Power MOSFET heatsink

[NE WAY]

For mounting of power MOSFET on heatsink of Aleph 5 clone on 2 separate heatsink, is there any preference to:

1) mount Q6 - Q8 on a heat sink, and Q18 - Q20 on another heat sink; or

2) mount Q6, Q7, Q18, Q19 on one heatsink, and the rest on the other.

I am asking this from the point of thermal consistency, and if there are other considerations such as interference etc.

Thank you

 

[Zen Mod]

find pictures of original Alephs and draw your own conclusions
in short, all matched ones are always thermally together
in this case, triplets on same rail

 

[Ultima Thule]

@NE WAY If you have 2 heatsinks, then mount Q6-8 together on one heatsink, do never separate them, the type of FETs used here have a positive temperature coefficient and need to track each other thermally in order to minimize thermal runaway in any each device.

Don't separate Q18-20 either, same reason as above.

However, these two FET groups (upper half vs lower half) don't need to be thermally (physically) closely connected to each other as there is no individual thermal runaway mechanism in play here, but rather dependent on the whole circuit and its bias adjustment capability.

That's a general rule for in principle all amplifiers using output gain devices with positive temp-co.

 

[NE WAY]

find pictures of original Alephs and draw your own conclusions
in short, all matched ones are always thermally together
in this case, triplets on same rail

Thank you 🙏 Yes I saw how they are mounted together but I wanted to be sure.