SC200 Amplifier Module

[Ian Finch]

Hi everyone,
The power rails are +/- 63 v . Will this be okay ? I dont think 3-8v will make much of a difference.... The AC transformers provide 44-0-44 VAC

I would not say okay, just a conditional maybe, depending on how good your systems is otherwise and how you use it.

When you exceed recommended supply ratings, you need to be very careful to avoid overload events, even very short ones, by not using speakers or combinations of speakers that sum to less in this case, than 6R actual impedance at the frequency range of interest. The transformer's VA rating also determines regulation (how much the rails drop under load) which can actively increase the safety factor if the basic design is competent, and any alterations you plan on are calculated and known rather than assumptions or guesstimations.

It isn't nominal, continuous power ratings that matter so much here. It's the - actual, momentary signal peaks that could be clipping with nasty peaks, causing multiple "second breakdown" events which will accumulate and eventually destroy the output transistors, if not the drivers too. The higher the rail voltage at full power, the worse the accumulated damage.

On the other hand, if you only need an amplifier for home use, it's unlikely you will ever need even a fraction of the 200W/channel available. Even 5-10W maximum power can be too loud for your neighbours. With care and a very fast (see Output Relays thread or Bonsai's Hifisonix website) protection circuit, you may well be comprehensively safe from expensive problems with a powerful amp as SC200.

 

[raviradh]

Thanks Ian so much for your wonderful advice. I am all the more convinced that I should build this amp now. Its the Altronics kit board. I think I will take your suggestion and build a whole new amp. It is mainly for home as for professional use I have other powered PA speakers and passives fired by Crown mid range amps.
15 years ago I built the Playmaster amp from Jaycar and it was a great kit and sold on eBay for a reasonable price.

I think this time I will source the transformer [40-0-40] and build a multi capacitor power board as some suggest. Get a good enclosure from ali express and plenty of heat sink.

And I agree Ian on the output protection module.

By the way is there any special care to build and tune up? On this kit?

Also welcome any suggestions for the VA rating which i assume 500 VA will be enough to feed both channels