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Old 27th January 2011, 09:19 PM   #581
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Woops they've got 42V ct (rated) actually so I checked again to see if it was 42 not 52 I measured and I got 48 hmm. The mains seems stable at 239-241.
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Old 28th January 2011, 04:19 PM   #582
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If its 42vaC between ends, thats nearly 59vdc, well below the 84v max.rating of the chips.
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Old 28th January 2011, 05:46 PM   #583
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the mains voltage varies a lot.
The difference between the unloaded secondary voltage and the fully loaded secondary voltage is the regulation.
For 80VA I'd expect >10%.
Your transformer is specified as 42Vac CT and you measured 48Vac @ unknown mains voltage error.

48/42 gives a regulation of 14.3%, That is not unreasonable if the test voltage actually equaled the rated mains voltage.

48Vac CT is equivalent to 24-0-24Vac. This should work well with 8ohm speaker and fairly warm with 6ohm speaker if you ensure sufficient cooling so that the chip never runs hotter than warm to the touch.
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Old 28th January 2011, 06:00 PM   #584
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Ok thanks guys I'll give it a go and see how it goes, can someone direct me to the currently recommended snubberized PSU design
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Old 28th January 2011, 06:13 PM   #585
AndrewT is offline AndrewT  Scotland
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I think the latest is version IV
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Old 31st January 2011, 10:43 AM   #586
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I think the latest is version IV
And where can I find a schematic of that version?
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Old 31st January 2011, 01:20 PM   #587
norture is offline norture  Indonesia
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Default Why not SMPS?

Why is it that many people prefer bulky transformers than using high-quality SMPS? It seems both are priced reasonably though.

And high quality SMPS IMHO will never let any high freq. noise from coming out of the amplifier. Add it with nice efficiency figures of more than 80% what do you guys say?
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Old 31st January 2011, 01:22 PM   #588
AndrewT is offline AndrewT  Scotland
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.......... high quality SMPS IMHO will never let any high freq. noise from coming out of the amplifier.........
are high quality SMPS fitted with a brick wall filter to remove all high frequency noise?
What happens if the load demands a fast transient current?
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Old 31st January 2011, 01:31 PM   #589
norture is offline norture  Indonesia
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Well, they switch at more than 150 kHz, and that is going through properly made LC filter there'll be hardly no noise at its output, right?

Any transient demands will be served nicely if we add a couple more caps at its output, right?
(just not as big as they are needed for LF power supply)
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Old 31st January 2011, 01:54 PM   #590
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Why is it that many people prefer bulky transformers than using high-quality SMPS? It seems both are priced reasonably though.
Because it's many times more work to build a good switching PSU than it is to use iron? Dunno about you, but I'm in this hobby to make stuff, not buy it off the shelf.
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