Things to do with full and half wave rectifiers

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ben_hex
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Things to do with full and half wave rectifiers

Post by ben_hex »

Just wondering what peoples thoughts and uses are for rectifiers, whether full or half wave.

I know what they do half wave cuts out the negative portion of an AC signal and a full wave inverts the negative portion of the signal. As illustrated below

HALF -

Image

FULL -

Image

But what are some more creative and interesting uses for them?

So far (beyond the obvious) I've had these two which I like.

- Synced LFOs with half wave rectification. So a 1/4 note synced sine wave into the half wave rectifier gives an 1/8 note rise and then holds at 0 for another 1/8 note.

- Full wave rectifiyng on a variety of wave shapes (great with E350) to control filter and VCA modulation etc

Looking forward to hearing peoples ideas.
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Count Edlington
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Post by Count Edlington »

I like to use full wave rectification to make envelope followers. pretty straight forward: full rectified wave --> slew , adjust rise and fall times to taste......wiggle.
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Post by kindredlost »

positive constraint on a voltage to a quantizer from an LFO or VCO. Of course a signal processor could do the same but the result is different.
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ben_hex
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Post by ben_hex »

Count Edlington wrote:I like to use full wave rectification to make envelope followers. pretty straight forward: full rectified wave --> slew , adjust rise and fall times to taste......wiggle.
great idea! I'll try that out for sure.
kindredlost wrote:positive constraint on a voltage to a quantizer from an LFO or VCO. Of course a signal processor could do the same but the result is different.
Been going uLFO - 8nu8r - ADDAC 207 for this (all euro). Works great. Interest with half wave getting a flurry of note then a rest. Great with tempo synced LFOs too.
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Post by Dave Peck »

1 - clock doubler - take your square wave LFO clock signal that you want to double, feed it through a HPF so that it turns into a series of short 'spikes, alternately positive & negative, feed that through a full wave rectifier to create a series of positive - only spikes at twice the base frequency. Use these to clock something else. Ta da!

2. Triangle LFO doubler - just send it through the full wave rectifier.

3. Crazy filter distortion flavors - send your resonant VCF signal to a mult. One branch goes to the VCA as usual, one goes through a rectifier (try both the half wave & full wave options for different flavors). Now send that rectified filter signal back to an extra filter input to create a distortion feedback loop. Play around with the levels for different results. You may also want to send the rectified signal through a signal processor or spare HPF to get rid of the DC offset that is inherent in a rectified signal and re-center it around 0 volts before sending it back to the filter. This will help prevent the signal from just going into full positive clip (and 'choking' the sound) at high feedback levels.
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Savage
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Post by Savage »

Something I like to do with a full-wave rectifier is, when I'm doing a bass line, I take the ramp (or sawtooth) wave from the VCO and run it through the rectifier, producing a triangle wave at half the frequency. Mix that half-frequency triangle into the bass line to get some nice low end in it.

You can also rectify a square (or pulse) wave and get a non-waveform constant voltage from a VCO. Then use that voltage for a control voltage based upon the amplitude of the VCO.
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Post by maudibe »

Used with an LFO to provide more natural 'string bending' modulation. If you play guitar you'll realise that vibrato can only ever bend a note up from its normal pitch and then return to normal pitch.

If you use a +/- modulation you are essentially detuning the 'string' which is not possible on a guitar. So applying a rectified LFO only moves the pitch sharp and not flat.



:tu:
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Post by Savage »

maudibe wrote:Used with an LFO to provide more natural 'string bending' modulation. If you play guitar you'll realise that vibrato can only ever bend a note up from its normal pitch and then return to normal pitch.

If you use a +/- modulation you are essentially detuning the 'string' which is not possible on a guitar. So applying a rectified LFO only moves the pitch sharp and not flat.



:tu:
Ahhh, but a whammy bar can bend down! And even without a whammy bar, I'll bend a note up a half- or whole-step and get a vibrato by rapidly alternating letting it down and bending it back up to the desired note. When I thought about it, I realized I always use a down-pitch vibrato on a bent note. But not wishing to pick nits, using your fingers alone a la B. B. King, which is easier and more common than the aforementioned method and that I personally prefer over a whammy bar, yes, that's true. Most guitar vibrato does raise the pitch slightly. :bananaguitar:
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Post by tonepanic »

Dave Peck wrote:3. Crazy filter distortion flavors...
Thanks for this tip, you can get some really unique sounds this way. More complex and/or multiple oscillators seems to make things even more interesting
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Post by maudibe »

Hi Savage…. of course if you use a whammy bar you can go down. Obviously. You can also bend the next forward and backward on a 'non thru' neck like like a stratocaster/tele to get up and down vibrato …careful you don't over do this technique

:bananaguitar:

But you can not bend down using finger vibrato, unless the note starts bent up in the first place….

