Blown K120 blues :(

Blown K120 blues :(

Postby redeyedjim » Mon Jul 23, 2012 1:10 pm

So...I was jamming with some friends yesterday and I think like I blew my new-to-me K120 -- exit sweet, sweet tone, enter razzy distortion. :? I've isolated the distortion back to the speaker, so I guess my next step is to recone it. I've read the recone thread that's a few down from this one and will probably order one of the Sound Speaker Repair recone kits unless someone tells me something different.

I'm not sure if it was already damaged and I exacerbated it, or if I sent it some tones it just couldn't reproduce? I don't think I blew it out with volume -- although this was my first chance to play it at greater than bedroom volume levels, the Mesa TA-15 I was using puts out 25 watts on its highest setting, and I wasn't playing it that loud -- my max volume was maybe 1:00 on the dial. I was using my Maxon AF-9 envelope filter, which has a wide dynamic range, and (wild guess here) is it possible I damaged it with that, even though it wasn't putting out that much power? I was also using various overdrive pedals, but again, I didn't think I was pushing the speaker that hard. We weren't playing particularly loud.

I don't know how possible it is to do a root cause analysis on this sort of thing, but I'd like to learn what I can from this and move on.

Thanks for any insight/advice about either the cause or reconing the speaker.
Last edited by redeyedjim on Mon Jul 23, 2012 4:08 pm, edited 1 time in total.
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Re: Blown K120 blues :(

Postby Pete B. » Mon Jul 23, 2012 3:39 pm

I would closely inspect the speaker-wire to speaker connections, looking for an intermittant connection.
I had a brand new recone fail about 15 min into a gig due to that once. The guy didn't service the little isolation grommets on the connector post.
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Re: Blown K120 blues :(

Postby redeyedjim » Mon Jul 23, 2012 4:08 pm

I'll do that, but I'm really interested in the root cause of this, and I doubt it was the speaker cable or the speaker terminals. If my vintage cone was just flawed or old, and either of those was the root cause of the failure, so be it. That should be resolved by reconing the speaker. However, if it was caused by something in my signal, then reconing is just setting me up for another failure. And that's my concern, because the volume wasn't particularly loud, and the wattage wasn't that great.

Can an envelope filter ruin a speaker even if the volume is only moderate?
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Re: Update - speaker reborn :)

Postby redeyedjim » Fri Aug 17, 2012 12:31 pm

Thought I'd bump with an update. After some data gathering and phone calls, i ended up sending my speaker to Woody Woodell in Goodlettsville, TN for reconing. I can't seem to find a good link for Mr. Woodell, but I know he's been mentioned on both rukind and TGP (and by Brad Sarno) as a great person for this sort of thing. Super nice, very knowledgeable, quick, and the work was performed for a very reasonable price, IMO. I received the recone back yesterday and he appears to have done a great job - I'd post some pics, but it looks like a K120 with a new cone, lol. OK, I suppose if anyone's interested I'll takew some pics this weekend when I have a chance.

I'm looking forward to breaking this in and getting something like my old tone back. Any tips on speaker break in?

By the way, as it turns out I did not blow the old speaker. As Woody explained it, the original K120 had a small piece of foam in the vent mechanism, and this foam has a reputation for deteriorating after about 15 years. The previous owner had it replaced, which involved removing and replacing the dust cap. The guy who replaced it didn't get all of the old dust cap material out of the speaker and a small part of the old dust cap came loose and lodged itself in a way that caused the horrible tremendous rattling sound I was hearing. Unfortunately Woody wasn't able to fix this without reconing the speaker.
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Re: Blown K120 blues :(

Postby Smolder » Fri Aug 17, 2012 1:09 pm

if it's not a factory kit used... I'd be interested in how you think it compares to original cone jbl's. For years the factory kit was the ONLY reliable way to get a jbl back to sounding like a jbl, but lately I've been hearing of some re-coners doing good work without the factory kit. Plus, I hear that jbl has been struggling with quality and production is backed up through september...
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Re: Blown K120 blues :(

Postby redeyedjim » Fri Aug 17, 2012 2:13 pm

Yeah, I had heard that, too. I'll follow up with Woody and see whose kit he used, but the price of the recone was certainly agreeable: $125 + shipping (both ways). Sounds good so far (if a little bright out of the box), but I am sure it will loosen up/deepen a bit after it breaks in.
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Re: Blown K120 blues :(

Postby JonnyBoy » Sat Aug 18, 2012 9:11 am

I have been really happy with one of my after market recones. I have it side by side original recones and they sound identical to the new JBL kit and sound better than old worn out JBL cones. Some aftermarkets are better than others for sure!! Sound Speaker Repair I believe has exact clones of the JBL Kits (or as close as you can get). From the paper pulp mixture coming very close to the flat aluminum wire, formers, spiders, and weight, height placements, exact glue etc... They really tried to get it right.

$125 is a totally reasonable price!! The aftermarket kits I used are about $90 after its all said and done even before the labor to install. And JBL E Kits are around $200 I believe just for the kit.

You can get kits that "fit" or "work" for much cheaper than $90, but that is where you get into the tone sounding a lot different (from what I have heard word of mouth). I dunno about that first hand, I am sure its splitting hairs for some people. The cheaper cones mostly use round copper wire, different paper, and the measurements of where the coil sits are off, but workable. That flat aluminum wire on the JBL kits fill the voice coil space just enough to move in and out and be super efficient.
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