When you run the IMD test check the bias current to be around 0.85A.
What does it mean to “checking the steady box”
Hans
What does it mean to “checking the steady box”
Hans
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I run it on my amp.
„steady state“ box
Could you post a screenshot of your Limits window ? So that I use same settings.
„steady state“ box
Could you post a screenshot of your Limits window ? So that I use same settings.
Don’t know whether I understand your questions which have probably to do with differences in terminology between Microcap and LTSpice.
Everything I did is visible in the circuit diagram.
1) both 950 and 11.5Khz signals at 0.4Volt input.
2) simulation time 80msec with a 100nsec timestep.
3) calculation to double precision
4) no “lossy” compression for the plot
That’s about what I instructed LTSpice, hope it answers your questions.
Hans
Everything I did is visible in the circuit diagram.
1) both 950 and 11.5Khz signals at 0.4Volt input.
2) simulation time 80msec with a 100nsec timestep.
3) calculation to double precision
4) no “lossy” compression for the plot
That’s about what I instructed LTSpice, hope it answers your questions.
Hans
That was heavy.
I attempted IMD vs Pout which might take days.
Here is 200mV input which I chose randomly before reading your post. It is my standard amplitude for transient analysis.
Still takes long time.
Anyway it depends on the gain of the amp. 3W. IM2 -219dB, IM3 -160 dB.
If you want to make a direct comparison with any amp, adjust for a output voltage of 5V peak.
I attempted IMD vs Pout which might take days.
Here is 200mV input which I chose randomly before reading your post. It is my standard amplitude for transient analysis.
Still takes long time.
Anyway it depends on the gain of the amp. 3W. IM2 -219dB, IM3 -160 dB.
If you want to make a direct comparison with any amp, adjust for a output voltage of 5V peak.
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The test takes very long especially when opamps are involved. The settings I use are below. When THD doesn't converge well, time step ratio has to be decreased for IMD too.
Yep, and the reason is to keep THDN at 100 mW "low enough". This because the opamp used is VERY noisy but one of the few, allowing this topology:
Wow, that’s a long time.
In LTSpice a 80msec burst followed by a FFT takes ca. 20 seconds.
Hans
P.S. with 200mV input for both signals, LTSpice gives IM2 -138dB and IM3 at -142dB, quite a huge difference to Microcap.
Hans
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The amp producing plot below required time step of 100u and took something like 6 hours, but that was worth it:
That was the simulation of my circuit, not the Hiagra.
So your amp has very low gain.
Waiting long time makes me tired because it blocks the program, can‘t do anything else in MC.
Perhaps it is possible to run MC two times from different folders?
Could it be that the amplifier runs into clipping early when using this test ?
Output amplitude doubles.
Output amplitude doubles.
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Correct, that amp has low gain. It's determined by what a simple preamp (AD797 or similar) can deliver without degrading specs (same issue applies to designing power supply).
I'm familiar with the nuisance that other use of uC is impossible. One alternative is to run it on another laptop but it's much slower. An other alternative is to run it on my i9 desktop but I don't have a UPS with enough power to keep it running during a power outage.
I'm familiar with the nuisance that other use of uC is impossible. One alternative is to run it on another laptop but it's much slower. An other alternative is to run it on my i9 desktop but I don't have a UPS with enough power to keep it running during a power outage.
With class A amps containing large RC constants, indeed, I noticed that clipping can occur initially.
Output voltage from IMD test 30Vp, normal signal has only 15Vp.
How you run that test under full power ?
Or do you reduce input voltage ?
How you run that test under full power ?
Or do you reduce input voltage ?
If I reduce gain, THD of my amp gets even better.
It is possible to run MC9 parallel.
Mc12 does not need install, could work.
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The IMD pic looks OK, issue is the maximum V(out) that doesn't cause clipping. Clipping in the sense that THD rises sharply. So not at the onset of clipping but lower. One of the marks of clipping can be that THD will cause errors in periodic steady state. The alternative,, simulation cycles, with 50 cycles is much too low. I use 500 or more even with tube amps but that takes much time.
In your settings, steady state is not chosen, like this thd is limited to -208 dB, for me that’s useless, steady state takes multiple times longer than“ much time“
Steady state limit is -250 dB
Correct, I use the default value, knowing that low order distortion below -60 dB for most ears is "good enough". And I won't calculate the voltages induced in wiring, caused by coupling, having measured such issues at work, RF circuitry, where -140 dB was "good enough".