How to measure volume output for pot selection?

[Chris4943]

I want to build an inline volume control. I don't know what size potentiometer to buy. How do I measure what's coming out of the volume output in order to buy the correct pot?
I've got a multimeter standing by but not sure where to stick it...

 

[rayma]

I want to build an inline volume control. I don't know what size potentiometer to buy.

If you have transistor system, a 10k volume control is pretty much standard.
With tubes, it can range from 100k to 500k. What are the components before and after the control?

 

[Chris4943]

If you have transistor system, a 10k volume control is pretty much standard.
With tubes, it can range from 100k to 500k. What are the components before and after the control?

Thanks for responding!

It's actually the headphone output of a Behringer UMC404HD audio interface.

An externally hosted image should be here but it was not working when we last tested it.

Also, I'll be splitting the 1 headphone output signal up to 4 different volume control units with headphone plugs. Not super high end headphones, run of the mill skull candy hesh 2 type headphones.

 

[wayne]

You might want a buffer for each with a volume control. The headphones are pretty low impedance and to drive 4 sets with pots is a tough thing to do at least with lowish distortion.

 

[Chris4943]

What's a buffer? The only thing I can find on google is in regards to software buffers.
Is there a measurement I could take from the output with a multimeter that would quantify how much power I've got, which I will then divide by 4?

 

[rayma]

I'll be splitting the 1 headphone output signal up to 4 different volume control units with headphone plugs.

Why can'y you use the headphone level control on the unit?

 

[Chris4943]

I guess l could. Im making little breakout boxes anyway with a headphone input so I thought it might be nice to have individual volume controls for each listener.

 

[rayma]

I guess l could. Im making little breakout boxes anyway with a headphone input so I thought
it might be nice to have individual volume controls for each listener.

Ok, then you definitely want to have 4 parallel 10k level controls, with a buffer for each wiper.
The Behringer should have no problem driving the 2.5k load. A buffer is a circuit with a high input R
and a low output R, with a gain of 1x (0dB). It could even be an op amp, if it can drive the phones.

You'll also need a power supply for the buffers. The Behringer level control should be set for the
maximum level needed, and then the individual controls can reduce that for each pair of phones.

 

[Chris4943]

Awesome, thanks. Is a buffer a part of a specialized pot, or is it a separate component?

 

[sgrossklass]

No, a pot will just be a pot. Motor drive was the fanciest those ever got. You will need to add buffer circuitry externally.

 

[Fast Eddie D]

This guy just wants volume controls like those cheap controls on cheap phones. not any fancy buffers.

What are the impedance of the headphones?

 

[Chris4943]

35 ohms.

 

[Fast Eddie D]

So you're going to drive 4-35 ohm headphones with your headphone amp? Is it rated for 8 ohm load?

Have you thought this out?

 

[Chris4943]

How do I measure what's coming out of the volume output in order to buy the correct pot?
I've got a multimeter standing by but not sure where to stick it...

See my first post.

All I have been asking for is how to measure and quantify what I have, so that I can 'think it out'.

Given the lack of an answer, I can only assume that you guys don't know how to do that. Fine, I won't let the door hit me on the way outta you guys' corner of the internet.

Not for nuthin, but I'm literally already doing it right now. I'm driving 4 headphones with 4 volume controls with no problems. The sky did not fall. Nothing caught on fire. Given that it is something I am experiencing in reality, you kooks are not realistic.

I thought I'd try my hand at figuring out some of the basics like how much power actually is coming out that I have to work with before I buy more pots to do more of what I'm already doing, but I came to the wrong place. My bad. Have a good one.