Presenting the Qi-Gon : Envelope Filter/ Envelope Controlled Auto-Wah/Tremolo

[drolo]

Qi-Gon is an envelope filter/auto-wah with envelope controlled LFO speed/tremolo
As you can see it is based on the Lovetone Meatball, with modified envelope follower. I borrowed biasing idea from the Dr Quack, which allows using any kind of opamp.

It has a continuous sweep direction pot, similar to the Y-triggered Filter. I have no idea if it works the same way technically but the results are the same. I know that Mark Hammer is quite knowledgeable about the Y-Triggered and may be able to tell. I possess one but have never managed to understand that crazy circuit ...
Turn to the left, the sweep goes up, then as you turn to the middle position the sweep gets weaker until there is no sweep at noon. Then the sweep gradually goes down as you turn to the right.

The filter LDR's can be controlled either by the envelope follower or the LFO. When in LFO mode, the envelope follower controls the LFO speed. Depending on the sweep pot position, the attack will slow down the LFO speed or speed it up. Sweep pot and Intensity of the envelope follower change the speed interactively.

Apart from the usual frequency range selection, there is one position where the caps are replaced by a resistor and the feedback resistor upped for a quite convincing tremolo effect in LFO mode. Works similar to the Tremvelope from Pigtronix. In regards to the Meatball's State Variable Filter, I changed the first opamp to be non-inverting, so that the low pass and high pass positions are in phase with the blended signal and only the bandpass is out of phase. (instead of the opposite on the meatball)

The pedal is using buffered bypass, so that the pedal connected in the send/return path is still active when in bypass mode. I modified the blend pot to blend between send/return signal and filtered signal instead of clean/filtered. Made more sense when using distortion.

I have also included an external expression control jack connected to the outer lugs of the sweep pot. I have only tested it with a manually turned pot as I have no expression pedal available, but it should work, provided the contacts of the expression pedal are isolated from ground.

Any suggestions or comments are more than welcome 

P.S. I did it on perfboard, YES, I am THAT crazy...

[~arph]

Nice I like it.. sounds very good!

[digi2t]

P.S. I did it on perfboard, YES, I am THAT crazy...

PHHHHHTTTTTTT!!!! Please... I'm doing an Infinitphase on vero.

http://www.diystompboxes.com/smfforum/index.php?topic=100664.0

You're a long way from crazy Mister. 

Nice effect btw, me likey.

[drolo]

P.S. I did it on perfboard, YES, I am THAT crazy...

PHHHHHTTTTTTT!!!! Please... I'm doing an Infinitphase on vero.

http://www.diystompboxes.com/smfforum/index.php?topic=100664.0

You're a long way from crazy Mister. 

Nice effect btw, me likey.

impressive !
i bow down unworthily ...

No pictures of the final build?

[digi2t]

Not finished yet. LED driver and power boards are done. Main board is missing some resistors. Still waiting on my enclosure as well. I`m starting to wire now. I`m hoping that it will be operational within the next week or two. Hen`s Tooth Cafe video will follow suit.

[bluebunny]

This is the coolest thing I've seen today!  I have only one suggestion: please show us your layout!  I might have to build this...   

[drolo]

This is the coolest thing I've seen today!  I have only one suggestion: please show us your layout!  I might have to build this...   

there ya go :-)

[deadastronaut]

cool, love it....

[moosapotamus]

Nice! I love the combination of filter and tremolo. Sounds awesome!

~ Charlie

[StephenGiles]

This has an amazingly smooth sweep until it is swept right up to the high end, which impresses me greatly - now I was going to finish my tax return this weekend!!

Now might I suggest 2 parallel filters

[Mark Hammer]

The sounds starting around the 9:50 mark really show off what it is capable. of.

The Depth control's ability to differentiate between envelope influence on LFO and filter  is very nice.  The sweep control is also quite clever.  As for the Y-triggered filter, one of the worst-drawn schematics anywhere.  I know what the bidirectional sensitivity control does, but I'll be damned if I can point to the components that do it.  That said, I gather that all such bidirectional controls function by setting inverted versions of an envelope signal against each other.  Depending on which polarity "wins", and by how much, that sets the direction of sweep.

Because downward sweep is NEVER the exact opposite of upward sweep, when it comes to range, setting the starting point is critical, and I gather that's what you did in your choice of zener.

This is smart.  A little busy to be a stopbox  but definitely smart.

[alparent]

OK! I need to make a PCB of this. And that layout is just the inspiration I need.
This thing sounds amazing!

[jrod]

Very cool! Love it!!!

[Keppy]

Nice work!

[Ronan]

Sounds very good, and has lots of control options to dial in what you want, very nice...

[alparent]

Ok, I'm putting this schematic in Eagle so I can make my PCB.
A couple of things I don't get:
1. 2 brakes in the signal. One after the return jack and one after the SP3T switch
2. Where are all the LED and LDR on your layout?

[drolo]

Ok, I'm putting this schematic in Eagle so I can make my PCB.
A couple of things I don't get:
1. 2 brakes in the signal. One after the return jack and one after the SP3T switch
2. Where are all the LED and LDR on your layout?

Yep, the layout was for personal use only initially. I did not think people would want to build this.
The brakes are where the signal gets routed on the bypass switch. I did not want to include the whole bypass switching but needed something to remind me where the ins and outs were :-)

For the LED/LDR i rolled my own from regular 5mm LEDS and Morley-Style LDRs.
The 2 for the filter are located right next to the 330k resistors north of IC1
The 1 for the LFO is located right under the 560k south from IC2.

Hope this helps.
Show me the results if you build it :-)

[alparent]

I don't want to impose. But do to my low IQ I would really appreciate if you could put out a complete schematic.
And maybe some pics of the LDR/LED setup.
My special educator says that pictures or good for me! 

[mipo]

I've never been interested in an EF/AW type pedal. . .   

I am now.   

[Mustachio]

Sounds great! lots of cool sounds you got going on there!

Well done nice work