JBL D120F / K120 reconing

[Rhodesplyr]

My brother recently retrieved two JBL drivers from storage that he used to use ~25 years ago in some PA speakers. One is a D120F, and one is a K120. Both had been reconed (not by him) with generic parts (Waldom cones, copper voice coils) before he acquired them, and the reconing jobs are on the sloppy side.

We're thinking about what to do with them, and there seem to be two main options. One is to recone with the JBL factory kit for the E120, the only factory kit still sold for these. The other is to send them to Wesley Audio in Georgia to a guy who says that he can do a vintage-correct recone of a D120F with non-JBL parts. He uses cones with a paper surround and edgewound aluminum voice coils to recreate the original D120F.

Since my brother is an excellent speaker reconer, he can install the JBL kits with no problem, but the kits are expensive, so the price difference isn't that great.

What would you do? Would you rather have a D120F with aftermarket parts that sounds like it did when new--and has lower power-handling, or would you rather have a D120F/K120 reconed with the factory JBL E120 kit that sounds a little bit different but handles more power?

[J M Fahey]

It depends on what you will drive them with and the exact sound you require.
If you want Dick dale's Surf era sound accurately, and you'll drive with an old Dual Showman head, go for the "vintage" solution, it will be the closest one.
If you want an excellent , loud, punchy speaker , to be driven by any 100W head, go the JBL way which will probably be more robust.
I don't think there will be much of a sound difference, they may differ perhaps in power handling.
I've heard Dual Showman cabinets driven by Plexis, sound was scary.

[jrfrond]

There's bigger fish to fry than that. If you want the speaker to operate at maximum efficiency, it will need to be regaussed (remagnetized), as happens with Alnico's, and this is a JBL recommendation as well.

I recone a lot of speakers, JBL included, since I am authorized. I will tell you that just aftermarket pleated paper cones and edgewound coils will probably yield decent results, but it probably will NOT sound like the original, unless he is having them wound on the same coil forms and with the same wind depth and wire specs as JBL.

Personally, I'd use the JBL kit to maintain the quality, but that's just me.

[J M Fahey]

Hi JR, do you have a magnetizer in your shop?
If so, can you tell me something about it?
I'm building a larger one than the one I have, which does up to 147mm and *may* handle 155mm; definitely not 169 and higher.
Pictures or any technical info would be great.

[Rhodesplyr]

John, I've heard about remagnetizing Alnico drivers, but, of course, not that many places actually have the equipment to do it. I think I've heard that it's a bigger problem with higher-powered speakers, but feel free to correct me on that.

One anecdote I heard about remagnetizing suggested that it can be dangerous. It was a story about a magnet assembly that came loose during this process and was fired through a wall like a projectile from a rail gun.

The guy who's reconing D120F *claims* that he's using aftermarket parts made to the same specs as the original JBL parts, and he has some good feedback. Since JBL no longer supplies exact D120F replacement parts, options are limited. Of course, since I haven't seen/heard his work--or heard an original D120F, I'm not in a position to judge which approach would get one closer to original performance. I saw one chart that showed that the E120 cone/spider assembly allows a good bit more cone excursion than the D120F or the K120.

[jrfrond]

I don't have a regausser in my shop. Neither does JBL anymore because they shifted all production to Mexico. They are pricey little gadgets (remember, these are SPEAKERS we are talking about, not pickups), and I'm not in the mood to build something I need once in a blue moon. The only place I know of with one available is Orange County Speakers.

If the dude has good feedback with the D120's, then I'd give it a shot. Recones can be redone if desired.

[J M Fahey]

OK, thanks.
I do use it regularly, I need a bigger one, so I'm collecting info everywhere.

[Rhodesplyr]

It turns out the local speaker shop where my brother used to work as a reconer apparently has a regausser. It makes sense since they used to build their own drivers. The owner of the store bought all the remaining Stephens Tru-Sonic parts when Utah went out of business, and he's still got a bunch of 15" cast frames and 40 oz. Alnico magnets. He built and sold all the twelves.

My brother described the machine as "a giant electromagnet on a heavy steel C shaped frame." Does that sound about right? The only thing I'd wonder about is when it was last used since they've become more of a pro audio retail store. I would guess it needs a hefty power supply in good working order.

If it still works, we have access to one about three miles away.

[J M Fahey]

Good !!!!
You are surely one lucky guy.
What you describe is reasonable, in fact I have somewhere a picture of that very machine.
It must weigh a Ton, literally.(or more)
My own is a rectangular frame of 2" thick iron plate, 4 feet high, 2 feet wide, with internal polepieces 6 inches in diameter, must weigh around 1/2 ton and needs 3x380V@45A.
It lives out of town, at a friend's factory, there is no way I get that kind of power in my close to downtown shop.