Has anyone ever measured the peak output voltage from pickups? I’m interested in any test data.
Im working on a design for a built-in buffer. Its a particularly loud guitar with a 3-in-series wiring option and I don’t want it to clip. I can’t measure it directly with a meter and I don’t have an oscilloscope. So what I did was to record some loud open-chord strumming using a x1 gain preamp, directly into the PC using the Audacity program. I had the guitar volume turned down ( to avoid clipping) to a x0.25 factor, set by interpreting ohms measurement on the volume pot. Then I looked at the trace, and used a function that tells me how much the trace can be amplified by to get to the programs peak available level. I compared that to a calibration track that I did using dc on/off pulses of a known voltage level.
After a bit of Math, I worked out that this setup, with three ceramic single coils in series is giving transients of +/-3V – which I find quite remarkable, but not too surprising given the loudness of it. For a comparison, I did the same thing with the ‘’vintage” neck humbucker on my LP, and got +/-1.5V.
This tells me that I need to have available voltage swings of at least +/- 3V to do what I want.
I understood what you said, but it seems to me you took the long way around. The peak AC value is what most meters read, unless they're the expensive variety that can do True RMS. But even then, you'd just multiply that number by 1.414, and that'd get you the peak value.
The catch of course is to be able to see the reading long enough. That's why many meters have a "Hold" or a "Capture" function, so the user can read the value after the measurement was taken.
You caught me at just the wrong time - my Strat is in pieces all over the shop bench (and floor, and cabinet, and.... ). I'll measure my bass in a moment, with my trusty Fluke 83 (that captures the maximum reading), and report back soon. When I get the Strat back together, I'll check that out too.
BTW, the initial pick attact (the largest transient by far) can indeed reach 3 volts p-p AC. I'd plan on at least twice that for the rail voltage, just for the safety factor (battery decay). 4 AA cells in series would let you split it, if needed for your planned circuit. Cell holders meant to be built into the guitar are now cheap and good-looking to boot.
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Sumgai - Thanks - Id be very interested in your readings. My meter is too cheap to do any ac transient readings that I would trust. My work-around method gives me a nice waveform trace that I can see, and it really is just the initial strike that gives the big swing.
Usually I build my buffers with a 9V battery, but for this build I want to try two 3v lithium coins cells for 6v, making a very compact package. I'm hoping that it will just about be OK, since wild strumming on all in series is not a normal use, and a small amount of initial clipping seems to be hard to hear.