JBL Woofer Aftermarket Recone Kits

[C Hart]

I have two poorly reconed JBL 122A woofers that I would like to restore. I don't have access to pro suppliers like MWA unfortunately. Simply Speakers and Speaker Exchange carry 122A kits which appear to be the same as those they sell for the 128H. Speaker Exchange carries a white coated 128H kit also at quite a high price.

Anyone familiar with either of these kits or know of others? It would be great to have some firsthand info and maybe even specifics that stumped both companies' support people.

The 122A and 128H are very similar from the T-S specs I've read except:
- 122A: MMS 100g, VAS 339.8, Eff. .67, LE 1.5, XMax 6.86
- 128H: MMS 90g, VAS 280.4, Eff .86, LE .6, Xmax 7.87

The mass is tuned by Aquaplas if my reading is correct.
Does anyone know if the kits are similar weights to the originals?
Has anyone used any effective Aquaplas-like material to add mass? (One support person suggested using 3 coats of Rustoleum Stone Paint which is a thickish textured finish. Could work maybe.)

Being a motor rookie, the LE is my biggest concern. Are the kits faithful to the electrical value? If not, how do they perform/measure?

The 128H coil is 2.5x the inductance of the 122A coil. If a faithful 128H kit is used, what will the effect be on the performance?

Any other advice?

 

[Macaroonie]

Member here 'Edgewound ' is a long established official JBL reconer and under the current situation has boiled down the specs of aftermarket cones etc.
I would contact him.

http://www.repairspeakers.com/

No affil .

Adding mass is not the only feature of Aquaplas BTW. Edgewound has the correct stuff , if you wanted any from the OEM it comes in ( from memory ) ten gallon drums.

 

[C Hart]

Thanks @Macaroonie. I did see those but he does not show any hifi woofer kits, just cloth surround pro stuff, but his FB videos do show 128H repairs. Will contact hm.

I would still like to hear from any members on the quality of those kits. They are a lot less $ to flush if the first job is botched.

 

[C Hart]

(response to edit) On the Aquaplas, I understood that mass rings were substituted later (True?). I'm sure it changes a bunch of cone behavior in subtle ways, but my assumption is that the driver will work mostly the same without it at a given mass. I did also hear that it was available in the large drums. IIRC I saw it on the net somewhere for ~$120, but that would be a supply of 3 lifetimes at least for me. I'm looking for a clever AK MacGuyver solution.

 

[Macaroonie]

I think you will find Ken real easy to deal with. His work is stellar. I know him from LH.
He had a rough time about a year ago , maybe a bit mor and that caused a build up of work he couldnt field quickly enough for some folks.
He's a one man band and knows his craft , probably better than factory is the level of care he puts in.
It's really difficult these days with no factory support the way it used to be.


RGDS Mac

 

[C Hart]

Back at it now and bumping the thread. Thanks @Macaroonie for the tip. I do see a lot of knowledgable traffic on AK and elsewhere from Edgewound. But I checked further and the Edgewound 128H kit is $300. There are a few decent 122As and 128Hs for sale right now for $200ish so I think that kit is financially wrong for these non-collectible L166s.

I can't believe no one has used either SS or TSE kits on a JBL 12" woofer, or figured out a reasonable substitute for Aquaplas. If you have any info on either please post. I will be buying someone's kit shortly and members' advice would be very much appreciated. Thanks!

 

[hjames]

Are you sure the speakers need reconing?
Most folks just replace the foam surround material when the foam deteriorates.
Also might be helpful to know roughly where you are (city, state) to offer alternative reconers to work with.
Aquaplas is a proprietary product that is mostly unobtainium, at least at reasonable prices.
BUT - it the concept is to increase the mass of the cone assembly, there are other approaches.
Folks have mentioned the mass rings - typically used in the 15 inch 2234 and 2235 woofers.
The audio guru who was guiding me on my Heathkit Valencia project used small lead triangles (try tropical fish shops)
and a bead of, I believe, gorilla glue at the edge of the cone to add mass.
Another addition was brushed on Varathane near the center dome for more mass.
A modded Altec woofer shown on the left, the stock woofer on the right.

 

[C Hart]

Hi @hjames. Pic thumbnail below. Thanks for the response and the ideas - exactly the MacGuyver stuff I was hoping for.

I'm pretty sure the foam is fine. But whoever refoamed last time put the surround on the wrong side, added an inch of some kind of rubbery stuff and mucked up the dust cap adhesive. None of that was disabling, but one of them recently developed a buzz. It might be just off center foam but in order to find out it will of course need to be disassembled. I tried vacuuming, checking for loose spider spots, rubbing tinsel leads, and sagging spider/rotating the driver. None were effective so I think the voice coil is warped or not parallel to the gap.

Home for me is in the Boston suburbs. I have searched but there are no hits for local speaker repair shops. If you have any recommendations that would be great.

 

[EarlK]

Assuming the voice-coil and cone are bona-fide JBL parts, I'd elect to refurbish those 122a's with new foams ( possibly new spiders ) and ( certainly ) new dust caps.

An over-sized 4-3/8" hard-paper dust-cap looks like it might just cover-up most of that glue mess ( post removal of the existing dust-cap and post the shimming your existing voice-coil).

The resulting hybrid is still going to be a lot closer to retaining the original JBL DNA of that woofer ( compared to your other current options ).

Solvents like Acetone ( &/or MEK ) should be used in very well ventilated areas ( iow, outside in Spring, for those of us living in snow-bound regions ).

 

[C Hart]

@EarlK thanks for the great advice. I'll definitely try to center it before any major surgery. The buzzing is a bigger issue than beauty at the moment but of course if they can both be addressed that would be a nice bonus.

Seems like the unspoken part of your answer is that reconing kits will not bring this driver back to full JBL performance, which is what I assumed/feared.

 

[hjames]

Have you checked the tinsel leads off the voice coil to be sure that's not the source of your buzzing?
If they are not shaped just so, they can be a buzz against the cone ...

 

[C Hart]

@hjames yes thanks for the suggestion. Unfortunately that very simple root cause was not the issue. Either there is a foreign object in the motor, the VC is misaligned, or the VC is damaged. Possibly all three.

 

[Macaroonie]

Looking at that ham fisted repair its a fair bet that there is junk in the VC gap or the cone is missaligned. EarlK has it right. BTW get a 30Hz tone that you can quietly apply to the driver. It will give you good insight into wats up.

 

[Macaroonie]

I had a closer look at your pic. To me the foam looks off center. Bottom left the flat area towards the cone looks wider than the other side. Backing this is the roll bottom left loos squashed. Conclusion is that the cone leans towards top right in the pic.
Might be just the camera angle but I would check that.
If im right , get the Acetone out or MEK remove the gaskets , then soften the surround , use matches or toothpicks to keep the loostened foam clear of sticky glue Get rid of the dust cap and adhesive dogs dinner as well , use shims and center the VC properly.
That should get you there..

 

[Macaroonie]

This is a refoamed JBL driver done right. One of mine 2108.
Wish I still had a pair of them.

 

[C Hart]

adhesive dogs dinner

LOL - it sure is!. BTW: That black stuff on the dust cap is not rubbery as I thought. It is a hard plasticky substance that makes me think "JB Weld".

I will start dissolving stuff probably in the next week and will report back. Wish me luck!

 

[Macaroonie]

Take it gently wit the solvent , it wont affect the cone and will flash off ( killing the ozone layer ).but will loosten the adhesive. Gently does it.