EmRR

Re: Altec 9067b Passive Filter
« Reply #20 on: May 19, 2013, 01:33:09 AM »
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde


EmRR

Re: Altec 9067b Passive Filter
« Reply #21 on: August 25, 2013, 01:31:09 PM »
it's LCL and CLC type filters

I cracked open a semi-faulty Langevin 255-A, and they use the other constant K variation for high pass, L shunt, series C, L shunt.  This one appears to have one open L, so it's half the filter slope.  Audio Cyclopedia has nice comparison charts of the various constant K filter types. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

Re: Altec 9067b Passive Filter
« Reply #22 on: December 28, 2013, 10:02:56 PM »
Hello ,

I ve open a Langevin 255a&b because the swith inside ( mini-copper ) is broken
I don't know how to repair ..
I've buy a 4 pole Rotary switch but i on't know a to put correctly the wire ..

A friends say that maybe is possible to use electronic relay ( a lot :) ) link directly to the pcb ...any ideas ?

here the photos inside the tube :)

https://www.dropbox.com/sh/w9sdsv8cbllnwct/MSQUERJaBC

Original :

http://rhythminmind.net/STN/?page_id=2361



Thanks
Sorry for bad english i'm french[/img][/img]

EmRR

Re: Altec 9067b Passive Filter
« Reply #23 on: December 30, 2013, 10:12:46 AM »
You might get another rotary disc from a Langevin attenuator, but I can't say for sure.  I have a few that have broken terminal boards, I'll try to remember and see what I can learn. 
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

Re: Altec 9067b Passive Filter
« Reply #24 on: October 10, 2017, 02:03:44 PM »
It is not too hard to work to the values of inductance and capacitance needed. Attached is a screenshot form LTspice showing the two basic circuits driven and loaded by 600 ohms. The formulae for calculation of the L and C values are given above each circuit and the values for 1KHz are shown on the circuit. Z0 in this case is 600 ohms.

Cheers

Ian

Checking this circuit I see it is not correctly designed.
Capacitors value must be multiplied by 2 in order to set the correct cut frequency.

Re: Altec 9067b Passive Filter
« Reply #25 on: July 16, 2020, 05:40:43 AM »
Hello, someone who can take me out of my ignorance and enlighten me on how to calculate what inductance and what capacitance to mount so that it filters at the desired frequency, that is to say that in a filter it passes high chebyshev it achieves a filtering in for example 7500hz that inductor And what condenser do I have to put to achieve a filter with an enhancement of at least 5 / 10db of narrow bell, and a drop of about 20db.
Thank you very much in advance.


 

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