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Wombat2 2nd September 2005 08:27 AM

Is it big enough?
I'm building a tri-amp 5.1 surround system. I'm using ESP P03A for the 12" woofers,(except centre) LM3876 for the mids and LM4752 for the tweeters. ie 4X 60W and 6 x 50W at +/- 35V (the LM4752 run on a single rail 24v supply for which I already have a 3A regulated PSU)

Would a single 600VA toriod be big enough for the 35volt supply? I'm thinking of running a snubberised regulated supply for the LM3876s and and unregulated for the bigger amps. If I split the tranfo I could go for a 42 v supply and get 100w out of the P03As :cool:

David L

rinox 2nd September 2005 09:45 PM

In my opinion the best is to use at lest two transformer, one dedicated for the bass and the other for the mid-high.... they will cost less then a single trasfo and the results will be better.

AndrewT 3rd September 2005 09:35 AM

42Vac will give a lot more than 100W into 8r. 35Vac should achieve 100W.
Your 600VA transformer will be undersized for 6 * 50W + 4 * 60W.
the rail voltage will sag badly on peaks and make the sound quality suffer. This will be particularly revelevant on long bass notes.
I would recommend a minimum of 2 by 500VA for your loading and further if you can find them cheaply then use a pair of secondaries for each channel. More easily achieved, a pair of secondaries for the bass and the other pair for mid and treble. Then have separate rectifiers for every channel with their own smoothing and snubbers.

richie00boy 3rd September 2005 10:21 AM

He means 42 V DC :) On the 35 V supply, your output power is 540 W, so a 600 VA transformer would be a bit undersized for continuous duty. Class-b amps typically demand VA = 2x amp power for continuous duty.

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