glebert 6/11/2018 4:48 PM
Roland JC120 speaker recone
Anyone know a shop with experience reconing these or a source for parts? Have one with a minor rub. Local speaker guy says he doesn't know if he can do it (I think voice coil availability/dimensions/tolerance/something), won't know until the speaker is torn apart. Only place that I see that lists anything about recone parts for these is Queensland Speaker Repair, but their website would lead you to believe they have EVERYTHING, and I find it hard to believe that they are the only place on the planet that has a kit for these. It's not like these are a totally obscure amp.

Thanks in advance,
Greg
 
J M Fahey 6/11/2018 5:53 PM
Weber can sell you parts, no sure a "JC120 specific" kit is available, itīs not an obscure amp although,what? 1000 times less available than Fender? but speakers are someting else, those are way more obscure.

All (some) brochures say is "R&P speakers", which some translate as "Roland & Pioneer" speakers, as clear as mud since Pioneer in any case is knownas a Hi Fi speaker manufacturer.

That said, these amps were intended as "Twin killers", same as same era and purpose Yamaha Gxxx, logic woud be that these are clones more or less accurate of "whatevef Twins used" so "should" be close to Jensen C12N or "me too" Oxford/Rola/Utah copies.

Unless your reconer is experienced with Guitar speakers I suggest you send them to Weber.

IF your is qualified, mind you that Hi Fi and Guitar have opposite goals; a Guitar speaker reconed "the other way" is muddy, too bassy, too soft and self destroys with any Bass you send it (they donīt expect an open back baffle by any means)., Almost forgot: can be 6 to 10dB less efficient

IF yours qualifies, then he should order parts from Weber, but must measure and supply:
*exact cone and frame diameter (12" is nominal)
* cone depth, fom edge to voice coil edge
* ribbed/unribbed. And if ribbed, how many.
* exact voice coil diameter
Usually diameters vary by quarters of an inch, so typical Guitar ones are: 3/4" (Champ) , 1" (C10R), 1.25" (C10Q), 1.5"(C12N), 1.75" (Celestion), 2" (C12K or many 15"), 2.5" (EV), 3" (Altec), 4" (JBL , Black Widow) but even so each Factory has its own version.
I am hopeful Roland chose to approximate Jensen so 1.5" VC is reasonable, *maybe* 2" for beefier, fatter sound, only measuring has the truth.
* voice coil length . Shorter canīt be assembled, longer is no big deal.
* voice coil winding length . I expect 8 to 11 mm ; Hi Fi guys LOVE extra long coils (13mm to 19 or 20mm) for "more Bass" , it works the opposite way on Guitar speakers.

Iīd suggest he cuts the cone edge clean around the frame with a sharp X Acto knife, same with spider , both tinsel wires, and pulls cut but otherwise intact cone/VC/spider assembly for inspection/measurement.

Absolute worst case, post pictures and dimensions here and I can help you choose some Eminence or Jensen speaker which will work very well there.

You might replace both and keep the healthy one just in case.
 
glebert 6/11/2018 7:57 PM
This is the info that Queensland Speaker Repair has for it, but like I said I don't know why they are the only ones who has this information,or if it is at all accurate. https://qsr.net.au/shop/speaker-reco...20-recone-kit/
,,,
Description
Dimensions of Parts (Measurements in Inches & Millimetres)

Cone – OD: 12″ / 304.80mm, Depth: 2.750″ / 69.85mm, VC: 1.250″ / 31.75mm, Surround: Cloth
Voice Coil – ID: 1.913″ / 48.59mm, FH: 1.5″ / 38.10mm, WW: .500″/ 12.70mm, Round Copper Wire, 8 Ohm
Flat Spider – OD: 5.487″ / 139.36mm, VC ID: 1.5″ / 38.10mm, C Stiffness
Dust Cap – OD 3″ / 76.20mm, Aluminum
Gaskets – 4 Piece Foam Set
Lead Wire – 2 Lengths, 100mm x 1.6mm
This Recone Kit will suit the following models & many others: ROLAND JC120

Since this is an amp that I am planning on selling having a custom voice coil made will basically kill any profit on this one. If a recone can't be done for less than $100 I will just put in something that sounds good and price it as non-original. I think the Yamaha G series speakers would be pretty close, those amps have a similar bite and chime as the JC120 do. Happen to have a G50 here that I can borrow the speaker from.
 
