Does anyone know voltage out of an Aikido 6SL7 / 6SN7 line stage pre? From memory it is about 30dB. NOS tubes, may change to 12S_7's. Voltage in from MacBook, phono stage (w/ too much gain) ... maybe CD player for a known 2V input? Thank you very much!
The amplifier stage should be mu/2 or x10 (20dB). The line amp has an amplifier stage and a white cathode follower (unity gain).
How do I safely measure the voltage out? I ask because I once tried testing and blew the PSU on a SS power amp several years ago, maybe I shorted something or had the meter on the wrong setting. Additionally I would like to test the voltage out of an EAR834 phono stage. If measurable, out of a pre-pre. The tools I have are a Fluke 27FM (Grey military model which is TRMS) Source being a MacBook or Analog Productions "The ultimate analogue test lp". I'm working on the phono stage and turntable, and can't turn up the phono stage without hum being too much of a problem.
Use an external coupling capacitor if you are worried about damaging the output.
A 10uF nonpolar electrolytic capacitor is fine.
How do I test to get answer in volts? Meter on what setting? Do I need other tools?
as far as non-polar electrolytic caps on hand, only 300uf
as far as non-polar electrolytic caps on hand, only 300uf
Put a 1khz test tone file (YouTube is fine) into the input, and set your meter to AC volts, and adjust the volume until this reads 1 volt at the input tubes grid. Now attach the meter to the output, and read what it puts out. I would think you'll get anything from 25-35 volts out, depending on the tubes used.
In a perfect world, with a perfect 6SL7, expect mu=70, so mu/2= 35.
This isn't a super accurate test, but will get you within 5% or so. If you get funky numbers try something lower, like 100-200Hz.
In a perfect world, with a perfect 6SL7, expect mu=70, so mu/2= 35.
This isn't a super accurate test, but will get you within 5% or so. If you get funky numbers try something lower, like 100-200Hz.
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No, it has to be disconnected, just measure the preamplifier.
Otherwise you'll be running the power amp at full blast!
Otherwise you'll be running the power amp at full blast!
Yes, not connected, with the amp off. Add a resistor to ground after the coupling capacitor,
similar in value to the amplifier input impedance (usually 10k-100k).
The 300uF cap you have is ok.
I'm embarrassed to need to ask this, but I will -
Did I measure RMS, peak to peak or average?
If I have to guess I'm going to say it 30V+ is too high of a figure to be RMS - I use this to provide voltage gain to a pair of F4 DIY amps - I rarely reach 95dB during playback seated 3m from the speakers.
Did I measure RMS, peak to peak or average?
If I have to guess I'm going to say it 30V+ is too high of a figure to be RMS - I use this to provide voltage gain to a pair of F4 DIY amps - I rarely reach 95dB during playback seated 3m from the speakers.
A tube line stage (with normal HV supply voltage level) can put out even more than 30Vrms.
Be sure to use 1kHz for testing, since most cheap meters are poor above that for AC Vrms.
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