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Topic: How pickup impedance effects overdrive/distortion pedals |
Jack Hanson
From:
San Luis Valley, USA
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Posted 21 Dec 2017 3:54 pm |
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Caveat: The following observation applies to electric lap steels only. When I play pedal steel, I want it to sound like a pedal steel, so the only effect I employ is reverb.
Having at least a dozen lap steels with various pickups of widely disparate impedances, I have come to the conclusion that a lower impedance pickup sounds way mo' bettah through a dirt pedal than a higher impedance pickup, most other variables (mainly amp settings, but also scale length, string gauge, and tuning) being equal.
Agree? Disagree? |
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Jim Sliff
From:
Lawndale California, USA
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Posted 21 Dec 2017 6:08 pm
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I think you mean "DC resistance" - not impedance. They're different, and what you can normally measure yourself from a pickup is the DC resistance in ohms. Impedance is a "liquid" factor and (very generally) changes with signal strength and harmonic content.
DC resistance makes little difference as far as output (measured in volts). Output voltage (an objective number from the pickup specifications) has obvious influence on any effect that depends on the level of the signal.
Your pick attack normally causes that "specification" output voltage to vary - but the voltage is not dependent on the DC resistance measurement.
While many conventional, passive pickups (both single-coil and humbucking) seem to have comparative output based on their DC resistance measurement, there are innumerable exceptions.
Simply changing magnet strength (or type), or swapping polepieces for a different alloy, or changing the cover type, or the style of mounting (especially moving between ferrous metal mountings and non-ferrous or non-metallic types) can significantly alter the output level - and/or overall sound.
And two pickups that "read" the same but are made with significantly different wire gages will usually have different output.
One example of inconsistent resistance but (usually) high output with5int the same style of pickup is found with many vintage Rickenbacher "horseshoe" pickups. I've worked on (and owned) lap steels where that type as read anywhere from 3.6k to around 11k ohms with some of the "lower" pickups having the highest output.
Some unique, non-humbucking pickups made with additional "boost" coils (like the rare Red Rhodes 6-string Velvet Hammer VHTBX Telecaster pickup for example) may show odd readings - 3-4k on the" low output" coil, 6+k on the "normal" coil and 10+k in combined "boost" mode - or the "normal" coil may read "zero" or in the "millions" of ohms (which normally means the coil is "open" or not connected). Yet the coil that seems to be defective still work fine! It's not "normal" - but it's not uncommon in pickups with unique construction.
As far as output, attack and certain effects go, some types of gadgets need a full, strong signal to operate properly:
Distortion, fuzz, clean boost, overdrive (now a catch all description that's almost become technically meaningless), octave generator, "wah", and envelope filter ("auto-wah") effects all need to be at the front of an effects chain (grouped together is fine) - but always before a volume pedal and/or any type of compressor or limiter.
Without a reasonably full signal/attack they don't respond properly. A volume "swell" or "squashed" signal (by limiter or compressor) can cause some to do almost nothing at all.
The DC resistance measurements you're getting are not uncommon, but can't be used "on paper" to determine a pickup's "output". Instrument type is also irrelevant. There are several factors that determine a pickup's "sound" (the "Q" - which more or less covers frequency response and related factors - is what is often compared as far as "voicing" goes), with output voltage being the most significant "volume" factor.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional |
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Jack Hanson
From:
San Luis Valley, USA
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Posted 21 Dec 2017 6:57 pm
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| Jim Sliff wrote: |
| I think you mean "DC resistance" - not impedance. They're different, and what you can normally measure yourself from a pickup is the DC resistance in ohms. |
Thank you for the correction/clarification. On a good day, I know just barely enough about electronics to wire up a Lionel train set. And thanks for your explanation; I feel a whole lot smarter having read it.
In any event, my decrepit old ears tell me the pickups that measure the smallest numbers on my multimeter seem to sound the best through my Earth Drive. And yes, I do run the guitar straight into the pedal, ahead of the volume pedal. |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 22 Dec 2017 12:56 am
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| Jack Hanson wrote: |
| In any event, my decrepit old ears tell me the pickups that measure the smallest numbers on my multimeter seem to sound the best through my Earth Drive. |
Jim covered the pretty complex side of PU impedance well enough, but for the more traditionally made PUs I agree with your observations: lower impedance PUs sound better through distortion units. (Never mind that you cannot measure the actual impedance up the frequency range with a DC meter.)
Low impedance traditionally wound PUs tend to have the widest frequency range and most even curve in the range that matters - high bass to highest audible treble. They also naturally attenuate low bass / subsonic frequencies, and are least affected by what load you put on them. All in all this result in a less complex - more straight - signal to drive the distortion unit, which results in "cleaner distortion" 
We can to a certain degree "clean up" the signal fed to a distortion unit from high impedance PUs by attenuating and/or filter out the low bass / subsonic frequencies by other means, but having the PU do it naturally produces a far better result. |
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ajm
From:
Los Angeles
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Posted 22 Dec 2017 8:36 am
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Going back to the first post, the real question in my mind is: What do you mean by "sounds better"?
While all of the technical talk is useful for someone who understands it, and for those of us trying to learn more about these things, for most people it doesn't mean much.
I have a feeling that you're trying to find a correlation between "impedance" (or what it means to you) and what sounds "better" (or what that means to you).
My gut tells me that the first big dividing line in your experiment is between single coils and humbuckers.
From there, you can try to start separating them by actual output level, or how hard you are driving the pedal.
As was said, impedance and/or resistance are often used to try to indicate an output level, but that is not really accurate. You really need more data. Ultimately, the total design and performance of the pickup is what matters.
Also, unless I missed it, are you talking pedal steel? Or six string? Or ......? |
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