Wednesday, June 23, 2010

So what should I do with.....

these compression drivers that just found their way to me?

They are even larger than they look. The voice coil diameter is six inches. The overall diaphragm is larger than a Lowther. Preliminary measurements say that the low frequency ability will be basically limited by the horn. Do I get out my old horn extensions that I used for the JBL 2482 and drive them down to 60 Hz? Do I whip up a field coil and convert them first just to get rid of the "ceramic sputter"?? If I only use them up to 200 cycles, then does it matter how the ceramic sounds? I dunno...

I am sure they will be slapped onto a horn soon enough just to evaluate for potential. ...kinda like dave was in Lisa's post below... I am thinking the same will result... we can make these into something with only some time and effort.. :^)

They are here on long term loan... but I bet a field coil will happen rather quickly, don't ya' think?


  1. Hey Big J,

    Are those Emilar EC-600s... four of them? Yowsa! These rare drivers provided my first foray into bass compression drivers and horns, after hearing Kevin Brooks' ALE jobs and getting wildly stoked on the concept. I still have a pair of EC-600s in the closet, on long term loan from Jonas Renkus's understudy who built the prototypes for Jonas back around 1980.

    They have plenty of excursion capability for superlative hi fi bass down to 60Hz. or so on the proper 45 or 50Hz. exponential bass horn. One problem- the tiny trapped air volume behind the diaphragm with the cover in place KILLS the response below 100Hz. Jonas intended the driver for very high output midrange duty, so the trapped air functions like the loading cap on an Altec; to limit diaphragm excursion. Loosen the cover and the response below 100Hz. just explodes, only problem is that now there is nothing to keep the diaphragm from dancing out of the gap. I never drilled relief vents in the covers of the ones I have here as they are priceless prototypes. Perhaps your benefactor would let you modify the ones you have. I can testify that double-stick Scotch tape doesn't last more than a song or two to hold the diaphragms to the top plates.

    Field coils? Why not? Check with Josh, I think he has been down this path with EC-600 diaphragms.


  2. I was wondering if they were Emilars also but it doesn't seem like it - they have radian written on them. If so, what model? Inquiring minds want to know. And yes, you must hook these up to see how low they will go - 60hz at least I'd think.

    I recall talking with Josh too and he did do some field-coil stuff using EC-600 diaphragms. Haven't heard from him lately though.

    I'd think with some experimentation, replacement rear-covers could be made with larger volume to lower the resonant frequency and create a larger more compliant rear air spring. Hell, maybe even tune it so it's like bass-reflex loading the rear wave somehow... ?


  3. I think the Radians are shown just to show how f'ing huge those compression drivers are.

    Impressive...I'm curious how low they go.




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