| Author |
Topic: Why Not 1M Pot For Volume Control? |
Jon Light
From:
Saugerties, NY
|
Posted 18 Dec 2018 2:03 pm |
|
If 500K passes more highs than 250K, why isn't 1MEG even better?
Further: IF the answer has something to do with the taper, then in an application where smooth taper is not essential (this will be a hand operated volume control for setting volume but not for riding the volume), in THIS application, would 1MEG be a good choice vs. 500K? |
|
|
 |
Georg Sørtun
From:
Mandal, Agder, Norway
|
Posted 18 Dec 2018 2:58 pm
|
|
Fact: 500K does not pass more highs than 250K, but 500K does not load a passive (coiled) PU as hard as 250K does.
As a pot is poth a parallel and serial resistor, what value a pot ideally should have in a given circuit depends entirely on what (impedance, etc) delivers the signal to the pot and what (impedance, etc) receives it after the pot.
Need more data/info to suggest an "ideal" value in your case. |
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 18 Dec 2018 3:23 pm
|
|
Thanks Georg. I am NOT solid with the theory being discussed here (I've never been able to understand the concept of loading. Which does not stop me from heeding the advice of those who know this stuff.)
Thanks for that correction.
The pot will be receiving a signal from a pedalboard with multiple stomp boxes. It will output to the combo amplifier. The output of the steel is buffered by a Freeloader.
The purpose is irrelevant to this discussion but it is to be able to feed distortion FX's with full pedal-down signal and have output level feeding the amp at my fingertips instead of having to tweak little knobs on the devices, on the fly. I am using a little clip-on box I made for this purpose and it is totally good with a 500K pot. I will be building this into the new steel I have on order and I'm trying to figure if something other than then 500K is optimum. I'm fine with no change. Unless it is recommended. |
|
|
|
Georg Sørtun
From:
Mandal, Agder, Norway
|
Posted 18 Dec 2018 3:31 pm
|
|
| Jon Light wrote: |
| The pot will be receiving a signal from a pedalboard with multiple stomp boxes. It will output to the combo amplifier. The output of the steel is buffered by a Freeloader. |
I suggest a value of 100Kohm, but pot-values between 47Kohm and 500Kohm will do equally well in your case. |
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 18 Dec 2018 3:43 pm
|
|
| Thank you Georg. |
|
|
|
George Kimery
From:
Limestone, TN, USA
|
Posted 19 Dec 2018 11:29 am Why not 1 m lot for volume control
|
|
FWIW, my Lehle 90 pedal is 2 meg output, but no pot or moving parts, just a magnet and a sensor. It is brite compared to my 120 pedal. I could not use it with my Evans amp because the Evans is a bright amp to begin with. It worked fine with my Katana and Stereo Steel. I just had to eq the treble down.
I liked the Lehlie and the Evans so much, I was determined to make it work. I consulted with Brad Sarno and he suggested a resistor on my guitar output jack or in a cord, creating a special "Lehlie" cord. We discussed a Black Box as a possible solution. I had one years ago but always regretted selling it, so I was up for that option before trying anything else. Bought one off the forum and it works like a charm with the Evans. I just simply turn the variable Z knob all the way down, to the left. Plus,I have the advantage of the tube buffer. Thanks to Brad, problem solved. |
|
|
|
Georg Sørtun
From:
Mandal, Agder, Norway
|
Posted 20 Dec 2018 1:42 am Re: Why not 1 m lot for volume control
|
|
| George Kimery wrote: |
| FWIW, my Lehle 90 pedal is 2 meg output, but no pot or moving parts, just a magnet and a sensor. It is brite compared to my 120 pedal. |
You did not say what impedance/load came after the VP (just the amp?), which matters as most magnetoresistive elements work both ways – same as a regular pot – and will add a varying amount of that impedance to the VP's PU-load as the VP is moved.
That a PU sounds brighter with a 2Mohm load than with a 500Kohm load, is as expected. The harder a (coiled) PU is loaded the darker it will sound – mainly because the PU's resonance frequency gets shifted with load, so putting a buffer with vari-Z before the VP makes perfect sense. (Putting just a resistor/pot there does too in most cases, and is of course a much cheaper solution  )
And, that you like a VP based on magnetoresistance is understandable – it will for instance show no wear over time.
Back to the OP's issues…
| Jon Light wrote: |
| The output of the steel is buffered by a Freeloader. |
The vari-Z on a Freeloader takes care of any PU-load issues, and as the pot Jon needs/uses is after that buffer and FX-units, its value isn't all that critical as long as it is at least 10 times larger than the output impedance of whatever active circuit that is feeding it. |
|
|
|
