Stamp controlled guitar processor
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Posts: 46,084
Here's the premise of what this topic will hope to discuss:
Designing a Basic Stamp controlled, tube-based guitar processor that will
allow you to store and recall a number of presets. Each preset will include
a number of control parameters around a tube-based audio circuit. I think
the standard 12AX7 would be the good choice.
We want to be able to store and recall the settings using a Basic Stamp for
at least the following parameters:
Plate voltage on the tube from 40 VDC up to 150 VDC in perhaps 10-volt
increments - (low-voltage for crunch, high-voltage for clean)
Input gain from + 10 to + 30 dB in 1 dB increments
Output gain from 0 to - 40 dB in 1 dB increments
Class-A or Class A-B push-pull modes (A single tube makes more asymmetrical
distortion, while a pair of tubes in push-pull mode cancels out a lot of
non-linearity. Thus it's cleaner in sound until the plates start starving
for electrons)
Tone control frequency and boost/cut (guitar amps do a LOT of boosting in
excess of 20 dB or more to get the proper sound).
Standard input theory for guitar amps (not Stamp related, but 1-meg or more
input impedance is needed on this box so as not to load the guitar coils too
much)
Standard output theory for audio processor boxes (not Stamp related, but you
need to get the audio out of this box and into an amplifier or mixing board)
What sort of gains, equalizations, and distortions typically work for metal,
blues and rock guitar amps.
Groupie control (oops, I'm getting carried away)
Anything else?
I'll post a bunch of the audio parameters, if the rest of you will help find
the best way to interface this to a Basic Stamp. I'm really an audio guy,
and just play with Stamps to keep me out of trouble. "An idle mind is the
devil's playground", as Sister Charles used to tell us in 8th grade.
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Designing a Basic Stamp controlled, tube-based guitar processor that will
allow you to store and recall a number of presets. Each preset will include
a number of control parameters around a tube-based audio circuit. I think
the standard 12AX7 would be the good choice.
We want to be able to store and recall the settings using a Basic Stamp for
at least the following parameters:
Plate voltage on the tube from 40 VDC up to 150 VDC in perhaps 10-volt
increments - (low-voltage for crunch, high-voltage for clean)
Input gain from + 10 to + 30 dB in 1 dB increments
Output gain from 0 to - 40 dB in 1 dB increments
Class-A or Class A-B push-pull modes (A single tube makes more asymmetrical
distortion, while a pair of tubes in push-pull mode cancels out a lot of
non-linearity. Thus it's cleaner in sound until the plates start starving
for electrons)
Tone control frequency and boost/cut (guitar amps do a LOT of boosting in
excess of 20 dB or more to get the proper sound).
Standard input theory for guitar amps (not Stamp related, but 1-meg or more
input impedance is needed on this box so as not to load the guitar coils too
much)
Standard output theory for audio processor boxes (not Stamp related, but you
need to get the audio out of this box and into an amplifier or mixing board)
What sort of gains, equalizations, and distortions typically work for metal,
blues and rock guitar amps.
Groupie control (oops, I'm getting carried away)
Anything else?
I'll post a bunch of the audio parameters, if the rest of you will help find
the best way to interface this to a Basic Stamp. I'm really an audio guy,
and just play with Stamps to keep me out of trouble. "An idle mind is the
devil's playground", as Sister Charles used to tell us in 8th grade.
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Comments
> Here's the premise of what this topic will hope to discuss:
>
> Designing a Basic Stamp controlled, tube-based guitar processor
Why does it have to be tube-based stuff? Many of the modern effects are
all op-amp based. You can control the rail voltages of the op-amps the
same way, as well as switch in/out various diodes/caps, etc to get
various distortion effects.
Combining 3 or 4 effects "clusters" along with a matrix audio switch
(maxim and Dallas both have serially-controllable units) would allow you
to cut various effects in/out, as well as call up various presets/etc.
This is along the lines of some things I have already been working on,
but none of it is tube-based, so if you want to go with tubes, I can't
really offer much insight.
Well, since I had planned this to use both Op Amp circuits for the
equalization, and tube circuits for the distortion, I think we'll all get
along. The problem with using transistor and op amp circuits for the
distortion circuits is that they behave and sound quite different from tubes
when overdriven. Tubes, being voltage-driven, produce a lot of even-order
harmonics at clipping, while transistors, being current-driven, make a lot
of odd-order harmonics at clipping.
Even-order harmonics are much more pleasing to the ear, so that's why guitar
players like the "sound" of tubes. But a properly designed audio circuit
will have little "sound" of it's own, as long as it's not clipping. And
certainly, you can make great sounding filters with a few opamps, as long as
they're not clipping.
It would be really cool (or groovy, or sick, or whatever) to combine both
technologies and have a Basic Stamp run the whole thing.
Mike Sokol
mike@f...
www.fitsandstarts.com
301-739-6842 (Office)
301-964-5682 (Mobile)
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: "Brian" <stamp@k...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, June 07, 2004 2:42 PM
Subject: Re: [noparse][[/noparse]basicstamps] Stamp controlled guitar processor
> On Mon, 2004-06-07 at 13:41, Mike Sokol wrote:
> > Here's the premise of what this topic will hope to discuss:
> >
> > Designing a Basic Stamp controlled, tube-based guitar processor
>
> Why does it have to be tube-based stuff? Many of the modern effects are
> all op-amp based. You can control the rail voltages of the op-amps the
> same way, as well as switch in/out various diodes/caps, etc to get
> various distortion effects.
>
> Combining 3 or 4 effects "clusters" along with a matrix audio switch
> (maxim and Dallas both have serially-controllable units) would allow you
> to cut various effects in/out, as well as call up various presets/etc.
>
> This is along the lines of some things I have already been working on,
> but none of it is tube-based, so if you want to go with tubes, I can't
> really offer much insight.
>
>
>
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