Single power supply for two amps

[oldjack]

I need to build power supplies for three amps already fitted into a single case but there is not enough room for three separate transformers. The largest amp (2x60w) requires +/- 40V for which I would fit a separate transformer/rectifier.
I know that a single transformer should not be used for the two smaller amps (2x30w each) but could I use a single transformer with each amp having a regulated power supply.
+/- 30V is needed for these amps.
The case is quite substantial and was originally built for the amps, prefilter and controls with the intention of having a separate case for the power supplies and I do not want to build another case.

 

[JonSnell Electronic]

As long as there is sufficient decoupling on the DC supply lines and the ground point is not compromised for earth loops, it should be fine.

 

[wwenze]

Why not? Active speakers have a single transformer powering two channels, studio monitors have two amps for the same channel, and AVR has 6 or more channels

Screwups are the exceptions, not the norm, and for most people with sufficient design experience things usually work without much extra thoughts; that's why screwups happen because nobody really knows what are the exact precautions to guarantee a no screw up due to sometimes they happen and other times not providing no correlation for future learnings.

 

[DF96]

No problem with running two amps off one supply. Just make sure you get the grounding right. Where people usually go wrong is in trying to half-split the supply so they think they are going to have two different PSUs fed from the same secondary; then they discover that two things can't be both joined and separate.

 

[AndrewT]

You could order a custom wound transformer.
a.) two secondaries to each amplifier. Requiring 6 secondaries for the three amplifiers.
or
b.) two secondaries to each different supply voltage. Requiring 4 secondaries, two to the big amp and two shared between the two 30W amps.

 

[oldjack]

Thats good, I will carry on with my pcb layouts, just hope the case weight is not too much with the amps and transformers.

Thanks everyone