Reconing a JBL D-130F - Photo heavy

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andy_tchp
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Reconing a JBL D-130F - Photo heavy

Post by andy_tchp » Sun Mar 20, 2011 3:27 am

Hi guys, apologies if this isn't 100% 'on-topic' for OSG, but I thought this may be of interest to anyone contemplating attempting their own recone (seems there's been a few of us that have blown up old drivers recently, and ended up posting about it in here :) )

I started out with my beloved, but wrecked JBL D-130F, with a seized voice coil.

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I did a bit of web searching and came across a company called Sound Speaker Repair, who did a recone kit claiming to be as close to original as possible (JBL no longer make the parts to properly recone a D-130.) Their kits also already have the voice coil, spider and cone assembly, er, assembled, which was a selling point to me, as affixing these parts together needs to be pretty much spot on to end up with a working speaker.

To start with, I cut through the old cone next to the surround with a stanley knife all the way around, and then did the same through the spider (the spider is the orange bit I'm cutting through here).

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Clipped the voice coil leads, and then lifted out the whole assembly:

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The cork gaskets were next, I used a screwdriver to lever them off the frame. In hindsight I probably should've used a blade underneath them to cut them away from the frame - there was a lot of glue left to clean off. (Copper tape covering the voice coil gap was due to me running out of masking tape before I started taking photos.)

Image


Here you can see the voice coil gap, which has been covered with masking tape. Debris getting in the gap = a very bad thing. The remnants of the spider, and the 40 year old glue holding it down to the mounting surface were stuck very well. I slid a razor blade tool underneath to help lift it up:

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Quite a long time later, I'd finished cleaning the frame. Lots of elbow grease, hobby blades, a kitchen scourer, and a 'goo remover' product made of xylene. PS - Don't wash your hands with xylene, it BURNS. I've dealt with lots of cleaners/chemicals on my skin, but xylene definitely caused the worst reaction. Acetone probably would've been a better assistant for this for that reason alone. I suspect it may 'deal' with speaker adhesives better too.

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Next is to clean the voice coil gap of any debris that might be in there. I'm using masking tape, and just wiping it around the gap using the adhesive to attract any dust/dirt. LOTS. I covered the voice coil with masking tape again then went to bed. When I started working on this again the next day, I cleaned the voice coil gap again just to be doubly sure there was nothing in there.

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Next step is to test-fit the assembly to make sure everything's looking OK. Here you can see the thick paper shims (provided in the kit) to centre the voice-coil in the gap.

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Now the moment/s which caused me some nervousness. Applying a bead of adhesive to both the basket and spider mounting surfaces before dropping the whole assembly into place.

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Note the shims are still in place - the voice coil will be lowered around these and be held centred in the correct position when you drop the assembly in position, like so

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No photos of the next step. The spider and the edges of the surround needed to be pressed down on their mounting surfaces to ensure a good bond. After this I glued the cork gasket pieces (4) in place. After this your hands will probably look something like this - the adhesive spreads very well.

Image


Once the cork gaskets were seated in place, and I was certain the edge of the spider was pressed fully down and bonding to its mounting point, I turned the speaker over and sat it face down on the gaskets so the weight of the speaker could help bond the gaskets (and the edge of speaker surround which is sandwiched between the gasket and the frame) to the frame.

About 9 hours later I glued the dustcap in place. No picture of this. As simple as it sounds - place the dustcap where it'll be mounted to the cone, trace around it with a pencil, run a bead of adhesive along the traced line and then press the dustcap into the adhesive. I followed the SSR instructions and used an upside down shot glass to apply pressure to the dustcap, then went to bed.

So, almost done. Just need to solder the voice coil leads to the speaker terminals, ensuring there's enough spare lead to allow for cone movement up/down without shorting out against the frame:

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Done, soldered and trimmed the excess. Quick check with the meter to make sure everything's still looking as it should (also worth checking before you start to make sure you've been sent the right ohmage kit).

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Back in its rightful place, after several weeks out of action:

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The mounting screws were done up just tight enough to know the speaker was affixed to the baffle (roughly approximating finger tight). Here's a quote from Harvey Gerst, who created the D130F during his time at JBL, with the reason why:
Opened the voice coil gap slightly on the D130F to allow more tolerance in
mounting. Most people didn't realize that even though 8 mounting holes were
available, only using four is the recomended mounting. And you don't screw them
down tight to the board - that warps the frame. You use two fingers to do the
final tightening - the casket will them complete the seal. When you warp the
frame by overtightening, the voice coil can go out of round and eventually drag
and short out. I opened the gap slightly to allow for this problem with just a
very slight loss in efficiency - less than 1 dB.
EDIT: A quick photo comparison:

Old spider and voice coil assembly after removal:
Image

And the new:
Image

My initial impressions of the newly reconed speaker are very favourable. I'm yet to use it in a band setting (Tuesday) but I plugged my G&L ASAT in and played at 'band volume' for a little while this afternoon, and it sounded absolutely beautiful - I've really, really, really missed the sound of the JBL paired up with my amp.

Cheers, I hope this may have been of use to anyone tossing up whether or not they'd like to do their own recones, but unsure of the process. I'll post back after Tuesday's rehearsal once it's had 4 hours of decent volume pumped through it in it's 'usual' context.
Last edited by andy_tchp on Sun Mar 20, 2011 5:58 am, edited 3 times in total.
"I don't know why we asked him to join the band 'cause the rest of us don't like country music all that much; we just like Graham Lee."
David McComb, 1987.

