Bob Carver technology at guitar pickups

As you know Bob Carver copied a 25000 dollars worth of amp with 500 dollars
worth of circuit. He copied the transfer function of the expensive amp with
the cheap one. No body could not understand the difference between two
amps.
Honestly talking , I am not a scientist but want to copy Fender Jazz Bass
pickup with this method.
Can it be done and how ? Guitar pickups are made from a magnet and wire
coil. They listen the vibration of strings.
I want to apply my new circuit directly to the strip microphone connected
to the guitars body and listens wood tone.
Please share whatever you know.

Best ,

Mustafa Umut Sarac

MustafaUmut wrote:

> As you know Bob Carver copied a 25000 dollars worth of amp with 500 dollars
> worth of circuit. He copied the transfer function of the expensive amp with
> the cheap one. No body could not understand the difference between two
> amps.

> Honestly talking , I am not a scientist but want to copy Fender Jazz Bass
> pickup with this method.
> Can it be done and how ? Guitar pickups are made from a magnet and wire
> coil. They listen the vibration of strings.
> I want to apply my new circuit directly to the strip microphone connected
> to the guitars body and listens wood tone.
> Please share whatever you know.

A microphone is somewhat more complicated to make than a guitar
pickup.  All you need for the guitar pickup is a small magnet
with magnet wire (insulated with enamel or a similar material)
wrapped around it.  Also, you need steel strings for the guitar.

It might be, though, that cheap mass produced microphones are
cheaper than magnetic pickups.  If produced in large quantities it
might be possible to produce a DSP box that could simulate the
magnetic pickup sound.  In small quantities it is likely more
expensive.  How many are you planning to make?

-- glen

Hello Glen , This is a research and I want to expand the results to a wider
base. A fender jazz bass pickup set starts from 200 dollars and climb to
mamy many hundreds of dollars.
Pickups seems cheap but a stradivari not.
I am researching a way similar to bob carver also. At his time , there
were no cheap dsp boards and he made everything analog.
My questions : Is it possible to produce same sound of an pickup with
analog circuit ?
Is it possible to extract a mathematical function of a Stradivari record
and apply it to cheapest violin with similar analog circuit ?
I listened mit digital stradivari research results and dsp or computer
modelling produce very ugly sound.
It was 90s research. Is there better , cheaper solution with cheap dsp
boards now ?
I think there is transfer function research at analog circuits.

best ,

Mustafa Umut Sarac

MustafaUmut wrote:
> Hello Glen , This is a research and I want to expand the results to a wider
> base. A fender jazz bass pickup set starts from 200 dollars and climb to
> mamy many hundreds of dollars.

As a side note, as I understand it digitized electronic drums are
commonly used by professionals and for recordings.  Drums having mostly
one degree of freedom, that is, how hard you hit it.  Drum pads have
something like a microphone that sends a signal proportional
(more or less) to how hard you hit it.  Electronic drum boxes
then generate a digitized drum sound based on that amplitude.

> Pickups seems cheap but a stradivari not.

Well, there are people trying to understand the special characteristics
of stradivari and reproduce those characteristics.  The sound of a
violin is a complicated function of the shape, thickness, stiffness,
and finish of the wood.

An electric guitar pickup has only a few variables.  The strength
of the magnetic field through the coil depends (nonlinearly) on the
distance of the steel guitar string from the magnet.  The voltage
is the derivative of (proportional to the change in) that field.
I believe the magnets are offset from the strings such that the
signal is approximately proportional to the string velocity.
If the magnets were centered under the strings, it would be a
much more complicated function of the string motion.
The approximate proportionality adds some harmonics.  If the
magnets were centered it would pretty much cancel the
fundamental (first harmonic), such that the second harmonic
would be the main sound.  The shape of the pole (magnet)
tips would have some effect on the harmonics, but not
a large effect.

In any case there are relatively few effects that could make
a difference between a cheap pickup and a much more expensive
one, unlike the case of the violin.  (They also make electric
violins, I presume using the same effect.)

> I am researching a way similar to bob carver also. At his time , there
> were no cheap dsp boards and he made everything analog.
> My questions : Is it possible to produce same sound of an pickup with
> analog circuit ?
> Is it possible to extract a mathematical function of a Stradivari record
> and apply it to cheapest violin with similar analog circuit ?

In the case of the drum and the piano, there is only one degree of
freedom, and that is how hard you hit the pad/key.  I don't believe
that is true for a violin.  One could probably build a DSP
device that would change the generated harmonics, and it
might be that one could make an expensive violin sound that way.

> I listened mit digital stradivari research results and dsp or computer
> modelling produce very ugly sound.  It was 90s research.
 > Is there better , cheaper solution with cheap dsp boards now ?
> I think there is transfer function research at analog circuits.

