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Tech: Any guitar effect electronic wizzos?

Bonzo3legs 08 May 11 - 05:17 AM
breezy 08 May 11 - 05:27 AM
Will Fly 08 May 11 - 05:56 AM
Bonzo3legs 08 May 11 - 06:19 AM
GUEST,Alan Whittle 08 May 11 - 06:46 AM
Will Fly 08 May 11 - 07:17 AM
Bonzo3legs 08 May 11 - 07:53 AM
ripov 08 May 11 - 09:05 PM
Bonzo3legs 09 May 11 - 07:40 AM
Mitch the Bass 09 May 11 - 10:11 AM
Bonzo3legs 09 May 11 - 10:31 AM
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Subject: Tech: Any guitar effect electronic wizzos?
From: Bonzo3legs
Date: 08 May 11 - 05:17 AM

I have a circuit in which a fixed voltage is passed via a potentiometer connected between +9v and 0v, is then buffered and determines the start frequency of a voltage controlled filter.

I want to replace the connection to +9v with a voltage proportional to the strength of the input signal, so that instead of the sweep ramping up to a point fixed by the potentiometer, it will ramp up to a point determined by how hard a note is played on the guitar.

The reason for this is that the decay portion of the sweep is smooth and ripple free, as it is independent of any signal from the guitar note fading away.

Any ideas? The voltage extracted may need to be just a short pulse, or perhaps some sort of sample and hold circuit would be needed???


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: breezy
Date: 08 May 11 - 05:27 AM

Dont know what yer torking bout mate, either it works or it dont.

This aint music this is science, go below !!

Any way effects are not needed if you can really play, they are a disguise and distraction from true talent !!!


peace

confession

I sometimes use the effects available on my Vox DA5, when I'm bored


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: Will Fly
Date: 08 May 11 - 05:56 AM

I haven't a technical answer to your question, but it does raise an interesting theoretical point.

Guitar FX tend to be mainly, but not totally, independent of the dynamics of the played guitar. This isn't an absolute - I've noticed an increase in intensity from a reverb pedal, for example, when the guitar/amp volume is ramped up - but, in general the FX will act on the guitar signal independently of any playing dynamics.

So (to get to the point), if you change voltage paths so that the FX do respond to a single guitar dynamic - attack, in your example - then remember that other factors such as tempo, volume, etc., may or may not be factors as well.

Given the technical sophistication of pedal and rack equipment these days, I would have thought that a programmable, rather than a physical, approach to FX dynamics might be an easier path.

Just a thought.


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: Bonzo3legs
Date: 08 May 11 - 06:19 AM

"then remember that other factors such as tempo, volume, etc., may or may not be factors as well."

Ah this enters the realms of midi, I am talking analogue only - opamps/transistors.


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: GUEST,Alan Whittle
Date: 08 May 11 - 06:46 AM

'I have a circuit in which a fixed voltage is passed via a potentiometer connected between +9v and 0v, is then buffered and determines the start frequency of a voltage controlled filter.'

by a potentiometer - you mean a volume pedal or some such...?

there is then some sort of compresser or noise gate, and you want more headroom - to stop the signal disappearing or distorting.

Is that roughly what we are talking about?


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: Will Fly
Date: 08 May 11 - 07:17 AM

I wasn't intentionally talking MIDI (I think) - just contemplating the possible effect of hard and soft pick attacks, via a string on voltage and, in turn, how that voltage difference would be translated by an FX processor (sweep, glide, etc.).

So - for example - you can have a high-pressure attack on a string with a pick, which might be translatable into a decay factor on a sweep or glide. But what would be the combined effect of hard attack and variable note cutoff. Hit a string with some force and leave it to ring - we imagine that the voltage increases with the volume - and the decay will be a function of the volume. But play the same note with a faster cutoff... what happens to the decay then? In other words, we don't just play with one constant (force), we also incorporate other dynamics which might muddy the waters...


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: Bonzo3legs
Date: 08 May 11 - 07:53 AM

Here's the circuit

http://www.4shared.com/photo/_3aCSHss/EH_Crashpad_clear.html

It's the Start Frequency pot connection to 9v that I want to replace with the voltage extracted from the input.


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: ripov
Date: 08 May 11 - 09:05 PM

Not really my game, my electric comes on 4 x 1/2 copper bars held together with 3/4 inch bolts.

I guess its the stop frequency you want to control, not the start, as that's the end of the ramp. But either way, yes you would need to sample and hold the voltage, otherwise you'd get some really weird effects. And amplify it quite a bit from signal levels. The problem then is that the circuit would be holding the highest voltage it had seen (corresponding to the loudest note you had played previously), so you would have to reset it just before playing the note you want to filter, let it sample the note, then close the start signal switch. With one foot? And this would delay the start of the sweep.

How about just extending the leads to the pot, (I'm guessing all the pots are on the FX box) and mounting it on your guitar where you can reach it, or use a foot operated pot? Then you can set it up a bar or so in advance

good luck with the project!


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: Bonzo3legs
Date: 09 May 11 - 07:40 AM

Yes, reset the circuit when the input level drops below a certain level, I've seen that somewhere - many thanks.


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: Mitch the Bass
Date: 09 May 11 - 10:11 AM

How about something like this http://www.hgmitchell.co.uk/c.jpg

The first diode, capacitor and variable resistor act as an envelope follower to give you a voltage proportional to the level of the input signal.

The second diode and capacitor act as a simple track and hold circuit. This needs a high impedance devide on the output, so a buffer will be needed. The output will track the input when it rises and then hold at the maximum.

The two transistors will discharge the capacitor when the input drops below a level set by the variable resistor and so reset the output when the input signal stops.

No guarantees, this is just off the top of my head. You'll need to decide on capacitor and resistor values to suit attack and decay times.

Mitch


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Subject: RE: Tech: Any guitar effect electronic wizzos?
From: Bonzo3legs
Date: 09 May 11 - 10:31 AM

Many thanks, I'll blow the dust off my breadboard this evening.


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