Adding modulation to BBD Delay (mn3205)

[Mikaellanden]

Hi!


SKIPPABLE CONTENT

I'm new to the forum so forgive if I break any rules (tried to read a bit before). I'm also still a beginner even though my slightly manic personality made it possible to learn a lot in a short time ( lots of sleepless nights, sneaking up at 4am to resolder a faulty pedal, beeing in social situations nodding my head to fit in but actually I'm in the middle of figuring out how to insert an expression jack to a phaser that also controlls the LFO of a vibratopedal ). However, I'm very far from understanding what I'm actually doing sometimes and that's why I would love some guidence from all you pros here:)

QUESTION

I have made a combo-pedal that uses an old phaser ( Guyatone ps-007 ) together with this BBD Delay by Allesz (echo pathetic)
http://effectslayouts.blogspot.com/2015/12/echopathetic.html


I'm really happy with how it sounds but I would like to add chorus/vibrato to the repeats. Is this easily done? say if I have a simple chorus circuit. Where on the mn3205 (or somewhere else?) would I add the chorus?
Or, can I just simply add an lfo to the time potentiometer? (guess that would be more of a vibrato but that's ok to)
Spacing is not a problem btw since I boxed it in a huge cigar box:D (shielded)

Would be super happy if any of you have suggestions on how to do this.
Thanks!

[j_flanders]

Where on the mn3205 (or somewhere else?) would I add the chorus?
Or, can I just simply add an lfo to the time potentiometer? (guess that would be more of a vibrato but that's ok to)

Chorus = Mix of dry signal + modulated echo (echo mix at 50%)
Vibrato = modulated echo only (echo mix at 100%)
Modulation speed is faster for vibrato and slower for chorus.

Yes, you can 'simply' add an LFO to the delay time 'control'.
Delay time is set at the clock chip by the combination of a resistor + capacitor (22k + 100k pot and 330pF cap in this case)
You can modulate either one: varying the resistor or varying the capacitor.

I guess the easiest way is to copy it from a schematic of an existing modulated delay that is using a similar clock chip.
That might also give you an idea on how to implement the depth control.

The only schematic I can think of right away is the one for the Behringer Vintage Time Machine. It has a modulation section very similar to the one in a Deluxe Memory Man.

The series 820pF caps in there would replace your 330pF cap.
You can also try (slightly) different values for the 330nF and 2.2uF caps for the faster vibrato and slower chorus setting, if you find either one a bit too slow or fast.
Deluxe Memory Man uses a 470nF cap instead of 330nF for example, making the vibrato mod speed a bit slower.

[Mikaellanden]

Thank you so much! will try this asap!:)

[Mikaellanden]

Just one question. If I use the behringer vibrato/chorus circuit. I guess I also have to build the power supply for it since they referring to vdd/2 and vcc/2 in the circuit. or can i use the supply from the opamps on the EchoPathetic?
http://effectslayouts.blogspot.com/2015/12/echopathetic.html


And one more newbie question, the 8 pin of lm4558 goes to +9 and pin 4 to GND even though it's not written on the schematic, right?

[j_flanders]

Just one question. If I use the behringer vibrato/chorus circuit. I guess I also have to build the power supply for it since they referring to vdd/2 and vcc/2 in the circuit. or can i use the supply from the opamps on the EchoPathetic?
http://effectslayouts.blogspot.com/2015/12/echopathetic.html

Vcc/2 is just your regular 4.5v half power supply, bias voltage.
I don't know why they connect to Vdd/2 instead of just to half power supply.
At max depth:
With Vcc/2 the triangle output at the depth pot swings between 4v and 5v (4.5v being the mid point)
With Vdd/2 the triangle output at the depth pot swings between 3.1 and 4.2 (3.75v being the mid point)

Deluxe Memory Man goes through a cap to ground(0v) instead.

And one more newbie question, the 8 pin of lm4558 goes to +9 and pin 4 to GND even though it's not written on the schematic, right?

Yes.

[Mikaellanden]

I'm so humble about getting this help!

I breadboarded the behringer lfo circuit yesterday but when I added it I only got high pitch noise. Like a tone. So I guess I did something wrong.
I could measure some "swing" between 4,4 - and 4,8 v at some places in the circuit (still don't know exactly how it works so did some guessing).

I will do some more tries on this but got some new ideas and of course - new questions to all you pros:D

The echopathetic, which I'm trying to modulate the repeats on is boxed together with a modded Guyatone phaser ps-007.
Could it be possible to "hijack" the modulation from that circuit somehow?
here's the schematic for PS-007

https://www.dropbox.com/sh/xec6p5g9h3l24c7/AAAIMA4w0nC4deYfkJmAX5TPa?dl=0

Another idea I got was to buy a LFO chip on Electric Druid
https://electricdruid.net/product-category/lfos-noise/

But can't find any info if those chips will work on mn3102 clock.

Again, sorry for a lot of newbie questions but I'm just happy to be stirred in any direction that is not a disaster.

Thanks!

[Mikaellanden]

Ok, I found one solution that worked. Blinking LED and a LDR to the time potentiometer. I also made a switch that shifts to a ldr outside the pedal that can create really interesting random pitch shifts

Still want to finish the other lfo but this will do for now. Thanks for all the help!