Tube circuit to give sharp decay/minimize sustain?

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8/3/2000 2:07 PM

jon

Tube circuit to give sharp decay/minimize sustain? Hi   This question may be more suitable for the effects board, but here goes...     I'd like to make a tube circuit kill the note very shortly after it's sounded, kinda like an automatic mute, for a staccato decay. I guess what I'm after is the opposite of sustain. I need the initial sharp attact, though.     Following a typical tube voltage amplifier stage, I've used all sorts of different solid state diodes, and LED's in reverse parallel pairing to ground, still get some "growl" as the note decays. I guess what's happening is that they're "gating" the signal, only allowing signals above a threshold to make it to the next stage. The decay envelope is close but the waveform's changed significantly. I'm looking for less harmonic distortion, more of the normal guitar tone. I guess the envelope would be like what you get when hitting a Fender-Rhodes electric piano key without the sustain pedal on.     Any better ways to approach this? I've tried a single-shot tube multivibrator scheme, so far the results have beeen pretty nasty.   thanx, Jon

 

8/3/2000 4:50 PM

JM

Sounds like what you are looking for is a gate. Some of the cheaper stompbox noisegate pedals might work for you if you set it so the gate kicks in and closes compleatly unless it's getting a lot of signal. If you set it just right it will let the beginning (the attack) of the note through but will close down and shut off the decay of the note altogether. I've never heard of a tube gate but if you are looking for a very high quality unit a company called Valley People and later Valley Audio made studio gates that were used on drums and reverb sounds as well as getting rid of noises.     JM

 

8/3/2000 6:29 PM
enorton	What you are looking for is a compression   /expander unit. Studios once used them   years ago before solid state. Still, I   don't know where you could find one.   You might try old AM radio stations. One might have one in a closet if you are lucky. They   used them to clean up old tapes.

 

8/4/2000 12:55 AM
jon	enorton,   never thought about scouring old radio stations for tube gear...thanx for the lead   Jon

 

8/5/2000 9:17 PM
anonymous	I'm not sure where you would find info on these guys but the MXR is the type of unit I'm talking about. You could certainly try the radio stations but most of the old compressor units were grabbed years ago these things run from several hundred to several thousand dollars, now the days of picking them up for nothing were a decade ago.     JM

 

8/4/2000 12:53 AM
jon	Hi JM,   I kinda remember a unit called a "noise gate-line driver", i think it was from MXR, around the same vintage as the attack delay units (late 70's, early 80's?) do you know of any schematics for gate circuits (tube or SS?) I'd like to try and apply this gating into a tube effect I'm working on.   Thanx,   Jon

 

8/10/2000 9:41 PM
PTJohn	Craig Anderton has a Noise Gate schematic in "Electronic Projects for Musicians." For opamp based stuff, it's pretty good. You could adapt his optocoupler idea into a tube circuit by using a higher voltage capacity opamp.

 

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