Ela M 251 style polar pattern switch?
« on: February 15, 2010, 08:30:31 PM »
I tried to figure it out using this:

http://recforums.prosoundweb.com/index.php/fa/11178/20959/

EDIT: I don't know if this link is working or not? It's Ela M251E schematic

and this:

http://www.flickr.com/photos/[email protected]/3285297712/

I came up with this:

POLAR PATTERN SWITCH.jpg - 0.05MB]http://www.zshare.net/image/72618756cc62ebb9/]POLAR PATTERN SWITCH.jpg - 0.05MB

Am I on the right track? I don't quite get the pads with question marks. Why are they there? For friction? Or should they be connected to ground, grid and 110 V to make loops and not  dead ends?

« Last Edit: February 16, 2010, 04:28:14 AM by pasarski »


Re: Ela M 251 style polar pattern switch?
« Reply #1 on: February 16, 2010, 04:48:01 AM »
Maybe I have to make myself clearer.

In my drawing I assume that the blades of the selector (mounted to resistive material) are connected to 0V, grid and 110V. So the current always flows to blades. Conductor "pads" with question marks don't have to be connected, so there's a dead end  when a blade is on one of them.

In a electric circuit which is worse? A dead end or wire dividing to two parallel wires?

Sorry for my ignorance..

e.oelberg

Re: Ela M 251 style polar pattern switch?
« Reply #2 on: February 17, 2010, 05:10:54 AM »
do you want to build this switch ?

nicholas

Re: Ela M 251 style polar pattern switch?
« Reply #3 on: February 17, 2010, 06:45:59 AM »
Yes that's my intention.

EDIT: I mean a simple version of it.
« Last Edit: February 17, 2010, 06:49:09 AM by pasarski »

e.oelberg

Re: Ela M 251 style polar pattern switch?
« Reply #4 on: February 17, 2010, 02:37:32 PM »
I used relays for switching, they wont get dirty ! I have a seven pin xlr connector in my elam clone and used two pins for switching the relays with 5volt. works fine

nicholas

Re: Ela M 251 style polar pattern switch?
« Reply #5 on: February 18, 2010, 07:13:43 AM »
I'll consider relays. Or a U87 type of switch. Or a cheapo mic with a pattern switch.

Still, is my question about dead ends and parallel wires too stupid or not clear enough?


e.oelberg

Re: Ela M 251 style polar pattern switch?
« Reply #6 on: February 18, 2010, 10:04:23 AM »
I"d guess two parallel wires are worse. You should keep the wire as short as possible from capsule to switch anyway.
btw I highy recommend the tim campbell ct12

nicholas

Re: Ela M 251 style polar pattern switch?
« Reply #7 on: February 18, 2010, 05:23:28 PM »
Thanks Nicholas!

I would love to get a CT12 but as this is my first build I try to get things working with a Chinese capsule first (I know it's going to be bright) and maybe upgrade to CT12 later.

I'm actually planning to do Ela M circuit modified to 5840 tube (values from Royer mod and a G7 PSU with ~100V B+). Only values I'm not sure about is that 100pF cap parallel with the trafo (what's that about?) and the pattern eight 1000pF grid cap.

I'll probably start a new thread when I get things going on (and get to the trouble shooting stage ;) ) It's going to take a while but I'm going to be thorough.

P



 

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