Lofi Generator - Please tell me there is an easier way.

[ThePastRecedes]

*If this should go in the members projects section please move*

I have had this idea in my head for a while. I've been reading about envelopes for a while and I finally got the time to draw out what I had in my head this morning.

The Idea was to have a pedal that noise/crackle would interact with my playing with a bpf on the guitar signal.  I wanted to emulate a radio recordings.

Lets start. Part 1
- Input stage. I have get to decide the gain/values.
- Then I've got switchable low and high pass filters.

Part 2
- Envelope follower from the meat sphere. Not my work. Comes out of the input stage. But theres a half wave rectifier and then and inverting opamp to create the envelope.
- Another inverting opamp stage to "reverse" the envelope.

Part 3
- The two transistors are there as a noise generator.
- The OTA is there as a current controlled amplifier. I got the idea from this: http://www.geofex.com/Article_Folders/VCA%20Applications.pdf
- The envelope controls the the volume of the noise.

Part 4
- A panner to pan between the guitar signal and the noise.


Tell me there is a simpler way! Would I just be better off using a simple resistor and a cap for the filters rather than what I have? Any comments are welcome good or bad!

I have yet to breadboard this idea.  I'm moving tomorrow so I won't get round to it for a while.

I've attached a schematic and the eagle file for anyone who wants to join my adventure.

[gtr2]

I've been working on something similar off and on for the last year.  I need to get back on it, as I've been to busy to finish it on the breadboard.  My goal is a bit different and I don't have an envelope follower.  But it will be fun to see what you come up with in the end

Josh

[davent]

Would any of the info in this geofex schematic be of any benefit?

http://www.geofex.com/FX_images/lofi.gif

dave

[ThePastRecedes]

I've been working on something similar off and on for the last year.  I need to get back on it, as I've been to busy to finish it on the breadboard.  My goal is a bit different and I don't have an envelope follower.  But it will be fun to see what you come up with in the end

Josh

What method are you using?

[Chi_Boy]

Would any of the info in this geofex schematic be of any benefit?

http://www.geofex.com/FX_images/lofi.gif

dave

Just for the record, there is an error in that schematic.  The center lug of the panner should go to VB, not GND.  the correction was posted at DIYSB, but the schematic never was changed.

I also built that and didn't care for panning in this application.  It make it an either or proposition between noise and guitar.  When I messed with it I wanted guitar with a controlled amount of added noise so I went with a blend with controlled volume on the noise section.

[gtr2]

Yes, I've also found blending in the noise works better than panning.

Josh