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Topic: Question for Brad Sarno (or other electronic geeks) |
John Groover McDuffie
From:
LA California, USA
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Posted 29 Oct 2008 3:12 pm |
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Do you have data on the resonant peak frequencies of various popular/common PSG pickups? It would be helpful info to have, especially as the amount of the peak can be controlled with your Freeloader.
Or is there a reasonably simple formula using DC resistance values to figure that out? |
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Jack Stoner
From:
Kansas City, MO
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Posted 30 Oct 2008 2:20 am
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I don't know if there is one resonant frequency, if there were then the pickup wouldn't "pickup" all the frequencies equally (or near equally).
A pickup is an "AC" device, any DC measurement is basically useless (e.g. if a pickup has a DC resistance of 19K ohms that's really only the total resistance of the wire on the pickup - nothing else and for that to mean anything other than the overall ohms of the wire would be to compare it to another pickup with the exact same magnets, exact same coil wire and wound exactly the same). |
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John Groover McDuffie
From:
LA California, USA
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Posted 30 Oct 2008 7:23 am
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| Thank you for playing. Next contestant, please... |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 30 Oct 2008 7:38 am
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John,
I don't think many steel pickup makers will log or list their resonant peak frequencies. Many guitar pickup makers will often list it though. It's an interesting topic. All typical magnetic pickups will have their primary resonant peak and that means all the notes and overtones generated by the strings that fall inside that resonant peak range will be louder than those outside the range of the peak. Kind of like boosting an EQ at that frequency. The peaks are kind of like putty though. Variables such as cable capacitance and loading can alter both the amplitude as well as the center frequency of that peak. From rig to rig, the character of a pickup's treble peak will often vary. One guy with short George L's cords and a Hilton pedal will get a very different tone than the guy with long runs of Belden cable thru a pot pedal, both using the exact same pickup.
Of the few pickups I recently analyzed, including 2 Emmons single coils, a L-710, a L-610, and a Tonealigner, they all had different resonant peak frequencies. But the range of all of them was between 2.2kHz and 3.7kHz, so you can roughly guesstimate that a typical resonant peak will live somewhere around 3kHz. It's interesting to note that the classic Peavey amps like the Session 400, have their treble control set exactly at 2.7kHz. This may have been designed to directly address and take control over this common peak in a steel guitar pickup.
Measuring DC resistance will never translate directly to this frequency data, unless you are comparing two of the same model of pickup and only varying that one factor of winds or turns, which closely translates to DC resistance. But magnetic field pattern, magnet type, magnet strength, bobbin geometry, winding patterns, wire gauge, wire insulation thickness, number of winds or turns, and more all contribute to a pickup's unique response.
Brad |
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John Groover McDuffie
From:
LA California, USA
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Posted 30 Oct 2008 8:34 am
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| Thank you Brad |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 30 Oct 2008 11:37 am
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| oops |
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