Driver Magnet Size

[jimd]

A friend of mine once told me the two drivers had the same magnet, I wasn't sure, but now have to have to admit he was right. I am willing to bet the magnet will weigh 1.2 lbs, the same as the Altec 802! Children of a common parent.

Like I earlier said, I do not have the experience with these drivers I have with the Altecs. In you opinions which is the better sounding unit, the 2420 or 2421? I also wonder if the two diaphragm are made of the same thickness of aluminum?

JIM

[jbl_man_uk]

.....Interesting thread...i have several 2420`s and 2410s here,but strangely the smaller bodied 2410 is louder in every case...u would have thought the larger pot and thus magnetic return structure would have made the 2420 the louder....obviously i swaped the diaphramms about to make sure that wasnt causing it...and tried it on several different units incase some of the 2420 were down on gauss...but every time the smaller 2410 was louder.

[speakerdave]

The magnets are the same size.

Imagine my surprise!

[jimd]

Dear Subwoof,

Replied to your PM, are ypu still out there?

Jim

[Earl K]

Dave, this my not be the case. They may have the same magnet, the larger structure of the 275/2420/85 may be more efficient and raise the flux density.

This was truly one of those eureka moments ( at least for me ) in the history of this forum .

Steve Schell ( anyone ), would you care to speculate on who was responsible for the redesign of the magnetic return circuit that resulted in getting more ooomph out of the 175 ( & its standard sized 1.2 lb alnico ring magnet ) ?

- I'm going to go with Bart Locanthi and those mid-fifties collaborations with Ampex ( Magnetics ) , as the design team responsible for filling in the ( product ) lineup ( & thus creating the 275 ) between the 175 & the 375 .

<> cheers

[Don McRitchie]

It was Bart. He was responsible for the 275 and 375 which ustilized cast pot structures. He was also responsible for JBL converting their bass drivers from machined pots to cast pots around the same time. Later at Altec in the early 70's, he did the same thing with the 416 and I believe the 515 so that they were redesigned with cast pots.