cgs30 band pass filter
2006-02-15 by Al
Hi there,
New to the forum and taking my first steps cascading some of the
cgs30 filters (the PCBs are pristine btw).
A few questions, hopefully you can put me on the right tracks.
Hope it's not too much to swallow in one post, but here goes
The notes on Ken's site mention that the Rev1 cct had the resonance
pot wired for 'bandwidth' and the Rev2 is altered to give resonance
adjustment. I'd like to try wiring a board with the pot for
bandwidth. Is this a question of swapping over the links on the board
to the pot, i.e. swap the outer connections over or is the track
different to/from the pot?
If it's wired for resonance, does it effectively act to
increase/decrease the resonance with or without affecting the
bandwithand? And if wired for bandwidth, would the resonance be
less/unaltered in any way other than by the Q? (not sure how clear
that question is to anyone else)
Perhaps it's better to ask, can it be wired so the bandwidth can be
adjusted and keep the resonance damped in any way? Some one suggested
to me that changing the 6K8 would help to achieve this, any thoughts?
btw If I'm asking is it 6, or half a dozen? please tell me :)
Also looked at the difference between Reverse Audio Taper (Neg Log)
pots and linear response for the frequency adjustment. The curves for
the two types are very different, how percievable is the difference
and is it worth going the extra mile to track down these elusive
pots? I'm aware of the use of the log curve in relation to how we
hear through studying acoustics, just not, practically, how the
filter would differ.
Oh dear there's more, hope that's ok to keep firing questions like
this - please let me know if not.
Ken shows the cascaded filters wired to the DC mixer cct and I'd like
to know if you could put a pot between the filter and input to the
mixer - the other inputs if used show a 50K pot at their inputs (for
attenuation/gain I figure?). Is it worthwhile to have one from the
filter if you're using them on other inputs? Or would it be
better/possible to link the cascaded filters to a socket and patch
this into the mixer, treating them as discrete modules?
nearly there :?
finally (fer now) would there be any benefit in using neg log pots
for the 50K pots on the mixer inputs (I ask because, looking into the
neg log thing, they seemed to use them in old equipment for volume
pots) and shielded wire through the filter boards (tinned copper bus
wire's the given) and to the mixer to cut down on interferance or is
that *pointless/undoable/over the top (*delete as applicable)
And
Phew, that'll do (I got some PSU q's too but I'm trying to figure
that meself first)
I've been saving 'em up as you can see but I hope you don't mind too
much
Any comments, directions to old threads, or advice on any of the
above are welcome.
Thanks in advance
Al
New to the forum and taking my first steps cascading some of the
cgs30 filters (the PCBs are pristine btw).
A few questions, hopefully you can put me on the right tracks.
Hope it's not too much to swallow in one post, but here goes
The notes on Ken's site mention that the Rev1 cct had the resonance
pot wired for 'bandwidth' and the Rev2 is altered to give resonance
adjustment. I'd like to try wiring a board with the pot for
bandwidth. Is this a question of swapping over the links on the board
to the pot, i.e. swap the outer connections over or is the track
different to/from the pot?
If it's wired for resonance, does it effectively act to
increase/decrease the resonance with or without affecting the
bandwithand? And if wired for bandwidth, would the resonance be
less/unaltered in any way other than by the Q? (not sure how clear
that question is to anyone else)
Perhaps it's better to ask, can it be wired so the bandwidth can be
adjusted and keep the resonance damped in any way? Some one suggested
to me that changing the 6K8 would help to achieve this, any thoughts?
btw If I'm asking is it 6, or half a dozen? please tell me :)
Also looked at the difference between Reverse Audio Taper (Neg Log)
pots and linear response for the frequency adjustment. The curves for
the two types are very different, how percievable is the difference
and is it worth going the extra mile to track down these elusive
pots? I'm aware of the use of the log curve in relation to how we
hear through studying acoustics, just not, practically, how the
filter would differ.
Oh dear there's more, hope that's ok to keep firing questions like
this - please let me know if not.
Ken shows the cascaded filters wired to the DC mixer cct and I'd like
to know if you could put a pot between the filter and input to the
mixer - the other inputs if used show a 50K pot at their inputs (for
attenuation/gain I figure?). Is it worthwhile to have one from the
filter if you're using them on other inputs? Or would it be
better/possible to link the cascaded filters to a socket and patch
this into the mixer, treating them as discrete modules?
nearly there :?
finally (fer now) would there be any benefit in using neg log pots
for the 50K pots on the mixer inputs (I ask because, looking into the
neg log thing, they seemed to use them in old equipment for volume
pots) and shielded wire through the filter boards (tinned copper bus
wire's the given) and to the mixer to cut down on interferance or is
that *pointless/undoable/over the top (*delete as applicable)
And
Phew, that'll do (I got some PSU q's too but I'm trying to figure
that meself first)
I've been saving 'em up as you can see but I hope you don't mind too
much
Any comments, directions to old threads, or advice on any of the
above are welcome.
Thanks in advance
Al