Thank you,
@TurtlePaul, the following is for consideration....
Not sure about him, may be may be not lol...
- The performance of the LC filter is sensitive to the connected speaker's impedance/EPDR. A very low or highly reactive load (low EPDR) can cause variations in the filter's frequency response, especially at higher frequencies, and increase (Phase) distortion/s
Not sure what your point is on this, seems like general statement? For analysis, I wouldn't use EPDR, "E" is as we know, "equivalent" in terms of output devices heat dissipation only and it really doesn't apply to class D amps such as the e 3 A7. So, to analyze/assess the effects on the filters, just use the actual values directly and not bother with some equivalent values that don't apply here.
- As mentioned, the ability to handle low EPDR is linked to the robustness of the PS/PF. That is it needs to deliver the necessary current (V/I in sync/PF) into low impedances without voltage sag or premature protection circuit activation, without Pumping/Voltage increase, and without V/I not in Sync occuring.
Not really, as explained in many posts on the topic, EPDR was developed to help consider the effects of reactive loads on the increased heat dissipation in the outage devices that could result in thermal damages and/or stability issues in class AB/B amps. Even then, it is more about the amplifier design, than the power supplies, low EPDR does not mean higher current, current is still a function of voltage and the real part of the impedance. Ohm's law still applies!
Quick ref to Wiki:
Ohm's law
An AC supply applying a voltage V
, across a
load Z
, driving a current I
Main article:
Ohm's law
The meaning of electrical impedance can be understood by substituting it into Ohm's law.<a href="
https://en.wikipedia.org/wiki/Electrical_impedance#cite_note-15"><span>[</span>15<span>]</span></a><a href="
https://en.wikipedia.org/wiki/Electrical_impedance#cite_note-HH1-16"><span>[</span>16<span>]</span></a> Assuming a two-terminal circuit element with impedance Z
is driven by a sinusoidal voltage or current as above, there holds
V=IZ=I|Z|ejarg(Z)
The magnitude of the impedance |Z|
acts just like resistance, giving the drop in voltage amplitude across an impedance Z
for a given current I
. The
phase factor tells us that the current lags the voltage by a phase θ=arg(Z)
(i.e., in the
time domain, the current signal is shifted θ2πT
later with respect to the voltage signal).
Just as impedance extends Ohm's law to cover AC circuits, other results from DC circuit analysis, such as
voltage division,
current division,
Thévenin's theorem and
Norton's theorem, can also be extended to AC circuits by replacing resistance with impedance.
- Even though classD is efficient, driving an amplifier into a very low EPDR load can cause the output transistors to overheat or draw excessive current, triggering protection circuitry or potentially causing damage if the protection is inadequate.
That is true, so no argument edit: I missed that you were referring to class D, thought you were on class AB/B amps, so no, that’s not true either, as others mentioned, this EPDR, an equivalency thing, doesn’t apply to class D amps as in this case you can't apply the equivalency any more.
- EPDR metric is primarily used to understand the maximum instantaneous current and heat stress a loudspeaker might place on an amplifier, particularly important for class A/AB designs (as noted/indicated) that dissipate more heat linearly. While classD is more efficient, the underlying current delivery challenges remain for any amplifier when faced with extremely low resistance points in a speaker's impedance curve. This implys all aspects of the setup need to be considered.
I guess true as long as it is clear that it is about the heat, not inflated current by using EPDR that is, as someone else put it, fictitious (I would add, just sort of..), current delivered should still be calculated using the actual impedance, not the artificially deflated EPDR value.
- For very low EPDR, the 3eA7/mono/SMPS (52V/9A) measure indicates/suggests no issue/susceptablety with 2R Loads although perhaps not the 3eA7se (although a 10A SMPS may help/assist). As mentioned, a modern/high-quality class D amplifier, engineered to handle difficult loads and is less susceptible to EPDR issues than a class AB amplifier of comparable Power rating, although the immunity is not universal across all classD models, and poorly designed units, even with FB, can still face problems.
I would add/emphasize that as already mentioned, the 5 A PS is practically adequate for the rated output of the 3 e A7. IMO, a 10 PS is really for someone who for whatever reasons has to need to push the amp to near its limit all day long, in such cases, they would be better off getting something like a McIntosh, Passlab or similar power amps that rated their output closer to the so called "continuous" rating, i.e. continuous in almost literal sense.
Above are just food for thought kind of comments, not meant to contradict yours at all.
