Lemme understand this - buying JBLs

Re: Lemme understand this - buying JBLs

Postby Smolder » Thu Sep 26, 2013 4:34 pm

bzbz wrote:well, I just re-read the last few "redone" threads, and am still kinda confused - I left messages at a bunch of companies, and will continue to investigate - but I would appreciate any constructive feedback I can get!


I talked with Edgewound (Ken @ Upland Speaker) just the other day. He's probably one of the foremost experts on re-coning of old JBL's. JBL moved the manufacturing of OEM re-coning kits to Mexico a while back. They've had continuous quality control issues. My last factory re-cone sounded amazing for exactly 5 hours and then failed. Instead of fixing the manufacturing process, JBL (or the parent company) decided to scrap it and stop making them. This put specialists like Kenny in a world of hurt. He's been doing research and trials for the last year or so and has found aftermarket parts that get very close... or as close as one can get.

At this point some places like Orange County still have some EOM kits for D/K/E140's and D123's, but they are very very pricy. If you can find someone with NOS OEM kits sitting around for a D/K/E120 or 130 you'd be one lucky dude.

Frankly, I'm a big fan of the D series... but have stopped even considering them. The paper is pretty old and the K series cone material holds up much better. Of course if you're an E fan, they are pretty much everywhere.
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Re: Lemme understand this - buying JBLs

Postby NSP » Fri Sep 27, 2013 6:58 am

I had Orange County recone my last E120 with the aftermarket kit and it's sounded great for the past year and many gigs. Side by side with my other original cone E120's they sound very similar. I wouldn't hesitate to use them again.
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Re: Lemme understand this - buying JBLs

Postby tatittle » Fri Sep 27, 2013 6:18 pm

I have been buying and learning to discriminate JBL's for the last 3 years or so. The post about clearly explaining good packing/shipping methods is right on. Nothing bums me like seeing a great and irreperable vintage speaker ruined by haste, negligence, and cheapness. I NEVER use UPS anymore because of multiple problems dating back to college when my Boogie was stolen---spent some of the key years of my life without a decent amp due to that. Occassionally I forget to stipulate shipping measures, and as often as not it seems they arrive damaged.

I can usually tell if it is a JBL cone from pictures at this point, though people have begun reconing with different kits (like LF) so this is still not foolproof I guess. What I cannot do is know if there is voice-coil rub, which causes rattling/buzzing sounds. Voicecoil rub begins only at certain freqs and volume levels I believe, so it takes an experienced ear to recognize it...and really a full spectrum test. With just a quick test at low volume the rubbing can be missed, especially since they will still make me smile to hear the familiar tone I love. Voicecoil rub can also mimic distortion somewhat, buzzing type sound. I have better luck avoiding voicecoil rub in used speakers with JBL's than EV e.g. though, probably because of the playing styles of the folks who typically own the drivers.

It is inherently very risky though, because people often sell speakers because they are replacing them---and replacing them for a reason. I confirm they work properly and then send them back immediately if they arrive rubbing (losing return shipping) if possible. The D120's do not have the power handling capacity of K/E, plus the age, hence the prices. I have not heard a recone that has the timbre and sensitivity of JBL kits either....JBL no longer manufacters kits.

My best quality score so far was a Craigs list ad where I got 4 x K120's in apparent MINT condition (Im not old enough to have bought one new). They came in a SUNN cabinet with a roadcase for $400 or $450. Dealing with folks in person, or folks who are in forums that share an interest and likely respect for the tone is the best bet. Unfortunately that takes more effort than saving ebay searches :)

So sad that JBL has chosen to maintain profits over there tradition of service, but they do have to stay in business as well or they wont be able to provide ANy products. When Big gov't and Big business grow and gain more power, the individual man loses. Hudge and Grudge.
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Re: Lemme understand this - buying JBLs

Postby bzbz » Tue Oct 01, 2013 4:26 pm

OK - I am about to ship my speakers to Uplandloudspeakers - but I got a suggestion - I still need to get a cabinet (I will post in that forum, I wanna find one that can be made here in the NY metro area) - but even though my speakers have been (reliably) determined to need a recone, I think I should have a cabinet made, or purchased - FIRST - wire up the speakers, and play - the speakers do work, after all - and then if I send them for a recone, I will at least be able to hear the difference, and know what I payed for -

does this sound right? There's no loss this way - and this way, when the speakers come back, I am ready to have them installed back into the cabinet, and I am ready to play

this makes sense, yes?
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Re: Lemme understand this - buying JBLs

