thermionic
Well-known member
- Joined
- Jun 3, 2004
- Messages
- 1,671
Hi,
I'm working on a project that needs a swept HP shelving filter. It uses an op-amp with a cap and a pot wired as variable resistor - a simple design, sweeping from <20Hz to 3k at full travel. The trouble is, even with a reverse-log pot, you don't really 'feel' the HP until it's well passed 12-o'clock, and the region that is most noticeable is squashed into the last half rotation. Towards the last 50-odd degrees of the travel it gets really sensitive / twitchy. So, if I stay with this HP design, to get a more even feel, I'll need an 'accelerated log' pot, i.e. a reverse-log pot, but with an exaggerated curve.
Can anyone see a way around this, short of paying for an unusual custom taper?
NB - feel is really important as the project needs to be used live, and the user doesn't want to twiddle the knob half the way around to get any effect, with the last few degrees of travel being twitchy.
Thanks in advance.
Justin
I'm working on a project that needs a swept HP shelving filter. It uses an op-amp with a cap and a pot wired as variable resistor - a simple design, sweeping from <20Hz to 3k at full travel. The trouble is, even with a reverse-log pot, you don't really 'feel' the HP until it's well passed 12-o'clock, and the region that is most noticeable is squashed into the last half rotation. Towards the last 50-odd degrees of the travel it gets really sensitive / twitchy. So, if I stay with this HP design, to get a more even feel, I'll need an 'accelerated log' pot, i.e. a reverse-log pot, but with an exaggerated curve.
Can anyone see a way around this, short of paying for an unusual custom taper?
NB - feel is really important as the project needs to be used live, and the user doesn't want to twiddle the knob half the way around to get any effect, with the last few degrees of travel being twitchy.
Thanks in advance.
Justin