 2397 clone business?


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[Don McRitchie]

I've placed the only information I have ever come across on the Cinetron system in the reference forum here:

http://audioheritage.org/vbulletin/showthread.php?p=111190#post111190

There's a mistake in the original article cited above that dates the system from 1969. It actually dates from 1965. As stated in the JBL document, the system was commissioned by Ampex and was never in production beyond the one system installation. I've sent an email to George Augspurger to see if has any background on the design of the horn. I would guess that the JBL version was developed by Locanthi, but I'll see if George can provide more definitive information.

[lfh]

Don,

many thanks for posting all that info! It's already a lot more than I hoped for!

The fact that the horn was designed specifically for Ampex might explain why it took so long until it was offered to the public: Perhaps Ampex got the exclusive rights for 10 years, even though the Cinetron never made it into their product line? :hmm:

Fredrik
(I wonder how they implemented the delay back in '65?)

[Mr. Widget]

Thanks Don... amazing documents like that are why this site was created in the first place. :bouncy:

Unfortunately reading it over brings up the question... what's a 140B??? ...and how about the LE14A-5???



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[Don McRitchie]

I'm guessing it is a variant of the D140F. It is referred to as a D140B on the parts list and the "D" always referred to drivers with aluminum domes instead of dust caps. Therefore I don't think it is related to the LE14. As discussed in previous threads, there were other varients on the D140F such as the D140R used in Rogers organs.

[Mr. Widget]

I'm guessing it is a variant of the D140F. It is referred to as a D140B on the parts list and the "D" always referred to drivers with aluminum domes instead of dust caps. Therefore I don't think it is related to the LE14. As discussed in previous threads, there were other varients on the D140F such as the D140R used in Rogers organs.I would guess that the 140B was a variant on the D140F as well... it would be interesting to find out how they had changed it... the LE14A-5 was mentioned in the smaller system as a LE14A with greater excursion capabilities... that would be more like today's LE14s... I wonder why they didn't roll it into the line.


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