I had the chance to measure above power supply.
First of all, I measured the rail voltages with a true RMS meter. They came out as +/- 63.1 V. I then loaded the negative rail with a 66 R power resistor. Voltage dropped to -62.3 V (forgot to measure the positive rail) within about 10 s. Loading with 33 R caused a drop to 61.7 V, but this was within about 1 s.
For comparison, the Hypex TR400 toroidal with 2x 10000 µF dropped from 61.7 V to 57.0 V with 66 R and to 54.05 with 33 R.
Ripple data to follow...
First of all, I measured the rail voltages with a true RMS meter. They came out as +/- 63.1 V. I then loaded the negative rail with a 66 R power resistor. Voltage dropped to -62.3 V (forgot to measure the positive rail) within about 10 s. Loading with 33 R caused a drop to 61.7 V, but this was within about 1 s.
For comparison, the Hypex TR400 toroidal with 2x 10000 µF dropped from 61.7 V to 57.0 V with 66 R and to 54.05 with 33 R.
Ripple data to follow...
No, audio SMPSs tend to be unregulated. This one specifically claims to be unregulated, but it is still remarkably stiff compared to a conventional supply (albeit the conventional supply came with less than half the power).
Some of the earlier Hypex SMPS used primary regulation, it's here on diyaudio somewhere.
Let's look at ripple performance:
To my surprise, the SMPS was very quiet at HF, but there was a good bid of rounded out sawtooth 100 Hz ripple:
- 50 mV pk-pk when idle, i.e. only loaded by its internal circuitry
- 320 mV on the positive supply when the negative supply was loaded with 66 R
- 350 mV on the positive side when itself was loaded (not sure this wasn't mostly determined by when I hit the stop button)
- 1.1 V when the positive side was loaded by 33 R
- 1.0 V when 66 R was applied across the whole 126 V, i.e. same load as loading one side with 33 R
I think we can safely conclude that there is no primary regulation or a feedback loop from the secondary to the primary side.
The conventional supply had 10 mV of 100 Hz Pk-Pk sawtooth ripple when completely unloaded, but 1,6 V when one side was loaded with 66 R (a little less than 1 A). The ripple performance of the SMPS is very similar to what the conventional supply achieved at a roughly equal percent loading. The difference is that the sawtooth didn't have any evident harmonics in the SMPS.
Some of the earlier Hypex SMPS used primary regulation, it's here on diyaudio somewhere.
Let's look at ripple performance:
To my surprise, the SMPS was very quiet at HF, but there was a good bid of rounded out sawtooth 100 Hz ripple:
- 50 mV pk-pk when idle, i.e. only loaded by its internal circuitry
- 320 mV on the positive supply when the negative supply was loaded with 66 R
- 350 mV on the positive side when itself was loaded (not sure this wasn't mostly determined by when I hit the stop button)
- 1.1 V when the positive side was loaded by 33 R
- 1.0 V when 66 R was applied across the whole 126 V, i.e. same load as loading one side with 33 R
I think we can safely conclude that there is no primary regulation or a feedback loop from the secondary to the primary side.
The conventional supply had 10 mV of 100 Hz Pk-Pk sawtooth ripple when completely unloaded, but 1,6 V when one side was loaded with 66 R (a little less than 1 A). The ripple performance of the SMPS is very similar to what the conventional supply achieved at a roughly equal percent loading. The difference is that the sawtooth didn't have any evident harmonics in the SMPS.
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Thanks for those measurements, worthwhile.
Indeed, those Hypex supplies are not regulated, I think it even mentions that in the data sheet.
But you say 'no harmonics of the sawtooth', not sure what you mean by that, by definition a sawtooth has a decreasing slew of odd harmonics to its fundamental.
Jan
Indeed, those Hypex supplies are not regulated, I think it even mentions that in the data sheet.
But you say 'no harmonics of the sawtooth', not sure what you mean by that, by definition a sawtooth has a decreasing slew of odd harmonics to its fundamental.
Jan
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