Altec or JBL Drivers That Fit Western Electric 32A Horn in WE 753C?

[farleybob]

Hi,

The good news is I just found a cool WE 753C speaker. The bad news is aside from a few small modifications, there's one big one -- the 713 driver is missing. It has an Altec 730A driver instead. I was wondering if there are any better Altec (or maybe JBL) drivers that might fit on the WE 32A horn without drilling more new holes in the mounting flange until I get up the nerve to rob a bank so I can get a 713A driver. Thanks, Steve

[gferrell]

I don't know about your question but that is 1 cool speaker.

[tom1356]

Nice Speaker. The super tweeter looks like a Lorenz LPH-65. They probably added that when the 713 went bad.
Good luck in getting it back together.

[Eaulive]

Even if not working, the cabinet is awesome! :applaud:

[Altec Best]

That is a Awesome speaker nice find.I would keep it We/Altec to try and keep it's originality.Is it For Sale ? :D

[farleybob]

Thanks everyone. Good eye Tom1356 -- that's exactly what the tweeter is, or was. Either the tweeter or the additional crossover added has bitten the dust. When I first listened I thought it sounded terrible. I removed the tweeter from the system, it actually sounds pretty good. The Altec 730 has extension up to 12 khz. Not the highest, but not that bad, either. Thanks Altec Best. Yeah, I'm going to hang on to it and try to get it back together, although it is looking like finding and paying for the 713 may be a tall order. Since my original post I've read that the Altec A8 used a 32A horn with an Altec 802/806/804. The Altec version of the 32A must have had a different bolt circle. I checked to see a 802 would fit. No luck. I really enjoy early monitors. Now, if I can just find a Lansing Iconic that has migrated to the East Coast.

[RKLee]

Let me put in my 2¢ in. That 32 horn looks like the standard JBL 3-bolt pattern. I wonder if JBL drivers would fit? Also a suggestion, I don't know it it would work or not, but it could be worth a few phone calls. Look up a local machine shop, and there are tech materials on the bolt spacings etc, I bet they can drill new holes for 2-bolt Altec compression drivers. I see that current 1" horns & drivers have both the 3-bolt JBL & 2-bolt Altec bolt patterns. Yeah, I know you didn't want to drill, but I would save this for future reference.

[tomt]

http://img220.imageshack.us/img220/6628/00512h.jpg (http://imageshack.us/photo/my-images/220/00512h.jpg/)

[herki the cat]

http://img220.imageshack.us/img220/6628/00512h.jpg (http://imageshack.us/photo/my-images/220/00512h.jpg/)
tomt;315587[quote/]

----------------------------------------------------------------------------------------------

There is no JBL or Altec driver equivalent to the original Western Electric 713 A, 713 B or 713 C Receivers. To begin with, these three ECO 713 series receivers plus the rest of the WECO product line __the 12 inch 728 B, & 728 C with phenolic diaphragm, & the 8 inch 757 A __ all have "four - ohm" voice coils. The WECO 753 C "four ohm" crossover network will not function correctly with other impedance drivers.

The 713 A, 713 B, & 713 C have identical magnetic structures with a rather wide Voice Coil Gap resulting in a modest flux density and identical diaphragm resonance at kHz; the 713 B Receiver uses a phenolic diaphragm which provides excellent diaphragm damping with a very fine sound quality all the way into the HF spectrum, and excellent true to life quality for reproducing the human voice.

Because of the small size of the 32 A horn, driver loading is very poor in the cross over spectrum in the WE 753 C speaker system equipped with a 713 A and 713 C Receivers with original aluminum diaphragm __ this results in bad Horn Honk. The horn should provide full acoustic loading down to 1.5 octave bellow the crossover frequency.

The cross over problem is further complicated with severe group delay aka, phase shift distortion & phase shift non linearity since the high frequency driver voice coil is not located in the same plane of the 15 inch Jensen low frequency driver voice coil, aka, a disparity of some 20 to 30 inches. Bell Labs addressed this problem when they voiced the 753 C System; this task required very special acoustic measurements.

The 713 B Receiver is free of Horn Honk, thanks to phenolic diaphragm damping. In the early 1950's I was able to visit Mr. Miller, the Bell labs Speaker Designer who worked for Mr. E. C. Wenty, inventor of the WECO 515 Receiver. I was told "Bell Labs was very timid about using extremely small voice coil gaps in permanent magnet speakers including the full range WECO 728 B." I have owned all of these WECO components in the late 1940's.
JBL has been very successfull with extremely small voice coil gaps resulting in drivers with flux density of 20,000 gauss which yields excellent high frequency response and motional impedance control.

Prior to this post WW-2 WECO PM field product line __ all WECO Speakers were field coil systems for movie theater; of course that magnet structure was 100% mechanically adjustable in the real world field.

Cheers herki the cat