Author Topic: Vox Repeater Percussion WAVEFORM help  (Read 396 times)

Atodovax

Vox Repeater Percussion WAVEFORM help
« on: January 21, 2021, 10:33:09 AM »
Hi everyone. Is there anyway to change the waveform of the VOX Repeater Percussion to a SQUARE or SINE waveform?

garcho

Re: Vox Repeater Percussion WAVEFORM help
« Reply #1 on: January 21, 2021, 10:58:28 AM »
If you post some links, pics, schematics, anything, you'll find better help quicker.

Isn't it already a square wave? You should read up on making sinewaves with analog circuitry, it's not simple or easy. However, you rarely need an actual sine wave, usually triangle, hypertriangle or something like that, comes close enough for the same effect. Have you built it already?
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iainpunk

Re: Vox Repeater Percussion WAVEFORM help
« Reply #2 on: January 21, 2021, 11:05:44 AM »
welcome to the forum

add a new LFO.
sine waves is kinda hard, but doable, normal triangle (not sawtooth like the original) is way easier and gives you both square and triangle in a single opamp.
putting clipping on a triangle might even make that more sine-wave like.
i'll post a schematic later today, i don't have the exact parameters for the amplitude of the LFO

Garcho, the original has sawtooth, to produce that percussive thump, that squares don't have

i also recommend adding a boost circuit like the EQD humming bird, to make up the lost volume

cheers, Iain
« Last Edit: January 21, 2021, 04:51:48 PM by iainpunk »
half man - half snail - 6 feet to scale - Snail man's - not frail - He's been - to jail - snail man is fuccing real
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garcho

Re: Vox Repeater Percussion WAVEFORM help
« Reply #3 on: January 21, 2021, 11:19:54 AM »
Quote
welcome to the forum

It's his 169th post  ;D

Quote
Garcho, the original has sawtooth, to produce that percussive thump, that squares don't have

Square waves don't thump? How exactly is the right angle of a saw tooth different than a square wave? Is it that a ramp is "thumping" half as often as a square (considering rising and falling edges as thumps)?

Cr-ri-im-ms-so-on an-nd cl-lo-ov-ve-er ov-ve-er an-nd ov-ve-er...
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Atodovax

Re: Vox Repeater Percussion WAVEFORM help
« Reply #4 on: January 21, 2021, 01:34:55 PM »
Thank you both for replying :D. Sorry i didnt put the schematic. Here it is.
https://www.....org/download/file.php?id=25048&sid=adcefa528fa287e761c1563f9827f5c7&mode=view

I was thinking if it was possible to do a square waveform from the original Sawtooh but without any added circuitry. I donnt want to add an extra lfo as i ve already heard that the original circuit is prone to ticking. Is there an easy way to transform that sawtooth to something more like a square? Maybe just a capacitor /resistor in there? hehe

Atodovax

Re: Vox Repeater Percussion WAVEFORM help
« Reply #5 on: January 21, 2021, 01:37:45 PM »
Maybe playing with r7s value can do the capacitor drain in a more squareish form?

garcho

Re: Vox Repeater Percussion WAVEFORM help
« Reply #6 on: January 21, 2021, 01:46:42 PM »
Quote
i ve already heard that the original circuit is prone to ticking. Is there an easy way to transform that sawtooth to something more like a square?

The reason a ramp or sawtooth "ticks" is because it has (basically) a 90 angle, like a square. Also, ticking is often because of current in the ground, not just from the way the LFO modulates the audio signal, which means you might have to address that regardless of LFO waveform. Many LFOs have a square wave in the circuitry somewhere, even if it's not tapped to use with the actual LFO.
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Vivek

Re: Vox Repeater Percussion WAVEFORM help
« Reply #7 on: January 21, 2021, 04:48:14 PM »
Thank you both for replying :D. Sorry i didnt put the schematic. Here it is.
https://www.....org/download/file.php?id=25048&sid=adcefa528fa287e761c1563f9827f5c7&mode=view



