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Cabinet speaker questions (what to do about volume)

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eds1275:

I might make a few of these for my own purposes. If I do does anyone want one? My soldering skills are top-notch. Wouldn't be for a while but I am going to be doing a mouser order in the not so distant future.

Green Giant:


--- Quote from: Afterburner on December 29, 2011, 01:25:23 pm ---
--- Quote from: Green Giant on December 15, 2011, 07:43:04 pm ---I came up with this idea quite a few years back.  I have it similar to what I assume you are doing, 2.1 speaker system with sub in bottom and 2 above monitor.

I bought a stereo potentiometer similar to one of these:  http://www.radioshack.com/product/index.jsp?productId=2062359

It works great.  About the only thing I think I should have gone with is a pot that has a longer turn down.  Right now I twist it about 180 degrees from nothing to LOUD.  


--- End quote ---

I like this solution.  I just promoted an older 2.1 set of powered speakers to duty in my MAME cab.  I was looking for a more convenient way to control volume.  On older version of MAME I had a dedicated VOLUME button that would bring up the volume slider.  But now MAME has switched to a VOL UP and VOL DOWN arrangement.

My remote speakers are connected using plain old speaker wire at both ends, so inserting a pot would be easy.

Regarding the range of the pot, you listed a 100k Ohm pot as your volume control.  Should I go to a higher resistance pot....say a 250k or 500k pot to get more range in volume adjustment?  Or am I thinking about this backwards and I really should go to a 50k pot?

I'll get a two channel pot and probably mount it to a small metal plate.  Then I'll use my router to hog out a thinner area for the plate on the inside of the cab and epoxy it in place so that the shaft comes through enough for me to grab it and make an adjustment.  

--- End quote ---
For the pot I am not exactly sure.  I would do an internet search on that one.

I think I bought the only stereo pot I could find in frys, but I am sure you can get a wide variety online.



It might even be that you need a non-linear pot to scale the audio in a linear method.  Anyone have any input on the exact logistics of potentiometers and audio output?



Update:  I did a little digging and you definitely want to make sure it is a logarithmic pot.

Even more digging and I found this guys random and very well written write up about doing exactly what I did.

http://scarvell.net/andrew/blog/?page_id=4

I guess great minds think alike.  You want a dual-ganged logarithmic potentiometer.  I am not sure if resistance is that important, what you want to find is which one has the greatest degree of turn.

Or more simply 360 degrees vs 180 degrees means you must turn it a full circle from nothing to loud as opposed to half a circle.  The greater the turn the greater you can tweak the audio.

Afterburner:

Wow...that was a great write up.  Thanks!

Another interesting question on speakers....

Today I scavenged a bunch of parts from a nice DLP TV that died prematurely.  I got some nice looking speakers out of it and was thinking of using them in my cab.

There were two pairs of speakers.  Each individual speaker is marked at 16ohms impedance.  My current speaker set with the amplifier built into the subwoofer says the speakers should be 4 ohms or 8 ohms.

I used a multimeter and tested the 16ohm speakers and measured 7.3ohms each.

So now I'm wondering if each individual speaker is really 8 ohms and 16ohms for the pair.  But each individual speaker coil is marked.  I'm thinking I can't measure impedance the way I did it.

darthpaul:

I'm using an L-PAD, since my coin door has three coin slots, I drilled a hole through the center change door and mounted it there.

Dawgz Rule:

The easiest thing I found was to use PC speakers that already had a volume knob.  I simply attached the volume knob to the bottom of the control panel with velcro.  Looks clean and also has a headphone jack built in.

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