I use the models that come with it.You may be using distortion-free components in MC12, since your plots are way beyond reality.
Additionally to the above: The paper describes a -120dB noise limit for the used AP 2722, that's why 60dB noise gain was used (by adding a resistor between + and - input) to raise the limit from -120dB to -180dB.You are right, I didn't know this AES paper.
It differs from the LA article in that gain is here 0dB versus a gain of 60dB.
at 1.1nV-rtHz input noise and 7.746V out, noise level is down at 20log(7,764/1.1nV) = -196dB referred to 7.746 Volt input.
So either his measuring gear limited the noise to -180dB and/or he used a much wider filter bin width.
And THD was indeed below noise so in that case < -180dB for this unity gain amp.
Hans
Hans
They seem to be rather insufficient and you also haven't included the input noiseI use the models that come with it.
Give me the circuit diagram and I will do the sim in LTSpice.
No problem to agree a NDA.
Hans
Thanks for the offer, I will consider that.
Maybe I will make a preliminary application with just one schematic.
-3 dB bandwith is 300+ kHz, 500+ kHz could be reached with some fiddling.
Maybe I will make a preliminary application with just one schematic.
-3 dB bandwith is 300+ kHz, 500+ kHz could be reached with some fiddling.
Do I have a dejavue? Nice try.Why brag about something that no one can check? Give at least the result of test of a real amplifieras dadod did.
Okay, here are the main graphs:
Bode diagram with Group Delay;
Loop gain curve on reactive load 50, 100, 500 nF and 2 uF
since your scheme is so secret
I‘m using a speaker cable that has some capacitance, no issues.
1 uF in sim pulls down the phase and gives a small peak in hf response.
Transient analysis still works, thd not much affected.
I could include the capacitance of my cable in the final hf compensation.
1 uF in sim pulls down the phase and gives a small peak in hf response.
Transient analysis still works, thd not much affected.
I could include the capacitance of my cable in the final hf compensation.
Attachments
I don´t care to much about gain phase at the moment because every small modification changes that and I have no time to play.
So I only make corrections if the transient analysis fails, this happens sometimes because MC12 is a bit sensible.
So I only make corrections if the transient analysis fails, this happens sometimes because MC12 is a bit sensible.
While loop gain might hide the issue of nested feedback loops, phase margin tells a more detailed story as when using opamp(s), already at fairly low frequencies, the value goes to 90 degrees and from then only gets less. Already ~50 years at Elektor, checking stability with a 1uF cap was standard procedure. So 1st thing with amplifier design is to look at stability, and correct it in a way that loads cannot cause instability.
Why do you want that ?The "good enough" amp I intend to construct is even stable with a 10u load.
Don´t worry, I built my monoblocks during covid and never had any problems.While loop gain might hide the issue of nested feedback loops, phase margin tells a more detailed story as when using opamp(s), already at fairly low frequencies, the value goes to 90 degrees and from then only gets less. Already ~50 years at Elektor, checking stability with a 1uF cap was standard procedure. So 1st thing with amplifier design is to look at stability, and correct it in a way that loads cannot cause instability.
My speakers are ACR RP200 with modified network.
Your amp with resistive load already has a considerable amplitude drop at 100 kHz.checking stability with a 1uF cap was standard procedure. So 1st thing with amplifier design is to look at stability, and correct it in a way that loads cannot cause instability.
I will hf compensate to have highest possible bandwith while beeing stable with normal speakers.
My amp is not intended to drive electrostats.
IMHO compensating for 10µF is overcompensating and that is a compromise.
Nice speakers. No idea what norms are used by speaker producers re amplifier stability. During covid about everything here was down so speaker projects were delayed.
My amp was designed to use the absolute minimum of components while providing 50W @ 4R below 1 ppm THD @ 20KHz. That has been achieved and was defined as "good enough".Your amp with resistive load already has a considerable amplitude drop at 100 kHz.
I will hf compensate to have highest possible bandwith while beeing stable with normal speakers.
My amp is not intended to drive electrostats.
IMHO compensating for 10µF is overcompensating and that is a compromise.
I added some RLC to ground because the midrange has some peak in the response.
So speakers + network form a bit more complex load. Later I will make braided cable with 16 wires, capacitance will go up...
Good and expensive speakers usually have complex networks to achieve a linear frequency response, that makes them more difficult to drive, they need powerful low impedance stable amplifiers.
So speakers + network form a bit more complex load. Later I will make braided cable with 16 wires, capacitance will go up...
Good and expensive speakers usually have complex networks to achieve a linear frequency response, that makes them more difficult to drive, they need powerful low impedance stable amplifiers.
Due to the minimalist design, there is no need to change compensation, whether using purely resistive load or the 10u cap.Your amp with resistive load already has a considerable amplitude drop at 100 kHz.
I will hf compensate to have highest possible bandwith while beeing stable with normal speakers.
My amp is not intended to drive electrostats.
IMHO compensating for 10µF is overcompensating and that is a compromise.
Both in sims and in real world I step from .05Uf to 10 uF looking for stability problems. All too often around .1uF to .5 uF there is transient oscillation that goes away at higher and lower cap. And then 6' of audiophile cable + .22 uF and no load can prove to be really bad for amps. You need to check at different drive levels and currents/loads since device fT's change a lot with current.
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