Burned Wharfedale Super# Voice Coil

I was hoping someone could suggest a solution to a burned voice coil in a Wharfedale Super3 Tweeter. This is the ALNCO version for which I have a working twin. I own the ceramic magnet version which is also on a 1" paper
former - edge wound aluminum. Is there any chance of swapping coils from
a sacrificial ceramic model? I have tried all the custom coil makers and vintage
speaker repair folks. A very laconic and ungenerous lot. I would appreciate a nudge in the right direction. Thanks in advance.

Jason
Rockaway Beach NY
 
I have tried all the custom coil makers and vintage
speaker repair folks
Well, that's a bad symptom, isn't it? :(
Sorry but if the Pros say it can't be done, .... there must be something to it.
Why do you think it's an edgewound aluminum coil?
In those years, the technology was available, no doubt, but justified only in "Pro" Cinema/Studio (think Altec/JBL) stuff, maybe a Vitavox driver meant for a Cinema, not so in Home Hi Fi.

Maybe you could "transplant" a cone/voice coil assembly from a Ceramic to an Alnico magnet, but not sure they would match (specs might have changed) and there is a definite possibility of damage, losing both in the process.
Worst case, I'd straight mount the ceramic teweeter in that cabinet and call it a day.
 
Now you have me wondering where I got the aluminum VC info from. I believe an early
catalog mentions that many models had them however the Super3 may not have.
When I inspected the VC it did look copperish however I chalked that up to aging varnish
or whatever they used as an insulator for the coil. To the point of simply using the ceramic versions, logic would dictate this solution but no part of my audio odyssey has been driven by logic. Rather a manaical pursuit of of the "right" sound. This has led me to older and older drivers through the Goodmans and Wharfedale line. I openly admit the folly of this strategy but have enjoyed process and the results. The ceramics do sound damn good and offer something my ten pound CD horns can't deliver.
 

VaNarn

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2010-12-11 12:39 am
Ivanhoe
Definitely round aluminium wire,that in the earliest models was of the cotton covered variety and in the later ones could be coloured in a green or a mauve wet bonding enamelled wire type.Winding height for the last named is 7/32" and I believe it is the same for the cotton covered version.The veteran Wharfedales can be disassembled with acetone to dissolve the cellulose nitrate bonding cement which holds the coil former to the cone neck.The only difficulty in repairing a Super 3,providing you can get a coil,is the need to solder the aluminium wire to the pigtails(which should be replaced as part of the repair).
 

VaNarn

Member
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2010-12-11 12:39 am
Ivanhoe
For sure Rockaway,given the correct parts and the right skills,what you have is repairable.You have the correct frame for the curved cone and the coil size is the same. You may have to shift the coil position to align for equal overhang about the outer pole plate as the ceramic magnet has an undercut edge at the gap interface.Also the flat corrugated spider can be beneficially replaced with a cup style one if the original shows signs of fatigue.
 

VaNarn

Member
Paid Member
2010-12-11 12:39 am
Ivanhoe
The ceramic magnet model has a very small black spider which may be difficult to see,given it is fitted on a circular ridge cast on the frame.The very earliest models used a felt or foam 1'' disc centrally mounted atop the pole piece to maintain clearance.This version was fitted with an aluminium dome cap.
 
Interesting. Mine also has the foam disc which has degraded somewhat but does not have the aluminum dust cap. I did spot the spider on the ceramic model. very understated given the massive magnet it harnesses. While my alnicos were stated to be from a pair of w70
speakers it is possible that someone swapped out the originals for an earlier permutation of the Super3. My plan is to locate an expendable ceramic version and remove the cone and coil assembly. Test it against the gap in the alnico. If it clears I will attempt to make the match permanent. I'll update whether it is a success or not. Please share any information, admonitions or seemingly trivial facts as all are of interest to me.

Regards,

Jason
 
Definitely round aluminium wire,that in the earliest models was of the cotton covered variety

Impossible.

Cotton covered aluminum wire is used for *heavy* duty work: high power transformers, welding machines , etc. where you need it to absorb impregnating oils and have no movement.
All the opposite of what a tweeter voice coil needs.

1) for the hair thin wire used in a tweeter VC, the "cotton wrapping" , if used, would be thicker :eek: that the copper itself.

2) the wire must be strongly and rigidly (not the same thing) bonded to the VC former.
Imagine adding a cotton layer between them :eek:

3) the assembly must be as light as possible.
Choice of adhesive *type* has a big influence in sound, imagine adding a cotton layer in the middle absorbing enough adhesive to be (somewhat) rigid. A mess.

