It had been my intention with the 861v4 to repeat some of the original power demand measurements that I did with the v2, and to see what the consumption of an LPS is. I measured min and max consumption as before, but only found a variation of about 3% between best and worst case, so all these figures are worst / typical / operating case.

With the stock v2, I had measured 33W input and 24W output from the SMPS. That means 9W is dissipated in the SMPS, which is 73% efficient.

With the LPS in the v2, I presume that the load was still 24W (I didn't measure it) but now the consumption from the mains was 360mA x 240V = 86W. That means the dissipation has gone up to 62W, and the efficiency is down to 28%. LPS manufacturers claim 45-55% efficiency, but only at full power (this one is running at third power).

The LPS in the v4 was interesting. I didn't measure the (internal) load currents, but the mains load was 230mA x 240V = 55W. I doubt the Lambda supply is any more efficient than the R3 Technology, and both of them are presumably less efficient with less load, so that leaves two unknowns. I don't know the internal load for the v4, and I don't know either the dissipation or the efficiency.

Either way, the electrical load of v4 must be significantly less than the v2. If the efficiency is the same, the load will have dropped from 24W to 15W. The efficiency is more likely to be lower, so the actual load will be less than that - maybe even 12W? Interesting stuff, and it suggests that the newer equipment draws less power than older, in spite of the increased DSP power, and the PSU demands may not be as high for everything as I put in my chart.

Using a separate transfomer to feed individual rectification/regulation boards is a longer term option, so I measured the secondary outputs of the Lambda supply. The 5V board took +/-9.3V, and the 12V board took +/-18.9V. The measurements of the R3 Tech supply in the V2 were much the same: +/-10V for the 5V board, and +/-19V for the 12V board. This points to both supplies having similar design and efficiency characteristics, and the transformers were a very similar size. (These are AC RMS measurements of course.)

That's just for the record, in case I get really carried away and stick a 1kVA toroid in a separate box, or try and fit an LPS into an HD621. One day, maybe. I'm very curious to hear how the Ruby 808.3 sounds. Based on what I heard, it should be a significant step fowards.

Nick

Edit: There are quite a few easy pieces to the jigsaw, and I've tried to place them when where I can. Unfortunately, I forgot to measure the DC currents on the output of the SMPS on the V4, and now they're all soldered up, I'm reluctant to do that. However, the DC outputs on the V2 use spade connectors, and the +5V/+12V/-12V loads drawn from the LPS are much the same as for original measurements on the SMPS, that I posted in the big spreadsheet.

However, more interesting than that was what happens when I disconnect all the DC outputs. All power supplies are most efficient at full load, and zero percent efficient at zero load, but what about the actual numbers? With zero output, the LPS continued to draw 220mA @ 240V, or 55W. This is a 70W power supply that is around 50% efficient at full load. Therefore we have a few points of reference for this PSU:

In general:
Consumption = Load + Dissipation
At zero load: 55W = 0W + 55W
At mid load: 86W = 24W + 62W
At full load: 140W = 70W + 70W

So the power dissipation doesn't vary very much - less than the load does. That suggests that having an oversize linear power supply will probably lead to greater power dissipation at whatever the equipment's actual load level is. And a small, harder-working, supply will dissipate less heat than a big supply that's cruising. Looking at the power measurements in the Wiki, I noticed that many of the other equipment has total consumption that was similar to the 861V4, and hence less than the 861V2, which drew just 24W internally. That suggests that some of the equipment that I thought might cause problems accomodating a linear PSU, like disc players, or the G-series units, may not need big power supply after all.

Last edited by WelwynNick; 2011-10-05 04:14. Reason: Additional Info