Not often, actually. That might be OK to assume for the purposes at hand, but if one checks out population spread for the purposes of designing for audibility it's another story - quite scary really - plus the effects of 'ageing' begin at pretty young ages. So IMO 20kHz is generally a safe overstatement. I guess most of us have experienced the wake up call when the VU meter's moving but can't hear anything during calibration tests, first happened to me in my mid 30s with a R2R test tape.......and seems that's normal...... human hearing is to 20kHz correct?
That circuit has global feedback, but yours does not, correct?
Correct - any idea why taking the pot out would make it oscillate though?
The higher the grid stopper, the better the rfi rejection, but values too high may work with the input stage's Miller effect to roll off the highs.
Spice should show this roll off, try experimenting and see what happens with the simulation.
This is obviously with no input connected.
You need to short the input for testing, or else high gain stages can start to oscillate. Just clip a jumper from the tip of jack to ground. When the volume pot was in it was shorting the input to ground(when turned down of course), hence no oscillation.
You need to short the input for testing, or else high gain stages can start to oscillate. Just clip a jumper from the tip of jack to ground. When the volume pot was in it was shorting the input to ground(when turned down of course), hence no oscillation.
Thanks - yes I tried that originally, too, no change unforunately!
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