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walsh tweeter design/rebuild

I should be able to get that for you.
I'll see if I have an opened up oem vc.
They are about 7.2 ohms
Very vine wire.
About ⅛in wide on the wind.
But I can look and some of my stuff, and measure the wire.
 
The DCR readings I have are 6.4Ω and 6.8Ω for my two OEM Infinity units. The VC wire measures @ .0038" in diameter, with about 25 - 35 turns on the 1.0" VC. This looks like maybe a 7-10W max VC to me.

My tweeters are crossed over at 3.5kHz and draw significant power from the amp sometimes (the event that blew one of them was @ 18W). I now have a tweeter protector w/6W bulbs and 600mA GMA fuses (@ 900mA blow at 6.5W tweeter power), which have popped repeatedly and will be upsized to 700mA. Just mentioning this in case you might want to use beefier wire than Infinity did (I certainly would).

Here's a magnet-wire link:

https://mwswire.com/wp-content/uploads/2016/10/Copper-Magnet-Wire-Data.pdf
 
Jimbo40 said:
I should be able to get that for you.
I'll see if I have an opened up oem vc.
They are about 7.2 ohms
Very vine wire.
About ⅛in wide on the wind.
But I can look and some of my stuff, and measure the wire.
Click to expand...

rayivers said:
The DCR readings I have are 6.4Ω and 6.8Ω for my two OEM Infinity units. The VC wire measures @ .0038" in diameter, with about 25 - 35 turns on the 1.0" VC. This looks like maybe a 7-10W max VC to me.

My tweeters are crossed over at 3.5kHz and draw significant power from the amp sometimes (the event that blew one of them was @ 18W). I now have a tweeter protector w/6W bulbs and 600mA GMA fuses (@ 900mA blow at 6.5W tweeter power), which have popped repeatedly and will be upsized to 700mA. Just mentioning this in case you might want to use beefier wire than Infinity did (I certainly would).

Here's a magnet-wire link:

https://mwswire.com/wp-content/uploads/2016/10/Copper-Magnet-Wire-Data.pdf
Click to expand...


Thanks! that's awesome info. So the original was very thin and short, 1/8" approx. I'll use some wires I have here, but now I have a better idea of what wires to try.

I'm planning to make a "frankens-tweeter" with 2 spare magnets I have, not copying the original, but following some guidelines. And use them as super tweeters, or crossed quite high. It's just an experiment with materials I have at hand.

Is the cone material too thin, like professional kitchen foil, or a bit heavier, like a beer can?
 
Jimbo40 said:
Its thin foil almost between regular and heavy duty. So thin with clear poly film on the inside.
Click to expand...
Thanks again. I have some sheets of Mylar, quite thin , I think they can serve as support for the metal foil. I'll try different materials, since I'll be doing it from scratch and i don't have any hurry. I must design even the "faceplate" to hold the vc-cone assembly since I just have 2 bare magnets.
 
Hey Guys,

Just finished this very informative thread. I bought a cpl. Walsh Infinity tweets that were dead. I'm going to attempt to re-wire them as detailed here. Just wondering if someone could refresh my memory, can I remove the cones using nail polish remover? Or in some similar manner? Seems I read that somewhere. I may try and just re-wire w/o removing the cones. But I like what rayivers did and may go that route if I run into trouble.

thanks.

Q
 
There are acetone free nail polish removers (ethil acetate), it's a good glue remover. I use it a lot when fixing speakers. It's nicer with some plastics, but you need to try on a hidden spot first, it usually doesn't damage plastics but it can leave marks or remove the glossy finish on some plastic surfaces.
 
This got left out of my diy post, but my tweeter had an uneven thick bead of amber epoxy (repair, most likely) around the cone/VC junction, which had to go. I didn't want to risk damaging the gold finish so I used a water based acrylic-paint remover called Clean Slate 2.0, which eventually softened the epoxy enough for removal but removed some of the gold coating too (thought it was anodized, apparently not). Knowing what I know now, if it had been my other tweeter (w/no epoxy bead) that blew and the VC couldn't be repaired, I would've cut the cone off the VC with a scalpel.
 
