Introduction: DIY Passive Car Woofer/Bass Control PART 1

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Hello!
In this Instructable I will take you through few simple steps, how to make a volume knob.

This circuit is universal for any kind of passive volume control application, where you want to manipulate with input signal. You can put this kind of device/module between any signal source and preamplifier, amplifier, etc.

It's very useful for example desktop headphones or similar items, where you can only change volume in taskbar. I made mine to control the bass level for my car woofer. I will mount it in car, when I make Part 2.

Step 1: Parts List

This project is simple as one potentiometer :)

You'll need:

- 1x Dual 50kOhm potentiometer (it doesn't matter if it's linear or logarithmic)

- 1x Project box

- Some wires (I used 2 colors)

- RCA male and female connectors (I got mine in local electronics shop)

- Hot glue gun

- Soldering iron and some solder

- Drill

Step 2: Potentiometer Wiring and Enclosure Prepairing

In this step, you have to wire potentiometer as it is shown on the picture. I have chosen the left side for common ground connection and right for input signal. Pins in the middle are meant for signal output.

So when potentiometer is in extreme left position, signal output is shorted to the ground, so nothing comes to your amplifier and you hear nothing. When pot is in extreme right position, it has shortcut to signal input pins and the music or bass effect is the loudest.

When you are done with that, you can start assembling your box. First you should drill two holes on one side. They have to be large enough to put female RCA connectors through. Then you solder wires to the right pins. I used black wire for ground and red for signal.

On the other side I drilled one hole and make two twisted pairs of wires (using battery drill) and soldered them on male RCA plugs.

I secured twisted pairs of wire with hot glue and female RCA connectors with screws.

Step 3: Closing Your Box and Wiring

When you're done with soldering, there is only one thing left to do. Close that box! :)
Drill a hole in top piece of the box anywhere you like it to be. I put it on the left side, because I want to add a switch later.

Also, before closing, check if it works fine on your musical setup. Mine still isn't in my car, so I tested it in my room with PSU.

If everything is alright just put the cover on and screw it on. If you wish you can add a knob any shape, that fit on your pot. You can also use different pots, like slide pot or pot with switch built in.
Talking about switches... In second part of Instructable I will show you how to add one. But not ordinary one, I will use one or two push buttons and IC with latch switch.

Till next time,

See ya :)