Tweeter/Mid min amp power rating for 20.1 in active setup?

Nuforce

Well-Known Member
Jan 5, 2021
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Hi all,

I have a pair of mint 20.1s in light oak, and I'm currently running them active, using a DBX analogue balanced crossover.

I am currently using a class A plinius power amp for the tweeter/mid drivers and a pair of 600w Emotiva monoblocks for the bass drivers.

I'd like to replace the plinius with a pair of valve monoblocks, but I'm unsure what the minimum power rating should be? Ideally, I want to use 845 or 300B tubes, but it is tough finding anything above 40w.

Any thoughts?
 

Addicted to hifi

VIP/Donor
Sep 8, 2020
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Australia
Hi all,

I have a pair of mint 20.1s in light oak, and I'm currently running them active, using a DBX analogue balanced crossover.

I am currently using a class A plinius power amp for the tweeter/mid drivers and a pair of 600w Emotiva monoblocks for the bass drivers.

I'd like to replace the plinius with a pair of valve monoblocks, but I'm unsure what the minimum power rating should be? Ideally, I want to use 845 or 300B tubes, but it is tough finding anything above 40w.

Any thoughts?
What speakers are these?
 

DonH50

Member Sponsor & WBF Technical Expert
Jun 22, 2010
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Monument, CO
How much you need depends very much upon how loudly you listen and how far away you are. Check out something like the online _Peak SPL Calculator for an idea about how much power you might need.

My gut says 40 W is likely too little. I personally would give up the 845/300B plan in favor of a more conventional 6550/KT120-class amplifier with 100+ W. The mid/tweeter panels cover a very broad frequency range. I don't know the 20.1's bass crossover off-hand, but long ago the 20's crossover was very low, something like 150 or 200 Hz, so they covered a large frequency band and thus needed a fair amount of power. Not like a typical conventional design with a woofer crossover that might be a few hundred Hz or even higher, and with a much steeper roll-off.

While I loved my old ARC amp, these days I would be talking with Ralph at Atma-Sphere ( @Atmasphere ). Modern OTL designs with excellent specs for the class and reasonable (to very high) power levels. But there are a lot of good power amps these days.
 
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