Got 'em apart. One is burnt. The other one looks fine, but I think I will do what rayivers did with his. The Ti diaphragms I am seeing, similar to Ray's diyaudio write up, are all listed as 24.8mm. Is that what I need?
 
So the one that looked good broke at the glue point that some of the people here have pointed out. It appears that that tweet was repaired. The glue used to re-mount the cone looked not 'hard or stiff' but more rubbery. I used Ray's 'scalpel' method to remove both cones. I'm guessing when I pick a glue to repair these I want one that sets more hard. I have the Gel type Gorilla Super Glue. It doesn't run like other super glues and takes about twice the time to set, so not very long... I'm thinking of just using that?? I will buy some of that non acetone nail polish remover.


Ray, if/when you see this. How are yours holding up? They sound pretty good still? What value fuse do you use, in the XO you have, to protect your Walshs?

Thanks
 
As much as my walsh tweeters are completely home brew, they have survived and play. I used the clear gorilla glue, sparingly, not the super glue. Buy it and run a string of it down the side of your work bench and let it set a few days. See if it's something you might use. My protection is that the voice coils aren't in any way fragile. Do they sound exactly like the originals. I'm sure they don't, After reading the information about how they were made I can assure you that the originals didn't all sound the same. It would take a kid or a woman to know, because testosterone kills male hearing above 20k by age 30. I don't think anyone would love their walsh tweeters enough to become a castrato to be able to hear them. I hope you can appreciate my humor, it often goes unappreciated.
 
Hey James,

I like what you did, you've built your own from scratch. Bravo! I have ordered a pair of the same VCs as rayivers, in his build thread over on diyaudio. I'm interested to see how those VCs hold up in the original tweeter. They are designed to repair oem JBL tweeters. I believe they are higher efficiency and have better power handling. I'm looking at the tech spec sheet for the Infinity 2000axt, it shows a 3.5uF Cap in series with a 5 ohm 5w LPAD in series with the Walsh. Since the Infinity 2000axt is a 3 way I believe the Walsh is XOed ~ 5000khz?? I'm thinking to XO lower also, I think rayivers also crosses them lower? I'm guessing I need to put a fuse in series with the tweeter to protect it? I will be running aprox 50 watts per channel. Probably not too loud. Would I put the fuse after the LPAD? or between - lead and ground?
 
In a series circuits it doesn't matter, it's all the same. I would place the fuse holder where I could easily get to them. I would consider right beside/ behind the speaker. You could hot glue the holder to the frame of the speaker.
 
Actually I think the XO in the infinity is parallel. Not a Series XO so I am confused about what I need regarding a fuse to protect the tweeter.. I was thrown because the XO for the Infiity is so simple. I believe this Walsh tweeter XO is a 1st order 6db roll off .
 
Fuse in series with the speaker. You have a 3.5uf cap and a 5 ohm 5 watt pot in series with the walsh tweeter. This circuit is in parallel with the other crossover components for the other speakers. https://stereonomono.blogspot.com/2010/11/infinity-2000axt-1973-1978.html. The confusion is occurring on the midrange circuit which taps power off a 10 to 15 ohm circuit to the midrange driver. You'll notice the midrange is out of phase with the other speakers, same with the Monitor 2 a's . If you just checked the wiring and not the schematic you might be tempted to say the factory screwed up. It's their design. They probably just tried it and thought it sounded better. A lot of speaker design ain't science, it's trial and error, and largely opinion as to what sounds best. I haven't built a lot of speakers but typically I wire them in phase.
 
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Thanks James,

The confusing part for me is with the tech spec schematic for the AXTs isn't accurate. It shows/mentions an emit tweeter but these speaks are clearly 3 ways. I dunno why that is unless they didn't have the permission to use the Walsh as a full on tweet from OHM?? Anyway, I think you are correct about how the schematic is drawn up. I do see that a lot in XOs. Certain drivers out of phase with others. I think they did a lot of 'by ear' design back in the seventies. Usually it is the tweeter that needs to be out of phase, unless the driver VCs are time aligned. Then it is 'ok' to correct the tweeter phase... I think I will use some PTC resistors, similar to the ones from lautsprechershop.de, to protect my tweeter.
 
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