Altec 9069B multitap inductor

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Apache5

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Hi. Im gonna do a multitap toroidal inductor for a friend that want it for an Altec 9069b HPF clone. Seems to be a LCL Pi filter. They want it toroidal because he saw internal pics and seems to be a toroidal type...  He showed me that pics and I saw like two or more toroids and no capacitors, maybe they are "packed"?
What I dont know is what material to put in the core, Can I put there a ferrite one? an Iron powder one? is that critical in an audio filter for line levels? Can someone guide me?
I read somewhere in that  forum that I need to do complete n rounds with an inductor to avoid problems with increase in distortion...  In a multitap, I need to do that with every tap?

Thanks

Arnau
 
Hola Arnau,si consigues algo de informacion adicinonal estaria genial que la compartieras.por lo que yo sé Seb de westfinga tiene su propio inductor multi tapped custom cinemag, aunque no creo que de ninguna informacion sobre valores de impedancia.
Un saludo.
 
Most filters/EQs of the era leading up to that unit used inductors with powdered permalloy (MP) cores. I don’t know what Altec used for that one. It came along just as ferrites were starting to appear as alternatives to MP cores (and which became the most common core material in the late 60s, until gyrators became dominant later on).

So it’s right on the cusp of that change. It’s an interesting question that someone who knows that EQ better than I do will have to answer. Note that Pultec continued to use MP even in its solid state units in the 70s.

I suspect that since it was a toroid rather than a pot core, it was probably MP. But that’s just an educated guess.
 
Thanks for your answers. I suspect its MP toroidal kind too but no sure.  I'm gona try ferrite path first because to do a toroid with such an amount of turns would be very difficult. On last tap it has near 0,8H. With ferrite N48 at AL:630 are more than 1000 turns. A MP toroid core has lower AL than that... I looked for someone with capability to do toroid mp inductors but no luck with that  :'(

Salut!
 
Cinemag makes a tapped inductor for the Pultec, maybe you can cross that over. I believe Sowter makes one too.

use 78 material from Ferrite for low turns.
 
Hi. Again Thanks for all info and help from people here in this fantastic forum.
It's been a while since I started that thread. Finally I have a working unit  :). Finally used ferrite core N48 640nm material for doing the multitap inductor. Basically using formulae we used the taps on: 6,3mH, 9,3mH, 15,4mH, 23,5mH, 46mH, 92mH, 200mH, 330mH, 481mH, 698mH.
And for caps: 35,2nF, 53,8nF, 90nF, 133nF, 267nF, 550nF, 1uF, 1,680uF, 2,670uF, 3,770uF.

With a friend we gonna do some kind of replica/recreation unit soon, for music production. Now we are recabing historical and technical information. We have problems finding year of altec 9069b aparition. We find them in some catalog from 60's but not sure about when it appeared for first time. Has anyone an idea of year of creation/aparition?

Thanks!  :)
 
Apache5 said:
Hi. Again Thanks for all info and help from people here in this fantastic forum.
It's been a while since I started that thread. Finally I have a working unit  :). Finally used ferrite core N48 640nm material for doing the multitap inductor. Basically using formulae we used the taps on: 6,3mH, 9,3mH, 15,4mH, 23,5mH, 46mH, 92mH, 200mH, 330mH, 481mH, 698mH.
And for caps: 35,2nF, 53,8nF, 90nF, 133nF, 267nF, 550nF, 1uF, 1,680uF, 2,670uF, 3,770uF.

With a friend we gonna do some kind of replica/recreation unit soon, for music production. Now we are recabing historical and technical information. We have problems finding year of altec 9069b aparition. We find them in some catalog from 60's but not sure about when it appeared for first time. Has anyone an idea of year of creation/aparition?

Thanks!  :)

Not sure, it's also unclear whether there's any evolution, or it's just a new branding of the versions that came before.  The Altec shows up about the time Don Davis came to Altec from Langevin (1961?), then Cinema Engineering before that, all have versions.  Before that are the UTC and RCA versions in the 1930's, all are the same basic technology, many cases the same frequency points.  Then there's the Universal Audio version.
 
Apache5 said:
Hi. Again Thanks for all info and help from people here in this fantastic forum.
It's been a while since I started that thread. Finally I have a working unit  :). Finally used ferrite core N48 640nm material for doing the multitap inductor. Basically using formulae we used the taps on: 6,3mH, 9,3mH, 15,4mH, 23,5mH, 46mH, 92mH, 200mH, 330mH, 481mH, 698mH.
And for caps: 35,2nF, 53,8nF, 90nF, 133nF, 267nF, 550nF, 1uF, 1,680uF, 2,670uF, 3,770uF.

With a friend we gonna do some kind of replica/recreation unit soon, for music production. Now we are recabing historical and technical information. We have problems finding year of altec 9069b aparition. We find them in some catalog from 60's but not sure about when it appeared for first time. Has anyone an idea of year of creation/aparition?

Thanks!  :)

Those 9069b’s may have predated the 250-T3 consoles from around ‘64/‘65, which I believe were the ones that were stock with 9465 preamps. Do some research on the dates for the 458a and 459a pre/program amps. The filters might have been introduced around the same time as those, with the early 250 consoles.

But EMRR is the historical expert here. He may know if anyone does.

EDIT: EMRR and I were posting at the same time I guess.
 
Nice!. Ok I have a catalogue where apears 9068a, 9069a and 9067a (the other two together). Its from 1965. The 9069a seems exactly the same as 9069b, dont know the diference between these.

The 250 console seems that has a RIAA EQ but it seems that dont has HPF and LPF.

Its very dificult to find information from these period about all that...
I am very grateful that I can still find people like you with knowledge about all this.

This kind of filter "T-filter" (if I name it correctly) seems a standart topology and sure it was the same as older... maybe they actualized mechanics and components.
If we dont find more maybe we must say that is from early 60s  ;)

Arnau
 

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