F4 power amplifier

Sorry, I should have more clearly stated that I have two monoblocks already, each with its own external power supply. I have a second ps in each chassis so that I can run four total channels if desired, but haven't been using that capacity. Once I decided not to run the extra channels (for biamping) I just pulled the fuse from the standard store power supply in each chassis... hence the extra, unused transformer.
 
Cal
Honestly not sure whether there is a lot to gain with 2 transformer per monoblock/1 per voltage rail setup you described, however there is a risk to call out

In case one of your transformers, or connection to your transfromets fail, you might have substantial DC in the output

Your speakers might not like it ;)
 
I think it's usually done when a transformer larger than 1kVA is required and 2 smaller transformers fit into the chassis easier than one huge monster.

I don't think it will really ad much improvement especially with a CRC supply connected. The amp is mostly seeing the output caps because of the resistors in between. There could be some improvement but not sure whether it will be that significant or even audible.
 
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Given that I have the parts just sitting there already loaded in the two PS chasses, any improvement at all is worth it as long as I'm not making any tradeoffs. The DC issue is real though. I actually already did the rewiring this morning because of tech issues at work that made my laptop unusable. I'll get back in there this afternoon and put both trannies on the same fuse to minimize the DC risk. Won't be able to listen until tonight...
 
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I think it's usually done when a transformer larger than 1kVA is required and 2 smaller transformers fit into the chassis easier than one huge monster.

^This is my situation. Although I was only considering 800VA

Cal
Honestly not sure whether there is a lot to gain with 2 transformer per monoblock/1 per voltage rail setup you described, however there is a risk to call out

In case one of your transformers, or connection to your transfromets fail, you might have substantial DC in the output

Your speakers might not like it ;)

^This makes me re-think some things.

Given that I have the parts just sitting there already loaded in the two PS chasses, any improvement at all is worth it as long as I'm not making any tradeoffs. The DC issue is real though.

^Agreed.

For balanced BA-3 monoblocks, I had planned on using 1 entire PSU per phase. Similar to Cal3713, I have everything already. 2x Dual mono BA-3s to be converted to a pair of balanced monoblocks. I haven't decided whether I will have balanced to SE be 'user switchable' on the BA-3 front end similar to some builds I've seen.

A difference is that I have 4 identical supplies from donuts through filtering. Is it wiser to use a donut per rail? In "balanced / mono mode" if I lose a donut, either one rail dies or one phase dies. In "SE / stereo mode" it seems that losing one channel is a better scenario than losing a rail to both channels. I could be missing other considerations.

I'm wondering If I should rethink the whole thing. If I move forward, DC protection is a much bigger consideration now.
 
Not very high IME. In 40 years of working with electronics I have seen few transformer failures. If properly designed and operated within their design specs, transformers are easily capable of running for 50 years trouble free.
The other parts of your power supply are much more likely to fail first.
My recommendation is to include speaker protection in your amplifiers. Unless you have DIY speakers and you know you can get replacement woofers at a cost you can afford, it is cheap insurance to include a protection circuit.