There are two questions.  One is what transfer function you want,
and the other is how to (cheaply) create that function.  I would
say that the problem for the violin is that the function isn't
known.  For piano and drums, it is much easier and people are much
happier with the results.

-- glen

On Jun 12, 4:51 am, "MustafaUmut" <mustafaumutsa...@gmail.com> wrote:

> Guitar pickups are made from a magnet and wire
> coil. They listen the vibration of strings.

No they don't.  They measure changes to the magnetic field.
Some modes of vibration cause changes to the magnetic field
more than others, not necessarily directly related to the
vibrations transfered to the surrounding air or to the
instrument body.


IMHO. YMMV.
--
rhn A.T nicholson d.0.t C-o-M

On Jun 12, 1:03 pm, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
> In the case of the drum and the piano, there is only one degree of
> freedom, and that is how hard you hit the pad/key.

Well, a piano also has a soft & sustain pedals, as well as
induced resonance to other undamped strings (if their keys
are held down).  The key hammer itself may have resonance
from its previous rebound.  That's a lot more than one
degree of freedom.

My recollection is that drum heads sounded differently
depending on how far off center you hit them and how tightly
the stick was held for the rebound.


IMHO. YMMV.
--
rhn A.T nicholson d.0.t C-o-M

On Tue, 12 Jun 2007 12:03:52 -0800, glen herrmannsfeldt
<gah@ugcs.caltech.edu> wrote:

>MustafaUmut wrote:
>> Hello Glen , This is a research and I want to expand the results to a wider
>> base. A fender jazz bass pickup set starts from 200 dollars and climb to
>> mamy many hundreds of dollars.
>
>As a side note, as I understand it digitized electronic drums are
>commonly used by professionals and for recordings.  Drums having mostly
>one degree of freedom, that is, how hard you hit it.

I think many drummers would disagree.   Where you hit the drum matters
as well, and also what you hit it with.   I have a relatively
inexpensive Yamaha electric drum (mostly because it's a pretty good
MIDI box, I rarely use the drum functions), and even it will modulate
well depending on where you hit the pad, i.e., you get a different
sound hitting the edge of the pad than you do hitting the center.

As far as I can tell it has no way to know what is hitting it, though,
e.g., a drumstick or a brush.  It needs to be hit pretty solidly to
sound at all, so brush-type stuff is just out.

>> Pickups seems cheap but a stradivari not.
>
>Well, there are people trying to understand the special characteristics
>of stradivari and reproduce those characteristics.  The sound of a
>violin is a complicated function of the shape, thickness, stiffness,
>and finish of the wood.
>
>An electric guitar pickup has only a few variables.  The strength
>of the magnetic field through the coil depends (nonlinearly) on the
>distance of the steel guitar string from the magnet.  The voltage
>is the derivative of (proportional to the change in) that field.
>I believe the magnets are offset from the strings such that the
>signal is approximately proportional to the string velocity.
>If the magnets were centered under the strings, it would be a
>much more complicated function of the string motion.
>The approximate proportionality adds some harmonics.  If the
>magnets were centered it would pretty much cancel the
>fundamental (first harmonic), such that the second harmonic
>would be the main sound.  The shape of the pole (magnet)
>tips would have some effect on the harmonics, but not
>a large effect.
>
>In any case there are relatively few effects that could make
>a difference between a cheap pickup and a much more expensive
>one, unlike the case of the violin.  (They also make electric
>violins, I presume using the same effect.)

There must be some, because many players (and listeners) can tell the
difference between a "good" and "bad" or "cheap" pickup.   I can tell
in a gross sense, but apparently my ear is not fine enough for much
more than rough discrimination in this area.   I'm sure it also
depends a lot on the playing style and amp configuration...e.g., it'll
probably matter a lot less playing lead with a lot of saturation and
feedback than it will with some intricate finger picking.

>> I am researching a way similar to bob carver also. At his time , there
>> were no cheap dsp boards and he made everything analog.
>> My questions : Is it possible to produce same sound of an pickup with
>> analog circuit ?
>> Is it possible to extract a mathematical function of a Stradivari record
>> and apply it to cheapest violin with similar analog circuit ?

This sort of thing is hitting the market now, and some of the
manufacturers are doing some fairly impressive things, for example:

http://www.thevxt.com/about.html

Some of the scuttlebutt on the "virtual microphone imaging" is that it
uses the pickup input to drive a model of what a "good" acoustic sound
would be.    I've played a VXT in order to compare it to my Taylor T5
(which just has an analog active preamp), and they're really quite
nice.

