Back when, I looked at the product output from my (very) old test bench, that was put together on a (very) tight budget. Kids today do not appreciate how expensive good bench instrumentation was. I bought an old spectrum analyzer (something like $700 for an old used Singer SA). Not much to speak of by todays standards, maybe 50 dB total dynamic range and 30 kHz bandwidth... but good for my design bench almost 40 years ago. Since the SA by itself was marginal for fully quantifying circuit performance, I fed the product output from my (cheap) Heathkit distortion analyzer into the SA input. The product output of the distortion analyzer is a deep notch filter with gain... feeding that output into the SA input extended my bench measurement floor a few more tens of dB.Audio1Man said:Hi All
PRR’s explanation of the crossover is correct. The meters rectifiers add distortion to the normal output signal. I have modified my HP 400FL and others to make the “External Monitor Output” clean. I have added an opamp (NE5534A) with a gain of 20dB. The signal is tapped before the Meter Amplifier (after the range switch) and the signal is very clean. I hope this may be useful to some of you.
Duke
Audio1Man said:Hi All
PRR’s explanation of the crossover is correct. The meters rectifiers add distortion to the normal output signal. I have modified my HP 400FL and others to make the “External Monitor Output” clean. I have added an opamp (NE5534A) with a gain of 20dB. The signal is tapped before the Meter Amplifier (after the range switch) and the signal is very clean. I hope this may be useful to some of you.
Duke
PRR said:> solid state 400 with DC inputs use a battery?
TWO >35V batts at 45mA.
More than a stack of 9V pedal batts can do.
At this level I would consider a motorcycle battery and one of those cigar-lighter 120V inverters.
Gold said:If there is such a thing as a 35v or more battery I haven’t found it.
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