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DIY Stompboxes => Building your own stompbox => Topic started by: Jonas on February 20, 2004, 11:59:26 AM

Title: Revolutionary noise gate
Post by: Jonas on February 20, 2004, 11:59:26 AM
I got this weird idea! and I'm gonna share it with you

A noisegate that cuts the noise after all OD, on the effects loop, but  the trigger comes directly from the guitar's output...

What do you think?
maybe nothing new after all

Cheers!
Title: Revolutionary noise gate
Post by: Transmogrifox on February 20, 2004, 12:07:18 PM
Not a bad idea.  It reduces the need to be constantly tweaking the gate threshold for changing noise levels.
Title: Revolutionary noise gate
Post by: smoguzbenjamin on February 20, 2004, 12:22:48 PM
You'd be building a noise gate with an effects loop. Good idea, but I can't say much about it because I'm not sure how a noise gate works. I must dig into that... :)
Title: Revolutionary noise gate
Post by: Fp-www.Tonepad.com on February 20, 2004, 01:32:22 PM
Jonas,

Not a new idea, but still a good one.

I think it's TC Electronics that includes a noise gate in their distortion pedals and from what I understand it works that way.

If you look at the mxr noise gate schematic available at tonepad (http://www.tonepad.com/project.asp?id=18), the way to quickly implement this mod would be to tap right before the 22k resistor (the one connected to the 10uF and 0.01uF caps), add a coupling cap and make that the 'send', and the left connection of the resistor would be the 'return'. You may need buffering for the input, but I don't think so.

Let me know if you give it a shot. And check out the newest pdf with a new layout and mods.

Fp
Title: Revolutionary noise gate
Post by: Jonas on February 20, 2004, 02:03:28 PM
I have some other projects on the line right now... but I'll consider it later on.
Title: Revolutionary noise gate
Post by: swt on February 20, 2004, 07:42:14 PM
The bad thing about having a noise gate, like some commercial fx have, is that there seems to be bad gating effect, that is, not so good sustaining, and maybe no feedback too. Some pedals seem to produce this, don't know why. I'm trying to do the same thing with a ring mod, because of bleed through, so if anyone's got a good design, and simple, let me know. Thanks!
Title: Revolutionary noise gate
Post by: GuitarLord5000 on February 20, 2004, 11:33:36 PM
Yeah.  The gate needs a good bit of tweaking to find that "sweet spot", where your notes sustain decently, but the noise is gated shortly after your note dies out.  I had one quite some years ago, but it got lifted, so I'm about to build the MXR gate.  
Now, if i'm not mistaken, a noise supressor works differently.  I dont have much experience with these, so I'll have to do some research to confirm.

Edit: Here's some info on the chip that apparently makes HUSH...er....hush.

http://www.analog.com/library/analogDialogue/archives/30-2/noise.html
Title: Revolutionary noise gate
Post by: smoguzbenjamin on February 21, 2004, 05:19:26 AM
Is that one IC?! 1 chip noise gate!!!! :D
Title: LDR gate
Post by: dev on February 21, 2004, 01:07:58 PM
Here is a gate idea you might want to try.  Its not perfect but simple enough to try out.  Place an L.D.R. between the output cap on the effect and the effect output(sometime the output volume).  You may want to place a large resistor across the L.D.R. to have a minimum volume.  Now take the signal from the effect, from a point that works best (its different for different types of boxes play around like using an audio probe)and feed it to a lm386 IC.
the feed.

effect's signal to small resistor(to isolate reverse signal noise from LM386) to large cap to to 100k volume or trim pot used as an input volume to pin 3 on the IC

pin 1 goes to pin 8

pin 2 to ground (sometimes)

pin 4 to ground

pin 7 not connected

pin 6 to small resistor (around 68 ohms to isolate power supply noise) to +9 volts

pin 5 to large cap this is the gate's signal output

now there are several different ways to get this output to turn on an LED to shine on the L.D.R. here are two

one is:

a 2n3904 or other NPN transistor

base to 470k resistor to ground

emmitter to ground or to small ressitor to ground

collector to LED to (pin 6 on lm386)same resistor as above(68 ohm) to + 9volts


another better way to turn on the LED is here

http://home.maine.rr.com/randylinscott/oct98.htm

you only need to use the first LED.  and it runs well off the +9volts buffered by 68 ohms(pin 6 on the lm 386)

importantly to cut down power supply noise use a large cap 100 to 1000uf from gound to pin 6 on the lm386
and another large cap from gound to +9 volts

Bread board this and see if it works for you. I've had really nice results, but I will admit no one has come up to me and said "wow you really have a noise free rig dude!". any I deas on this are very welcome.

good luck
Dev