hardware volume control

ODYSSEY · 03-12-2001, 04:29 PM

How would I go about making a hardware volume control? I'm using a SB Live and all four channels. Before the sound get inputed to the amp I need a hardware volume control. I want to make one knob controling all four channels volume. Is there a POT that contols for items? How do I use the POT, ie which wire goes where? What type of POT do I need. I want to be able to mount the knob in-dash or console. Any suggestion?

ODYSSEY

Arby · 03-12-2001, 06:04 PM

There is a small, 5 pin header on the sblive that you can hook up momentary switches to to control the volume. Lemme go find some more info.

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http://mp3box.2y.net

Arby · 03-12-2001, 06:36 PM

I'm planning on doing this for my next project, so I dug up a little more info. I took a couple of pictures of my SBLive:

http://mp3box.2y.net/temp/livevol1.jpg
http://mp3box.2y.net/temp/livevol2.jpg

I belive a switch between the top and the bottom would be volume up, and a switch between the middle and bottom would be volume down.

Hope this helps you.

ODYSSEY · 03-12-2001, 08:01 PM

That is a good idea. But what if your system/sound card happens to lock-up? I want something that not depentant on the computer. Any suggestions?

ODYSSEY

Kain101 · 03-12-2001, 08:29 PM

use a poteniometer (it is basically a variable resistor)... wire it so that it has an input and output and u can just connect it between your existing wires with out cutting them

TheDingo · 03-12-2001, 10:04 PM

I just have volume control built in to hot keys on my touchpad...

ODYSSEY · 03-12-2001, 11:36 PM

Any type of poteniometer? Do I need 1K, 10K?I was thinking about using 4 like the one below. Then just stacking the four on top of each other and put a rod in the hole.

Caviar · 03-12-2001, 11:55 PM

chek out Tehota's thread...... he has added volume switches to his Passat.

Kain101 · 03-13-2001, 12:52 AM

go with the 10k... and i like the stacking idea

Mp3_Truck · 03-13-2001, 02:53 PM

im staying away from the soundblaster live and going with a hercules 5.1 with upfront bay contols and rear rca ouputs, i beleive they make a model with hardware volume built into the bay, i just have to see if it controls the front bay outputs or the rca rear outputs.

ODYSSEY · 03-19-2001, 06:39 PM

ok, I got my pots. Stupid question. How do I use it? I have three connectors? I know one is input, output, then ?. Sorry I don't know too much about elec.

ODYSSEY

Bj · 03-20-2001, 03:58 AM

wire it like this

(o) front view (cool ascii view hey)
|||
123

pin 1 is ground
pin 2 is output
pin 3 is input

so for the left channel......

the active wire from the sound card, goes onto the 3rd pin, your amplifer input hooks up to pin 2. The shield from both amp and sound card, go to the ground pin, but unless you've done this before, it may be a tad hard to understand.

why? because 10k impedance had to match your soundcard output and your amplifier input.

If you have them unbalanced, you may experience noise from the amp when you have the pot in the halfway position.......then you will have to build a matching resistor network.......

But in most cases just wire it up and it should work

Enjoy

[This message has been edited by Bj (edited 03-20-2001).]

Dtrixter · 04-09-2001, 01:57 PM

The potentiometer stacking is a good idea... one word of caution though, the pot that you have choosen is not a "heavy-duty" type. It will wear out fairly quickly used frequently. It will also be rather delicate and need to be handled carefully.

Aaron Cake · 04-09-2001, 04:21 PM

BJ explained it perfectly, but there is one thing to add:

Be sure to get a high quality sealed pot. Normal pots are very cheap and wear out quickly with any sort of use. Also, sealed designes keep the horrible dust found in cars out. When I clean out my player, the rag comes out pitch black from all the greasy dust that is formed. Terrible stuff. Normal pots will last a few months then become crackly.

You will pay more for a sealed pot (probably close to $8 a piece) but it is worth it. Multiturn is not necessary.

jjohnson · 04-11-2001, 07:02 PM

A company called Xicor ( http://www.xicor.com ) makes some really neat little digital pots. They are basically a small DIP package with no external components needed.

You hook 3 pins up just like a normal pot, and then connect 2 momentary switches (or a rotary pulse switch if you want an "analog" feel to it) to the digital Up/Down inputs. It works exactly like a digital car stereo with up and down volume buttons. If you hold down a button it will accelerate to zero or full volume.

They have several models with different resistance values and the IC's even have onboard nonvolatile flash memory to store the volume level even when power is removed! They offer linear and logarithmic versions (for audio).

For a stereo signal you could gang two together so they step in unison. There's even a mute input you could connect to a small switch.

I have a couple of these I was going to mess with but never got around to it. I'll be sure to post some info if I ever use them.

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