Vintage Synth Explorer Forums

Hi I want to build a simple passive attenuator, and thought of this :


but I was told that it is not right and that it should be wired like this :


Can anybody please explain why ?
many thanks

Either one should work, actually. The impedance loading of the two are different, of course. You'll probably also find the behavior of the volume taper to be quite different between the two.

Many thanks for the reply. Yes i have tried both of them and they do work with different behavior.
I have a question regarding wiring #2 ; if the pot is fully closed then all the signal is shorted to the ground, muting the signal.
Can this short damage the circuit that sends its output to the input of the attenuator? Should a resistor be placed between the pot and the signal to avoid short circuit?
Wiring #1 produces no short circuit and I thought that it should be the best solution but as I was advised it is not. I really can not understand why...

I would have used #1 myself for the reason that you stated...you are shorting the output with #2. A resistor in series would take care of that.

You probably have noticed that with #1 you can't attenuate to no signal at all.

I am glad I am not the only one thinking this way;)
I have tried both and as you have mentioned , you can not get a clear mute out of wiring#1.
I am feeding 1khz pulse waves into the attenuators and what puzzles me regarding #1 is that by looking at the oscilloscope I have noticed that the signal gets "noisy" when the pot is turned near its end . Wiring #2 looks smoother.
That's why I seek some logical explanation

Number 1 you're limiting the current not dividing the voltage. If you run a wire from the unconnected lug on the pot to the sleeve then you should get regular behaviour from it, including a constant impedance and full mute of the signal.

Number 2 doesn't really make sense to me electrically. I can see how it works, but I don't know why you'd use it.

thanks for your input, I will try your wiring suggestion and I will report back.

Stab is of course correct. I was wondering why you weren't connecting the third lug myself

Actually I was looking for the simplest solution while testing signals, not full mute , just a bit of attenuation.
I am using croc clips on pots , so less wires the better.

So to say all 3 wiring methods actually work. Wiring #3 seems to be the best option

Wiring #1 , as Stab kindly pointed out works by limiting the current. Is it bad ? I dont know, it works though.
Wiring #2 , was actually my bootlegged version of this :


and finally wiring # 3 ,as Stab suggested that by connecting the third lug to ground, it will be dividing the voltage and providing a constant impedance.