freefrog
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EDIT - For the tittle, please read: "Do various caps sound differently WHEN tone pot is full up? Another useless and stupid test".
I HAD to do that one despite of my busy weeks…
-guitar pickup used: a basic single coil with a ceramic mag glued below the poles. R=6k, L= 3H.
-method involved: like Helmuth Lemme, I excite the guitar pickup with a low impedance coil fed by a loudspeaker output. The coil has been glued on the pickup. The pickup is plugged through a guitar harness including…
a) a 500k volume pot;
b) a 500k tone pot (modern wiring);
c) small banana plugs allowing to plug and unplug different caps on the tone pot.
The whole stuff is plugged through a short low capacitance cable to the calibrated soundcard which feeds itself various softwares.
Programs used in this case:
-Right Mark Audio Analyzer provides the test signal;
-Ableton Live records (sonically) the frequencies produced by the pickup;
-a VST plug in (Voxengo Span) sums up and shows the peaks produced all along the audio spectrum. I’ve set it on “max” and not on “Real time” analysis: once a peak is recorded, it remains without moving on the screen.
Conditions of this test:
a) several signals of several seconds are sent to the pickup through the exciting coil:
-a pulsing 1khz mono sound to emulate a cycling pick attack,
-then a “multitone” (polyphonic) signal to reproduce a chord,
-then again a 1khz signal, supposed to mimic a single note played loud.
Keep in mind that volume and tone pots were FULL UP in each case;
b) the pickup sends its signal to the calibrated soundcard and the result is recorded through Ableton;
c) I replay the track through Voxengo and capture what it shows…
How the screenshots themselves have been done:
-the blue lines on a dark screen with grey grid are the original pictures provided by Voxengo Span;
-the red lines on a transparent screen without grid and with black frame around = the same pictures, whose colors have simply been reversed and the background erased ;
-each transparent screen with red lines has been stuck above the original pictures, in order to show if the frequencies measured were the same or not.
I’ve carefully checked the size of these pictures BUT I’ve “aligned” them upon each other with a single reference point: the 1khz peak. In two cases, it gives a “misplaced” collage, shown by the grey line on the bottom of the picture.
Depiction of the screenshots shared:
Picture 1:
Blue= frequencies produced by a 6k / 3H single coil excited by real guitar strings, really plucked by a pick and fretted all along the neck.
Red= frequencies produced by the artificial signal test sent to the testing PU through my coil exciter.
Picture 2: in red AND blue, the frequencies produced by the testing PU while the tone pot has NO cap (it’s grounded directly).
This test has been done twice (hence the red and blue lines) in order to check the consistency of the frequencies measured : it appears to work, since the blue line is barely apparent under the red one.
Picture 3:
Red line = tone pot without cap.
Blue line under = tone pot with a PIO 47n cap.
Picture 4: the same with an Orange Drop 47n cap.
Picture 5: the same with a Mylar 47n cap.
Note that pictures have not been done in this order (the measurement 6 was finished before the 4, for example).
Note the scale used: 5db between horizontal lines. OF COURSE, the level of the signal has been strictly the same with all tone caps. The volume and tone pots were fully open all the time and nothing has moved physically except the caps, firmly connected to the hardware.
Discuss.
I’ll try to redo all that sh*t with…
-50 wiring;
-other caps;
-various tone pot settings.
For the moment,
1) I’m done - so much efforts for so rare and esoteric results!
2) I lack of time, as usual. I post this topic while it’s Sunday morning here but I’ve still a life to live…
I HAD to do that one despite of my busy weeks…
-guitar pickup used: a basic single coil with a ceramic mag glued below the poles. R=6k, L= 3H.
-method involved: like Helmuth Lemme, I excite the guitar pickup with a low impedance coil fed by a loudspeaker output. The coil has been glued on the pickup. The pickup is plugged through a guitar harness including…
a) a 500k volume pot;
b) a 500k tone pot (modern wiring);
c) small banana plugs allowing to plug and unplug different caps on the tone pot.
The whole stuff is plugged through a short low capacitance cable to the calibrated soundcard which feeds itself various softwares.
Programs used in this case:
-Right Mark Audio Analyzer provides the test signal;
-Ableton Live records (sonically) the frequencies produced by the pickup;
-a VST plug in (Voxengo Span) sums up and shows the peaks produced all along the audio spectrum. I’ve set it on “max” and not on “Real time” analysis: once a peak is recorded, it remains without moving on the screen.
Conditions of this test:
a) several signals of several seconds are sent to the pickup through the exciting coil:
-a pulsing 1khz mono sound to emulate a cycling pick attack,
-then a “multitone” (polyphonic) signal to reproduce a chord,
-then again a 1khz signal, supposed to mimic a single note played loud.
Keep in mind that volume and tone pots were FULL UP in each case;
b) the pickup sends its signal to the calibrated soundcard and the result is recorded through Ableton;
c) I replay the track through Voxengo and capture what it shows…
How the screenshots themselves have been done:
-the blue lines on a dark screen with grey grid are the original pictures provided by Voxengo Span;
-the red lines on a transparent screen without grid and with black frame around = the same pictures, whose colors have simply been reversed and the background erased ;
-each transparent screen with red lines has been stuck above the original pictures, in order to show if the frequencies measured were the same or not.
I’ve carefully checked the size of these pictures BUT I’ve “aligned” them upon each other with a single reference point: the 1khz peak. In two cases, it gives a “misplaced” collage, shown by the grey line on the bottom of the picture.
Depiction of the screenshots shared:
Picture 1:
Blue= frequencies produced by a 6k / 3H single coil excited by real guitar strings, really plucked by a pick and fretted all along the neck.
Red= frequencies produced by the artificial signal test sent to the testing PU through my coil exciter.
Picture 2: in red AND blue, the frequencies produced by the testing PU while the tone pot has NO cap (it’s grounded directly).
This test has been done twice (hence the red and blue lines) in order to check the consistency of the frequencies measured : it appears to work, since the blue line is barely apparent under the red one.
Picture 3:
Red line = tone pot without cap.
Blue line under = tone pot with a PIO 47n cap.
Picture 4: the same with an Orange Drop 47n cap.
Picture 5: the same with a Mylar 47n cap.
Note that pictures have not been done in this order (the measurement 6 was finished before the 4, for example).
Note the scale used: 5db between horizontal lines. OF COURSE, the level of the signal has been strictly the same with all tone caps. The volume and tone pots were fully open all the time and nothing has moved physically except the caps, firmly connected to the hardware.
Discuss.
I’ll try to redo all that sh*t with…
-50 wiring;
-other caps;
-various tone pot settings.
For the moment,
1) I’m done - so much efforts for so rare and esoteric results!
2) I lack of time, as usual. I post this topic while it’s Sunday morning here but I’ve still a life to live…
nice post mate 
