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Old 12th February 2008, 02:57 AM   #1
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Default Voltage swing on a guitar pick-up?

Starting way simple here....What is the voltage swing on a typical electric guitar pick-up? How much current can this pick-up source?
Without this info it is near impossible to design an amp I would say....I would like to build a one tube bedroom amp for my son to learn on.....I have gutted a burn't 220VAC-110VAC 100W TX for the core...bobbin is reusable so I can do the B+ with this....push comes to shove I can wind it as an isolation TX for appx. 189 VDC.
I've got to make all the gear from from stuff I can scrounge.....I will go to a TV repair shop shortly to see if a tech will sell me a torched tube set so I can accumulate some stuff.
________________________________________Rick...... ....
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Old 12th February 2008, 05:31 AM   #2
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Rick,
As a guide look at this schematic.
http://www.schematicheaven.com/fende...-bmstr_rev.pdf

The numbers in boxes are the signal levels at 1kHz to produce 10 Watts output.
They will two and a half times higher for the full 70 watts.

That is, for full output:
about 20 to 25 milli Volts on the Normal Channel
and
about 10 milli Volts on the Vibrato (Lead) Channel

It doesn't specify if this is peak, peak to peak or RMS.
I would interpret them as RMS voltages.

Check out a few other schematics to see if there is any other guidance.

Cheers,
Ian
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Old 12th February 2008, 03:23 PM   #3
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A guitar pickup can produce more than 2volts, but to allow for crunch you should have enough gain so that 100mVpeak will saturate the last stage.
For bedroom practice 1watt is plenty if you use a typical guitar speaker. If you use a HiFi speaker the sound will not be so loud, and the tone a little dull.
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Old 12th February 2008, 05:13 PM   #4
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Quote:
Originally posted by SemperFi
A guitar pickup can produce more than 2volts, but to allow for crunch you should have enough gain so that 100mVpeak will saturate the last stage.
For bedroom practice 1watt is plenty if you use a typical guitar speaker. If you use a HiFi speaker the sound will not be so loud, and the tone a little dull.
Input impedance for a typical passive guitar pick up should be at least 500K, and 1M is not unusual. 12AX7A is standard input tube for most guitar amplifiers, running anywhere from a 1/4 - 1/2mA cathode current. Grid stoppers range all the way up to 68K (limiting input bandwidth.)

SemperFi is on the money about output levels, and other comments.
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