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#31

Build Reports / Re: Grawlix — A Green Ringer w...

Last post by jessenator - June 09, 2026, 11:13:10 PM

Fan-freakin-tastic, my dude.

[Texture]

#32

Build Reports / Grawlix — A Green Ringer with ...

Last post by Aleph Null - June 09, 2026, 08:20:00 PM

I've been exporing analog octave circuits lately and nothing sounds quite like the Green Ringer to my ears, but it generally needs help to sound its best. Grawlix is a Green Ringer with some quality-of-life features added.



I repurposed an old enclosure as the original occupant had been superseded by a newer design.



The first half of the circuit is the classic Green Ringer topology with modernized and streamlined values. The bias network is a little eccentric, but it gets the necessary voltage at the base of Q2 to maximize the headroom and octave effect. Instead of a fixed gain, Q1 can now be adjusted. This lets you set the level that hits the rectifier section for the most prominent octave. It can also be cranked up to some serious fuzz. The Texture control pans between metallic fuzz and full octave up. The further clockwise, the more prominent the octave will be. This also makes diode matching less critical, as the Texture control can be adjusted until the octave pops. Q3 buffers the output—I tried to ditch this, but the rectifier is very picky about what comes after it!



The octave section is followed by clipping diodes. These have a similar effect to placing an overdirve after a Green Ringer; they act as a crude form of compression to keep down the crazy transients the octave can produce. With the Gain control low, they don't do anything. After about half way, they start to color the signal.

Tone is a tilt EQ with a mid bump around 800Hz. Clockwise, it cuts the thump of strong transients that can be created with the Gain set low. Counterclockwise, it cuts the fizz and treble without getting too dark. In the middle, it gives you a throaty midrange, similar to running a Tube Screamer after your octave.

Last is a make-up gain stage to ensure a good amount of boost is available at all times.



This circuit definitely does the Green Ringer thing, but I think it's also a reasonable substitute for a Moonrock or a Superfuzz. It can fuzz, but it's more open and dynamic than most octave fuzzes.

Here's a demo:

As always, I have extra PCBs. If you're interested, DM me!

#33

Open Discussion / Re: The secret M117 flanger

Last post by Scruffie - June 07, 2026, 10:55:36 AM

Plus, if you're really missing said high content, you can make R22 & R25 6k2 on the madbean collosalus and it should more than compensate for the difference.

Thanks for the suggestion! I'll have to try that out on my Collosalus (2022 version) build. I'm still not quite happy with the performance with it. I've noticed that Q2-Q5 have a huge effect on the sound, so I've been swapping several different transistors types in those positions. Right now it sounds pretty good, and has the most eclectic combo of transistors in those positions.

Let us know how it works out!

Yeah, all the transistors are doing different jobs so you will get a better sweep width with transistors best suited, don't need to go crazy, just 2N3904/2N5088 should be fine.

Also making the mixing resistors 100k/56k removes the volume drop in a true bypass set up.

#34

Open Discussion / Re: The secret M117 flanger

Last post by lars - June 06, 2026, 09:59:24 PM

Plus, if you're really missing said high content, you can make R22 & R25 6k2 on the madbean collosalus and it should more than compensate for the difference.

Thanks for the suggestion! I'll have to try that out on my Collosalus (2022 version) build. I'm still not quite happy with the performance with it. I've noticed that Q2-Q5 have a huge effect on the sound, so I've been swapping several different transistors types in those positions. Right now it sounds pretty good, and has the most eclectic combo of transistors in those positions.

#35

Open Discussion / Re: The secret M117 flanger

Last post by Scruffie - June 05, 2026, 03:23:05 PM

Yeah, I'd only really trace it just for completion, as you say, no MN3004 and I don't think there's anything majorly exciting hidden in there, just an interesting little piece of MXR history.
If you're up to de-soldering the pots I'll have a look over though when I get a chance, not impossible they've tweaked here and there.

The MN3004's have a minute amount of extra high frequency content over the MN3007 but then you're just trading benefit in one area for some negatives in another... at the time Panasonic had only stopped producing BBD's a few years earlier so the choice of chip may have just been what was practical to source.

Plus, if you're really missing said high content, you can make R22 & R25 6k2 on the madbean collosalus and it should more than compensate for the difference.

#36

Build Reports / Re: Polyphemus [One Knob Overd...

Last post by Aleph Null - June 04, 2026, 10:25:14 PM

Thanks! It's definitely easier to control the gain with my foot.

#37

Open Discussion / Re: The secret M117 flanger

Last post by museums - June 04, 2026, 07:57:29 PM

Yeah, the forum does appear to be having some issues, there's a note on the homepage up at the top right.

Yeah, it's been doing that a while now. Occasionally I get someone else's account on the main page...

Think the mystery is solved, still, might be interesting to trace and see if there was any other alterations to the circuit... I do notice an extra diode in the astable section area.

This is seriously cool. LMK if you need a donor. Not that there are any 3004s to build anew 

The thing is you wouldn't need MN3004s because this version is clocked low enough that you could use MN3007s and clock it at normal freqs and get the same results.

#38

Open Discussion / Re: The secret M117 flanger

Last post by jessenator - June 04, 2026, 07:23:50 PM

Yeah, the forum does appear to be having some issues, there's a note on the homepage up at the top right.

Yeah, it's been doing that a while now. Occasionally I get someone else's account on the main page...

Think the mystery is solved, still, might be interesting to trace and see if there was any other alterations to the circuit... I do notice an extra diode in the astable section area.

