One steady state and slow swept tones they check out identically (well within expected variance, one amp might have 0.001%THD/IMD and the other 0.099%.
He lacks the ability to do really short, 1ms, white noise pulses.
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I'm wondering about TIM, something I've tended to dismiss (with the exception of Crown DC-300).
TIM (transient IM) would can happen if your negative feedback loop was so slow some signal made it through before the negative feedback arrived at the front end to apply correction. Given the speed with which signals flow, outgoing and return feedback, that shouldn't be an issue with any decent design (which clearly excludes Crown DC-300.)
We'll do the Hafler test, found a very detailed "how to" and the Baxandall (spelling?) compare the output with the input. The two tests should produce similar results.
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This is way out of my comfort zone, feels nice to stretch the brain a bit.
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Somehow I suspect the manufacturer changed the manufacturing process and something very subtle is different.
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As might be suspected, I absolutely hate the DC-300. It sounded gritty with muddy midrange.
We installed 20 in a sports complex. For a PA system, they were adequate, with proper LF input rejection and output DC offset protection.?
I'd loved to have been able to do the Hafler test on the DC-300. Their smaller amp (DC-75 of DC-150) sounded great.
The DC-300 had a slew rate of 8V/uS, slow by today's standards.
I need to pull up the diagram of the DC-300 and study their feedback loop....
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