Tremolo for Chopper Sound

[aziltz]

Which Tremolo circuits will do the hard ON-OFF square wave?  I know the EA tremolo doesn't quite get all the way off.

Thanks,

[blanik]

tremulus lune does EVERYTHING !   

[.Mike]

...or if you have the ability to burn PICs, I made a Tremulus Lune variant that does the choppy thing. It uses the Tremulus Lune signal path, but uses a PIC VCLFO that is extremely flexible. It can be as choppy as you want it to be.

I think I'm the only one who has built it... link



Mike

[aziltz]

is there a stripped down version that does square wave trem with depth and speed?  like the catalinbread valcoder?

[soggybag]

I haven't built the tremulous lune (yet!). I would have guessed that it might not make a good "chopper", because of the LDR. My thinking is the light history of the LDR would smooth out a square wave, especially at higher rates.

This makes me wonder if a FET could be used in place of the LDR, maybe a Photo FET.

[Cliff Schecht]

I designed a tremolo a while back that did everything from a nice sinusoidal sweep to a complete stutter, and never with any popping at the output. I was originally going for a stereo tremolo with 9 knobs and some switches (I like tweaky pedals) but I could cut it down to a single channel and post a schematic tomorrow. The great thing is that my design eliminates the use of those pesky LDR/LED combo's and doesn't require any parts matching or trimpots to eliminate deadspots. Actually, it uses all standard parts (as far as guitar pedals go) and had a very pleasant sound. Time to give the Tremulus Lune a run for its money!

[Cliff Schecht]

I haven't built the tremulous lune (yet!). I would have guessed that it might not make a good "chopper", because of the LDR. My thinking is the light history of the LDR would smooth out a square wave, especially at higher rates.

This makes me wonder if a FET could be used in place of the LDR, maybe a Photo FET.

Why bother? You're just introducing more specialized (and usually expensive) parts unnecessarily into the design. The trick with the Lune is what you said, the slow response time of the LDRs prevents the signal from changing TOO fast and causing popping. A photoFET would react MUCH quicker and really make the whole idea of using a light dependent device moot. My design uses your standard JFET as the variable component and a few other tricks to eliminate popping at the output. Seriously, I promise to post it tomorrow .

[aziltz]

I designed a tremolo a while back that did everything from a nice sinusoidal sweep to a complete stutter, and never with any popping at the output. I was originally going for a stereo tremolo with 9 knobs and some switches (I like tweaky pedals) but I could cut it down to a single channel and post a schematic tomorrow. The great thing is that my design eliminates the use of those pesky LDR/LED combo's and doesn't require any parts matching or trimpots to eliminate deadspots. Actually, it uses all standard parts (as far as guitar pedals go) and had a very pleasant sound. Time to give the Tremulus Lune a run for its money!

if its not too much trouble, i would really appreciate that!

[connie_c]

is there a stripped down version that does square wave trem with depth and speed?  like the catalinbread valcoder?

I asked a similar question here a few months ago and was pointed at the heart throb tremelo http://www.aronnelson.com/gallery/main.php/v/MarkMs-Gallery/album15/album76/Hearthrob_Tremolo_LAYOUT.gif.html

and the vox repeat percussion which i think is what the valcoder is based on.

http://www.diystompboxes.com/smfforum/index.php?topic=75372.0

[MarcoMike]

what about upgrading a simple EAtrem with a squarewave oscillator? the standard CMOS thing ... and a switch to select between normal and squarewave...

[ItZaLLgOOd]

if its not too much trouble, i would really appreciate that!

+1

[Cliff Schecht]

Alright, I promised: http://www.aronnelson.com/DIYFiles/up/stereo_trem.pdf

There's a few values that can be tweaked/eliminated. If you want a mono tremolo, eliminate C5, C9 and R33 (and all circuitry in between). R4, R5, R7 and R8 can be omitted if you don't care about some deadspace in the pots (I left them out for simplicity during my testing). The switch chooses between in phase and out of phase stereo tremolo although when inverted, the knobs interact. Not a big deal, it just allows for more tremolo options. Questions/comments welcome!

[aziltz]

Looks Great!

[Cliff Schecht]

Here's a quick walkthrough of the pots/switch and what they do (sorry, no labels yet):

LFO
100k linear pot at bottom - Skew control - Controls the shape of the triangle wave, varies from a triangle wave (when the op amp "+" terminal is at GND) to nearly a sawtooth wave.
1Meg log pot - Tremolo speed control - You should know this one

FET driver/wave shaper
100k linear going into U2A "+" terminal - offset control - controls the amount of tremolo effect on the first channel
100k log in feedback path of U2A - Waveshape - varies the waveshape from a nice undistorted triangle (smooth tremolo) to a square wave (choppy tremolo).
Switch S1 - invert/nonivert - For stereo operation, this switch determines whether both channels tremolo together/alternating. When the switch is set to invert, the first set of controls will interact with the second set of controls. This is a side effect of having a switch like I do but was a comprimise I made to keep the overall parts cost down.

Input
R22 probably needs to be made smaller (maybe 2.2k) so that the input signal can be adjusted as necessary. While the original idea for this tremolo was a distortion AND tremolo, I quickly found out that the distortion produced by a JFET biased near the cutoff region is not very pleasant. Further notes below.

Output
This section still looks a bit funky because it's missing a second volume knob. I guess at the time, my idea was to set the second channel volume against a set first channel volume but a better bet would be to simply used a dual-ganged pot to control both outputs simultaneously. The mixer dealy I was going for just didn't pan out like I expected it to... If the dual-ganged pot idea is added or a channel is eliminated, then the input gain control can probably be omitted as well.


That would have been much easier with designators on the pots! Now I remember why I didn't post this schematic, I never found time to finish the design!! Azlitz has offered to do a board for the schematic but first, I'm going to make him redraw it with some corrections .

[Top Top]

The kay tremolo clone from GGG is very choppy, but it does not have a depth control.

Pretty simple circuit though.

[aziltz]

That would have been much easier with designators on the pots! Now I remember why I didn't post this schematic, I never found time to finish the design!! Aziltz has offered to do a board for the schematic but first, I'm going to make him redraw it with some corrections .

indeed.