solar inverter and tube amps

[R.G.]

I did a series of articles for Premier Guitar, a couple of which were on powering musical gear from generators. I think they're still available on the PG website.

Grounding and waveform purity are issues. Also DC offset, which does happen. But there's nothing inherently wrong with running an amp from an inverter if you're OK with the details.

The details are often that you get a lower DC output voltage. Motors and light bulbs respond to the RMS value of the input waveform, so stepped sine and even simple square wave inverters work them well enough. Electronic power supplies use diodes and caps to produce DC equal to the peak of the input voltage. This is nearly always smaller than the peak of the actual equivalent RMS sine wave.

The extra hash harmonics in the not-a-sine-but-plays-one-on-TV from the inverter go mostly to heating, singing and possibly to re-radiation.

Power supply filters and "conditioners" can help to the extent that they round off the corners some, but can't help much with the peak voltage issue.

The deluxe answer is a ferroresonant "constant voltage" transformer. These use a big transformer and a BIG capacitor to make a resonant filter on the AC line wave being sent in. The harmonic-neutralized ones will output a real sine wave from the hash sent in at mostly the right frequency. I highly recommend them for questionable power situations, although you're probably OK from a sine-ish output inverter.

[Aurora]

Can't see why this should not work.... In field operations, I've been running all sorts of strange electronics with modern PSUs on anything from very cheap generators to very advanced ones. We had a cheap 700W generator running a typical picture tube TV for our montain cabin for 15 years, until my brother took over the cabin, without any problems at all. There may be something in the peak sine vs RMV values, but today there's a myriad of DC-AC inverters claiming "True Sine" output, and then that probelm should be done with, too........ I would keep away from the very cheap inverters, though.......

EDIT: on designing an amp from scratch, to go off grid, a DC -HT converter would be the optimum design, -- IMO...

[Andy Le Blanc]

appreciate the responses, Ive run sound on generator etc.. and theres a fellow in state running shows from a RV with a solar array... but ive
noticed PS issues with our computers, IE which computer PS likes which inverter.
I believe that there is quality issue as well as a capacity issue.
I think also that a tube rig should be good on stepped wave if the current is available.

just hadn't tried it yet, I might hold off a bit until I'm absolutely positive that I have a unit that will handle the current/voltage requirement under a load.