This is seriously cool. LMK if you need a donor. Not that there are any 3004s to build anew 

#39

Open Discussion / Re: The secret M117 flanger

Last post by Scruffie - June 04, 2026, 06:07:37 PM

There are two 4013s in the pedal, each with two flip flops. One of the 4013s dedicates one flip flop to each of the MN3004s to make the biphase clock pulses so each MN3004 has its own driver. Im honestly not sure this is even necessary considering the clock freqs (13KHz to 500KHz), which are roughly halved compared to an SAD1024 unit or generally any Panasonic BBD equipped flanger pedal. The other 4013 is the oscillator. Of the 4 flip flops available, I believe 3 are used.

I was reading the old schem wrong about the BBDs being in parallel. The input pins of the two MN3004s are connected in my unit and the clock phases are matched which IIRC is the differential operation shown in the SAD1024 datasheet. Maybe the folks at MXR looked at the performance of the Panasonic BBDs and traded super short delay times for better performance with differential configuration? The sound of the pedal is spectacular. Better than an SAD1024 MXR IMO.

The only DIY project I have seen that offered these alternate BBD configurations is the BYOC flanger, but Im pretty sure they were running parallel multiplex and calling it differential.

Side note - The lag here is like an hour or two for posts to appear. Never experienced that on another simple machines forum.

Thanks for that, so it's just using one half of each CD4013? What an odd design choice... Definitely not using the chip handling oscillator division in parallel? That might make a little more sense in lieu of a clock buffer, given the BBD's have equal clock capacitance to an MN3007.

The BBD's were in series in the original which it did look like was the direction it was heading in the gut shots Jessenator sent me, is parallel confirmed?

Are you able to measure the clock frequencies as well out of interest?

If someone posts some decent gut shots it shouldn't be too hard to trace and confirm seeing as we already have the 117 schematic.

I'll PM you. Let me know if you need different angles than what I captured.

Thanks, unfortunately to get a good look at the traces you'd need to unsolder the pots.

But, I thought of a much simpler solution... just test for continuity between pin 2 of both MN3004, if it beeps, they share the same clock.

If it doesn't beep, check pin 2 of one doesn't match to pin 12 of the other.

Still no beep? Then it's time to test the CD4013 for continuity.

Probed around in mine. One half of the inner 4013 handles generating the two phase pulses for each MN3004. The  outer 4013 is then the other half of the clock circuit although I believe based on photos earlier in the thread that there is a single oscillator feeding the two flipflops. BBDs are in parallel like the original design.

Ahhh, this is making much more sense, so they've parallel multiplexed (I assume unless there's an extra op-amp to achieve differential operation) and halved the clock to achieve the same delay times as the original probably, as you note regards SAD vs. Panasonic, to avoid the MN3004's heavy signal drop off at those higher clock frequencies and also so there's not a heavier high frequency roll off from running them in series.

No, parallel clocks was probably a little overkill but suppose it doesn't hurt, especially with the longer clock traces.

Also helps makes sense as to why the later version just uses a single MN3204 but with heavier noise reduction circuitry.

Think the mystery is solved, still, might be interesting to trace and see if there was any other alterations to the circuit... I do notice an extra diode in the astable section area.

Yeah, the forum does appear to be having some issues, there's a note on the homepage up at the top right.

#40

Open Discussion / Re: The secret M117 flanger

Last post by museums - June 04, 2026, 03:13:33 PM

There are two 4013s in the pedal, each with two flip flops. One of the 4013s dedicates one flip flop to each of the MN3004s to make the biphase clock pulses so each MN3004 has its own driver. Im honestly not sure this is even necessary considering the clock freqs (13KHz to 500KHz), which are roughly halved compared to an SAD1024 unit or generally any Panasonic BBD equipped flanger pedal. The other 4013 is the oscillator. Of the 4 flip flops available, I believe 3 are used.

I was reading the old schem wrong about the BBDs being in parallel. The input pins of the two MN3004s are connected in my unit and the clock phases are matched which IIRC is the differential operation shown in the SAD1024 datasheet. Maybe the folks at MXR looked at the performance of the Panasonic BBDs and traded super short delay times for better performance with differential configuration? The sound of the pedal is spectacular. Better than an SAD1024 MXR IMO.

The only DIY project I have seen that offered these alternate BBD configurations is the BYOC flanger, but Im pretty sure they were running parallel multiplex and calling it differential.

Side note - The lag here is like an hour or two for posts to appear. Never experienced that on another simple machines forum.

Thanks for that, so it's just using one half of each CD4013? What an odd design choice... Definitely not using the chip handling oscillator division in parallel? That might make a little more sense in lieu of a clock buffer, given the BBD's have equal clock capacitance to an MN3007.

The BBD's were in series in the original which it did look like was the direction it was heading in the gut shots Jessenator sent me, is parallel confirmed?

Are you able to measure the clock frequencies as well out of interest?

If someone posts some decent gut shots it shouldn't be too hard to trace and confirm seeing as we already have the 117 schematic.

I'll PM you. Let me know if you need different angles than what I captured.

Thanks, unfortunately to get a good look at the traces you'd need to unsolder the pots.

But, I thought of a much simpler solution... just test for continuity between pin 2 of both MN3004, if it beeps, they share the same clock.

If it doesn't beep, check pin 2 of one doesn't match to pin 12 of the other.

Still no beep? Then it's time to test the CD4013 for continuity.

Probed around in mine. One half of the inner 4013 handles generating the two phase pulses for each MN3004. The  outer 4013 is then the other half of the clock circuit although I believe based on photos earlier in the thread that there is a single oscillator feeding the two flipflops. BBDs are in parallel like the original design.