I designed my amplifier such that it can handle full-power square waves without slew-rate limiting. It's of no practical use at all, but it assures you that whatever may happen, your amplifier won't go into slew rate limiting.
If I should ever design an amplifier for driving electrostatic headphones, I would design the output current limiting for a power bandwidth in the 3 kHz to 8 kHz range. High enough for almost all music, and the lower the current limit, the smaller the shock you would get if the insulation should fail. (European FM power bandwidth: 3183 Hz, that 8 kHz comes from a very old article of Otala's research group.)
If I should ever design an amplifier for driving electrostatic headphones, I would design the output current limiting for a power bandwidth in the 3 kHz to 8 kHz range. High enough for almost all music, and the lower the current limit, the smaller the shock you would get if the insulation should fail. (European FM power bandwidth: 3183 Hz, that 8 kHz comes from a very old article of Otala's research group.)
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I think that an amplifier ideally should have as much margin on its slew rate as the amplifier has loop gain. For example, an amplifier with a loop gain of 10 should have a slew rate 10x higher than 2*pi*f*v. Nearly all amplifiers have much more loop gain than slew rate.
Ed
Ed
A good article and a long list of useful references.
https://hifisonix.com/wp-content/uploads/2018/03/SID_and_TIM_W_Jung_77-79.pdf
https://hifisonix.com/wp-content/uploads/2018/03/SID_and_TIM_W_Jung_77-79.pdf
I don't intend to use tubes, or a massive output transformer > because I want to have quite high power output to avoid the high distortion of clipping.
PS.
In the 70's/80's (?) Sanyo marketed an amplifier with a SR switch with enough SR reduction to help suppress the 'clicks & pops' of vinyl records 🙂
https://www.google.com/search?q=san...jIwoAfo3wGyBwcwLjE3LjIwuAeJPQ&sclient=gws-wiz
Loop gain is a small signal characteristic, whereas slew rate is concerned with large signals. They should not be mixed together.
That SR switch changed the Miller compensation capacitor (see the “worked examples” in my post #4 above). That changed not only the SR, but also the loop gain and thus the distortion level.
@alexcp - My reasoning is as follows: non-linearity in the output stage can cause the integrator to slew on normal audio signals. The class B output stage is a worst-case. The crossover notch causes the amplifier to run open-loop momentarily at every zero crossing.
Ideally, an amplifier should be designed not to slew under those conditions. The slew rate must be adequate to cover the amplifier's open-loop gain on a normal audio signal that would not overdrive the amplifier running in closed-loop.
A ratio x can be defined for how much of the differential pair's tail current is used:
x = Vin_peak * gm_differential_pair / I_tail
where
Vin_peak = Vout_peak / closed_loop_voltage_gain
An amplifier with x<1 can tolerate any non-linearity without slewing. x>1 is permissible as long as the output stage never becomes too non-linear. Optimal class AB biasing does that.
My amplifier has x=2. The Wolverine has x=13.
Ed
Ideally, an amplifier should be designed not to slew under those conditions. The slew rate must be adequate to cover the amplifier's open-loop gain on a normal audio signal that would not overdrive the amplifier running in closed-loop.
A ratio x can be defined for how much of the differential pair's tail current is used:
x = Vin_peak * gm_differential_pair / I_tail
where
Vin_peak = Vout_peak / closed_loop_voltage_gain
An amplifier with x<1 can tolerate any non-linearity without slewing. x>1 is permissible as long as the output stage never becomes too non-linear. Optimal class AB biasing does that.
My amplifier has x=2. The Wolverine has x=13.
Ed