Multi-Flanger from Japanese stompbox book

[armdnrdy]

Last night I had the thought to delete the CV master control. This control might be useful if one had a free hand, (playing keys) but I don't see much use for it with guitar.

If I find that the different CV inputs are unbalanced, this can be dealt with by changing resistor values in the CV mixing node before IC8A.

I would imagine that all I have to do is delete the CV master (P8) and connect R54 directly to the output of IC8A.

[Fender3D]

I'd rather delete P12 (LFO depth) and leave CVMaster.
I guess it might be useful having a master for the complex voltage waveform, instead of setting 4 controls.

P8 will do the same work as P12 when using LFO

[armdnrdy]

No,No,No....

I would rather be able to adjust each CV option separately to get different effects.

Remember that the different CVs get mixed at R47-R49....so with the separate adjustments come different settings with more sound options available.

I just don't see the reason for an "overall" CV depth adjustment.

[armdnrdy]

Here is the latest revised drawing:

Here is a PDF for an easier read:
https://dl.dropboxusercontent.com/u/53299166/DIYstompboxes/Multi-Flanger%207-25.pdf



I deleted the C.V. Master control, (sorry Federico   ) changed the Gain control (P1) to a trimmer, (will probably delete this trimmer once overall circuit gain requirement is established) added standard limiting diodes in the feedback loop of the mixing op amp, (IC4B)
Cleaned up and spread out the circuit to make it a bit more readable.

There are a few things that I noticed about this circuit while reviewing others flanger designs for reference.

The resistor values in the Sallen-Key lowpass BBD output filter. 150K? The standard value in everything that I reviewed is much lower, 10K-15K. (Panasonic data sheet MN3009 shows 33K-39K with higher value caps)

Another thing that I noticed is the lack of high frequency "roll off" caps in the feedback loops of the op amps in the signal path.

Any ideas?

[Fender3D]

...
I deleted the C.V. Master control, (sorry Federico   )

Hehe,
with all your changes and brainstorming this should be named now armdnflanging...  
(and the former designer may only be proud about the guitar adapting)

my only concern was about having a complex mix of P3, P6 and P7 and the need for a  "more-up" or "more-down" environment...

Moreover CVMaster allow you to play with Manual just lowering it, instead of the (carefully-mixed-before) 3 above (Morley enclosure time?)

...
added standard limiting diodes in the feedback loop of the mixing op amp, (IC4B)

Great, I think every flanger should have clipping-limiting diodes before BBD...

There are a few things that I noticed about this circuit while reviewing others flanger designs for reference.

The resistor values in the Sallen-Key lowpass BBD output filter. 150K? The standard value in everything that I reviewed is much lower, 10K-15K. (Panasonic data sheet MN3009 shows 33K-39K with higher value caps)

Another thing that I noticed is the lack of high frequency "roll off" caps in the feedback loops of the op amps in the signal path.

Any ideas?

Yeah, resistors have higher value, but capacitors are accordingly lower...
BTW
I'd rather prefer lower res/higher caps, 'cause in PCB you'll find lotsa pF adding to your tiny caps due to layout..

Again it's a good practice at least providing room for a roll off cap in op-amps feedback loop

uh oh

here's my scrooge heritage coming...
D18 and D19 may be saved for another pedal...
C28 and C29 should be 0.1uF and near regulators pins...

[armdnrdy]

Thanks for the reply Federico.

my only concern was about having a complex mix of P3, P6 and P7 and the need for a  "more-up" or "more-down" environment...

I thought about that....what if each C.V. option is a different amplitude. If that is the case, I think that I would find a different "fix" to bring the C.V. options to the same level. I don't think that having to adjust the C.V. level is such a good idea for a guitar pedal...... Especially with the option that I've provided to switch between them "on the fly".

I'd rather prefer lower res/higher caps, 'cause in PCB you'll find lotsa pF adding to your tiny caps due to layout..

Again it's a good practice at least providing room for a roll off cap in op-amps feedback loop

I may calculate the cut off frequency and adjust the resistors and caps accordingly.
I'll add 100pf ceramics to the feedback loops.

D18 and D19 may be saved for another pedal...
C28 and C29 should be 0.1uF and near regulators pins...

I think your right about D18 & 19. I copied the PS from the Music from Outer Space site. The diodes are kind of redundant.

I'll meet you half way on the PS caps. Since this PS is starting out A.C. and is only half wave rectified, I'll keep the tants for their low ESR qualities, and add .1 caps for their high frequency qualities. There is no such thing as too much power supply filtering!

Deal?  

[Fender3D]

hmmm
Ok I can throw few pennies for 2 more caps indeed...

Now back to the breadboard you lazy kid...

[armdnrdy]

hmmm
Ok I can throw few pennies for 2 more caps indeed...

Now back to the breadboard you lazy kid...

Even though I despise bread boarding circuits this large....I decided the middle of last week...that's where this thing is headed! 

I just needed to bring a few ideas closer to "home" before I order parts that I don't have in stock.