Multi-Flanger from Japanese stompbox book

[armdnrdy]

Hi all,

Since DIY stompboxes has a pretty far reach, with members spread out around the world,  I thought I'd give this a shot!

On a few different sites one will find the schematics, PCB and component layouts that were scanned from a Japanese DIY stompbox book. Looking at the info available for the Multi-Flanger, it seems as if there is at least one page (in Japanese) missing that would explain the many trimpots and calibration.

Also, on the schematic there is mention of a Feedback (regeneration option circuit) that's not depicted anywhere on the two available sheets.

My question is: Does anyone in this great big Stompbox building land have the original book or the missing information? Being from Southern California, I'm a bit rusty on the Japanese I learned in the third grade, but I know a few people that would be willing to help me out.

I'd like to build this beast and any additional info would save alot of time.

Thanks,
Larry

[Fender3D]

...On a few different sites one will find the schematics...

A link would be welcome for googlazy ppl like me  

as if there is at least one page (in Japanese) missing that would explain the many trimpots and calibration

flanger's trimmers setting is usually more or less the same, despite schematic or brand name.
Post a schematic and we may help...

[Mark Hammer]

I certainly wish I had the rest of the documentation for it.

As near as I can tell, the output of the delay path is at pin 7 of IC3b. That gets fed to pins 2 and 6 of IC6 (mixing stages) via a pair of 100k resistors.  That node linking pin 7 and the two resistors, is the point where one would normally tap the delay path to feed back to the input+delay mixing node in a flanger, and which is indicated by the pair of open dots with the japanese writing above it and the arrow pointing to it.

I would imagine the feedback path would need to be something like what we normally see, like a cap, a pot, and another cap, to mix in varying amounts of delay feedback to that first filter stages after the input gain-set stage.

[armdnrdy]

http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/multi-flanger.gif.html?g2_imageViewsIndex=1

Here's the schematic. As you can see it's not a normal flanger! I count 12 control pots and 7 trim pots!

[armdnrdy]

Hey Mark,

I agree, I've been looking at flanger feedback circuits with similar entry and exit points to get a better idea of what it needs. It looks pretty general. A cap, feedback resistor, feedback trimpot, and a feedback control pot.

[Fender3D]

at a very first glimpse:

VR6 is BBD's null
VR5 is BBD's bias
VR4 set the peak level, rise signal to BBD until clips, similar stuff was usually trimmed 3dB BEFORE clipping
VR3 will center Envelope's range, shouldn't be difficult to set when you listen for both uppest adn lowest flanging points
VR2 should set the "higher" flanging point (lowest delay) when in TRIGGER mode
VR1 will center LFO's range (check ADA Flanger T3 setting)
VR7 will set the lowest delay.

[armdnrdy]

Thanks Fender3D,

That info helps quite a bit. I know how to identify and calibrate trimpots in a "normal" flanger, but I've never encountered some of the features that are included in this design. I think that the additional features are what attracted me to take a stab at this build.

PS: Thanks again for helping me through my first (MXR) flanger build last year.

[Fender3D]

You're welcome,
those features might be a nice plug-in for phasers and flangers and maybe VCFs...
hmm ADA Flanger has VC input... (and Manual control is indeed a VC, ... almost all flangers involved)  
... breadboarding time anyone?

[Mark Hammer]

If you attempt it (and I have a toner transfer pattern for it just waiting for the opportunity), note that an MN3009 will be tricky to get hold of.  An MN3007 CAN be substituted, pin-for-pin, but will quadruple the delay time, pushing it well out of decent flanging territory.

Now, normally, my patent reply would be to say "...but you can just look for the relevant clock cap, and reduce its value to up the sampling frequency, thereby producing less delay time".   But look at that lower right hand corner, and you'll see a timing cap of 5pf there.  Moreover, squeezing out a higher clock rate from the chip than normal would almost certainly require buffering of the clock lines to the BBD, for which there is clearly no allowance on the board.

If you can find an MN3009, more power to ya, but in the absence of one, I'd leave this as an idea rather than a project you're committed to.

[armdnrdy]

Hey Mark,

I already have two MN3009s and a couple of 2SA798s, so that should take care of the hard to get componants unless you want to include the dual 50KB center tapped pot!

I have plans worked out to modify a dual 50KB with silver conductive paint, copper tape, 5 minute epoxy and a small length of 24 gauge wire. (I'll let you know how that turns out)

On the subject of that pot, I was looking at that part of the circuit trying to figure out exactly what the dual pot is doing. It looks like a blend circuit but I don't what it's blending. It looks like maybe between effect outputs? Stereo Panning?

[Mark Hammer]

TWO 3009s?    Did I ever tell you you're my bestest friend?    If you have a chance to do so, pop an MN3007 out of a chorus and stick the 3009 in just to hear the difference.

