12V 2A power supply

You'll likely need 'tone controls' to get the best out of ceiling speakers.

A decent power supply often costs much more than the amp itself. A 60 vA transformer alone will cost about 20 quid.

picturesque using 1920s technology. Perhaps a well polished breadboard with transformer, motor rectifier, output synchronisation meter driving a big open relay, and a few large LCs to clean up the output. Wire it all with bare square wire bent to square routes 1920s style, add a row of screw terminals and bare wire fuses, put an ebonite cover on the twisted pair mains connection and you're done.

You'd want to do it on black slate, mate, with polished brass screw terminals.

Id rather do it on a futon with a Polish screwed brass.

A CB benchtop power supply, as used to be dead common. 13.8V, 10A, for a tenner or twenty quid. Two quid down the boot sale, guv.

You could use a motorcycle battery and a cheap 12v supply as we did for CB and the first car radios for the home use. The battery will supply all the transient current you could want and the output would be stable.

But you can squeeze a bit more out of it if the psu doesn't sag. And since 12v4A regulated psus cost no more nowadays its worthwhile.

NT

That'll work, for sure. I'd only use that if the battery was really spare or end-of-life for car/bike use and if there was an available float charger to keep it up. Knowing someone in a workshop, where there are dud and semi-dud batteries available all the time, would be useful. In other words, I'd not spend money on buying a battery for the job.

As it happens, I'm buying a similar 100W mobile amp for workshop use and there will be an old 70Ah car battery, topped up with a Lidl float charger, under the bench, feeding it. If that battery eventually pegs out, I don't care all that much, and if the one from the van pegs out, ditto, because it's sitting idle and probably won't last much longer.

Interesting ideas but a 12V battery and a charger tend to go against the minimalist approach I am chasing. I am just looking for something a bit more stable than a wallwart.

Only difference is a regulated supply can only sag downwards. It doesn't magic up more current. That is down to the transformer rating and reservoir capacitor ratings. Of course if it's a SMPS, it will likely be regulated anyway.

Quite. Hence there being no need for regulation on a power amp PS. Over-current protection is a different matter.

I doubt you could fit a 12 volt 5 amp supply in a wall wart anyway.

Well, I also have a very expensive, ultra-stable bench power supply of

Thank you for ruining my evening ;-)

Wouldn't like to bet on it, taking the size of some of the linear wall warts here and the size you can get a 12V 5A SMPS's... B-)

Linear would be a problem I think.

Yeah but when it sags down there is less power available. Poor power supply regulation does affect the "sound" of an audio amp particularly when driven hard with decent bass.

A generously rated transformer and good reservoir capacitors improve the regulation of the PS.

Depends what you mean by regulation. A generous transformer and caps will simply let the voltage go higher when the amp is producing little power - assuming it's not a class A design. Which doesn't much matter. A regulated supply will hold the voltage constant. Which isn't needed.

Ah the Marshal 'Punch'

Wit a crappy cheap underspec transformer and some rather larger HT capacitors,. you could get another 50W out of it if you played the chords staccato..

Which with MOST music is pretty irrelevant. MOST music has short duration peaks. Hence 'music power' ratings. Just put in big capacitors.

Oh, don't worry; I doubt if they paid full list price for it. :)

Just to check - the amp is a TA2020 so which class is it?

No, regulated supplies are designed to have no sag within their ratings, no movement up or down.

It *will* be regulated.

A nonsequitor there. Regulation addresses loss of peak power due to rail sag, eliminates unnecessary amp heating and power waste, and for very small supplies excessive voltage at low load.

NT