Postby NSP » Tue Oct 01, 2013 5:36 pm

bzbz wrote:OK - I am about to ship my speakers to Uplandloudspeakers - but I got a suggestion - I still need to get a cabinet (I will post in that forum, I wanna find one that can be made here in the NY metro area) - but even though my speakers have been (reliably) determined to need a recone, I think I should have a cabinet made, or purchased - FIRST - wire up the speakers, and play - the speakers do work, after all - and then if I send them for a recone, I will at least be able to hear the difference, and know what I payed for -

does this sound right? There's no loss this way - and this way, when the speakers come back, I am ready to have them installed back into the cabinet, and I am ready to play

this makes sense, yes?


Makes total sense if you don't mind waiting for the speaker to get sent out after purchasing the cab. Do you have a buddy with a cabinet you could use to check out the speaker now? How was it determined that a recone is necessary; flexing it and listening or feeling coil rub?
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Re: Lemme understand this - buying JBLs

Postby bzbz » Tue Oct 01, 2013 5:48 pm

I had it tested at an ultra-reliable electronics shop - they don't do re-cones and so have no vested interest in diagnosing a speaker as needing one - they found poor frequency response, the multimeter readings were way off....

but I don't mind waiting - I should get a cab first
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Re: Lemme understand this - buying JBLs

Postby tatittle » Thu Oct 03, 2013 7:51 pm

I would definitely wanna hear the speakers before I reconed them. My experience is no recone sounds like an original JBL assembly, and since they dont make em anymore that means once you change the original cone/coil there is no going back. The down side to original parts is they have often been driven hard and are worn out or have gotten significantly looser than the speakers sounded new...so there is some subjective analysis as to when to recone. This may be what "poor freq's response" they reported is measuring. If the speaker is blown or has significant voice coil rub it is either unusable or a constant annoyance.

The DCR on an 8 ohm impedance JBL should be around 6.5 ohms. You can measure that with a $5. multimeter hooked up to the terminals and set to lowest ohm setting. 16 ohm models are about 13.5 ohms, though a few early JBLs were listed as 16 ohm impedance and actually measure like an 8 ohm (D123's, D131's etc). If this reading is too HIGH, it is probably just dirty connectors. The terminals fill up with gunk and can be carefully taken apart, cleaned, and returned to proper performance (Ive done it with great results). If the DCR is very low though, it is likely a sign the voice coil is burning out, which cannot be repaired.

I encourage you to make sure they dont work correctly yourself, everyone makes mistakes. Its good to have the freq tested like you did as well of course, but if they are just a little off and your not using them for audiophile stereo applications it probably wont make too much difference. Audiophiles (reproduction) have a much stricter tolerance of what discrepancies are acceptable, tighter than is nec'y for live music production generally. Once those original parts are removed they are gone...and there are only so many left before the JBL speakers we know and love go extinct. I dont have experience with Upland (EDIT: I have run into Edgewound online and he is one of the best alive re: knowledge of JBL's), I am sure they are great---I just havent heard any recone that had the magic of an all JBL speaker; thats because there just are not parts available made to the exacting standards JBL upheld--too expensive and difficult to manufacture practically in the consumer, economic and regulatory climate we are in today in America Im afraid.
Last edited by tatittle on Fri Oct 04, 2013 12:06 pm, edited 1 time in total.
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Re: Lemme understand this - buying JBLs

Postby Smolder » Fri Oct 04, 2013 6:56 am

here is what ken@upland (edgewound) says about his aftermarket kits.

"JBL Professional no longer manufactures recone kits for the Musical Instrument Series of loudspeakers. All E-Series kits that were the OEM Spec replacement for the D/K/E-Series models have been discontinued since the production line had been moved from Northridge, CA to Mexico. Production quality issues could not be remedied in Mexico, so the decision by Harman/JBL was to simply discontinue the parts leaving hundreds of thousands of outstanding loudspeakers unsupported by the factory after 50 years of continuous support of the finest loudspeakers ever manufactured by an American company.

What is pictured for sale here is my version of a pre-assembled recone kit that adheres as close as possible to the production/assembly techniques that were used in Northridge, CA for decades on the JBL Professional production line. The details that make this kit stand out from typical aftermarket parts is the treatment of the cloth surround and the fit of the factory OEM aluminum dome. I have a small surplus of OEM domes that are key to making the speaker sound right. The voice coil is edgewound copper-clad aluminum ribbon wire faithful to OEM dimension and DC resistance for nominal 8 ohms impedance, wound on a high power Kapton former. The all paper vintage D120F cone is also available, though the E120 kit offers more well rounded performance and durability. My personal preference.

