18Hz subsonic filter?

[RomancintheTone]

I know it'd be simple to do, but I don't wanna screw it up. Can anyone send me specs, or even just tell me, how to put together a simple 18Hz subsonic filter as a protection circuit after my octave pedal?

[bongomania]

It's not so simple to do well. You can make a simple filter out of one resistor and one capacitor, but it will not just roll off the subharmonics you want to lose. It doesn't matter if you calculate whatever frequency using simple RC filter math, the slope of the rolloff will be so shallow that you won't lose enough of the subharmonics, and you will lose too much of the lows you wanted to keep.

There are some products you can buy, but the one really good one I know of will be a bit over $100.

[MAMMOTHvolume]

Originally Posted by RomancintheTone

I know it'd be simple to do, but I don't wanna screw it up. Can anyone send me specs, or even just tell me, how to put together a simple 18Hz subsonic filter as a protection circuit after my octave pedal?

your amp should have a built in one.

[DavidMP]

Here you go

[Nyarlathotep]

Would that operate at a 9VDC level if you changed the opamps to those that ran on 9Vs?

Im tired and can't seem to find anything on OpAmp voltages. I did find the inverting and non-inverting schems I was looking for before tho....

[Thunderscreech]

Originally Posted by Nyarlathotep

Would that operate at a 9VDC level if you changed the opamps to those that ran on 9Vs?

Im tired and can't seem to find anything on OpAmp voltages. I did find the inverting and non-inverting schems I was looking for before tho....

The opamp used is a TL07, which is very common and runs on a range of voltages. The more you put in, the more headroom you get. TL07's have a reputation for being noisy, however. There isn't so much a single voltage as there is a reccomeneded voltage range (say, 3-36 volts) so anything in that range will work before you start getting clipping.

Someone who knows more than me had better check that statement for accuracy.

[Nyarlathotep]

Thats kinda what I figured from memory, but I just kinda wanted someone to confirm it.