J M Fahey 6/11/2018 9:52 PM
Quote Originally Posted by glebert View Post
This is the info that Queensland Speaker Repair has for it, but like I said I don't know why they are the only ones who has this information,or if it is at all accurate.
Canīt confirm or deny, because so far I have never repaired a JC120 speaker.
I guess they either have and measured it , or have a link to some US supplier who sells themthe kits.
In any case I would ask Weber , asking is for free
Some numbers do not match, although they might describe cone and spider "as received" and imply that reconer should get a small sharp scissor (I use the small curved ones designed for nails) and cut cone and spider mouth to fit coil.
Description
Dimensions of Parts (Measurements in Inches & Millimetres)
Voice Coil – ID: 1.913″ / 48.59mm, FH: 1.5″ / 38.10mm, WW: .500″/ 12.70mm, Round Copper Wire, 8 Ohm

I expected a 1.5"/38.1mm Inner Diameter (in fact slightly larger so it can freely move without touching center pole piece) OR 1.75"(44.5mm , same considerations) OR 2" (50.8 mm, again same) BUT they are apparently using a non standard diameter .
Ok, they use what they want, itīs their privilege.
I have seen that with other Japanese speakers ... but all Hi Fi type.

Cone – OD: 12″ / 304.80mm, Depth: 2.750″ / 69.85mm, VC: 1.250″ / 31.75mm, Surround: Cloth
Cone hole for VC smaller than supplied one, but thatīs quite common, reconer is supposed to open it up to fit.
Flat Spider – OD: 5.487″ / 139.36mm, VC ID: 1.5″ / 38.10mm, C Stiffness
Same here.

Dust Cap – OD 3″ / 76.20mm, Aluminum <-- not critical, itīs mainly decorative, and is glued to cone, not voice coil.
Gaskets – 4 Piece Foam Set <-- generic
Lead Wire – 2 Lengths, 100mm x 1.6mm <-- generic
This Recone Kit will suit the following models & many others: ROLAND JC120

Since this is an amp that I am planning on selling having a custom voice coil made will basically kill any profit on this one. If a recone can't be done for less than $100 I will just put in something that sounds good and price it as non-original. I think the Yamaha G series speakers would be pretty close, those amps have a similar bite and chime as the JC120 do. Happen to have a G50 here that I can borrow the speaker from.
Ask Weber, he might have the required voice coil (he stores all other necessary parts) and either repair it or sll you the parts .... again asking is free.

Pity the dust cap is Aluminum ... if it were cloth it could be cut away with a sharp scalpel knife flush with cone, you measure the VC without further disassembly , you may even try to straighten or clean it so it scratches no more and then reglue cap with nobody noticing it ... but Aluminum does not allow that.

Your Tech might try to unglue the aluminum cap without damage; I can do that but itīs tricky.

EDIT: in case I wasnīt clear enough: since itīs a case of cure or kill anyway, please post a couple speaker pictures: straight back, straight front, front closeup showing, say, 1" around dust cap (I am interested in how itīs glued to cone) and the only tricky one: a sideways one through a frame hole, speaker on a table , maybe on a couple books, pointing up, and taken at a height enough that I can see the speaker to spider joint, so I can estimate VC diameter by comparing it to magnet and frame diameter.
Oh, also state magnet diameter.
If possible, in mm, way more precise than those ancient units based on the Kingīs d*ck length or whatever.

**Maybe** you can safely unglue dustcap from cone, expose VC, and recenter it, saving all the fuss about reconing , given parts are not too common and to boot Iīm not so sure they are the proper ones.

Did I mention that cost is peanuts?
In $$$ of course, it takes some effort and patience.
Make that a lot of patience.

The dust cap can be reglued afterwards, and all this is based on adhesive being black dyed Elmerīs Glue or Contact Cement, both being able to be re-dissolved with the appropriate solvent.
If they used Epoxy ... forget it.
 
glebert 6/12/2018 10:27 AM
Juan, thanks for all the help. I will take pictures but will probably take a bit. Just happened to look at the speaker in some different lighting and realized that the cone has some unevenness or warping and what looks like a water stain. I'm guessing the warping of the cone may have pulled the VC off center?