Do various caps sound differently with tone pot is full up? Another test...

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. :laugh2:

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…
 

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freefrog

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Had not enough place above to upload the picture with a Mylar 22n... :D
 

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MesaDCLP

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Why do the different value Mylars appear to be identical?

It seems that all the pictures show very little difference from the scale settings you've selected. You should try setting the scale from 0 to ~-66 dB and the frequency from 40 hz to 5 khz. That would show the difference better due to the increase resolution.
 

jonesy

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I think it would be interesting to see some pics of all your test gear.

Do you wear a white lab coat?
:)
 

Mookakian

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If your often running tone on full, prob best to get some higher value pots so you can use the cap to its full ability...ill say that much :)
 

freefrog

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Why do the different value Mylars appear to be identical?

I don't know WHY but yes, they appear to be identical in their behaviour.

It seems that all the pictures show very little difference from the scale settings you've selected. You should try setting the scale from 0 to ~-66 dB and the frequency from 40 hz to 5 khz. That would show the difference better due to the increase resolution.

I've selected this scale on purpose... :laugh2: because on a so wide spectrum, we shouldn't see any difference, theoretically. That's precisely why I've found interesting to post this topic.

Do you wear a white lab coat? :)

No: when I do these tests, I generally wear a pajama.:naughty:

If your often running tone on full, prob best to get some higher value pots so you can use the cap to its full ability...ill say that much :)

I agree. That said, the goal of this test was to see if yes or not, a cap makes a difference when a tone pot is full up - because I've read (and expressed myself) many opinions and translations of subjective experience about this subject...:hmm:
 

rocknhorse1

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If you are using your volumes and tones on ten, IMO, It would be best to not even have a knob...just go direct to the jack, like Neil Young does on his bridge pickup.
 

freefrog

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If you are using your volumes and tones on ten, IMO, It would be best to not even have a knob...just go direct to the jack, like Neil Young does on his bridge pickup.

I have several guitars with bridge pickup wired like that but it's not for every PU / amp / player...

That said, a tone control on ten is NOT the same thing than no tone control... That's what my test is all about. :naughty:

so what is your conclusion freefrog? And thanks for all of your effort.

You're welcome. No clear conclusion for the moment: I archive more and more results and they appear to confirm the same idea but I'm still not sure that my tests aren't affected by some unexpected and misunderstood experimental artifacts. Furthermore, I'm not sure that my sampling is wide enough to be meaningful.

If we talk about my humble feelings, it's different: I keep thinking that different types of cap used with a tone pot affect the tone differently, even when the pot is full up. This intuition rooted in my aural experience is confirmed to me by the three sorts of pseudo-scientific tests that I've already posted here (and by the work of tech head hobbyist that I had done elsewhere the 8 previous years but it's another story).

Now, keep in mind that I'm not at all a specialist in electronics - in my family, the engineer in electronics is my brother.

So, people will decide themselves if they want to agree with me or not (anyway, this question of caps is largely a question of "faith", here or on other guitar forums). :laugh2:


:)
 

Mookakian

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there is something about tone rolled back I just have to feel when playing an electric, up full is ok at times but i dig my cap tone :D
 

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