Hey all, I've made a vero layout for the envelope detector out of the meatball and I want to use it with the ross phaser. I'm not too clear on how to go about it, would I just add it in where the lfo goes to the stages or is there more to it? I was hoping maybe to add a sequencer as well, again, I'm not sure how to do it, but I'd like to have all 3.
Adapting envelope control to the Ross can be done in several ways. You can have the speed increase when you pick harder, have the regeneration increase, or have the wet/dry mix become more intense.
To accomplish speed control, an LDR under envelope control would be placed in parallel with the phaser speed pot.
To have the picking strength intensify the phaser effect, you might have a 250k-500k pot in series with a 10k resistor to replace the 27k resistor that brings the wet signal to the mixer stage. Then, as you play any LDR in parallel with the pot will drop the effective resistance lower to mix in more of the wet signal.
Envelope-controlled regeneration is a little more complicated, but do-able.
I was hoping to sweep the phase stages with the envelope, is that what you mean by intensifying the phaser effect?
Thanks for the reply by the way.
Nope. I was essentially describing envelope-controlled mixing, where the phasing would not be audible unless you picked harder.
So would it be easy to control the sweep with an envelope filter?
I think if you trawl through Jeugen Haible's site you may find some info in the Envelope-controlled regeneration front. Also, the electro-music.com site is a good place to look or ask for ideas.
What's his site called?
Quote from: Mark Hammer on May 20, 2009, 07:47:34 AM
To accomplish speed control, an LDR under envelope control would be placed in parallel with the phaser speed pot.
Mark, is this the only way to do it? Would it not also be possible to mix the envelope into one of the control pins 1 and 16 of the 13700 LFO? Just curious, as I'm planning an eight stage Ross with two LFO's, so each LFO can control 4 stages each, or have both LFO's simultaneously control all eight stages, or have one LFO control the speed of the second LFO. I was planning to experiment with directly injecting a CV from the first LFO into the second LFO's control inputs, I'd assumed that the LFO is indeed a VCLFO in essence.
Quote from: daverdave on May 20, 2009, 10:35:44 AM
What's his site called?
http://www.jhaible.de/index.html
Quote from: daverdave on May 20, 2009, 10:31:15 AM
So would it be easy to control the sweep with an envelope filter?
Surely just apply the envelope to the control pins of the four phase stages, via a 10K resistor, just as you would the LFO? Though you may need to bias the control inputs with trimmer, lug 1 to +ve, lug 3 to ground, lug 2 to the control inputs.
Quote from: frequencycentral on May 20, 2009, 01:05:03 PM
Surely just apply the envelope to the control pins of the four phase stages, via a 10K resistor, just as you would the LFO? Though you may need to bias the control inputs with trimmer, lug 1 to +ve, lug 3 to ground, lug 2 to the control inputs.
via a series resistor!
Quote from: Lurco on May 20, 2009, 01:36:07 PM
Quote from: frequencycentral on May 20, 2009, 01:05:03 PM
Surely just apply the envelope to the control pins of the four phase stages, via a 10K resistor, just as you would the LFO? Though you may need to bias the control inputs with trimmer, lug 1 to +ve, lug 3 to ground, lug 2 to the control inputs.
via a series resistor!
That sounds easy enough, I'll give it a try. How would I bias it though, I mean, how would I know it's biased?
Quote from: frequencycentral on May 20, 2009, 02:00:50 PM
Quote from: Lurco on May 20, 2009, 01:36:07 PM
Quote from: frequencycentral on May 20, 2009, 01:05:03 PM
Surely just apply the envelope to the control pins of the four phase stages, via a 10K resistor, just as you would the LFO? Though you may need to bias the control inputs with trimmer, lug 1 to +ve, lug 3 to ground, lug 2 to the control inputs.
via a series resistor!
ah! you want the outputted voltage (or current) of that 10k envelope resistor to go to +ve or ground (depending on the extremer trimmersettings)?
my thought was that synth guys prefer mixing (adding) resistors for decoupling?
Quote from: Lurco on May 20, 2009, 03:25:20 PM
ah! you want the outputted voltage (or current) of that 10k envelope resistor to go to +ve or ground (depending on the extremer trimmersettings)?
my thought was that synth guys prefer mixing (adding) resistors for decoupling?
