TI CD4066 + 4069's in the MXR envelope filter

[gmr1]

Just got a handful of both to build up a couple MXR EF's using the current GGG layout. I'm now reading it takes a bit of maneuvering to get the TI chips to play nice.

Using the search, I've found varied suggestions on this - from resistor and cap changes, to just using better sockets... Anyone have adjustments to suggest that worked for you?

I'd like the normal mods to work, but have also read some of these changes effect them.

Thanks! - Greg

[earthtonesaudio]

For the oscillator, I think the general advice is to use a trimmer for the bias voltage.

[bobp1339]

I had to pull R16 down to 39k to get the TI chips to work. I used a 100k trimpot in place of the resistor.

BTW, the TI chips sound a little bit brighter than fairchild. Maybe it's my imagination 

BobP

[gmr1]

excellent. I was thinking trim pots are the way to go.

The chips are so cheap, I should just order some other brands for testing purposes. Fairchild and Phillips make them as well, correct?

Thanks for the help guys!

- greg

EDIT: looks like the original has RCA chips.

[bobp1339]

I have tried Fairchild and TI. I have seen build reports with Phillips.

In my pedal, the Fairchild need about 47k on R16.

Enjoy!  This is a great sounding pedal!

BobP

[gmr1]

Is that R16 resistor the only change you needed to get the fairchild chip to do it's thing?

[bobp1339]

Yes. Once I did that, it worked great! 

Once I had sound, I also changed C4 (output to ground cap) to .01 from .1 to increase the output volume.

BobP