Need to make a RCA volume control (Headunit-less install)

[Sway]

Hi guys,

Doesn't really fit in this forum, but there's not an I.C.E forum so tough!

I've removed my headunit, and have fitted a cheap amp to run my HTC Desire HD.

All running fine, except the software volume control is awful. Levels change massively sometimes for small volume changes, levels 'switch' between really low and really high.

So I need to make a simple (I think!) volume control to mount in the space the headunit has vacated (there will be a few other switches incorporated into a new panel)

I need it to have RCA inputs and outputs, just a single pair each side. A decent volume knob (gotta feel nice in the hand!).

It will be fitted between the headphone plug - RCA lead plugged into my phone, and the RCA inputs to the amp.

Sure it's a pretty simple circuit, but whilst I can solder to a decent standard, circuit design is beyond me.

What do I need, and what do I do?

Cheers,

Sam

[TonyRPH]

All you need is a simple (dual gang) potentiometer, with a 'logarithmic' (sometimes referred to as audio or LOG) taper.

If you want one with a quality feel, then buy one made by 'Alps'

Here's a link to a suitable one

50k or 100k will do - but 50k probably better - but if you need to buffer the output then I would use a 100k.

Here is a detailed explanation of how it all works.



You want to keep the leads between the output (known as wiper) of the potentiometer and the amp as short as possible, otherwise you will get high frequency roll off. (reduction of high frequencies, dependant on the position of the pot.)

So if you have the amp at the back, and the potentiometer at the front of the car, then you'll need a buffer, to reduce the output impedance.