The kit will include a small bottle of black adhesive and a proper centering shim. Please be versed in the art of reconing or have a qualified tech do the work for you. Assembly details matter.

If you would like for me to do the recone, simply ship the speaker to me and add $85.00 for labor and return shipping. I've been Factory Authorized Service for JBL Professional since 1988, so you can be sure the assembly will be pristine. "
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Re: Lemme understand this - buying JBLs

Postby Eyesoftheworld » Sun Jan 12, 2014 8:44 am

I have noticed that there are speakers with different ohms. Is there any difference with sounds based on the ohms of the speaker? Also and this might be a stupid question the ohms on a speaker is that the min, max or exact ohms to send to the speaker?

I have been searching for speakers because if the ohms has to be exact then that will dictate the power amp I get, I assume.

thank you
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Re: Lemme understand this - buying JBLs

Postby Smolder » Sun Jan 12, 2014 9:00 am

Speaker load and output impedance are a middle point to give you as close a match as is possible. My understanding is that impedance output from an amp varies depending upon what is being played. In theory, if your output transformer is 8 ohm and your speaker is 8 ohm, there should be very little difference than if your output transformer is 16 ohm and your speaker is 16 ohm.

If you mismatch... say, plug a 16 ohm speaker into an 8 ohm output, you should hear a difference in tone, efficiency, and loudness. Most speakers and OT's are either 4, 8, or 16. For most amps a single step mismatch won't hurt... blackface and silver face fenders are good with this kind of mismatch, I've heard marshalls, not so much. Some guitarist mismatch by one step purposely in order to get a specific tone, volume, and feel.
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Re: Lemme understand this - buying JBLs

Postby Eyesoftheworld » Mon Jan 27, 2014 3:33 am

What preference would you guys choose for a 1x12 cab between a JBL k120 or E120? Also for a 2x12 would you rather have 2 of the same speakers or can I get a fuller range of sound by having a K and an E is the cab?

Thx in advance
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Re: Lemme understand this - buying JBLs

Postby RiseandFall » Mon Jan 27, 2014 9:15 am

What preference would you guys choose for a 1x12 cab between a JBL k120 or E120? Also for a 2x12 would you rather have 2 of the same speakers or can I get a fuller range of sound by having a K and an E is the cab?

Thx in advance


And while your minds are pondering this....I have a pair of 8ohm K-120's connected to the 8ohm lead on the back of my MC40. It sounds great, but would it sound....greater....if I connected to a different post....say the 16ohm?

Thanks.
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Re: Lemme understand this - buying JBLs

Postby Smolder » Mon Jan 27, 2014 3:29 pm

My preference (duplicating Jerry's tone aside) I much prefer the alnico mags of the K and D. If your amp is solid state, the impedance match is much less important. If you mismatch a tube amp in that manor you'll sacrifice about 30% volume... That can be good or bad.
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Re: Lemme understand this - buying JBLs

Postby tatittle » Thu Feb 20, 2014 7:56 pm

The total load of multiple speakers depends on whether they are wired in parallel or in series. Your 2 x K120-8 can be wired for either 4 ohms or 16 ohms. Although JBL 8ohm impedance speakers measure 6.5 ohms DCR in good shape so 3.2 and 13 ohms are the probable actual load (close enough). You can find wiring diagrams explaining how to calculate total load and series/parallel wiring online. It is pretty important to match the load to the output transformer. You can measure the actual load with a multimeter by removing the 1/4' plug from the speaker jack in the amp (with the amp turned off) and touching red probe to the tip and black to the shaft. If you have an extention cab you need to do the math involved.

While the rule Ive heard with Fenders (which reputedly are forgiving) is 100% up or 50% down; so 4ohm tranny can handle 8 ohms or 2 ohms. Using an improper load will definitely affect tone and volume, higher than amp designed for will mean quicker break-up/distortion and less volume at same settings; lower will mean louder and cleaner at same settings generally. Perhaps more important mismatch loads can lead to damaging the amp...the circuit is designed to see a specific load, the amp shouldn't even be turned on without a load attached to it (and definitely not played through w/o a load). You can think of it like different diameter pipes carrying water, the thinner the pipe the faster/more torque the water flows. The wrong load risks overheating the amp and damaging components. No load is like blocking the pipe.
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