Looping ADSR loop greater than 0.6v?

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Paradigm X
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Looping ADSR loop greater than 0.6v?

Post by Paradigm X » Wed Jan 27, 2016 8:21 am

Hi

I love the looping mode on the vcadsr, but it would be great if it could loop between a value greater than 0.6v (and 5v), so it never goes 'silent'.

Would this be possible, maybe with a pot to control the lower level? Panel space is a concern but could fit one in on the 2u version.

many thanks
Ben

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Synthbuilder
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Post by Synthbuilder » Wed Jan 27, 2016 3:00 pm

I just wrote a couple of posts that assumed you meant lower than 0.6V... Doh!

Yes, you can make the range between the low and high points of the envelope smaller. On the schematic you'll see a diode that creates the 0.6V needed for the end of cycle detector. What you need to do is to replace the diode with a series combination of diode and a pot.

I'm not in the office right now so I can't give you any more details but I'll get onto it when I'm back at work tomorrow.

Tony
Last edited by Synthbuilder on Thu Jan 28, 2016 4:53 am, edited 1 time in total.

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Post by Synthbuilder » Wed Jan 27, 2016 3:04 pm

Oh... If you had a VCA module you could do this easily. Just feed the ADSR output to the VCA's CV input and adjust the gain and CV controls to set the low and high volumes.

You can never have enough VCAs. :hihi:

Tony

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Post by Paradigm X » Thu Jan 28, 2016 4:30 am

Hey thanks tony. I think i know what you mean about the pot etc, used something similar on a 606 mod.

I havent actually got any pure vcas yet, somehow ended up with 3 vcadsrs, but no actual vcas. Next on my list when im not skint!

incidentally, been meaning to ask, but didnt want to overask (!), can you use the vcadsr as just a VCA?

Many thanks as always

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Post by Synthbuilder » Thu Jan 28, 2016 4:58 am

Right the diode in question is D7. Lift the cathode (black band) end of it from the circuit board and join a 10K pot from it's now free end to the now vacant solder pad. That may work...

Let me know if you do try it.

What you will find is that, since you are changing the start and end points of the loop, the frequency of the looping will change. Reducing the range will speed up the looping.

Tony

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Post by Synthbuilder » Thu Jan 28, 2016 5:06 am

Paradigm X wrote:can you use the vcadsr as just a VCA?
Not easily. You can lift one end of R44 (the end not connected to U5 pin 6) and use that as your CV input for the VCA. But it's a 12K input resistance which is pretty low for an input. The CV sensitivity is expecting to see 8V for unity gain - again, this isn't standard, I use 5V for unity gain, so the VCA will be significantly quieter than dedicated VCAs.

Really you need some dedicated VCA modules - with separate gain and CV depth controls. They really do alter the way you patch as they can add voltage control to depths of modulations.

Tony

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Post by Paradigm X » Thu Jan 28, 2016 11:35 am

Hey many thanks.

I will try it, hopefully this weekend.

A dual VCA is next on my purchase list.

edit, although just realised the ringmod can be used as a vca. but i like it as a ringmod too. im starting to see why people end up with towering black walls of modules...

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Post by Paradigm X » Fri Feb 26, 2016 4:43 am

sorry, i forgot to mention, i tried this, and it seems to work :party:

i say seems because im using a newly built pcb which has never quite worked (yet), ive got looping mode working ok, and the LED works fine but i get no output from the adsr socket. checking on a scope on the led shows the range changing with a pot (i think a 10k log would work better than lin from the visual.

but not had time to troubleshoot the whole module.

if you remove the LED there is room for a 9mm pot, and youd just have to relocated the LED, relatively easy, apart from drilling for klutzes!

hoping to get this finished and troubleshot this weekend if i can get time.

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