need chorus and flanger for 3207

[hamedbb]

hi, i have no access to mn3007 at all, but i could buy some mn3207. all i need is a reliable  chorus and a flanger with  PCB layout that has been designed for 3207 chip or really works with it. i want it to be straight forward. i searched a lot but couldnt find any reliable projects. Any suggestions?

[Mark Hammer]

There are some at the Madbean site.

[ElectricDruid]

If I can blow my own trumpet for a minute, the Flangelicious is a simple flanger project that works with a 3207:

https://electricdruid.net/flangelicious-a-super-dooper-flanger/

Can't help with the chorus though. That's still in development!

HTH,
Tom

[POTL]

If I can blow my own trumpet for a minute, the Flangelicious is a simple flanger project that works with a 3207:

https://electricdruid.net/flangelicious-a-super-dooper-flanger/

Can't help with the chorus though. That's still in development!

HTH,
Tom

I have long wanted to ask about this scheme.
I wonder, instead of the MN3102, a dual-channel opamp in an LFO and several transistors, you use a microcontroller. These components are not part of the audio path, but they affect the operation of the MN3207, does this somehow affect the sound of the effect for better / worse, or can the microcontroller be programmed to the desired frequency?
Does it make sense to use the original MN3102 chip and transistors, replacing only the LFO with a microcontroller, or is there no difference with your method?
I watched the stuffing of the Chase Bliss and JHS pedals, their analog effects have tamp tempo, but continue to use the MN3102 / 3101.
Something like that

[Kevin Mitchell]

A tap tempo chorus is a bit overkill IMO. The lfo in most chorus pedals oscillates fast and you'll likely be hitting the tempo switch a few times to get what you want. If it's too slow, it won't be very audible.

That schematic you shared still uses the 3102 clock. You're likely not going to find an analog BBD chorus without one or a clock alternative such as a logic chip. I do like his schematic using the tap tempo in a phase 90 circuit and have built one myself.

If you want a chorus and flanger in one using the mn3207, I'd like to recommend the Echo Flanger (check out this board) I've built one with mn3007 BBDs and love it. Very versatile.

[ElectricDruid]

I have long wanted to ask about this scheme.
I wonder, instead of the MN3102, a dual-channel opamp in an LFO and several transistors, you use a microcontroller. These components are not part of the audio path, but they affect the operation of the MN3207, does this somehow affect the sound of the effect for better / worse, or can the microcontroller be programmed to the desired frequency?

The micro controller can be programmed for the correct frequency, as you said. The output from the micro controller is a dual-phase clock signal between 25KHz and 500KHz. It does affect the sound to a limited degree because of weird effects caused by the use of an NCO on the micro controller. With high resonance settings and a bit of background noise going through the pedal you can hear odd "watery" sounds, rather than the typical "flanged hiss". So it's slightly different, but I don't know that I'd call it significant. It's always been hard to make a quiet flanger because of the gain caused by the resonance and the fact that you recycle a signal through a noisy BBD many, many times. Flangelicious is no different there.

Does it make sense to use the original MN3102 chip and transistors, replacing only the LFO with a microcontroller, or is there no difference with your method?

That's a choice you can make, a design decision. for the Flangelicious design I was deliberately trying to build the simplest possible flanger I could that still had all the features we expect, so I rolled the LFO and the clock chip up into a single micro-controller. The circuit is only four 8-pin chips. That's about half what many flangers need.

It's quite possible to use a tap-tempo LFO chip like my STOMPLFO or TAPLFO to replace the analog LFO and then use the output of that to modulate the standard MN3102 clock. It just adds parts is all. It'll give you much the same features, but keeps you closer to the classic analog flanger circuit.

I watched the stuffing of the Chase Bliss and JHS pedals, their analog effects have tamp tempo, but continue to use the MN3102 / 3101.
Something like that

Yep, exactly. Stick a digital LFO with all the features that implies (tap tempo, loads of interesting wave shapes, etc etc MIDI?!?) into a standard chorus or flanger circuit and off you go!

HTH,
Tom

[POTL]

as always, thanks for the detailed answer =)
Midi is interesting, but I'm still far from the digital world, I hope in the future I will find time to study.
Another issue is that the classic flanger has a useful Manual adjustment, the implementation is standard when we connect the extreme foot of the depth adjustment not to the virtual ground, but to a buffer with adjustable voltage.
I am interested in your opinion, if I use an LFO on a microcontroller that works from 5 volts, and the rest of the circuit from 15 volts (for example, MXR Flanger), should the Manual adjustment be connected to 5 or 15 volts?

[ElectricDruid]

as always, thanks for the detailed answer =)
Midi is interesting, but I'm still far from the digital world, I hope in the future I will find time to study.

MIDI _is_ interesting, but it's a "whole other can of worms".

Another issue is that the classic flanger has a useful Manual adjustment, the implementation is standard when we connect the extreme foot of the depth adjustment not to the virtual ground, but to a buffer with adjustable voltage.

Yes, I had trouble implementing that Manual control behaviour on my firmware version, but I found a way in the end!

I am interested in your opinion, if I use an LFO on a microcontroller that works from 5 volts, and the rest of the circuit from 15 volts (for example, MXR Flanger), should the Manual adjustment be connected to 5 or 15 volts?

Good question. I'd say 5V, because the typical behaviour is for the depth to be limited when the manual setting is pushed to extremes. But if the circuit is expecting a 15V modulation signal, you'd need to find a way to increase the sensitivity so that you can use a modulation voltage which is 3 times smaller.

HTH,
Tom