I just tested two Meanwell RS-50-5 supplies with the pots turned all the way up into a 4 ohm load. One goes to 6.01 volts and the other goes to 5.07 volts.
I have been looking for a quality HV SMPS supply for some time to make a big (1 KW) tube amp. So far, the best solution I have found is thirteen 48 volt 3 amp supplies wired in series. I got them cheap on the surplus market. All of my DIY attempts at large SMPS devices have ended in fireworks or dead parts.
My big amp will use a few small 6.3 volt tubes. They will likely be driven by a small transformer or a DIY buck converter from the main heater supply which is 26 volts as I will be using 26 volt output tubes. They are currently powered with a Meanwell RS-150-24 which is turned up to 26 volts for a one channel test breadboard. It is likely not big enough to run both channels.
There are a lot of LED-driver SMPS which meet your requirements.
Most of them have a constant current output, though.
I don’t know how they behave when you don’t draw the specified output current.
https://www.digikey.de/en/products/filter/led-treiber/137
Most of them have a constant current output, though.
I don’t know how they behave when you don’t draw the specified output current.
https://www.digikey.de/en/products/filter/led-treiber/137
There are quite some 7.5V SMPS's which can tuned down a bit to fall within the 6.3V tolerances
Or it would be very easy to drop one volt as well.
Depending on your needs, but like the Meanwell EPS/RPS series
edit:
Putting two 3V or 3V3 supplies in series is also an option.
Or using a 12V supply (at 12V6) and putting the heaters in series.
There are 15V supplies that go up from 13.5V or so.
So in that case I would use a very simple low side constant current regulator (voltage drop of around 0.7-0.8V)
In that case the series heaters are protected against overloading as well.
Or it would be very easy to drop one volt as well.
Depending on your needs, but like the Meanwell EPS/RPS series
edit:
Putting two 3V or 3V3 supplies in series is also an option.
Or using a 12V supply (at 12V6) and putting the heaters in series.
There are 15V supplies that go up from 13.5V or so.
So in that case I would use a very simple low side constant current regulator (voltage drop of around 0.7-0.8V)
In that case the series heaters are protected against overloading as well.
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Usually, the SMPS will have a couple of resistors in series with the adjustment pot. Changing one of these a little should get you another 0.3-0.5v out of a 6V output. Treat the SMPS like a valve amp though.
That could also work, although some have an under voltage protection on board.
Also it could mess with the stability of the feedback loop (phase margins etc)
12V SMPS with series connected tubes. If you need to power a single tube, use a buck converter from 12V.
Any other solution will cost many times more.
Any other solution will cost many times more.
So you're willing to spend good money on a tube amplifier that you put a lot of time, effort, energy and money on, but than cheaping out on unreliable Chinese parts? That don't even pass any UL/CE test when it comes down to safety and emissions.
For companies like Meanwell or Recom the prices for lower voltage part is basically the same.
In general it's also not advisable to have less than 25% load on a SMPS, since many will go into hiccup/energy saving mode.
What is the suggested range of load for a general (not audio) SMPS? Between 25 and...75(?)%?
Is there any standard to define the maximum current allowed by the SMPS (EG when the voltage drops 5%)?
Thanks
I was thinking something similar when I was playing with the idea of building a PP UNSET with GU50 (I have many of them) for a instrument bass amp, but the idea to chase 1kV with 1A always scared me. I'm used to play with 500V in my amps with standard PSUs, but twice that scaries me.
The 25% is more a (very rough) rule of thumb.
The thing is, many go into some kind of energy saving mode/hiccup mode for light loads.
In my professional experience it's a bit hard to determine, therefor we use about 25% rule of thumb.
Which is probably on the higher safe side.
Any high quality SMPS can easily be used with 100% load with adequate cooling.
For the majority I was able to overload even up to around 110-115%.
However that's not officially supported by the manufacturer obviously.
Most of the time, this is also stated in the datasheet.
Several amplifiers working for years say they aren't unreliable. I just don't waste money on Meanwell because the specs are trash for the price compared to almost any ATX supply, and the the Meanwell is made in China, too.
Why even mention "Chinese" BTW?
Feel free to waste money though 🙂 Also, a good SMPS can work from 0 load to over 100%. Just don't buy a cheap POS.
It's been a LONG time since I had to load the 5V side of a computer PSU with a floppy drive to make it work...
Derate to 40-50% power when you run it at 75°C, too.
EDIT: They are 20$ now...
https://www.ebay.ca/itm/192554155666?
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