Hi,
been searching for an answer but didn't succeed (maybe due to a lack of language knowledge
).
In most Spice sims I find only a resistor (4 or 8 ohms) as the load for amp performance simulations, sometimes there's a cap in parallel. Has anyone some sort of a "lib" of usual real-world complex loads? Let's say some simple speaker, a usual 3-way one and a rather challenging one?
TIA, Holgi
been searching for an answer but didn't succeed (maybe due to a lack of language knowledge
).In most Spice sims I find only a resistor (4 or 8 ohms) as the load for amp performance simulations, sometimes there's a cap in parallel. Has anyone some sort of a "lib" of usual real-world complex loads? Let's say some simple speaker, a usual 3-way one and a rather challenging one?
TIA, Holgi
here , let me Google (forum search) that for you...
A community dedicated to helping everyone learn the art of audio. Projects by fanatics, for fanatics! - Search Results for spice loudspeaker model
A community dedicated to helping everyone learn the art of audio. Projects by fanatics, for fanatics! - Search Results for spice loudspeaker model
An externally hosted image should be here but it was not working when we last tested it.
Buy Bob's book -- it's full of good stuff.
Hi,
been searching for an answer but didn't succeed (maybe due to a lack of language knowledge
In most Spice sims I find only a resistor (4 or 8 ohms) as the load for amp performance simulations, sometimes there's a cap in parallel. Has anyone some sort of a "lib" of usual real-world complex loads? Let's say some simple speaker, a usual 3-way one and a rather challenging one?
TIA, Holgi
Your countryman is well made.
I always use a simulation of a real load to my amp.
Sorry, I could not upload. Look at
http://micka.de/org/en/download/spice-tsp_en.pdf
Thank ya all, that's loads of stuff to read
@sreten: Just reducing the resistive load to some reasonable smaller value doesn't win the game. A pure resistor is in no way reactive as a real speaker(-box) is.
@nigel: For measurements when the amp is built-up this is fine. But for simulation you leave me alone... hmm... Do I have to connect the speaker to D+ and D- of a USB port and install a Sim-driver? (just kidding)
@rajko: Looks pretty interesting, mostly since the results are comparable to what I achieved so far.
So here is a comparison of 1khz 50/50 pulse driven into a pure 8R load (no schematic) and into a 3-way speaker for which I modeled the speaker chassis 1-by-1 along with the xover - but w/o box, showing output voltage and current.
Again, thank you! I now will start to model the box and see how it influences the response.
BR,
Holgi
@sreten: Just reducing the resistive load to some reasonable smaller value doesn't win the game. A pure resistor is in no way reactive as a real speaker(-box) is.
@nigel: For measurements when the amp is built-up this is fine. But for simulation you leave me alone... hmm... Do I have to connect the speaker to D+ and D- of a USB port and install a Sim-driver? (just kidding
)@rajko: Looks pretty interesting, mostly since the results are comparable to what I achieved so far.
So here is a comparison of 1khz 50/50 pulse driven into a pure 8R load (no schematic
) and into a 3-way speaker for which I modeled the speaker chassis 1-by-1 along with the xover - but w/o box, showing output voltage and current.
Again, thank you! I now will start to model the box and see how it influences the response.
BR,
Holgi
And always remember that real world loads, as speakers are dynamic and never the same. A transmissionline or bassreflex speaker has huge resonances which will show up in great detail in the feedback path in your amplifier.
You would get the best understanding if you laplaced your amplifier and have a look at the poles and zeros.
You would get the best understanding if you laplaced your amplifier and have a look at the poles and zeros.
audio frequency amp output/loudspeaker load interaction is characterized by damping factor vs frequency, which is the amp output (complex) Z vs frequency divided by the load Z at the same frequency
we typically have huge damping factor and therefore little amp Vout reaction to load Z variation at audio frequencies with the standard low output Z negative feedback audio power amp circuits
what does vary is the current supplied to the load - and the output devices, their drivers, bias and the power supply, heatsinking all have to be designed for the expected real world load current over the range of phase angle
but if you have competently designed, sized the outputs, ect. - then the usual result is there is almost no influence on stability for audio frequency complex loads
and the distortion is pretty much the same or less for complex load vs the same I delivered into a pure R
that "real workd loads are difficult for amplifiers" seems a popluar meme though:
we typically have huge damping factor and therefore little amp Vout reaction to load Z variation at audio frequencies with the standard low output Z negative feedback audio power amp circuits
what does vary is the current supplied to the load - and the output devices, their drivers, bias and the power supply, heatsinking all have to be designed for the expected real world load current over the range of phase angle
but if you have competently designed, sized the outputs, ect. - then the usual result is there is almost no influence on stability for audio frequency complex loads
and the distortion is pretty much the same or less for complex load vs the same I delivered into a pure R
that "real workd loads are difficult for amplifiers" seems a popluar meme though:
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