That's true, as they said, it's just an approximation.
Perhaps comparisons should be made between professional equipment (oscilloscopes, function generators, and audio analyzers) and the LTspice, but in our tube amps.
Perhaps comparisons should be made between professional equipment (oscilloscopes, function generators, and audio analyzers) and the LTspice, but in our tube amps.
I have argued with folks on this forum before, them saying that my measured voltages and distortion numbers etc. "Are WRONG" because it doesn't match either their simulation or calculations from a tube data sheet. I can see using these tools as a starting point and then tweaking the real world built amp from there. I use the power supply sim software PSUD2 regularly. But it's a bad idea IMHO to rely solely on them or trust their results like it's a bible, and then dismiss the actual built results because it doesn't match a simulation of some calculations.
That goes against the whole idea of scientific testing, and honestly I am shocked how many classically trained engineers dismiss real world results when it doesn't match what they calculated/computer sim'd.
That goes against the whole idea of scientific testing, and honestly I am shocked how many classically trained engineers dismiss real world results when it doesn't match what they calculated/computer sim'd.
Simulation makes a lot of assumptions. Perfect tubes, sometimes people use perfect transformers (no DCR, leakage inductance etc), perfect voltage sources (no ripple, zero impedance). Even taking all of that into account when possible I have seen better, similar and worse distortion and power output results comparing simulations with real prototypes. DC operating points are pretty good though, provided you use a decent tube model.
Right, it's why I use that PSUD2 software, it's usually pretty close to the actual DC voltage output and makes designing a power supply to a required voltage much easier. At the end of the day though, the measurements from a real prototype prevail over anything calculated or simulated.