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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Re: Citation II AC balance posted by sorenj07 on April 7, 2007 at 08:20:07:
The test signal is a 60 Hz sine wave. It's derived from one of the 6.3 volt windings that feed AC to the power tube heaters.The typical DMM will read 60 Hz sine waves just fine, but it will not accurately read what you find when you sum the waveforms at the cathodes - in part because it is not a good sine wave. As well, since we are adjusting AC balance, a twist of the pot to one side or the other increases the amplitude of the signal in one side and decreases the signal from the other side of the push-pull outputs. The net voltage change that results is very small despite significant changes in the waveform. A standard DMM is no better at reading that than the amp's little stock meter since both are average responding - changes in the wave form in many cases don't change the average voltage much at all - as the original poster can attest to.
I've looked at this 100s of times. My suggestions above are the only way to go (unless you have a spectrum analyzer).
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- Re: Citation II AC balance - Jim McShane 09:11:49 04/07/07 (0)
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