CLC High Pass T Filter Rotary Switch Pole count

[LazyTurtle]

Hi, after checking several schematics I´m trying to figure out why is a 3 pole rotary switch placed in most designs I´ve seen.

For example, for a CLC high pass T filter the rotary switch should connect to both capacitors for each frequency, but the multitapped inductor would share common GND with all the stages.
So, for a 6 frequency steps HP T filter, wouldn´t a 2P6T  switch be enough? Check the attached image.


Thanks

 

[abbey road d enfer]

Hi, after checking several schematics I´m trying to figure out why is a 3 pole rotary switch placed in most designs I´ve seen.

Can you point to a specific example?

 

[LazyTurtle]

I think the altec 9067b is designed following this topology...
I´ve checked several new high pass filters  based in the Altec and also think they have that topology.

 

[abbey road d enfer]

I think the altec 9067b is designed following this topology...
The Westfinga high pass filter based in the Altec also has this topology...

Please post schematics, can't find them.

 

[LazyTurtle]

You can check this topic where this type of rotary switch is mentioned:

https://groupdiy.com/index.php?topic=51217.0

As you can see the switch seems to be 3 pole...but I still don´t get why...

 

[abbey road d enfer]

You can check this topic where this type of rotary switch is mentioned:

https://groupdiy.com/index.php?topic=51217.0

As you can see the switch seems to be 3 pole...but I still don´t get why...

Where can I see that? There is no schematic and the pictures are extinct.

 

[LazyTurtle]

It is mentioned in the post itself.
Search for the "switch" word.

 

[LazyTurtle]

This is the picture of a unit a built several months ago.
It is a unit bought as a DIY Kit.
This is a CLC T filter and as you can see (hope it is clear enough) the rotary switch uses three decks (yellow, black and green cables, one colour per deck).

 

[LazyTurtle]

In this video you can check this DIY kit better.

https://youtu.be/hGeKeApbq0gs

As you can see this unit uses 3 decks, 1 pole per deck.

 

[abbey road d enfer]

It is mentioned in the post itself.
Search for the "switch" word.

Why not saying which post? I had to read the whole thread to find the shade of an answer in post #19.
It looks like Altec used a particular arrangement that needed a 3rd switch. See attachment.
I don't know why they would use this arrangement; I can't imagine one second their engineers overlooked the simpler 2-wafer arrangement.
My only guess (but it should be substantiated with more hard evidence) is this arrangement has less interaction between sections if there are pull-down resistors.

 

[LazyTurtle]

Thank you very much for all the valuable information, and sorry for the reference to the post I sent.
I thought maybe searching for "switch" in the topic you could've reached faster to the post itself.