I was thinking something like this:
(http://i210.photobucket.com/albums/bb292/frequencycentral/Thang.jpg)
I'm still waiting on parts to turn up, but I just had another couple of questions. There's a buffer already at the start of the circuit so would it work ok to insert the input of the envelope detector from pad A on the tonepad layout (it's just after the input buffer) without using a seperate buffer for the envelope detector? And how would I go about biasing the output of the envelope detector to the control pins of the stages, is there a voltage it has to be to get the maximum sweep?
Quote from: daverdave on May 23, 2009, 08:45:47 AM
There's a buffer already at the start of the circuit so would it work ok to insert the input of the envelope detector from pad A on the tonepad layout (it's just after the input buffer) without using a seperate buffer for the envelope detector?
Maybe it will work, I guess it would depend on the nature of your detector. Worth trying. You may need to experiment.
Quote from: daverdave on May 23, 2009, 08:45:47 AM
And how would I go about biasing the output of the envelope detector to the control pins of the stages, is there a voltage it has to be to get the maximum sweep?
The trimpot I suggested holds the OTA's open at the point fixed by the voltage divider (which is what the trimpot is). So you would get different sweeps depending on where the trimpot is set. Might be worth having it as a pot as opposed to a trimpot - maybe limit it's range at either end with a fixed resistor though.
What you're doing is quite experimental, I'm suggesting stuff that should work, but it's going to require some tinkering on your part ( :icon_redface:!!).
Thanks for the replies mate. I'll give it a go when the parts turn up. I'll keep you updated on how it goes. The envelope detector I'm using is out of the meatball, it's actually a pretty simple circuit, just a precision rectifier into a buffer driving an led/ldr as far as I can tell.
Quote from: frequencycentral on May 20, 2009, 03:52:00 PM
Quote from: Lurco on May 20, 2009, 03:25:20 PM
ah! you want the outputted voltage (or current) of that 10k envelope resistor to go to +ve or ground (depending on the extremer trimmersettings)?
my thought was that synth guys prefer mixing (adding) resistors for decoupling?
I was thinking something like this:
(http://i210.photobucket.com/albums/bb292/frequencycentral/Thang.jpg)
even worse! when the trimmer is turned up, it will short +ve to ground :icon_rolleyes:
Oops, that connection between lugs 2 and 3 is an over sight, I'll remove it. :icon_redface:
EDIT: OK it's correct now, just click refresh to see it.
Right, I've rigged up test circuit with the meatball envelope detector and the ross phaser. I'm not sure how to wire the ldr side of the vactrol to the sweep pins of the phaser though, do I need to make a voltage divider with 9v on one side and ground on the other? Does anyone have any suggestions on how I should wire it?
I tried using an ldr voltage divider with the ldr coming from 9v and a 1M resistor going to ground. It didn't seem to do anything though, I'm not sure if it's my envelope detector circuit. I know the phaser works. I'll try sweeping the phase with a pot and see if that works.
Right, I rigged up a manual control to the control pins of the stages. I used a 100k pot with a 10k resistor coming from +9v to pin 3 of the pot, the 2nd pin of the pot going to the stages and the 1st pin to ground. It worked fine but when the pot was turned near to the 1st pin there was a wierd dip followed by a rise in volume, sort of like a strange click.
Anyone know a way to solve this?
If I can get it to sweep properly this way then I though using an ldr voltage divider might work, having a 10k resistor from +9v then a ldr under it going to ground, then using a 100k resistor in parallel with the ldr to set it's value. Any input would be greatly appreciated.
I'm following your thread with interest, it would help to see a schematic of how you're marrying up the env detector to the phaser though.
I don't have a decent schematic drawing program, I don't suppose you know an easy to use free one I can get?
I rigged up the pot again the same as before, with a 10k resistor from 9v to lug 3, lug 2 to the phase stages, and this time lug one through a 20k resistor to ground, that got rid of the weird pop sound I was getting, and the sweep seems pretty good. Again frequencycentral, if you know a decent easy to use program for drawing schematics let me know and I'll post the methods I'm thinking of trying. I have a few ideas of how to connect the envelope.
I'm almost ashamed to say I draw all my schematics using MS Paint. :icon_redface:
That's well cool, you should ney be ashamed man. I'll have a do at drawing some and post them.
This is how I intend to connect them anyhow
(http://img196.imageshack.us/img196/5452/envelopephaserstagesinp.png)
Well I've just tested my envelope circuit and it works perfectly, so now it's just a question of connecting them together.
