gritty effect

birt · November 02, 2005, 04:16:41 PM

i was thinking... would it be possible to get a very gritty kind of sound by switching the guitar signal on and off very fast.

anyone else got a clue?

can this be done by a switching transistor or something like that?

Harry · November 02, 2005, 07:12:07 PM

That would be an on/off tremolo. I've experimented with it and I don't think grit is the word it's more of a saw type sound (when set for fast).

jmusser · November 02, 2005, 07:19:28 PM

It seems like about any fuzz would fill the bill if it was biased so that it heavy attack to trigger it. Dragonfly's "Dirty Sanchez" shouldn't take much work to get what you need, because it's already pretty Gatey to start with. I have had several that needed work. There are several circuits out there including Fuzz Faces, that use trim pots to set bias, and all it takes is to adjust it so that it needs all the pick up voltage it can get to fire off the transistor.

Peter Snowberg · November 02, 2005, 08:57:49 PM

if you drive a shunt MOSFET with a white noise source run through a sample and hold driven by a random clock which is then modulated by an envelope follower, I'll bet you could get some good grit. I've got a circuit on the drawing board which is AVR based that I may get to one year.

Paul Perry (Frostwave) · November 02, 2005, 10:20:05 PM

Quote from: Peter Snowberg on November 02, 2005, 08:57:49 PM
if you drive a shunt MOSFET with a white noise source run through a sample and hold driven by a random clock which is then modulated by an envelope follower, I'll bet you could get some good grit. I've got a circuit on the drawing board which is AVR based that I may get to one year.Â

My brain couldn't quite parse that, Peter! Do you mean, amplitue modulate the white noise by the envelope of the original signal?
Or is the s&h clock frequency modulated by the envelope?
My feeling with these approaches, is that you really need at least a crude vocoder, to get some pitch variation back in.
I guess an overdriven splatter fuzz with reconstituted envelope would go close.

birt · November 03, 2005, 06:35:35 AM

Quote from: jmusser on November 02, 2005, 07:19:28 PM
It seems like about any fuzz would fill the bill if it was biased so that it heavy attack to trigger it. Dragonfly's "Dirty Sanchez" shouldn't take much work to get what you need, because it's already pretty Gatey to start with. I have had several that needed work. There are several circuits out there including Fuzz Faces, that use trim pots to set bias, and all it takes is to adjust it so that it needs all the pick up voltage it can get to fire off the transistor.

i don't really think that's the sound i'm looking for. the saw sound of a fast on/off tremolo will be closer i think. any suggestions for a good one to build?

Dave_B · November 03, 2005, 08:59:05 AM

Quote from: birt on November 03, 2005, 06:35:35 AM
i don't really think that's the sound i'm looking for. the saw sound of a fast on/off tremolo will be closer i think. any suggestions for a good one to build?

Have you looked at the R.G.'s Variable Stuttering Pedal? It on the front page at Geofex.com. Then search for it here, since there's been some discussion about it recently.

Mark Hammer · November 03, 2005, 11:22:13 AM

Bat Macumba!

I'll let the others fill you in.

Harry · November 03, 2005, 12:24:42 PM

I used a real simple op-amp based multivibrator (honestly I don't even know what a multivibrator is) circuit that casued an led to flash on and off (strobe-style). Then I placed an LDR next to the LED and had it intercept the guitar's signal. So it goes on/off/on/off/on/off... Let me know if this sounds like what you want and I'll draw it up and post it (it's only 8 or so components so it's real simple). Personally, I think it's a real cool effect and I'd like to build it into a pedal one of these days. When it's set at a slower pulse it sounds like an echo, When set fast you get that good ol' Link Wray saw ripping sound.

MartyMart · November 03, 2005, 12:28:51 PM

Quote from: Harry on November 03, 2005, 12:24:42 PM
I used a real simple op-amp based multivibrator (honestly I don't even know what a multivibrator is) circuit that casued an led to flash on and off (strobe-style). Then I placed an LDR next to the LED and had it intercept the guitar's signal. So it goes on/off/on/off/on/off... Let me know if this sounds like what you want and I'll draw it up and post it (it's only 8 or so components so it's real simple). Personally, I think it's a real cool effect and I'd like to build it into a pedal one of these days. When it's set at a slower pulse it sounds like an echo, When set fast you get that good ol' Link Wray saw ripping sound.

That sounds quite cool Harry, please post it up ?
Is it very "clicky" or has it more "rounded" wave shape ?
Cheers,
Marty.

birt · November 03, 2005, 12:45:14 PM

that sounds good! please show me the schem

Harry · November 03, 2005, 12:56:06 PM

Not clippy or rounded, really. The LDR is the only part that is connected to the guitar so it's not crackly. And the whole point of the circuit is to turn the signal on and off directly so it ain't real rounded. It's choppy.
Well, sounds like you guy's are interested so I'll get cracking and get it drewn up. It may not have all the kinks worked out cause I don't think I'll be able to test as I blew my op-amp a while ago...

Harry · November 03, 2005, 04:00:22 PM

O.K. well after turning my room upside down I failed to find my soldering iron, so this'll remain unrefined for now. I actually ended up stepping on anÂ op-amp sitting dead-bug style all 8 pins into my foot!!!! Maybe you guys can help me out with getting the kinks worked out. Well here it is, hopefully someone can get some use out of it:

edit: pic wasn't showing up i'm trying this: http://www.geocities.com/thegoodonesarealreadytaken/simple_staccato_tremolo.bmp

birt · November 03, 2005, 04:28:26 PM

is there a specific reason you use that opamp? or is a tlo72 also good?

and how do i get 4,5V from a 9v battery or psu?

Harry · November 03, 2005, 04:49:23 PM

Good questions, unfortunately I don't know. I used that power supply and that opamp, because I was using this electronic projects experimenters kit and that's what it provided (6 AA batteries) and the BA728. You'll have to ask someone that's knows their stuff.

Apparently the picture showed up for you, for some reason it ain't showing up for me now? I think my geocities site (where i have it uploaded) may be down temporary. Let me know if it's not showing up for you too.

birt · November 03, 2005, 05:06:58 PM

the pic is gone

Harry · November 03, 2005, 05:28:39 PM

it's back.

birt · November 03, 2005, 05:44:45 PM

nice

hey are you sure that second led blinks at the same time as the other one?
cus when the blink one at the time you could make a second input with a second ldr so you get 2 signals switched very fast. like for example guitar and siren or radio. and then feed that into an envelope filter, hehe, madness

Harry · November 03, 2005, 06:12:30 PM

Yeah it blinks at the same rate except when the first one's on the others off and vice versa they alternate. You gave me an idea set it up with two inputs and two outputs that way you could have either a stereo set-up guitar ping-ponging, or have one channel guitar the other bass!!!!! Wow that would be interesting as hell.

You may also be interested in: Vox Repeat Percussion, Walco Sound-Go-Round, and I think the EA Tremolo (haven't ever been able to find that one though) those are all on/off style trems I believe.

Well the pictures back off, so it may just take some luck to view it. If you want it either save it when it's up or email me or suggest a picture uploader upper.

Harry · November 03, 2005, 06:33:40 PM

O.K. I noticed a mistake I made (in red), Also added the other channel idea.

I really got get this wired together.

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gritty effect