[LAD] May I asked something OT?

[Ralf Mardorf]

On Mon, 2010-07-19 at 20:17 +0100, Folderol wrote:
> On Mon, 19 Jul 2010 14:04:24 +0200
> Ralf Mardorf <ralf.mardorf at alice-dsl.net> wrote:
> 
> > On Mon, 2010-07-19 at 01:30 -0400, Tim E. Real wrote:
> > > On July 18, 2010 03:57:06 pm Ralf Mardorf wrote:
> > > > A lot of kids wish to have a kill switch for their guitars.
> > > > A kill switch is a short circuit, to 'stop' the audio signal.
> > > >
> > > > I'm not fine with this solution, but the kids argue, that e.g. an
> > > > interruption does cause unwanted noise, especially for over drive
> > > > sounds. IMO even using opto-electronics won't solve the issue, because
> > > > the noise of the transistor overdrive effect still would be hearable,
> > > > while for a short circuit there is silence.
> > > >
> > > > Has anybody an idea to solve this without a short circuit?
> > > >
> > > > I'm really not a fan of short circuits. Note, it's not possible to do an
> > > > interrupt all the times behind the latest noise generator and even an
> > > > interrupt could cause noise itself, while a short circuit indeed is a
> > > > good way to cancel sound.
> > > >
> > > 
> > > If you play a Gibson you can set the neck pickup volume to zero and 
> > >  the bridge pickup volume to full and then toggle the pickup switch, 
> > >  rapidly if desired, like Eddie van Halen on You Really Got Me.
> > > Tim.
> > 
> > Yes, but this could cause noise by the switch or by effects, e.g. the
> > sustainer. I guess the kids prevent any noise by a short circuit,
> > perhaps even the sustainer then will be 'killed', if so, OTOH I guess
> > this won't be good for the effects and amps. As some people mentioned
> > before, it would be better to use some kind of gate at the end of the
> > effect chain. I really wonder what happens to e.g. a sustainer or to the
> > pre-amp of the guitar's amp when doing a short circuit. I guess because
> > of a short circuit there really will be silence. I also wonder if just
> > interrupting would cause that annoying noise, believing the hype, it
> > should cause annoying noise. Btw. for all this Japan avant-garde a
> > Gibson switch or a foot switch isn't good, they do need a momentary
> > switch. Because it's really used by kids, I wonder how old the equipment
> > would become. A short-circuit protection won't protect against impulses,
> > OTOH just interrupting might also cause impulses.
> > 
> > Thank you all :)
> > 
> > Ralf
> 
> I'm not really clear on what your objection is to shorting the guitar
> pickups. I've never heard of it causing any problem.
> 
> There is a remarkably effective click-free way of muting a guitar. The
> original involved a light-dependent-resistor and a filament bulb, but
> these days you'd be better off using an LED as the light source.
> 
> The L.D.R. (typically ORP12) is in a light proof box with a
> hole in line with the LED. The LDR shunts the guitar output. When
> 'dark' it has a typical value of 5 Meg, and has no noticeable effect.
> When 'light' it is typically 100 Ohm and effectively shorts out the
> pickups.
> 
> However the trick is NOT to switch the LED off and on, but to keep it
> on all the time and arrange the pedal/switch so it slides an opaque
> vane or shutter between the LED and the L.D.R.
> 
> These switches can be made *extremely* robust and never wear out or
> become noisy.
> 
> A variant of this was used as a swell pedal in the original GEM portable
> organ of the middle 1960s - I know. I had one :)

I never opened a Morley pedal, but I guess this is the way they use
opto.

But it's solved, I did error in reasoning:

-------- Forwarded Message --------
From: Gordon JC Pearce <gordonjcp at gjcp.net>
To: linux-audio-dev at lists.linuxaudio.org
Subject: Re: [LAD] May I asked something OT?
Date: Mon, 19 Jul 2010 20:04:28 +0100

On Mon, 2010-07-19 at 14:45 +0200, Ralf Mardorf wrote:

> http://www.instructables.com/image/FC6ZZ0XF8JUW8E8/What-is-a-killswitch.jpg
> 
> This is what I call short circuit. It won't harm a pre-amp doing it by a
> potentiometer, but I wonder if doing it fast, again and again by a
> switch won't cause impulses, when the short circuit will be released
> again? Perhaps I do error in reasoning and it's quite save.

Yes, it's entirely safe.  At that stage you've got a few tens of
millivolts of signal at best, across about a 1k impedance source.

Gordon MM0YEQ