Gain/Vol Pots

[mmadscientist]

Good Morning!   Question: All my completed builds and breadboard projects have one thing in common.  Both Gain and Vol pots do not have the dramatic sweep I thought they would.  I expected that when marked as a volume pot, the range would sweep from no signal to wide open, same w/ gain.  The result however is much less......  In some cases the signal level remains the same and the "apearance" of slight volume reduction occurs.  Why is this?  Is it me?  Thanks in advance......................

[mmadscientist]

c'mon guys......  Am I the only one w/ weak vol??

[Nick Ellingworth]

Are you using log or linear pots?

If you are using linear pots try some log pots.

The reason for using log pots is that the human ear's reaction to volume is logarithmic. for more info read the the secret life of pots at: http://www.geofex.com

[Peter Snowberg]

Patience....

You can't expect answers to questions with no data in an hour and a half. It's nice when it happens, but give some time for your answers to appear.

You didn't name any circuits and we don't have any schematics so it's much like asking someone who has never seen you before why your leg hurts. It's just hard to guess.

Volume and Gain are generic terms that get misused quite often, but you're right about what you should expect most of the time from a volume pot.

I have a little breadboard setup for prototyping effects that includes a DPDT switch to true bypass the circuit under test. You need a comparison option like that to get a frame of reference.

More info please.

[mmadscientist]

Thank you for your replies.  The cct's that I've finished and boxed are the bazz fuss and buzz box.  I have been breadboarding all kinds of stuff.  I am using log pots for all vol. applications.  I have followed the layout/schematics to the tee.  It's wierd, most of the time the percieved level reduces a little, but the actual signal level remains at the same level (I can tell by watching  the meter in sonar).  Sorry if I was impatient.

[Peter Snowberg]

It's cool; no worries.

Do you have a meter? If so, turn the volume pot you're using all the way up and measure the resistance between the wiper and the CW lug (the one on the right as you face the shaft of the pot. I've seen pots that still have a good bit of resistance in them even when they're turned "all the way" in one direction or the other and that couple play into what you're seeing.

You can try reversing the CW and CCW conections on your volume pot to see if that is the cause.

Some circuits don't have too much voltage gain (think of that as volume increase) so a problematic pot can cause the situation you're seeing.

[mmadscientist]

The thing thats crazy is that this pot thing is just about the only common denominator between everything I work on.  I mean everything.  And all different pots from different suppliers.  I have no idea....  I dont even know what I could be doing wrong!  How many ways can you screw up a pot (repeatedly) ?  I will say this though: When I replace a resistor w/ a pot everything is cool.  Full sweep.  When adding vol or gain....  weak.

[mmadscientist]

Sorry I forgot to say this: I will check all those things again so I'm not wasting anyones time.  Thanks.

[mmadscientist]

Okay here it is:  I read something when I started this "journey" about checking your ego at the door when debugging cct's (paraphrasing), that usually it's something simple that you couldn't believe you could ever have screwed up.  Thanks for the replies, in checking everything and trying to connect the pot in evry combo possible I caught the problem.  I misunderstood and was connecting both lugs back into the cct path, instead of one out and one to grd.  Thanks for your time man.

[Peter Snowberg]

GREAT!

So I'm guessing you have proper volume now?

It's always great to hear of circuits that suddenly start working.

While it's important to check everything over and over yourself, if you get stumped please don't hesitate to ask for help here. After all that's one of the major functions of this place.

We have all drank from a well that our own hands did not dig.

Best of luck with all your builds and welcome to the community!

[Mark Hammer]

Hands up, all of you who were ever in such a big hurry to finish something that you forgot to connect a ground wire from the 3rd lug of a pot to ground.  I see a few of you in the back who look a little uncomfortable.  C'mon now, 'fess up!!  I've done it, you've done, and lord knows we'll all do it again.