The link did not work for me

PRR

Re: Vox Repeater Percussion WAVEFORM help
« Reply #8 on: January 21, 2021, 05:42:53 PM »
> The link did not work for me

For historical reasons, the URL of "the other forum" can not be posted on this forum.
https://i.postimg.cc/wxHC68dX/file.gif
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iainpunk

Re: Vox Repeater Percussion WAVEFORM help
« Reply #9 on: January 21, 2021, 05:49:45 PM »
Quote
welcome to the forum

It's his 169th post  ;D

Quote
Garcho, the original has sawtooth, to produce that percussive thump, that squares don't have

Square waves don't thump? How exactly is the right angle of a saw tooth different than a square wave? Is it that a ramp is "thumping" half as often as a square (considering rising and falling edges as thumps)?

Cr-ri-im-ms-so-on an-nd cl-lo-ov-ve-er ov-ve-er an-nd ov-ve-er...
1) oops, i did that because the question reads like one of those first time poster questions.
i apologize for that, it's been a rough day.

2) the square wave doesn't thump as much as it chops.
the LFO of the repeat percussion has an instantaneous sweep up and a ''hanging'' curve down, this gives a perceptual thump, since we interpret that as coming above the average audio level, where the square wave just chops like a helicopter, because the tops of the waves are flat, no such peak is interpreted subconsciously.

the LFO from the repeat percussion is quite odd, since the amplitude that comes out is 0 to 0.6v
i haven't tried these suggestions yet, so i recommend bread-boarding it first.
if you want a more gradual triangle, you could try changing the 39 ohm resistor, if you put in a higher resistance, it might get smoother. if you want more square wave signals, you could try adding a large non-polarized cap across the 330k that goes in to the base, maybe with a series potentiometer to tone it down, it will drive the base in to fully opening and closing.

cheers, Iain
half man - half snail - 6 feet to scale - Snail man's - not frail - He's been - to jail - snail man is fuccing real
『snailpilled』

Atodovax

Re: Vox Repeater Percussion WAVEFORM help
« Reply #10 on: January 21, 2021, 09:05:14 PM »
Quote
welcome to the forum

It's his 169th post  ;D

Quote
Garcho, the original has sawtooth, to produce that percussive thump, that squares don't have

Square waves don't thump? How exactly is the right angle of a saw tooth different than a square wave? Is it that a ramp is "thumping" half as often as a square (considering rising and falling edges as thumps)?

Cr-ri-im-ms-so-on an-nd cl-lo-ov-ve-er ov-ve-er an-nd ov-ve-er...
1) oops, i did that because the question reads like one of those first time poster questions.
i apologize for that, it's been a rough day.

2) the square wave doesn't thump as much as it chops.
the LFO of the repeat percussion has an instantaneous sweep up and a ''hanging'' curve down, this gives a perceptual thump, since we interpret that as coming above the average audio level, where the square wave just chops like a helicopter, because the tops of the waves are flat, no such peak is interpreted subconsciously.

the LFO from the repeat percussion is quite odd, since the amplitude that comes out is 0 to 0.6v
i haven't tried these suggestions yet, so i recommend bread-boarding it first.
if you want a more gradual triangle, you could try changing the 39 ohm resistor, if you put in a higher resistance, it might get smoother. if you want more square wave signals, you could try adding a large non-polarized cap across the 330k that goes in to the base, maybe with a series potentiometer to tone it down, it will drive the base in to fully opening and closing.

cheers, Iain


Thank you very much for the hint :) Should i wire the potentiometer with both of its pins tied together acting just as a variable resistor ? between base of transistor and capacitor?

Atodovax

Re: Vox Repeater Percussion WAVEFORM help
« Reply #11 on: January 21, 2021, 09:06:24 PM »
> The link did not work for me

For historical reasons, the URL of "the other forum" can not be posted on this forum.
https://i.postimg.cc/wxHC68dX/file.gif

Sorry about this. I dindt know that those links were forbiden!