Another response from Ernie Ball:
Here is another Q&A from Ernie Ball regarding using those using the 250k for active basses:
On 10/10/2013 12:58 PM
Message: I've been told by a few that they use the 250 ohm version of the Ernie Ball volume pedal for their active basses. They have asked why that is not a suitable match over the 6181 25 ohm version. What is the negative impact of using the 250 ohm version on an active instrument? Noise? Tone loss?
It does have to do with impedance. You want to match up the output impedance with the input impedance. For instance... the volume pot on one guitar or bass will be a 25k(active). You could run that into a pedal with a 250k(passive) pot but your control over the volume will happen in a very small portion of the sweep of the pedal. Now if you reverse that idea... and say you run a guitar or bass (which utilize a 250k volume pot) into a 25k pedal, the 25k pedal will load down that pickup and you'll have loss of highs and an overall different tone, much more drastic than going the other way (25k into 250k).
I hope this helps.
Ernie Ball Customer Service
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