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Re: Reconing a JBL D-130F - Photo heavy

Post by sookwinder » Sun Mar 20, 2011 5:40 am

great thread !!!
Speakers (and the repair there of) are the one area that I am uneducated and nervous about. This at least has shown me that it isn't impossible.... but I hope I never have to refer to this thread for actual advice :D
relaxing alternative to doing actual work ...

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Re: Reconing a JBL D-130F - Photo heavy

Post by øøøøøøø » Sun Mar 20, 2011 6:21 am

I think it's 1000% on-topic! So glad you did this and took the time to document it. If I had a vote, it would make it into the Library.

You did a great job, and demonstrated just how "no big deal" reconing a speaker is.

For anyone following along-- MEK is the chosen solvent, usually, for removing that type of speaker glue. Takes it right off. BUT beware... MEK is a "big boy toy." Really toxic, hazardous, etc. Must be used outdoors and wear gloves, etc. Don't get MEK on your skin or inhale much of it. Doing one speaker recone every now and again shouldn't be too hazardous to your health, but I'd honestly be reluctant to take a job where I had to work with it every day.

Too bad JBL no longer offers a "proper" recone kit, but it's good that the aftermarket options are increasing. It's encouraging that this one at least tried to get it right in all the important ways. Can't wait for the long-term assessment of how it sounds, compared to original.

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Re: Reconing a JBL D-130F - Photo heavy

Post by andy_tchp » Fri Mar 25, 2011 6:51 pm

Aw, shucks :blush:

@ sookwinder - But you've built complete amps before, right? See, I want to get into that next, but I'm still really nervous about getting into it. I'm sure you'd have no issues reconing a speaker at all, as far as I can tell, you just need basic 'mechanical common sense' (I think you'll get what I mean by that), and be able to work methodically - and if you can build a functioning valve amp, you must already have both of these traits in spades IMHO.

@ øøøøøøø (Brad) - Absolutely correct. I will admit to being very nervous before I started, but to be honest the only real 'hard work' was cleaning the ancient adhesives off the frame, which took AGES. The rest was all of about 15 minutes actual work including all the double-and triple checking, the rest was waiting time.

I read the MSDS, and will keep MEK in mind (along with some gloves) next time I need to do something like this, but may still need to rely on plain old acetone - Methyl Ethyl Ketone may be difficult or impossible to procure where I am, as it is well known as a precursor chemical used in the production of meth(yl)amphetamine.

Anyway, I gave the 'new' speaker an almost 4 hour solid workout on Tuesday. Now, I'm a firm believer in 'confirmation bias', but it sounded great in the band setting. I initially needed to tweak the treble control a touch lower, as the speaker was a bit 'stiff' (for obvious reasons) starting out. It seemed to 'warm up' (both literally and in a tonal sense) as time passed, and I tried to not be too put off smelling all the adhesives heating up for the first time.

Having said that, as far as I can tell, it sounds as good as it did prior to the recone, and almost exactly the same as the old speaker. Slightly 'peaky' (I hate trying to verbalise tone) when you're directly on-axis with it, which is the same as it was before. Efficiency seems to be the same, with the volume control in much the same position as it's ever been. Speaker responsiveness may have been slightly 'faster', but to be honest, this could just be confirmation bias - I had the bass control set ever-so-slightly lower on the amp, as I didn't want huge cone excursion on it's first outing (it got it anyway ;D ), which could just as likely be the reason.

My ears had also had a solid workout after 4 hours, so I'll revisit 'how does it sound' again at the next rehearsal with fresh ears, and will also use the tilt-back legs so it's pointing right at me.

So, overall, <ebay>AAAAA, good experience, would recone again</ebay>.
"I don't know why we asked him to join the band 'cause the rest of us don't like country music all that much; we just like Graham Lee."
David McComb, 1987.

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Re: Reconing a JBL D-130F - Photo heavy

Post by Woolly Mammoth » Sun Mar 27, 2011 10:01 pm

Hey Guys,

I am new to this forum, it looks like a great place !!

From what I have been told none of the JBL D-130 recone kits have a surround like the original.
Is that what you guys have found ?
Any other recone kits that anyone would suggest, or advise against ?
Any shops that anyone has used and had good luck with D-130 recones ?

Thanks for reading,

DAVE

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Re: Reconing a JBL D-130F - Photo heavy

Post by andy_tchp » Mon Mar 28, 2011 12:39 am

Hi Dave, and welcome!

The cone used in the recone kit I used (from Sound Speaker Repair in AZ) has a paper surround, 'gooped' around the edge (as were the original D-130Fs) which looks identical to the original surround that it replaced. Initial reviews of my particular speaker post-recone are very, very favourable.

The spider provided in this kit is a genuine JBL part, and they've made a concerted effort to make the voice coil as close as they can to the original.

Fact is, even if I had been able to find a 'real', NOS, JBL D-130 recone kit, the speaker still would've sounded slightly different post-reconing. The original 'soft parts' were anywhere between 35 and 40 years old, and had thousands of hours use on them.

Cheers!
"I don't know why we asked him to join the band 'cause the rest of us don't like country music all that much; we just like Graham Lee."
David McComb, 1987.

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