Your measurement didn't take inductance of a coil in series (low-pass filter) into account
This is not confirmed yet, as the test was only short-term. However, in any case you get annoying whistles and 100x higher noise+distortion than with resistor. And, it is easily detectable by ear, as shown in the listening test thread. So, the warning to customers with elstat speakers similar to those listed here is IMO fair. I understand that neither manufacturers and OEM assemblers, nor fans of the amp would be happy, but let's keep emotions and business interests aside.
That will not give you a reliable number- you need a network analyzer or an impedance analyzer like the ones built into loudspeaker measurement gear (e.g., CLIO). The problem is that the speaker's equivalent impedance has a lot of elements in the network, whereas the capacitance meter is designed to measure something much closer to a pure capacitance (albeit with a small ESR and ESL component).
Yes but that was a fixed capacitance,in speakers that is phase,impedance and freq dependent and it varies during playing.
But can't it just be resolved by using data from a speakers' impedance / phase diagram?
Not with that method, no. A loudspeaker load is far different than a simple series RC.
Nano to micro is a difference of 1000 so if my math above checks out the speaker is at that frequency equal to 281600 nanoFarad or about 700 times the listed value on the ICEpower amp.
World records. World records happen
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281uF sounds like a lot. That would be another factor of 100 higher than PMAs already challenging 2.2uF. But I haven’t looked deep into the math (yet). But thanks.
High capacitance speaker exist but they are rare. Pavel is concerned about the edge cases, but for 99.9% of speakers, it’s irrelevant.
That is correct. I am testing a “niche” situation, though existing situation, for few speakers. Some electrostats are “lighter” load, as we can see inductance effect above 10-20kHz. But some are even worse than my dummy load. I think it is good to mention such possibility. One should evaluate the info with respect to his technical conditions, for most it will be a non-issue.
If you have impedance plots with impedance modulus |Z| and phase angle φ, then Z = |Z|*exp(jφ) = |Z|*(cosφ + jsinφ). If you read |Z| and φ at one frequency, you have more possibilities how to build the same impedance. For example, we know |Z| and φ that is negative at the chosen frequency point. Then we can make a model even with R1+C1 or with R2//C2 - different values. However, to simulate the complete measured plot, the circuit may be much more complicated. So we can do it simply only at one frequency, or in case of a simple complex impedance.
.Yes, you've written what I did but in complex (imaginary) numbers. But when broken down into components, then the load the amplifier sees would be exactly that C equivalent value (or L, but that doesn't seem to be an issue) component at that exact frequency, right?
