Adding a volume knob to a cab?

indecks

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I have a cab that has two speakers in it, and from what I can tell, it supports stereo sound. My cab doesn't seem to have a volume adjustment knob anywhere in sight. I know that with many boards, the pcb will have a volume knob, up/down button or slider. But on some games this isn't the case, so my question is regarding installation of a volume knob.

From what I can see, I have access to the speaker wire and it is pretty easy to get to. How would I go about installing a volume knob? What parts would I need? Can I just go to radio shack and get a volume knob, strip the wires somewhere and tap the new wires into this area? Please bear with me, I don't know where to proceed here.
 
True but I'm bound to find a board or two in the future that won't have this. When I purchased this cab, the seller hooked up a 300 in 1 board which didn't have a volume knob or adjustment, and the speakers came on full blast.

I'd like to be able to lower the volume manually with a knob.
 
Unfortunately I don't think you will find it to be as easy as just installing a volume knob.

A volume control, or potentiometer, is simply an adjustable resistor. It varies the amount of resistance on a circuit from 0 ohms up to the max level of the pot (usually 5k or 10k on a volume pot). A speaker ciruit from an arcade board has a range of about 4 ohm to 8 ohm, so inserting a volume control will either damage the boards amplifier or just give you no sound whatsoever.

What you could do is add amplifier circuit with a volume control and drive the speakers separately from the audio amp on the boards. You could do this by either building your own low power stereo amp like this one : http://www.quasarelectronics.com/kit-files/electronic-kit/3115.pdf or just buy a cheap set of amplified computer speakers and retrofit it to drive the speakers in your cabinet.

Either way, you will have to adjust the output level coming from your boards to a very low level to avoid overdriving the amp circuit and distorting the sound.

True but I'm bound to find a board or two in the future that won't have this.

The only boards I've ever seen without a volume control are not amplified, so you wouldn't be able to connect speakers directly to the board without an amplifier anyway.

Brian.
 
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Unfortunately I don't think you will find it to be as easy as just installing a volume knob.

A volume control, or potentiometer, is simply an adjustable resistor. It varies the amount of resistance on a circuit from 0 ohms up to the max level of the pot (usually 5k or 10k on a volume pot). A speaker ciruit from an arcade board has a range of about 4 ohm to 8 ohm, so inserting a volume control will either damage the boards amplifier or just give you no sound whatsoever.

What you could do is add amplifier circuit with a volume control and drive the speakers separately from the audio amp on the boards. You could do this by either building your own low power stereo amp like this one : http://www.quasarelectronics.com/kit-files/electronic-kit/3115.pdf or just buy a cheap set of amplified computer speakers and retrofit it to drive the speakers in your cabinet.

Either way, you will have to adjust the output level coming from your boards to a very low level to avoid overdriving the amp circuit and distorting the sound.



The only boards I've ever seen without a volume control are not amplified, so you wouldn't be able to connect speakers directly to the board without an amplifier anyway.

Brian.

Ah. OK, thanks for the info. Thankfully the two boards I have coming to me both have volume adjustments (a CPS2 game and a Primal Rage). So I guess that answers that, lol. Thanks for the help you two.
 
You could just do it the way the Dynamo cabinets (like HS-5) are wired, or the way Atari did it and use a rheostat... will work with whatever board you put in the cabinet. Use between 50 and 100 ohms and put it between the board and the speakers. Pricey ($20-$25) new, or use one out of an old Atari cabinet.
 
I would think that if you wired the pot up as a voltage divider rather than a variable resistor then it should be okay. But I've never seen a board without a volume control, I actually removed the rheostat from my machine when I rewired it.
 
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