Volume Control Potentiometer Question

[myrmidon]

Hi There,

I have been reading the various posts on the forum about adding an inline pot to the audio 'line out' (non-amplified) signal. However, I want to do something slightly different. I find that most Arcade PCB's volume pot don't give enough granular control - either the audio is way too quiet, or I move it a tiny bit, and suddenly the cabinet speaker is pumping major volume.

So my plan is to wire an additional pot inline in the harness (somewhere between the PCB and speaker). However, after a quick glance at Radio Shack's site, I see there are quite a multitude of pots available (all with different resistance ratings). Whilst I understand the fundamentals of electronics, I have absolutely no idea which one one would use for this application.

Can any of you guide me in the right direction?

Thanks
Olaf

[cholin]

The reason youd have that experience with the low - high volume is beause the resistance on the pot is too high (i think?).  So in order to travel from 0-100k resistance in one turn, every nudge will make quite a difference.

If you use a single 100k (ish?) potentionmeter with several turns or something, it should do the same...

Another reason for the immediate loudness *could* be log pots.  Loook it up, hard to explain.  They have 2 variables so it doesnt tune linearly.

[myrmidon]

Thanks for the response cholin.

The pots that I am referring to are the one that are already installed on the original arcade PCB's. Therefore, I don't want to replace/remove those, I simply want to add an additional pot inline.

Is this something that one can do, or is the increased resistance 'bad' for the onboard audio amps?

Apologies for the layman's terms, but I don't know what the impact will be to the electronics.

Thanks

[Stobe]

I don't think you'd have any problem with doing this.  In theory, you're only adding another resistive element in series with the existing pot.  They would simply be additive if there was nothing else between the PCB's output and your new pot.

As for the actualy resistance to look for (as per your orignal question), I'm not sure.  You'd almost have to try one out to see if it gives the reponse you like.  Obviously starting with your PCB "too-loud" and adding your new pot to decrease the volume.

Hope that helped a little.

-Stobe

[RandyT]

Most amplifiers are designed with a specific speaker load rating in mind, usually 2 to 16 ohms, with 8 ohms being common.  Adding a pot in series with the speakers will change the resistance and may be a problem, possibly enough of a problem to be detrimental to the amp circuit, but not all amp circuits are the same so YMMV.

RandyT