Volume pot question

[Laudanum]

I posted regarding the pot value and input impedance on the tech board.  But I have a more basic question about pot values.
Does a 100K pot have more "range" than a lower value pot?  In other words, would the increase in volume be more gradual with a 100K pot versus a lower value pot?
I can assume that the answer would be yes if only the pots themselves were considered but that would probably be a poor assumption when the circuitry that follows is part of the equation.
So, I'll await answers from the more technically savvy individuals than myself ... which means just about anyone

Thanks

 

[Grainger49]

This answer assumes that there is no buffer between the input and the volume control:

No, any volume pot, 10k ohms to 100k ohms, will range from no volume to the full input volume.  The reason for changing values is that the inputs need to have a resistance that  1) is high enough to feed the full low frequencies to the preamp/amp and 2) not current limit the output stage of the source (because of a low impedance/resistance).  Putting a source output stage into current limit distorts the sound.

The sensitivity of the preamp and the gain control the point at which you can drive your amplifier to full power.  If you have a "hair trigger" problem a series resistor between the input and the volume pot will allow you to adjust better at the lower range of the pot.  It also limits the full output from the pot.

Just to be clear, potentiometers are linear and log or audio taper.  In a linear taper 1/2 way up is about 1/2 of the total resistance.  In audio taper pots 1/2 the way up is not 1/2 of the resistance.

 

[Laudanum]

Hi Grainger.

I understand that any value pot will range from no output to full output.  I also learned about the series resistor trick (or L-pads to present constant input imped. to source) for a pot that gets too loud too soon.

I was just wondering whether a 100K pot would have less "hair trigger" effect, as you put it, compared to a 10K pot.

If I understand you correctly, the answer is no ... that If I have a "hair trigger" problem with a 10K pot I will also have one with a 100k pot. 
If I misunderstood, please correct me if you would.

Thanks

 

[Grainger49]

Hi Grainger,

. . .  I was just wondering whether a 100K pot would have less "hair trigger" effect, as you put it, compared to a 10K pot.

If I understand you correctly, the answer is no ... that If I have a "hair trigger" problem with a 10K pot I will also have one with a 100k pot. 
If I misunderstood, please correct me if you would.

Thanks

Right the value of the pot makes no difference.  Like above, the series resistor limits the volume across the range.  I.E. it makes the lower settings lower and the highest setting lower.

 

[Laudanum]

Thanks

 

[Paul Joppa]

An "audio taper" or "log taper" pot will have less of a hair-trigger effect than a "linear taper" pot.

Look for a data sheet - they are readily available from the web catalogs of the major suppliers. Try different brands until you find one that shows the resistance plotted against the rotation angle. Here's a sample search at Mouser:

http://www.mouser.com/Passive-Components/Potentiometers-Rheostats/Potentiometers/_/N-5g9h?P=1yzxs46Z1z0vkozZ1z0z7xgZ1yzvm31

 

[Laudanum]

Hi Paul.

I was planning on either using the included Alpha pot or an Alps 100K Blue Velvet that I already have in the parts bin.  I was asking because I have a small op amp headphone amp that has a 10K alps audio/log taper pot. It also has a gain of 5, which, if I did the conversion right, should be close (just a little lower) than the 15 db gain of the Crack.  So knowing how that 10K pot behaves with the same source I will use with the Crack, I was wondering if the 100K pot would act differently.  But based on Graingers answer and your info, it appears that it's not the pot value but the way the pot tapers.  And knowing that the audio taper pots arent true audio tapers, different pots of the same value from different manufacturers will behave differently depending on how the manufacturer decided to "build" the taper.  So, I guess I just wait to see how the pot behaves after the build.

Good info, thanks gents.