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Tweeter repair?

Vinylhammer

Vinylhammer

headbanger
Does anyone know any place that can repair dome tweeters?

I picked up a pair of Sansui sp-100i speakers today and they turned out to have dead tweeters. These are not old Sansui kabuki style speakers, they are bookshelf size heavy(about 45lbs each) vintage about 1989.

I would like to see if I can get the tweeters repaired before returning them to the seller. Here is a link to k-nisi website with pics:

http://translate.google.com/transla...=s&rls=org.mozilla:en-US:official&hs=S0v&sa=G
 
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I have repaired many tweeters with a tweezers, magnifying loupe, soldering kit, and a pair of large you-know-what.

Almost every busted tweeter has a break in the voice-coil wire, where it first leaves the bobbin to connect to a binding post. I unsolder the good wire from its post, and start looking for the stub of the broken wire, with the voice-coil/driver diaphram assembly in hand. When you find the stub, unravel it one full revolution. You need not try to strip the enamel from the wire, as the soldering process usually does it for you.
Maintain phasing upon reassembly.

Seth
Forever Analog
 
No easy way in to voice coil

NoTransistors said:
I have repaired many tweeters with a tweezers, magnifying loupe, soldering kit, and a pair of large you-know-what.

Almost every busted tweeter has a break in the voice-coil wire, where it first leaves the bobbin to connect to a binding post. I unsolder the good wire from its post, and start looking for the stub of the broken wire, with the voice-coil/driver diaphram assembly in hand. When you find the stub, unravel it one full revolution. You need not try to strip the enamel from the wire, as the soldering process usually does it for you.
Maintain phasing upon reassembly.

Seth
Forever Analog
Click to expand...

NT: Help me find a way into this one (JBL LE25), PLEASE!



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You'll have to drill off the heads on those rivets. Use a large drill bit and just drill in far enough to spin the heads off. You might be able to replace them with screws. Watch out the metal filings don't end up in the coil. Use locktite and lock washers to prevent the new screws from getting loose.
 
StarMover said:
You'll have to drill off the heads on those rivets. Use a large drill bit and just drill in far enough to spin the heads off. You might be able to replace them with screws. Watch out the metal filings don't end up in the coil. Use locktite and lock washers to prevent the new screws from getting loose.
Click to expand...

Thanks. I might as well, nothing to lose now. Was hoping for some secret way in, I guess.

I wonder what the thinking was to come across the top, through (or under?)the cone to the coil? I guess to keep it sealed.
 
Nice project link. I just cleaned up a pair of aluminum minis as used in that project. All three drivers in each cabinet are still working, but an upgrade is probably in the cards. This gives me some ideas.
 
Audio drivers are not interchangeable.
The actual resistance of the voice coil, in conjunction with the value of the crossover capacitor, is what determines crossover frequency. Many audiophools do not understand this relationship.

Seth
Forever Analog
 
NoTransistors said:
Audio drivers are not interchangeable.
The actual resistance of the voice coil, in conjunction with the value of the crossover capacitor, is what determines crossover frequency. Many audiophools do not understand this relationship.

Seth
Forever Analog
Click to expand...


Cap is 3uF. Plus, I might burn in JBL hell if I swap drivers in an L-100. Found a reasonably priced replacement LE25, but still going to open up this one.
 
Seth,
I got the tweeter taken apart. Unfortunately the wires are broken in the part that wraps into the magnet assembly and about 1/5 of the turns are burnt out. I don't think I can solder fine enough but I might give it a try, can't hurt anything. I did hook up an epi tweeter in one of the speakers and it sounded decent.
 
Usually, the wire simple just opens up in one spot. How yours became such a mess is beyond me. If you solder, will the coil fit back into the magnetic gap?

Seth
Forever Analog
 
Did not have any luck trying to solder the wire back together. The only thing I can see doing is buying some magnet wire from Radio Shack and trying to wrap the coil myself guessing on length and gauge. This would probably throw the impedence/response of the tweeter way off but its dead anyways.

The wire was burned through about 10 times in the same area. Somebody must have been abusing these speakers badly.
 
NoTransistors said:
Audio drivers are not interchangeable.
The actual resistance of the voice coil, in conjunction with the value of the crossover capacitor, is what determines crossover frequency. Many audiophools do not understand this relationship.

Seth
Forever Analog
Click to expand...

Right you are!

He is unlikely to find another tweeter. But it should not be too much of a problem to find a 1" dome tweeter of the correct impedance that will have a similar frequency response and SPL. This may be his only recourse.
 
The tweeter is not mounted in the typical fashion and the tweeter hole is 5 1/4 inches. It looks like the crossover frequency is at 1500hz and the listed speaker impedence is 6ohms but that does not necesarily mean the tweeter is 6ohms. Efficiency is listed as 88dB/w/m. Picking a replacement tweeter would be a crapshoot and difficult because of the low crossover frequency as well as the mounting size.

I think I'll look into the rewiring the voice coil or returning them to the seller. The speakers have very nice build quality, it would be nice to get them working again.
 
I did not think I would be able to do it, but I rebuilt my tweeters.

I measured the length of wire from the one coil that was only broken once at 6 1/2 ft long. Did a little research on the web and found I needed 40 gauge magnet wire to come out to 6ohms at this length and bought some magnet wire off the bay.

The wire came in today so I started my project this evening. I measured out the wire and carefully wound the voice coils, applied a little Aileens tacky glue to the voice coil to hold wire in place. Soldered the wire ends to the terminals and allowed to cool. Measured ohm's with my Fluke meter and adjusted wire down a little until I got to 6ohms. Installed tweeters back into speakers.

Gave them a quick listen and the speakers sounded great. Played my CBS Labs - Seven Steps to Better Listening test record to check frequency response and the test tones sounded balanced. Went to the hearing test site to check frequency response further: http://www.phys.unsw.edu.au/jw/hearing.html
and came out within -3dB between 60Hz to 12 kHz.

Now its time for more music.
 
NoTransistors said:
I have repaired many tweeters with a tweezers, magnifying loupe, soldering kit, and a pair of large you-know-what.

Almost every busted tweeter has a break in the voice-coil wire, where it first leaves the bobbin to connect to a binding post. I unsolder the good wire from its post, and start looking for the stub of the broken wire, with the voice-coil/driver diaphram assembly in hand. When you find the stub, unravel it one full revolution. You need not try to strip the enamel from the wire, as the soldering process usually does it for you.
Maintain phasing upon reassembly.

Seth
Forever Analog
Click to expand...

I owe a big thanks to Seth and this thread. I picked up a pair of Mission 734 floorstanders for a really good deal, but one of the tweeters was cooked. Upon taking the tweeter apart, the breaks were very apparent and I just needed to unravel each side of the coil one revolution each. The enamel was tricky for me and didn't melt during my soldering. I had to unsolder it and scrape it off with a utility knife. When all was done, the multimeter read 3.0 ohms, should I be worried about that? :scratch2: Anyhow, I have some pretty decent speakers that were discounted due to a very-easy-to-fix problem :D
 
Very nice speakers.

Glad it worked out for you.

My birthday is in two weeks.

Seth
Forever Analog and Covered In Parrot Poop
 
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