rectifier help please

[gary h]

hi all,

perhaps someone would double check my thinking on this:

I'm building 8 of PD's chip amps for an active crossover. I have 3 transformers. 2 smaller ones (120VA) have dual primary and secondary and fit well with the rec board. I'll use these for the tweeter and mid pairs.

I also have a 400VA transformer for the 4 bass drivers which each get their own chipamp. The transformer has 6 pairs of primary windings (100-10-10) to make dual 120 primaries, but it has a single pair of 10 gauge secondary wires supplying +/- 21V.

My question is: Should I divide the secondary into dual leads to use with the dual secondary rec board? I think I remember reading PD advising against this but I'm not sure. Will just 4 MUR860s be plenty enough to rectify a theoretical peak of almost 20 Amps? (the data sheet claims 8 A average current, 16 A with repeating load, and 100 peak/ each.) If splitting the secondary is advised, would this require some sort of RC divider?

Thanks for the help,

gary

[AndrewT]

A single secondary on the 400VA transformer can only give a dual polarity supply if each polarity is half wave rectified.
Don't do this for a power amp.
Buy the proper dual secondary transformer.

[gary h]

Thanks Andrew.

I'd like to understand this better, is this because a halfwave rectification requires a lot more filtering? What does this do to the transformer?

I'll order the new transformers. Anyone need a 25 lb donut shaped paperweight?

gary