Another with a lot more processing going on is the Fender VG:

http://www.fender.com/vgstrat/home.html

Now THAT guitar does some heavy-duty native signal processing.  Turn
the knob for automatic drop-D or other alternate tunings (where it
models the effect of the strings being configured in arrangements
other than EADGBE, without actually changing the tuning).   So you can
be ripping along with standard tuning and just turn the knob in the
middle of a song to get an alternate tuning.   Yikes.   I haven't had
a chance to play one or even hear one yet, though.   My suspicion is
that with that much processing some sound quality must have been
sacrificed, but I don't know.

Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

On Jun 12, 5:04 pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
> On Tue, 12 Jun 2007 12:03:52 -0800, glen herrmannsfeldt
>
> <g...@ugcs.caltech.edu> wrote:
> >MustafaUmut wrote:
> >> Hello Glen , This is a research and I want to expand the results to a wider
> >> base. A fender jazz bass pickup set starts from 200 dollars and climb to
> >> mamy many hundreds of dollars.
>
> >As a side note, as I understand it digitized electronic drums are
> >commonly used by professionals and for recordings.  Drums having mostly
> >one degree of freedom, that is, how hard you hit it.
>
> I think many drummers would disagree.   Where you hit the drum matters
> as well,

yah.  and if you don't believe that, i suggest you listen to Afro-Celt
Sound System (now possibly called AfroCelts, the name change
disappoints me, but they also appeared on Letterman with Peter
Gabriele and sounded so friggin and uncharacteristically commericial,
that i am not surprized) or any decent celtic frame drummer.  or a
tympani player.  or even someone hitting a tom.  them's Bessel
functions have some parameter to what the radial position (or is it
the concentric position?  which is the correct term?) of the hit is.

> and also what you hit it with.

yeah, them cushy mallets are different than a stick.  and then there's
rim-shot.

percussion can be like a didgeridoo.  some folks (like me) can make
only one sound out of it.  the gifted can make a near unlimited number
of sounds out of it.

r b-j

Eric Jacobsen wrote:

(I wrote)

>>As a side note, as I understand it digitized electronic drums are
>>commonly used by professionals and for recordings.  Drums having mostly
>>one degree of freedom, that is, how hard you hit it.

> I think many drummers would disagree.   Where you hit the drum matters
> as well, and also what you hit it with.   I have a relatively
> inexpensive Yamaha electric drum (mostly because it's a pretty good
> MIDI box, I rarely use the drum functions), and even it will modulate
> well depending on where you hit the pad, i.e., you get a different
> sound hitting the edge of the pad than you do hitting the center.

There is some dependence on position, but it is relatively small.
The "what you hit it with" is done by programming of the control box.

I have some professional drum pads which I bought used for much
less than they cost new.  They actually have two sensors one on the
metal rim, and one on the pad.  I don't know the Yamaha, though.

I have an Alesis D4, which is old technology now, but still
pretty powerful in terms of the programmability of different sounds.

> As far as I can tell it has no way to know what is hitting it, though,
> e.g., a drumstick or a brush.  It needs to be hit pretty solidly to
> sound at all, so brush-type stuff is just out.

(snip)

>>In any case there are relatively few effects that could make
>>a difference between a cheap pickup and a much more expensive
>>one, unlike the case of the violin.  (They also make electric
>>violins, I presume using the same effect.)

> There must be some, because many players (and listeners) can tell the
> difference between a "good" and "bad" or "cheap" pickup.   I can tell
> in a gross sense, but apparently my ear is not fine enough for much
> more than rough discrimination in this area.   I'm sure it also
> depends a lot on the playing style and amp configuration...e.g., it'll
> probably matter a lot less playing lead with a lot of saturation and
> feedback than it will with some intricate finger picking.

Yes, but I believe much smaller than the difference between a
cheap violin and a Stradivari.

(snip)

-- glen

Ron N. wrote:

> On Jun 12, 1:03 pm, glen herrmannsfeldt <g...@ugcs.caltech.edu> wrote:
> 
>>In the case of the drum and the piano, there is only one degree of
>>freedom, and that is how hard you hit the pad/key.

> Well, a piano also has a soft & sustain pedals, as well as
> induced resonance to other undamped strings (if their keys
> are held down).  The key hammer itself may have resonance
> from its previous rebound.  That's a lot more than one
> degree of freedom.

There have been statements that some pianists have extra
ability as far as the keys, that is, more than just how
hard the key is pressed but maybe how smoothly is is pressed.
Since when the hammer hits the string it has been released from
the rest of the mechanism, the important variable is the velocity
when it hits the string.  A violin player has much more control
over the note being played, with the ability to vary bow speed
and pressure throughout the note.

> My recollection is that drum heads sounded differently
> depending on how far off center you hit them and how tightly
> the stick was held for the rebound.

Maybe somewhere between the control available to a piano
player and violin player.  I bought an Alesis drum box
from a professional, who used it in a recording studio.

I would be very surprised to find a professional violin
player using a digitized representation of violin notes
on professional recordings (or almost anywhere else),
at least with current technology.

-- glen