thewisepranker wrote: ↑Fri Mar 17, 2023 6:05 pm Out of curiosity, have you measured the mains power consumption? I tried to find some info about the efficiency of these but there doesn't appear to be any information, which usually means well you can probably guess...

yellowbeard wrote: ↑Fri Mar 17, 2023 6:14 pm Well done young fella! I'd say you danced a little jig when that sucker lit up...

projuicer wrote: ↑Fri Mar 17, 2023 6:48 pm #therigwhisperer

jvok wrote: ↑Fri Mar 17, 2023 8:21 pm Nice job, take it radio brians getting its 1000w upgrade after all?

sinus trouble wrote: ↑Sat Mar 18, 2023 12:30 am Excellent work Brian!!!!

radium98 wrote: ↑Sat Mar 18, 2023 7:08 am Nice , keep AIRF UP

BriansBrain wrote: ↑Sat Mar 18, 2023 11:24 am At most I will only be running at 600W to try and keep the Electric costs down

thewisepranker wrote: ↑Sat Mar 18, 2023 3:14 pm

BriansBrain wrote: ↑Sat Mar 18, 2023 11:24 am At most I will only be running at 600W to try and keep the Electric costs down

You might not save much by running it at a lower power. Most transistors are less efficient at lower powers. This is quite evident on the BLF278 datasheet. Not accounting for losses, efficiency for the BLF278 is about 65% at 250 W output for a total of 1 kW. It's only about 50% at 150 W output for a total of 600 W.

Total power budget is 1747 W and at 65% efficiency the BLF278s at 1037 W uses up 1595 of those, which leaves about 152 W for everything else.

The gain of the BLF278 is about 22 at 250 W output, so requires conservatively about 2 W to drive it. There's four BLF278s so there's 8 W, at 50% efficiency for the BLF245 that's 16 W. That leaves us with about 136 W for the fans and power supply inefficiencies and some micros and logic. How efficient has the power supply got to be to achieve this? Let's assume 5 W per fan, for a total of 10 W, leaving us 126 W. Assuming no other losses, that's roughly 92% efficiency for the power supply which is unlikely, but let's just go with it.

Given that the power budget is:
10 W for cooling
92% efficiency for the power supply
We can have a bit of a guess at the power consumption at 600 W output. At 50% output stage efficiency the power supply will be required to deliver 1200 W at 92% efficiency (just go with it) which is a total consumption of 1304 W. Drive requirements are now lower, at about 1 W per output device, so the driver now only consumes about 8 W, still at 50% efficiency, plus 10 W for the fans, for a total of roughly 1322 W.

This translates to a reduction in output power by 42% for a reduction in power consumption of only 24%.

A caveat to the above - yes I know that all of the power consumption has to be factored into the power supply efficiency calculations, but there's not enough data. The bulk of the losses are in supplying the largest consumer, which is the output stages.

I'm curious to know what the difference really is!

BriansBrain wrote: ↑Sat Mar 18, 2023 11:24 am Also as Brian's linear now is 150W this would make it a nice worthwhile 6.02 dB increase

jvok wrote: ↑Sat Mar 18, 2023 10:01 pm Would be interesting to see an input power measurement at 600w to prove/disprove wiseprankers theory

Albert H wrote: ↑Sun Mar 19, 2023 2:11 am Yes. Pranker's just about right - we've got a very similar rig here (a Seil 1200W beast), and that works out at about ~60% efficient at 1200W out, but backing it off to 500W actually reduces the overall efficiency to ~48%! Things are better at 800W - it's about 54%. As you get closer to its full rated power, the efficiency improves. Peak efficiency is at 1185 W out, which suggests that they did some serious work on optimising it for its rated output!