Custom Bespoke JBL 124A/2203+

This is a special build I was asked/tasked to complete for a special anniversary edition of a reproduction JBL 4315, with white Aquaplas cone. This unique pair of 124A is specially built to be a 12" version of the 15" JBL 2230A/135A as found in the 4350 Studio Monitors and L45 Flair HiFi speaker system. As an added request, I reversed the polarity of the magnet to conform to modern industry standards with positive voltage applied to the red terminal causing forward cone movement.
I updated the specs to conform to the 2235H voice coil and blueprinted moving mass with the careful application of Aquaplas. Free Air resonance is ~20Hz. These turned out very nice.
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[@ericgonzales854]

Always a pleasure

[@lycancatt4248]

with that low of an fs it probably does sound quite different from the orriginal driver, nice work!

[@edgewound]

Thank you very much! The original 124A/2203A has an Fs of 16Hz with a pretty soft spider. My goal was to replicate the Fs of the LE14H-1 and 2235H. I have a no-rot 2203 recone kit in the pipeline that will eliminate the need to replace foam surrounds every decade. I've done it the 2206H. I call it a 2207H. I made a couple for a customer by request. They work really, really well for Hi Fi with an Fs under 25Hz. See the video here during testing:
th-cam.com/video/SDqCu2EKgvY/w-d-xo.htmlsi=7kwU-Oalvtv_1JFz

[@lycancatt4248]

@@edgewound ah nice! i did not know the 2203 fs was that low thats frankly amazing! still sitting on a pair of 2225s and gaus hf4000s for a low power rig sometime when i have a big enough room..anything interesting to be done for these old 15s? they've seen some abuse..

[@edgewound]

@@lycancatt4248 For HiFi? Yes...The 124/2203/2230/2231/135/136/LE14A all had a soft soft spider for a really low Fs. they were susceptible to spider fatigue and being driven out the gap at high levels of bass...and foam rot. The 2235 has a bit stiffer spider and longer voice coil winding to make up the difference at 20Hz. The factory spec recone kit for all these 15" drivers is the C8R2235. I have a no-rot 2236H kit that replaces the 2235H assembly. It drops right into the 2225 frame. Here's an impromptu video of the first pair I built for a customer that didn't want to hassle with foam surrounds anymore. He loves them. Listen with good earbuds or headphones and you'll get a remarkable indication of what they sound like. These were playing really loud...barely breathing hard.
th-cam.com/video/mPY0sMijm6A/w-d-xo.htmlsi=dCUNWzt5a_05xiyr