Re: Pickup info
Posted: Fri May 20, 2011 1:25 pm
Ed -
I'm certain that you know - after all these many months - that I'm not in the least bit interested in the ubiquitous and traditional magnet/coil variety of pickup. Your semiconductor design has me totally enamored as it is a light year ahead of a similar quest that I made many years ago.
You may have, at least, partially answered one question in a response to Georg earlier in this thread but I'll pose it again in an effort at clarity. To wit: - In a "conventional" magnetic pickup, the length of the string subject to detection is sometimes referred to as the "capture length", "capture aperture" or a phrase quite similar and is determined, in part, by the width dimensions of the pickup elements. In your response to Georg, you indicate that, - in your design - it might be in the neighborhood of a half inch or so. This is much greater than the length of the resistance element in the IC used. Is this reasonably accurate? I find no reference to indicate a possible dimension. The absolute dimension is not critical to my thinking but would be very informative.
In addition, can you give me the approximate depth of the combination of IC package, PC board and solder "bumps" on the bottom - if any? The desire for this is explained below.
Traditional guitar builders place the center of the magnetic pickup approximately 2" from the center of the changer finger or thereabouts. I assume that this was adopted as a result of a perceived notion as to what a PSG should sound like re the relationship of fundamental to harmonic frequencies. A compromise, at best.
It should be obvious to everyone that the placement of any pickup in relation to the center of the changer finger will determine the ratio of the detected amplitudes of the fundamental to the harmonics - the sensing of the nodes and antinodes in the vibrating string. I believe that I'm on firm ground here but, in the simplest of terms, as one moves the pickup further from the changer then the greater the resultant detected amplitude of the fundamental to that of the harmonics. This might even be termed a mechanical tone control (Gasp!). IF - IF - the depth of your assembly is thin enough then I propose to place it between the strings and the neck as opposed to it being buried and screwed within a cavity. With a reasonable range of adjustment - longitudinally - one should be able to satisfy a personal, tonal "sweet spot" - one not needing much tweaking in the search for a personal optimum. I would anticipate the need for relatively fine adjustment but that is simply a mechanical design problem to be tackled at a later time. Needless to say, your configuration lends itself directly to individual gain, EQ and lord knows what for each string thereafter. This, in contrast to having a fixed pickup location and resorting to an array of broad-band amplifier adjustments which may, or may not, produce the desired end result. In my experience - and within my personal preferences - this circumstance has proven to be lacking and very frustrating.
Since there is no magical dimension between strings and neck (fretboard) I view my proposal to be feasible providing that I can shoehorn your design within that space and with reasonable clearances at both top and bottom.
What sayeth you -yay or nay?
Richard
I'm certain that you know - after all these many months - that I'm not in the least bit interested in the ubiquitous and traditional magnet/coil variety of pickup. Your semiconductor design has me totally enamored as it is a light year ahead of a similar quest that I made many years ago.
You may have, at least, partially answered one question in a response to Georg earlier in this thread but I'll pose it again in an effort at clarity. To wit: - In a "conventional" magnetic pickup, the length of the string subject to detection is sometimes referred to as the "capture length", "capture aperture" or a phrase quite similar and is determined, in part, by the width dimensions of the pickup elements. In your response to Georg, you indicate that, - in your design - it might be in the neighborhood of a half inch or so. This is much greater than the length of the resistance element in the IC used. Is this reasonably accurate? I find no reference to indicate a possible dimension. The absolute dimension is not critical to my thinking but would be very informative.
In addition, can you give me the approximate depth of the combination of IC package, PC board and solder "bumps" on the bottom - if any? The desire for this is explained below.
Traditional guitar builders place the center of the magnetic pickup approximately 2" from the center of the changer finger or thereabouts. I assume that this was adopted as a result of a perceived notion as to what a PSG should sound like re the relationship of fundamental to harmonic frequencies. A compromise, at best.
It should be obvious to everyone that the placement of any pickup in relation to the center of the changer finger will determine the ratio of the detected amplitudes of the fundamental to the harmonics - the sensing of the nodes and antinodes in the vibrating string. I believe that I'm on firm ground here but, in the simplest of terms, as one moves the pickup further from the changer then the greater the resultant detected amplitude of the fundamental to that of the harmonics. This might even be termed a mechanical tone control (Gasp!). IF - IF - the depth of your assembly is thin enough then I propose to place it between the strings and the neck as opposed to it being buried and screwed within a cavity. With a reasonable range of adjustment - longitudinally - one should be able to satisfy a personal, tonal "sweet spot" - one not needing much tweaking in the search for a personal optimum. I would anticipate the need for relatively fine adjustment but that is simply a mechanical design problem to be tackled at a later time. Needless to say, your configuration lends itself directly to individual gain, EQ and lord knows what for each string thereafter. This, in contrast to having a fixed pickup location and resorting to an array of broad-band amplifier adjustments which may, or may not, produce the desired end result. In my experience - and within my personal preferences - this circumstance has proven to be lacking and very frustrating.
Since there is no magical dimension between strings and neck (fretboard) I view my proposal to be feasible providing that I can shoehorn your design within that space and with reasonable clearances at both top and bottom.
What sayeth you -yay or nay?
Richard