(http://i1277.photobucket.com/albums/y492/drolobucket/Qi-GonFilter_zps3612e494.png)
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... :icon_mad:
Nice I like it.. sounds very good!
QuoteP.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 (http://www.diystompboxes.com/smfforum/index.php?topic=100664.0)
You're a long way from crazy Mister. :icon_lol:
Nice effect btw, me likey.
Quote from: digi2t on January 18, 2013, 06:34:55 AM
QuoteP.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 (http://www.diystompboxes.com/smfforum/index.php?topic=100664.0)
You're a long way from crazy Mister. :icon_lol:
Nice effect btw, me likey.
impressive !
i bow down unworthily ...
No pictures of the final build?
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.
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... ;D
Quote from: bluebunny on January 18, 2013, 10:05:02 AM
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... ;D
there ya go :-)
(http://i1277.photobucket.com/albums/y492/drolobucket/Qigong-Layout-BUFFER_zpsbfc6e7fa.png)
cool, love it.... 8) 8) 8)
Nice! I love the combination of filter and tremolo. Sounds awesome! 8)
~ Charlie
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 :icon_biggrin:
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 :icon_lol: but definitely smart.
OK! I need to make a PCB of this. And that layout is just the inspiration I need.
This thing sounds amazing!
Very cool! Love it!!!
Nice work!
Sounds very good, and has lots of control options to dial in what you want, very nice...
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?
Quote from: alparent on January 19, 2013, 08:09:25 AM
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 :-)
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!
I've never been interested in an EF/AW type pedal. . . :-\
I am now. :icon_biggrin:
Sounds great! lots of cool sounds you got going on there!
Well done nice work :icon_wink:
Quote from: alparent on January 19, 2013, 01:05:10 PM
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!
I have no access to my files right now but hope this will bring you further.
(http://i1277.photobucket.com/albums/y492/drolobucket/Qigong-Layout-BUFFER_zpsbfc6e7fa-1_zpsde4b3503.jpg)
Quote from: drolo on January 18, 2013, 11:42:02 AM
Quote from: bluebunny on January 18, 2013, 10:05:02 AM
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... ;D
there ya go :-)
Cool! Thanks!
Quote from: Mark Hammer on January 18, 2013, 08:32:26 PM
This is smart. A little busy to be a stopbox :icon_lol: but definitely smart.
I guess by busy that you mean the too many knobs ... i really wanted to keep it to the essential but it's so hard with an envelope type of circuit. Either you settle for one sound and try to make it as good and consistent as possible or you go the opposite route but there are so many variables ... and so many possible sounds ... i could easily have doubled the amount of knobs :-)
I guess it's one of those pedals that you have to spend some time with. Once you get to know it, it's easy to dial in the sounds you want quickly.
Well, you kept it a lot simpler than this thing! http://urekarm.tripod.com/synth/fuzzyballs.html
But I know what you mean. Swept filters have a tendency to invite more and more features. I'm sure somewhere out there is someone fiddling around with linear vs exponential sweeps, variable slope, auto-panned output, and any of a million things one can use.
Yesterday, I finally got an expression pedal set up to use with my Line 6 M5, and the unit allows for manipulation of up to 5 parameters at once via movement of a single expression pedal. Let me tell you (aklthough clearly I don't need to), it is VERY easy to get carried away with control features on a simple swept filter! :icon_lol:
While I have filter afficionados' attention, have any of you ever worked with the Mike Biegel meisterstucke EHX Bi-Filter? http://www.ehx.com/products/bi-filter Just curious as to what that's like.
I must have missed this in January and discovered it yesterday - nice work. I particulalry like the tremolo function. It's very clever.
I found this as I have been playing with an LFO-controlled state variable filter as of late. Mine has crude envelope control of the LFO speed and I stumbled upon this looking for other examples.
One thing you mght want to consider addding is a notch filter, which can give quite a convincing phaser effect. You can do this by tappling the (+) input of U1B or by adding the LP and HP. I think you have a spare splot on your rotary switch that could accomodate this without too much difficulty.
good ideas !!
I was going to design and build an envelope controlled phaser/vibe with the same principle as this one, but I hardly get any time to work on pedals these days ... so this idea could be a quick fix for a phasey tone.
I had read that you could create a notch filter but not quite understood how to implement it. Do I just connect the outputs of LP and HP together and do I need some DC blocking Caps between them? Maybe someone knows an example where that arrangement would be used. Some sound examples would be great too :-)
It seems that you can get the notched filter by directly tapping the (+) input of the first op-amp in the filter - your U1B. I have only done that straight into an op-amp buffer and this may not work too well with you mix pot. Instead, I would suggest you mix the LP and HP by connecting e.g. a 10k resistor from each of the outputs: LP -10k - notch - 10k - BP. As a bonus, you should be able to do right on the rotary switch so it will not require any extra wiring.
Edit: fixed typo
I will definitely try that out :-)
Thanks
Re-upping this because I can't see the schematic, and because it's a wonderful sounding circuit that I'm trying to build and I have a couple of questions if drolo or anyone else could help...
(https://i.postimg.cc/0bH4vMV5/qi-gon-filter.png) (https://postimg.cc/0bH4vMV5)
1) I have only 3v9 zeners, is the envelope likely to trigger properly with the minor increase over 3v6?
2) Is the opamp type likely to be crucial for the envelope function? I've built the meatball and remember that the 1458 (LM1458?) is supposedly important to avoid having to tweak the circuit
It's probably going to be ok. You can also try using 2 LED's in series that have about 1.8v voltage drop. Or you can also hook up a trimpot as a voltage divider and adjust to taste.
This biasing was intended to make it work with any opamps.
I built the Mercury long ago, from your pcb, easy and great sounding, thank you! this envelope seems interesting, do you think this envelope would control the optical phaser part?
it should work, you just have to tweak the output voltage range to suit the best