[A3rd.Zero]

should rotary switches for a passive or active preamp (for source selecting purposes) be non-shorting or shorting?

Thanks,
Milo

 

[Budgie]

Thats a good question! When I get home from work I will measure the source selector in my preamp and see which it is. I will try to predict the future and say it is a non-shorting type. (seems like I can remember a faint bleed through from the radio tuner audio when the volume is maxed out, so it would have to be a non-shorting to hear that.)

 

[ofb]

is there a trick in the question that i'm missing? you'd want non-shorting, otherwise you'd be feeding in two sources at once, briefly. shorting would be for a stepped attenuator so you don't briefly have zero resistance and thus full gain.

 

[lini]

Quote:

Originally posted by ofb shorting would be for a stepped attenuator so you don't briefly have zero resistance and thus full gain.

I'd also vote for non-shorting - but are you sure about the quoted part? If I'm not mistaken, the attenuator is usually in the direct signal path (= not in the feedback loop or whatever...), so non-shorting would just equal no signal/infinite resistance - whereas the shorting type should create a lower resistance during the transistion, which should result in a short volume peak...

Greetings from Munich!

Manfred / lini

 

[ofb]

Quote:

- but are you sure about the quoted part?

there's enough ways to wire an attenuator that i'm easily confused.

let's dive into my confusion. put it in the direct signal path as you say. it has various steps of resistance. the least produces the most sound, and the most the least. in either it shunts the unwanted portion to ground. with non-shorting, you briefly have no resistance; everything goes straight into the amp and nothing is shunted to ground.

with shorting you briefly bridge two resistance steps at the same time, and the lesser takes effect until the transition point is passed.

that's what i'm thinking on my first pot of coffee anyway.

 

[lini]

Quote:

Originally posted by ofb there's enough ways to wire an attenuator that i'm easily confused. (...) that's what i'm thinking on my first pot of coffee anyway.

Well, then let's just agree on the first part, 'cause now I'm confused, too.

The advantage in bein sober is with you, anyway, because it's almost bedtime for me here - and I've also reached my second cup of grog...

Grinnings from Munich!

Manfred / lini

 

[Budgie]

I measured resitance through the selector switch and the switch does not "make before break" and it does not short the unused inputs to ground. Pretty much a regular old multiposition two pole rotary switch.

 

[A3rd.Zero]

Thanks all!

As usual I had already made the purchase before I asked the question

and it was in fact a Non Shorting now that I check the order sheet. I thought I had heard in a post recently that there was a bump heard in a non shorting switch but I may have been mistaken. It was one of those "should have gone with my gut on this one but insted I tried to remember stuff" issues. Boy I love DIY!!!!

thanks again,

Milo