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Altec 3000G Tweeter Wiring Question

For Reference;

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Regarding the mylar diaphragm sounding different ( or "off" ), the third page of the Badmaieff article has a couple of clues as to why that might be ( perhaps a change in the 30ohm coil impedance also occurred with the change of diaphragm type ) .

:)
 
Thanks! Wow, 30 ohms! Is that at 22kc? Anybody know the DCR?

I'll sweep mine when I get them from Roscoe and post the data here.

Last few 8 ohm nominal tweeters I measured were up to maybe 10-12 ohms at 10k, and that's what I would have blindly expected from the 3000.

I'll never know what was wrong with my replacements but they didn't just sound "off," they basically didn't work.
 
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Joe Roberts said:
I sent some 3000s to Bill Hayes for a rebuild, maybe around 1990. They didn't work properly when I got them back. At the time I was super busy, never followed up, and threw them in a box somewhere.

Eventually I took them apart and found that the replacement diaphragms were polyester. I was under the impression that the diaphragms should have been aluminum (duralumin) and the 1940s design mic that was supposedly the donor for the diaphragms specified aluminum.

I no longer remember which mic that was...maybe Bowtie knows. It was a familiar standard Altec microphone.

And the Badmaieff article in Audio magazine when the 601A came out also specified aluminum. I'm wondering if they may have switched parts in later production 3000s.

Sam, when you had parts, were the diaphragms polyester or aluminum?

Anyway, the diaphragms were glued in and mounted on a cylindrical frame that looked pretty much like a dynamic microphone element. Not field replaceable by goobers such as myself, unless the whole assembly was available.

I have since often wondered if that assembly was, in fact, a complete microphone element.
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Sam Cogley said:
I was very close to repairing a damaged 3000-series tweeter a number of years ago, but the parts got lost in a move. I have two dead examples on a pair of 601Cs, at some point I'll pull them off and try again.
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I spoke to Tim Hayes about the stuff he was selling of his dads on eBay as I was interested in buying them at the time... He told me that the 3000 tweeter could only be repaired with the jig that his father had... He sold all of the diaphragms and jig to one gentleman...He even gave me the phone number to call the gentleman that bought the stuff as he was a friend of his... He was going to send me a copy of the jig ..I had no diaphragms and he didn't want to sell any so a jig and no diaphragms was pretty useless for me..
 
I'll pull one of my dead ones apart and give it a try again sometime. They usually just blow one of the hair-thin wires between the terminal and the VC.
 
Sam Cogley said:
They usually just blow one of the hair-thin wires between the terminal and the VC.
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Same failure mode as a WE 555...but you can easily see that conductor.

555 lead wires can be repaired with a drop of conductive glue...maybe that would be the approach to take with the 3000s?

WE 555s seem to go open from mechanical fatigue rather than overdissipation. Not sure about the tweeters failure mechanism.

Anybody have DCR or measured impedance specs of a 3000? EarlK's observation of the 30ohms mention has gotten my curiosity up.
 
I have a pair of black 3000Hs and one measures 10.9 ohms and the other 11.3 ohms. I had a single gold 3000A years ago which looked like it was pulled out of an Altec 601A and if memory serves me right, it measured a bit higher, maybe 20 ohms (?) it did not work too long, just died one day.

JE
 
H'mm, I guess that makes them 16 ohms nominal, that pair at least.

Come to think of it, I still have the 414s that were factory matched with the 3000As that I sent to Bill Hayes way back when, and they are 16 ohm 414Zs. I think that system used an N3000 xover in an unlabeled unpainted can.

Do you have access to an impedance sweep machine in Manila?
 
Joe Roberts said:
Do you have access to an impedance sweep machine in Manila?
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If you mean something like this setup, I don't know anybody in my circle who has them. But I have a Leader Audio Gen + Fluke 87 DVM here. I think those tools can be used the old fashioned way to measure impedance vs. frequency, right? Just need tips on how to do it. I'm bringing this pair of 3000Hs back to the States.

JE
 
I use the DATS pc software/USB doodad from Parts Express but I used to do it with a resistor and RCA VTVM back in the stone age.

Basically, you set up the resistor and speaker as a voltage divider across the terminals of the generator. I'll look for a picture/schemo rather than trying to describe the setup. I'm on a laptop with a funky keyboard.

Check this out:

http://www.turneraudio.com.au/loudspeaker-response-testing.html
 
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setup1 said:
I have a pair of black 3000Hs and one measures 10.9 ohms and the other 11.3 ohms. I had a single gold 3000A years ago which looked like it was pulled out of an Altec 601A and if memory serves me right, it measured a bit higher, maybe 20 ohms (?) it did not work too long, just died one day.

JE
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Hmmm, for my 601c pair I bought two 3000h tweeters, one green and one black. I asked a friend to put it on the body of 601, the green one put it directly but the black one he tooked the diafragm and the magnet and put it in the original green body of the tweeter of the 601c. After a year when I decided to make a new x-over I measured the DCR of the twwters and a big WOW: the green one have 30 ohms and the black one 70 ohms. What is wrong?
 
klauss00 said:
Hmmm, for my 601c pair I bought two 3000h tweeters, one green and one black. I asked a friend to put it on the body of 601, the green one put it directly but the black one he tooked the diafragm and the magnet and put it in the original green body of the tweeter of the 601c. After a year when I decided to make a new x-over I measured the DCR of the twwters and a big WOW: the green one have 30 ohms and the black one 70 ohms. What is wrong?
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If you're getting good sound, don't worry about it. I've shared everything I know about the 3000 series tweeters above. Beyond that, it's a mystery to me.
 
Even whit this difference in DCR? The green one “ This might be the best 3000 out there. It was the standard for the ALTEC lab, comes with the test results and is in excellent condition“ and the black one it appear as calibrated and have light blue membrane
 
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