Nuforce STA200

Purchased one in April of ’17, for shits and giggles. Sold many of my " expensive " amps, because after a few months of this little guy breaking in, it bettered many of them. My only negative issue, because of it’s high gain, I do get a small amount of hum from my 104 db sensitive speakers, which was bothersome at some point. Hum is at constant level, does not increase with volume. Have not even done my AVM mod to it yet ( which I do to almost everything ). An amazing amplifier.

NuForce uses a hybrid approach, very similar to Carver's idea, and << cough >> borrowed by Yamaha in the EEEngine design. Not sure if Yamaha ever licensed it or waited for patents to expire.

The voltage + and - rails are Class D, and they swing up and down. In between the rails is a Class A or A/B (not sure) linear amplifier.

It's quite clever. By keeping the voltage rails from deviating too much from each other, the power dissipation in between is always limited to a few watts compared to a linear power amp of the same output.

For instance, a 120 W amplifier might have +- 50 V rails. The amp between has to dissipate a lot of heat as a result of the 100V difference. But if the voltage between the two rails is kept small, say 30V, then the heat and size of the amplifier can be made much smaller, with much less wasted power.

Best,

E

@erik_squires My understanding about the STA 200, is, it is a conventional AB design, taken from a circuit developed by Goldmund, also used in the Job 225. But yes, Nuforce ( Nuprime ) does use designs in other models in which you speak of.

@mrdecibel

Then I stand corrected. :)

Erik

Ordered a pair of Goldenjacks 10 db attenuators. Will see if it reduces the hum, without affecting the sonics ( doubtful ). If this does not work, might need to go back to passive ( never liked ), change to a lower gain preamp, or a different amp ( although I do like the STA 200 ). I gave up on tubes a while ago.