UTC A11 Input Impedance Switching

idylldon · Apr 8, 2012

Hello everyone,

I'm planning to use an A11 for a tube pre I'm putting together and found this schematic for selecting the input impedance:

http://www.frontiernet.net/~jff/pultec_mb1/images/DualPultecMB1.pdf

It appears that terminals 1+3 are connected together and are connected to two of the terminals on the switch. The number 2 terminal is separate. Does that appear correct?

Thanks,
--
Don

mitsos · Apr 8, 2012

No, connecting any two terminals together would short that part of the winding and quite possibly damage it. To me it looks like switch position 1 is going to pin 3, position 2 to 2, and position 3 to 1. Which seems to make sense since impedance would increase as you turn the switch.

idylldon · Apr 9, 2012

Yeah, that was my other thought but it sure is awkwardly drawn.

Thanks!

Cheers,
--
Don

PRR · Apr 9, 2012

> It appears that terminals 1+3 are connected together

It is supposed to be two crossovers. Like an LA freeway. Bad idea for drivers. Confusing on drawing.

Cheating with colored pens:

idylldon · Apr 9, 2012

Thanks, PRR! I was wondering why the person who drew it didn't just do it like you did!

Cheers,
--
Don

UTC A11 Input Impedance Switching

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UTC A11 Input Impedance Switching

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