The diagram IS drawn in a manner that makes it cumbersome to intuit the signal flow and how the controls work.  Since there is no inversion in either of the two output/mixer stages, and there is no point in having two such output stages if they both provide the same signal, I am thinking the dual-ganged 50k pot does one of two things: ether it adjusts wet-dry balance such that one output contains more and the other less, or it provides the wet/dry signal inversion to produce sum and difference.signal

[Fender3D]

^^
It is a strange way to provide phase inversion
When pot is in center position, you got wet signal only;
full CW or CCW, you have dry signal inverted on one output and normal on the other (and vice versa)

[Mark Hammer]

Well, however weird they do it, I will say that, having both triggered-transient-generator sweep, and envelope-controlled sweep on my Tone Core Liqui-Flange, I have naught but good things to say about any flanger design, analog or digital, that includes those options, which this one does.

[armdnrdy]

Mark,

So, the two outputs inverted from each other....faux stereo effect? creating the illusion of separation?

Also, I understand what most of the controls are: LFO Pitch=Rate, Form=wave form, ect, ect.

But the two I'm a bit unsure about are: EF. Sens (is it envelope follower sensitivity?) and INV SENS. (no clue)

About the PCB pattern, I pulled that off of you site ( Ampage, link at upper left of this page for others reading this) about a year ago and have been pondering a build ever since.

There's a few problems with the original pattern that I was going to fix. I was planning to add an on board, regulated LT1054 bipolar power supply, rework a bit of the routing to relocate jumpers that run under ICs, and add the pads for the regeneration circuit. (I've followed and labeled all of the controls back to the number designations and there's no provision for the feedback circuit. The arrow with the Japanese writing above it points to a jumper on the board that has to be installed and has no place for the feed of the regen. unless one wants to stuff two wires in one pad.

                                                                   
                                                                       

[Fender3D]

But the two I'm a bit unsure about are: EF. Sens (is it envelope follower sensitivity?) and INV SENS. (no clue)                                              

They set the CV amount from the Envelope follower inv is... inverted (look at it as at up and down control on other EFs)

Mark,
I found one MN3009 on a strange BIK rack unit...
I posted pictures on the other site, please drop me a line if you know anything about it...

[Mark Hammer]

INV Sens should probably be labelled Modulation Amount.  There is a contro for setting the modulation amount for the envelope, and for the transient/AR generator.  The design provides for inverted sweep of each kind, but when it comes to downward sweep, it is not simply the mathematical "opposite" of upward.

So, you'll see VR3 which adjusts a voltage bias from which the envelope or transient will be subtracted.  How much it should be subtracted is determined by INV SENS, such that all possible modulation sources (LFO, envelope+/-, AR+/-) at the mixing node of IC8a (Where the 4x100k resistors meet) provided the desired amount of sweep.

I have a dysfunctional Roland J106 in the basement that I picked up for $50 several years back.  It has been a perennial head-scratcher as to whether I cannibalize it for parts (it contains a pair on MN3009s and MN3101s, among other things), or get it fixed.  Everytime I'm ready to get it fixed, I see something that could make excellent use of the parts, and everytime I'm ready to rip it up, I see someone extolling the virtues of an intact J106.

[armdnrdy]

Mark,

I'd say that if the MN3009 is socketed....cannibalize!!...or better yet, just call it borrowing...

[armdnrdy]

Okay....with the addition of the dual 50KB center tapped pot to my parts collection...that completes the acquisition of the "hard to find" components for this build.
I've now bumped this project up a few notches, and would like to begin routing the board.

I've redrawn the schematic and made a few changes, and have a few other changes in mind:



Better PDF copy:
https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Multi-Flanger%20II.pdf


I added a footswitch (SW2) to choose between straight flanger and Envelope/Triggered flanger.
I added an "Attack" control (P14) who's placement was "lifted" from an almost identical circuit.
I'll probably make P1 (Gain control) a trimmer and delete the "Peak Level" circuitry.
Added a 15VAC wall wart power supply. (straight from MFOS)
Added a "Regen" circuit from the Boss BF-1.

Let me make something perfectly clear......I know absolutely nothing about Envelope controlled effects! Complete neophyte here!

I was wondering if I would get any mileage out of making the Envelope/Trigger switch (SW1) a footswitch.
Also, I've been trying to wrap my head around the Envelope/Trigger circuit.
It seems that when the Envelope/Trigger switch (SW1) is in the Envelope position, the trigger, which includes the Attack and Release controls, is still connected to the mixing node (R47-R50) through the trigger sens. control. (P6)
My question is: are the Attack and Release controls still active when SW1 is in the Envelope position?

[anotherjim]

Interesting, and a lot of work done...

The Regen path you have - it looks like it's hitting the output of the first amp. Is that right? I would put a virtual earth mixer in there which, so long as it's only in the path to the BBD input, shouldn't harm overall phase.

[armdnrdy]

Interesting, and a lot of work done...

The Regen path you have - it looks like it's hitting the output of the first amp. Is that right? I would put a virtual earth mixer in there which, so long as it's only in the path to the BBD input, shouldn't harm overall phase.

I'm not really sure what you mean.

The original drawing had the regen. circuit input and output points marked on it. There are additional pages to these Japanese book projects that never made it to the net. I'm sure that the exact regen circuit that the circuit designer had in mind would have been on one of those missing pages. In lieu of missing info....all I did was fill in the blanks with "standard" regen circuit components.