Wednesday, December 31, 2014

Electric Guitar Output Voltage Levels

I was recently interested in how much output voltage you get from guitar pickups. To find out, I connected a guitar to an oscilloscope and did some measurements. Here are the numbers:


  • The values are peak voltages in millivolts (double the values for peak-to-peak)
  • The 'A' values represent the maximum transient peak voltage I observed (just after the string leaves the pick)
  • The 'B' values are measured after about two seconds into the tone.
  • I picked (strummed) hard. That's obviously a very subjective statement. Your mileage will vary.
  • The values are averages over three to five repetitive measurements.
  • The scope used has an input impedance of 1MOhm and an input capacity of 18pF. Probe attenuation was at 1X.
The guitar I used has a volume control and a tone control. For the measurements, volume was on maximum output and the tone control was on minimum impact.

I used the following pickups:
  • Single coil (neck and middle): GFS Pro-Tube lipstick
  • Humbucker (bridge): Artec Vintage Humbucker LPC210N
The measured DC series resistance of the pickups are as follows:
  • Neck: 4.8K
  • Middle: 6.2K
  • Neck & middle (parallel): 2.7K
  • Neck & middle (series): 10.9K
  • Humbucker: 8.3K
The difference between soft, medium-hard and hard picking was in my case about a factor of 2 to 3. Meaning: picking the open A string softly I got about 10mV, medium-hard 20mV and hard 30mV (which you'll find under 'A' in the table, above).

And here the screenshots referred to in the table:

a.bmp - neck pickup, open A string.

b.bmp - neck pickup, open E chord. This is one of the lower samples. Most other measurements came in higher.

c.bmp - bridge humbucker, open A string.

d.bmp - bridge humbucker, open E chord.

8 comments:

  1. This is very helpful, thank you!

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  2. Excellent work and very useful. Well done.

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  3. Very useful information - thank you.

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  4. Saved me the test with Humbucker pick which I do not own.
    I did not realized that it produces at least 3 times stronger signal.
    Now I know why some preamps have the 10dB attenuator switch. This must be to match the gain to Humbucker pickups.
    Thanks a lot

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    Replies
    1. The «gain» at the signal levels they are showing is sensitive and must be kept clean; This is common to any pre-amp levels; They are showing like 280 mv for bridged humbucker which would explain why it is popular;

      Even at that voltage a designer for the electric would want to run it hot on a bench to look for noise in any place → especially the wire wound variable resistance which is notorious for oxides causing a diode effect – which would be an unwanted distortion that is serious and has to be avoided;

      ◘ 10,094,960 views on stage is not the place to discover this;

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  5. I have just started to design a tube amp that will have both guitar and line in inputs so, knowing voltage ranges from start to finish of the amp circuit will be essential to setting up proper gain stages. Thanks for this valuable information! Well done! Phil Donovan

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