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Class D Switching Power Amplifiers and Power D/A conversion

Phase shift in class D amplifiers. How it affects the sound?
Phase shift in class D amplifiers. How it affects the sound?
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Old 1st June 2019, 08:43 AM   #81
maty tinman is offline maty tinman  Spain
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Quote:
Originally Posted by jan.didden View Post
]

Maximum output power for Ri = RL is only true if you can freely chose RL. With audio where RL is fixed at 4 or 8 ohms, max power occurs with minimum Ri. The smaller Ri is with respect to RL, the more power is transferred to the speaker.

Jan
The interesting question, with class D amplifier: Ri is Z (w), so that we no longer have a simple resistor divider as class A and class AB amplifiers.
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Old 1st June 2019, 09:47 AM   #82
jan.didden is offline jan.didden  Europe
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Class A, AB amps to also have an Ri that increases with F. The cause is the same in all types of amps, the drop in loop gain with F.

Jan
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Old 1st June 2019, 10:00 AM   #83
maty tinman is offline maty tinman  Spain
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You are right but the phase shift, usually, is < 6 degrees at 20 kHz.

John Siau (Benchmark AHB2 amplifier) commented days ago that in that amplifier was very small.
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Old 1st June 2019, 10:06 AM   #84
maty tinman is offline maty tinman  Spain
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Well, he wrote about the linear phase.

Review and Measurements of Benchmark AHB2 Amp | Page 17 | Audio Science Review (ASR) Forum

Quote:
A non-linear phase response may be more audible than a non-linear frequency response. Errors in the phase response may create the impression that the frequency response is different.

The frequency response of the AHB2 extends down to 0.1 Hz and up to 500 kHz so that the phase response is linear within the 20 Hz to 20 kHz audible band...
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Old 1st June 2019, 10:09 AM   #85
maty tinman is offline maty tinman  Spain
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More about phase response here: Review and Measurements of Benchmark AHB2 Amp | Page 17 | Audio Science Review (ASR) Forum
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Old 1st June 2019, 11:48 AM   #86
jan.didden is offline jan.didden  Europe
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Originally Posted by maty tinman View Post
But there are lots of power amps that start to roll of at 30, 40, 50kHz and that have much larger phase shift than the Benchmark, which is really the exception here. What is the phase shift of an nCore at 20kHz, anyone knows this?

Jan
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