Do you have a depth control, to set the amount of envelope that the phase stages see? It occurs to me that it might also be useful to be able to set 'where' the envelope sweeps from too - a bias control I guess?
Yeah, the envelope has controls for sensitivity, attack, decay and intensity, that should provide enough control over the ammount of envelope. I reckon a bias would be usefull, not sure how to include it though, any suggestions?
I think that little schematic I posted on page 1 would set how 'open' the OTA's are and so dictate the start point of the envelope sweep. You might want to add a resistor at either side of the pot though, as the whole travel of the pot may not be useful, and at the +ve end it could damage the OTA's. It would also work as a 'manual' control I also think.
I think you're right, it would be almost the same as the manual control I tried with it, 10k from 9v and 20k to ground either side of a 100k pot. I'll rig it up and see what happens.
Quote from: frequencycentral on July 16, 2009, 03:51:28 PM
I think that little schematic I posted on page 1 would set how 'open' the OTA's are and so dictate the start point of the envelope sweep. You might want to add a resistor at either side of the pot though, as the whole travel of the pot may not be useful, and at the +ve end it could damage the OTA's. It would also work as a 'manual' control I also think.
you really don`t want to wire a seriesresistor to the wiper?
Quote from: Lurco on July 17, 2009, 02:13:47 AM
Quote from: frequencycentral on July 16, 2009, 03:51:28 PM
I think that little schematic I posted on page 1 would set how 'open' the OTA's are and so dictate the start point of the envelope sweep. You might want to add a resistor at either side of the pot though, as the whole travel of the pot may not be useful, and at the +ve end it could damage the OTA's. It would also work as a 'manual' control I also think.
you really don`t want to wire a seriesresistor to the wiper?
I'm not sure what you mean exactly, but if you're thinking that the current might be too hight for the ota's then I reckon they should be ok. I tried it out with a 10k resistor from 9v to lug 3 of the pot and a 20k from lug 1 to ground and it seemed to work fine. I'm not sure what pot would be best for the sweep, I used a linear and it seemed ok, might try a log and see if it sounds better.
ah it works!! ;D
The one thing is the envelope only seems to sweep part of the phase, not the whole sweep, and the intensity control seems to shift the phase shift and you can hear the sweep better when intensity is set to 0. Not sure why, I think I need to do a bit more tinkering.
Sounds good though, like a weird envelope filter, could do with a bit more umph. I might try the regeneration mod Mr Hammer posted a while back, and add the extra stages mod. Should be a beast then. Just need to get the envelope to sweep more of the phase.
I would guess that your envelope sweeps from about half the power supply up to a little below the +ve. Maybe the OTA's want to see a voltage swing thats nearer to being close to ground to close to +ve. I've used a env in a filter build I did that uses an LM324 which might do the job: http://www.diystompboxes.com/smfforum/index.php?topic=73021.0
Would that sweep the whole of the phase you think?
Quote from: daverdave on July 18, 2009, 10:39:14 AM
Would that sweep the whole of the phase you think?
I think so. LFOs tend to peak and trough either side of half the power supply voltage. Whereas most ENVs go from half the supply voltage upwards. So I'm guessing that's whats happening with yours. Why don't you measure the voltage at the output of your ENV when it's at rest and also at it's maximum. Oh, hang on, you have a LED/LDR combo in there too don't you? Hmmm, I'll have to give it some thought.........
Yeah, that's a point. I read a post by mark hammer on mods for the ross phaser. One that he suggested was reducing the 10k resistor from the lfo to the stages to 2.2k and that would give a wider sweep, I might try reducing the 10k and 20k resistors at either side of the ldr to see if that helps. There were some other mods for the phaser as well, one was to get more regeneration, I think it was to reduce the 27k resistor in the feedback loop to 22k, I can't find the post though at the moment, I could do with reading it again.
Just lowered the resistor values on each side of the ldr, not sure it did much, maybe the sweep is slightly better. On thing I've just realised is the value of the cap I used in the input of the envelope detector. I used a 470n cap, the meatball has a switch for bandwidth here, it uses a 22n, then a 470n and then it's a disconnection to turn off the envelope.
I'm trying to think whether the 470n was for full bandwidth or whether the 22n is.
Also the intensity control seems to be most effective when the pot is set to 0 (with the wiper nearest 1), I'm wondering if increasing the value of the pot would make a difference.