Old Space Filter WIP thrown open

[StephenGiles]

https://www.dropbox.com/s/5ffoimb5uefgux1/Space%20Filter%20ver%203.png

Finally found a second 13700 in my dead veroboard pile, going to try this out tonight.

Excellent, now I have a breadboard again I intend to devote some time to it over Easter.

[StephenGiles]

Is SSM 2164 quad VCA available? Don't want to waste time if it's not.

No - obsolete/discontinued.

But: http://www.coolaudio.com/docs/datasheet/V2164MD_DATASHEET.pdf by Behringer: http://www.coolaudio.com/index.html
available here: http://www.mammothelectronics.com/Coolaudio-V2164D-Quad-Voltage-Controlled-Amplifier-p/400-1034.htm  and  http://uk-electronic.de/onlineshop/product_info.php?products_id=1267  and  http://synthengineering.co.uk/products/coolaudio-v2164d-quad-vca 

Dual VCA: http://www.coolaudio.com/docs/datasheet/DATA_V2162%20Specs_2011-12-06.pdf  compare: http://www.thatcorp.com/THAT_Alternatives_to_SSM2164.shtml

Ah, thanks for that.

[StephenGiles]

How do we make IC1b output respond ONLY to the leading edge of a guitar note, so that any jitter arising from it's decay would be ignored by the envelope generator, yet still be proportional to the strength of the guitar note played?

I think that may be the missing link here.

[armdnrdy]

I've read in different threads R.G. explaining that this is kind of the hard part!

He did mention a circuit that pulls it off to a better degree than most.....I'll have to see if I can locate that thread.

I think that it was within the last month but....as I'm getting older...sometimes what seems like a month turns out to be a year! 

[StephenGiles]

I'm thinking perhaps an "adaptive" leading edge trigger together with a sample & hold might hold some clues?

[armdnrdy]

Check out MFOS sub commander to see how Ray Wilson implemented that section.

I listened to the sound sample and...it tracks extremely well!

http://www.musicfromouterspace.com/analogsynth_new/GUITARSYNTHAUG2007/GUITARSYNTHAUG2007.html

[StephenGiles]

Thanks Larry, I'd forgotten about that  - need to study the circuit description.

[armdnrdy]

Here's something else that might be useful:

http://www.musicfromouterspace.com/analogsynth_new/SOUNDLABMINISYNTH/guitartrigger/guitartrigger.html

I haven't looked into the compatibility with your circuit but....it's something to check out.

Or better yet...this one is powered by 9-15 volts instead of a bipolar supply.

http://www.musicfromouterspace.com/analogsynth_new/HOT_TIPS/PDF/guitargatenov2012.pdf

[StephenGiles]

Here's something else that might be useful:

http://www.musicfromouterspace.com/analogsynth_new/SOUNDLABMINISYNTH/guitartrigger/guitartrigger.html

I haven't looked into the compatibility with your circuit but....it's something to check out.

Or better yet...this one is powered by 9-15 volts instead of a bipolar supply.

http://www.musicfromouterspace.com/analogsynth_new/HOT_TIPS/PDF/guitargatenov2012.pdf

I'm just wondering if those gates/triggers go high to a fixed highth (!!) as opposed to an "adaptive" highth proportional to strength of guitar notes played.

Anyway thanks for the links from which I have printed out the articles for breadboarding.

[armdnrdy]

I have a feeling that "as is" it doesn't provide for dynamics.

Here's another link with a brief description:

http://www.musicfromouterspace.com/analogsynth_new/HOT_TIPS/guitartogate.php

It states that this circuit was designed to be followed by a VCA or VCF.
That is where you might be able to gain back pseudo dynamics.

Edit:
I just thought that you will still have dynamics in the dry guitar signal if you add a mix control or wet and dry level controls.

[StephenGiles]

Maybe the spare OTA in IC2 could be used as a "comparator peak follower" - so that if a threshold voltage is exceeded, it momentarily peaks to that higher voltage.

[StephenGiles]

Any mileage in the one shot properties of a cheap old 4047 I wonder?