In that case you would need to test with every possible speaker combination using an dummy load emulator to make sure it works ok.
You would need a dummy load with resistance, inductance and capacitance to emulate a speaker.
I think you are being too fussy.
I have sold lots of amplifiers all tested using my big 4 ohm speaker.
I haven't had one complaint from a customer.
You would need a dummy load with resistance, inductance and capacitance to emulate a speaker.
I think you are being too fussy.
I have sold lots of amplifiers all tested using my big 4 ohm speaker.
I haven't had one complaint from a customer.
Using the speaker as a test load would be ideal if designing an active speaker with amplifier buit in. There the situation remains constant ever after.
But yes, we really need an universal dummy load !
It would be very strange if it didn't exist yet. Wonder what standars like IEC, DIN or ANSI or what ever have to say about this ?
- Elias
But yes, we really need an universal dummy load !
It would be very strange if it didn't exist yet. Wonder what standars like IEC, DIN or ANSI or what ever have to say about this ?
- Elias
Fussy, yes, definitely, but proper testing of a product is part of the qualification of a product.
Nigel, your 650W speaker may already be an extreme load and a good test. More than one dummy load could be used. Each stressing the amp in a different way. A capacitive load without resistance could be one. An inductor and capacitor in parallel could be another.
Elias, the standards agencies may have something but I don't see why we can derive something ourselves.
The dummy load, whatever that maybe, could be sized to cause a certain amount of phase shift. This could expose a less than adequate phase margin. I think we can test for gain margin by reducing the gain of the amplifier via the feedback network.
Nigel, your 650W speaker may already be an extreme load and a good test. More than one dummy load could be used. Each stressing the amp in a different way. A capacitive load without resistance could be one. An inductor and capacitor in parallel could be another.
Elias, the standards agencies may have something but I don't see why we can derive something ourselves.
The dummy load, whatever that maybe, could be sized to cause a certain amount of phase shift. This could expose a less than adequate phase margin. I think we can test for gain margin by reducing the gain of the amplifier via the feedback network.
In RF and microwave world there is the concept of 'load pull' where the load impedance and frequencies and stepped. It can be very time consuming measurement, but usually shortens the total design time.
While the goal of varying the load impedance is different for RF and audio amplifiers, I think a 'load pull' would be handy for audio as well. Actually, it would be quite straightforward to make an automated tester.
While the goal of varying the load impedance is different for RF and audio amplifiers, I think a 'load pull' would be handy for audio as well. Actually, it would be quite straightforward to make an automated tester.
testing amplifiers with load
Good evening Nigel, the old school way of plugging speakers in to amplifiers to have a good sound test is my way also.. things start to shake, rattle and roll at 80hz with out put levels rising up pass 30watts all good fun
Good evening Nigel, the old school way of plugging speakers in to amplifiers to have a good sound test is my way also.. things start to shake, rattle and roll at 80hz with out put levels rising up pass 30watts all good fun
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