"Son Of Storm Tide" Flanger

tiego · Joined: May 15, 2010 Posts: 15 Location: France

Right
I think I did fuck up the env circuit ( worked on test then not when I patched it)
i ll check the soldering and all tomorow
rrrhaa

jumunius · Posted: Tue Jul 17, 2012 5:16 pm Post subject:

tiego · Joined: May 15, 2010 Posts: 15 Location: France

Took my wire away from D1 checked the soldering , seems ok.

the env follower doesnt work internally in the SOST no more.
dont even know where to start to debug , I guess that D1 Diode...

fonik · Posted: Wed Feb 20, 2019 6:47 am Post subject: envelope follower

I don't know how many SOST have been built over the years. I just finished building one and I found that the ENV- follower was not working properly. It was more like a comparator with no threshold.
According to LTSpice changing R61 from 1K to 100K makes it much better. Will check that in the module soon.

fonik · Posted: Mon Feb 25, 2019 2:50 am Post subject:

I checked everything in real life now.

R61 must be changed from 1K to 100K to make the envelope follower work properly. With 1K it works more or less like a comparator, holding the inverting input of the OpAmp at almost 0V.

Accordingly one has to change R5 from 470K to 100K to have a decent impact onthe modulation.

fonik · Posted: Mon Feb 25, 2019 5:05 am Post subject:

SOST and just the internal envelope follower. sound source is a gated square wave:

Rvlt · Joined: Mar 05, 2008 Posts: 33 Location: Berlin

Hey Matthias,

do you run your SOST on 12V or 15V? I built the SOST for my 5U / 15V system, and I always thought the ENV works fine, but I will check again. Maybe you could run Spice sim. with 15V as well?

Cheers
Lars

fonik · Posted: Mon Feb 25, 2019 9:29 am Post subject:

Rvlt · Joined: Mar 05, 2008 Posts: 33 Location: Berlin

Alright,

I will try changing the resistors tomorrow and make a before/after comparison.

So theoretically ...if I put e.g. a sequencer line into the SOST and vary the input level, the flanging sweep then should also vary a lot more than before. With the old resitor values it stays more or less static. Is that correct?

(too bad I have my MS20 in the studio and not near the modular/workbench..)

fonik · Posted: Mon Feb 25, 2019 12:02 pm Post subject:

theoretically yes. however, the settings are a little bit fiddly and as you can hear in my video above, the effect is more noticable with slow changes.
with the old values i actually had the input audio modulating the flanger since the comparator switched at every zero crossing (at audio rate!).

Rvlt · Joined: Mar 05, 2008 Posts: 33 Location: Berlin

I changed both R61 and R5 and now the ENV Mod potentiometer is way more useful than before. It now feels like a modulation amount knob like it should be, before it was kind of the same sound over the whole knob range.

And you're also right: it is a bit more fiddly to use envelope modulation on the SOST (or any flanger?) than on some filter. Doesn't sound "right" on every signal.

Boerge · Joined: Sep 02, 2009 Posts: 80 Location: Germany

Just compared the schematics of SoST-Flanger with the original StormTideFlanger - Jürgen used the same Envelopefollower back then. So he made the same mistake twice?
Made a short simulation too. I'm not shure, if I coult trust LTSpice, as it says 140Volts on output, by +/-15V as power supply...

env-follower.png

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Scematic of my simulation, with the corrected resistor

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env-fol-sim.png

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Sim of the original schematic

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Boerge · Joined: Sep 02, 2009 Posts: 80 Location: Germany

Ooops... missed a dot in the values for V3. 5Volts input is a bit too much Wink

But with 0.5V input LTSpice runs still to 24V output...

fonik · Posted: Tue Feb 26, 2019 6:36 am Post subject:

It obviously is a mistake. The R61 (R2 in your simulation) has to be in the 100K ballpark, not just 1K.

Zek · Joined: Jan 28, 2021 Posts: 1 Location: Brussels

Here is a demo of the Son of Storm Tide Flanger. Great effect! I hope you like it!
https://www.youtube.com/watch?v=JUiCBT7mnng

wrentema · Joined: Feb 08, 2021 Posts: 2 Location: Berlin

Hi. I'm just starting my build. I'm looking for an alternative for the BF245A/BF545A (both obsolete)

Any suggestions?

So far I'm thinking:

J113 / MMBFJ113
or
2SK3666-3-TB-E

I'm not so experienced with finding alternative transistors so any help would be appreciated Smile

Or if anybody has any BF245A/BF545A transistor lying around.. let me know too.

Thanks.

wmonk · Posted: Mon Feb 15, 2021 5:02 pm Post subject:

Banzai Music in Berlin still has them in stock. http://www.banzaimusic.com/BF245A.html

With JFETs it can be a bit tricky at times to find a suitable replacement. Would need to look into the schematic.

wrentema · Joined: Feb 08, 2021 Posts: 2 Location: Berlin

StephenGiles · Joined: Apr 17, 2006 Posts: 507 Location: England

I think a flanger is lost on a synth, best on guitar !!