4) there is no "free space" in , of all places on Earth, a VC gap. :eek:
Some high tech, high power VC (Gauss) went even to the extreme of using rectangle (a.k.a. "ribbon) aluminum wire without insulating varnish :eek: , trusting good quality anodizing as insulator.
 

VaNarn

Member
Paid Member
2010-12-11 12:39 am
Ivanhoe
We are dealing with an earlier insulation method and the cotton covered aluminium wire was still in use with the Dual Concentric Tannoy HF diaphragm into the 1970's.You may recall seeing cotton covering on Litz wire.The suspension variant may have been a special production item intended to use up stock alnico magnet assemblies or it the result of a repair that was limited to available spares.In cases where you have early model Wharfedale speakers preceding the roll surround model introduction around 1962,availability of replacement assemblies,using exact matching cones ceased as a result of a fire in the factory that manufactured them.I am not a fan of the earlier suspension technique as it relies on friction to hold things in place.
 
Rockaway...I'm still kind of interested as to why you are so intent on rebuilding this Super 3...is it to maintain the authenticity of your W70s? If so, I get it...but if not this tweeter is far from the sonic cats-pajamas...i'd be more inclined to swap in a pair of known good ceramic versions into the W70s, which are just as capable.

There were countless versions of these tweeters produced by Wharfedale America (BIC Industries) and quality control on this side of the pond was a constant source of irritation to Gilbert Briggs...the W60s, W70s W90s etc. were American and Foreign Market designs that GB was never really too in love with. And having owned almost every iteration of these models myself they don't measure up to the purely British engineered and rendered Wharfedales IMO which is why, no doubt, they receive little to no attention in the recent Briggs biography written by his grandson.

If your pursuit is one of attempting to repair to see if U can do it...good on you...but it will be a tricky process indeed...good luck, Leo
 
Leo,
You make some good points. I should clarify that (as I think You know) I plan to use these (the alnicos) drivers in an open baffle system that uses a Goodmans FR driver as the meat or midrange. I use a Wharfedale w15rs as a helper below 150hz and the tweeter comes in around 3khz. In addition to the ceramic version of the Super3, I have used the Wharf. PST/4 as well as a wide range of HF drivers including Coral (holy basket), Bozak, JBL le26, Kinap horns and of course the Goodmans Trebax built in to my Triaxioms. Nothing sounds quite as engaging as the Super3. I fire it up as in the Airdale and run this way, I can listen for hours with little to no fatigue. I will sometimes use a super tweeter (Realistic/Fostex) for everything over 16khz. I try to use 15ohm drivers since they make it easier to match impedance. They are also high efficiency and since I use vintage tube gear this is a plus as well. I have to use an active crossover since I lack the skill and inclination to design passive. (i am playing around with a PIO cap in line with the the Super3) Not very sophisticated. I have no measurements to prove the value of this approach other than the large grin and occasional tear that appears on my face when something in the music approaches startling realism. I believe that Briggs' real baby was the SFB but limited commercial success led to an early demise. I trust his ear (long gone as it is) implicitly since I have experienced first hand the genius of his design. I will stop gushing now.....
 
Hi..Jim?

Yes...I should have recognized you...a man after my own heart...following his subjective sonic pursuits...science be dammed:p...

I believe I trundled off some Wharfedale drivers to you a year or so ago via a friend's collection.

It all makes perfect sense...Gilbert would be proud of you...and like you I have a tremendous respect for his efforts...at least on the British side of the pond.

Having restored a pair of SFB/3s I concur wholeheartedly that this was G-Bs statement loudspeaker...and the specific Super 3's in those units are special for reasons that defy my ability to dissect.

The Super 3s you are working on are fine under the right circumstances particularly OBs but not IMHO in any of the W60 W70 or W90 iterations....

I think we may have a Super 3 to match your good one here on DiyAudio see: http://www.diyaudio.com/forums/tubes-valves/233898-help-needed-identify-british-made-amp.html

And maybe a few other spare drivers of interest to you as well...best regards Leo
 
Leo,
Just got home and finally a chance to reply. Thanks again for the "Heads Up" on that pair of tweeters on the other thread. I think you must have sent tweeters to someone else though.

It's not surprising that the scientific branch of our eccentric hobby has less appeal for me. I never had any aptitude for math. It's nice having another Luddite in my corner. Thanks for the support. Your opinions are, I am certain, much better informed however than mine.

So back to the business at hand. What features distinguish the Super3s that were in the SFB from those of the W90 -W60 Era?

Thanks,

Jason (Jim was close)