Altec HF driver repair. How to fix an open voice coil.

Hi all,

Fired up a rebuilt set of Radio Craftsman tube amps last night that I just bought only to find one had a short in the phase splitter which caused a tremendous growl-hum gawd awful full output noise, shut down as fast as I could but not before it took out the HF driver in my Big Reds, buggar!

So today out came the 604 and I removed the HF voice coil assembly and found the problem...yup, you guessed it, broken lead wire to the diaphragm right where Altec put the 90* bend in the flat wire from the terminal to the diaphragm. This apparently was a design flaw from the late 60's and into the 70's, and mine being from the mid 70's had this type of lead wire. After an hour of trying to remove the insulation on both ends of the flat wire, not sure what it is but it's impervious to MEK and Xylene, I finally got it by gently heating the leads and then the coating film came off in a neat little strip. I was then able to solder the 2 pieces back together and I put in a little bit of radius to avoid this happening again. It was also obvious once I got it apart, that one side had already failed some years ago and had been repaired in the same manner.

Just thought I would share my experience in case any of you find yourself in a similar situation.

Cheers

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Test 1 2 3. Just seeing if I can still post after all these years. Looks like you and Ron gave up on your 9846 plans.
Glad you guys are still around. Art...

Nice repair KHz. That’s delicate work! I have to use a microscope for that stuff now.

Hey ART. Good to see you check in. I actually dug the 9846’s back out with plans to get back to it. I’m currently trying to recone the woofers myself. Having some issues with the kit. Non-stock parts. And I’m missing one N-501-8A crossover.

Hi boys,

Thanks for the compliments, it was a little tricky but not bad. Nice to be back as well, it`s been a while since I have spent any time with hifi, just seems work and the property and other projects and life just gets in the way, but I'm back in full force. I've mounted new shelves for my amps and am in the process of building some tube pre/power amps, 01A, 300B etc. Still working on the design but all DHTs.

As for the 9846's, I am still going to build them, I look at the 411-8As every few months, I have the new surrounds for them, several drivers, 802D, 808-8A, 806A and 802-8G to play with....it's just my shop is currently filled with my '49 Ford F1 build and '68 Firebird rag resto and I'm reluctant to fill it with sawdust. My Dad is giving me his commercial table saw whenever I want it but I fear once that arrives, the vehicle projects will pause and I'll be building speakers for a while. :rolleyes:

I have all new caps to upgrade my Mastering Labs xovers and might do that this weekend while I'm smoking bacon.

Keep well.

Cheers

Car guys and audio. My Turbo LS Nova is in the garage, which is where I will have to sand and repair the 9846 cabinets. So that will have to wait for nicer weather. Sanding dust and car parts don't go together. And it's a 1 car grudge.
Same for the basement where my audio room is. I build engines down there too.

Like you, I come and go from the audio hobby. Been awhile, I forget how much I enjoy it. And you don't get grease under your fingernails!

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Originally Posted by RonSSS

Car guys and audio. My Turbo LS Nova is in the garage, which is where I will have to sand and repair the 9846 cabinets. So that will have to wait for nicer weather. Sanding dust and car parts don't go together. And it's a 1 car grudge.
Same for the basement where my audio room is. I build engines down there too.

Like you, I come and go from the audio hobby. Been awhile, I forget how much I enjoy it. And you don't get grease under your fingernails!

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Hi all,

I'm still alive, still planning to build the 9846's, still have the '68 Firebird rag in the garage, still haven't finished it but the '49 Ford is now outside under cover so I have room to setup my Dad's tablesaw which I now have in the container. It's funny how time flies when you don't do anything. :D

Hope everyone is doing well. Check in and let us know what your are doing.

Cheers

Paul

Ever think going mopar? also i have some boxes by the way

Did you find plans for the 9846 enclosure?

Come on KHZ the 9846 is worth the build. We have been using ours almost daily since the rebuild
in 2005. They never fail to impress bi-amped in our modest home theater setting.
Glad you guys are still around and hope you stay well... Art

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Originally Posted by Phil-G

Ever think going mopar? also i have some boxes by the way

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Yes, there's a '71 Baracuda with a 340 (auto) down the road under a tarp, been there 15 years, I should go down again and make him an offer, he's had it since '75, plum crazy purple, my fav, but rusty.

Cheers

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Quote:

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Originally Posted by Alien_Shore

Did you find plans for the 9846 enclosure?

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Yes

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Quote:

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Originally Posted by Art J.

Come on KHZ the 9846 is worth the build. We have been using ours almost daily since the rebuild
in 2005. They never fail to impress bi-amped in our modest home theater setting.
Glad you guys are still around and hope you stay well... Art

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Thanks Art,

Well the decision has been made to setup a system in the shop so I can try my A7-500s that I've had for 10 years and haven't put power to yet. Yes, the 9846 will get started in the spring, it's too cold here right now to be working in the shop daily, plus I still need to do some organizing. I'm currently building several tube preamps and SET power amps, may even try bi-amping the A7s.

I also need to figure out how to have the BBS send me a notice when I get a reply to my posts, does anyone else have a problem with notifications?

Cheers