:goo:
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Post by Dave Peck »

tonepanic wrote:
Dave Peck wrote:3. Crazy filter distortion flavors...
Thanks for this tip, you can get some really unique sounds this way. More complex and/or multiple oscillators seems to make things even more interesting

...another variation on this - in addition to using the rectified signal in a filter feedback loop, use a mixer to combine the undistorted filter output with the output of the rectifier. Playing with different settings of these feedback levels going back into the filter, and this separate clean/distorted filter mix after the filter, can give a really wide range of different sounds. Anything from a slightly fuzzy or sqwawky filter to extremely mangled audio.
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Post by rampy »

This is awesome, I love the posts that I actually learn something from!
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tonepanic
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Post by tonepanic »

Dave Peck wrote:...another variation on this
Cool. I also came up with something interesting using a rectifier in the feedback path of a ring modulator. I was trying a bunch of rectification in the feedback of XYZ module, but nothing else to report.

Here's the result of my messing around with rectification in feedback paths of a filter and a ring modulator, with some interesting cross modulation between sounds thrown in as well:

http://soundcloud.com/sieve-ochre/fragment-gamma
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rjungemann
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Post by rjungemann »

Run a sine-wave LFO through a full-wave rectifier for more interesting "wobbles" than a regular sine wave.

Run an LFO through a full-wave rectifier then into a quantizer for interesting arpeggios.
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Post by fisherking111 »

Wow! So many deep tips on a a technique I've only ever used for a cool distortion sound!
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Post by listentoaheartbeat »

tonepanic wrote:Here's the result of my messing around with rectification in feedback paths of a filter and a ring modulator, with some interesting cross modulation between sounds thrown in as well:

http://soundcloud.com/sieve-ochre/fragment-gamma
Great sounds! Is this two VCOs going into the RM with the output being mixed in with one of the input signals, or is it just one VCO being multiplied with the RM's output directly?
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Post by tonepanic »

listentoaheartbeat wrote: Great sounds! Is this two VCOs going into the RM with the output being mixed in with one of the input signals, or is it just one VCO being multiplied with the RM's output directly?
Thanks! Two VCOs. In this patch it is making some of the high frequency sort of metallic sound and is being fed into another osc FM input to create the noisy drone that fades in. And actually one of the RM inputs in this case was the output of the filter that has the rectifier feedback loop, so it's a little bit hard to isolate exactly what the RM was doing. Increasing the RM feedback seemed to make the sound dirtier (in a good way).
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Post by microfauna »

Add a DC offset or LFO to an audio signal before full or half wave rectification. By doing this you can modulate the waveshaping.
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listentoaheartbeat
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Post by listentoaheartbeat »

tonepanic wrote:
listentoaheartbeat wrote: Great sounds! Is this two VCOs going into the RM with the output being mixed in with one of the input signals, or is it just one VCO being multiplied with the RM's output directly?
Thanks! Two VCOs. In this patch it is making some of the high frequency sort of metallic sound and is being fed into another osc FM input to create the noisy drone that fades in. And actually one of the RM inputs in this case was the output of the filter that has the rectifier feedback loop, so it's a little bit hard to isolate exactly what the RM was doing. Increasing the RM feedback seemed to make the sound dirtier (in a good way).
Cool, thanks for the details. What's the lead sound?
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Post by tonepanic »

listentoaheartbeat wrote:Cool, thanks for the details. What's the lead sound?
Two oscs from VCO-2RM mixed going into a MMG. I'm using Dave Peck's rectifier feedback trick on the MMG, which gives it a bit of an edge.
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Post by listentoaheartbeat »

tonepanic wrote:
listentoaheartbeat wrote:Cool, thanks for the details. What's the lead sound?
Two oscs from VCO-2RM mixed going into a MMG.
Ha, funny.. I just tried the VCO2RM at Schneider's and thought that it was really cool for cutting through lead sounds.
I'm using Dave Peck's rectifier feedback trick on the MMG, which gives it a bit of an edge.
Definitely going to try this. Especially interested in giving the MMF-1 a little more edge. The dual inputs on the MMF-1 and MMG will come in handy here.
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Post by richardhamilton »

What a great thread! Thanks to all the contributors, and ben hex for kicking things off. Just picked up a MI Kinks and wasn't sure how to use a wave rectification; I do now, and these ideas will keep me busy for a while. :tu:
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Post by oneunkind »

oscillator-> vca> rectify-> offset-> amplify-> rectify-> offset-> amplify-> rectify-> offset-> amplify-> rectify-> offset-> amplify = a wavefolder thing

uhm, if u happen to have too many rectifiers and maybe a blinds or something?

(i've found it helpful, sometimes, to invert every other stage. but different things have a little different results.)

sure, it's a wasteful patch. but what else to do on sundays?
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Post by moremagic »

maudibe wrote:If you use a +/- modulation you are essentially detuning the 'string' which is not possible on a guitar. So applying a rectified LFO only moves the pitch sharp and not flat.
this kinda depends on the guitar and how you play it :miley:
pushing the headstock on my tele away from me for a tiny dip is a nice touch sometimes


i use rectifiers to feed pos only signals to my ring mods, since i have more of them than 2 quadrant vcas. having another frequency doubling stage is nice when going into the wavefolder to hit the visual cortex, as well
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Post by i.murray.fraser »

The other day I tried feeding two clocks into the BHWR, a faster one to the positive and slower one to the negative. Depending on the relationship of the two, there were some interesting rhythms that came out.
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