LM3875 Voltage

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Puffin said:
am just concerned that any over voltage could mean that if the chip reacts, blows up etc, that it will take my speakers with it ?!
This is my main concern. No one has commented ?
I would say, every electronic part is destroyable, either by over-intensity or by overvoltage with different effects.

In the case of the LM3875, due to the internal complexity... perhaps the manufacturer has made some destructive tests and knows what happens, but not the DIY guys…

So, your LM3875 may burn or explode… or not. And can destroy your driver… or not, nobody knows, that's is just a bet !

And I agree you might just have to live dangerously, like Achilles with its heel :)
 
Puffin said:
I have run the amps for many hours, but I suppose that is no guarantee that they might not self-destruct in time
"Many" hours is not enough to determine if it's going to last. What happens if you have a short surge on your mains? The margin for this is almost zero. High voltage can come after 6 months, or one year or never, who knows?
 
I changed the trannys to 25v secondary's to see what difference this would make. The heatsinks are by no means large, but I could barely feel any warmth from them at all. This was after 3 hours running.

I think I will live dangerously and keep 30v trannys going.
 
I think the 30v tranny gives it an "edge". Maybe living life on the edge is what I like ?!

I seem to remember that over the years there have been many manufacturers of various items that have preformed spectaluarly, cars etc but have ultimately been unreliable, Hi Fi amps included.

I do not think that running the amp with 45v per rail is neccessarily "dangerous" as someone else posted, NS must have built in some leeway with the specs to account for fluctuations in voltage.
 
What is edge really? Edge to the expense of blowing your speaker and getting 1-2 dB higher output IF you can manage the cooling issue and a hotter chip.

If I had a choice to use a more safe supply voltage I should choose so. Why? I'm an electronic designer as profession and I see reliability as a very important thing and I would never choose to do something that could jeopardize this.
 
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Puffin said:
I do not think that running the amp with 45v per rail is neccessarily "dangerous" as someone else posted, NS must have built in some leeway with the specs to account for fluctuations in voltage.

NS does not "build leeway" into the specifications of the device! You must account for voltage, temperature, etc. variation in your design. That is not their responsibility...
 
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