Mercury, a discrete current amplifier

[Aiace]

Hello you all,
I'm working at the project of the pictures. It's a current amplifier with no feedback able to provide 1W to 600 Ohm load with 0,04% of distortion. It can provide till 3W with 0,08%, so it can be used also for high impedance speaker like the famous Philips 9710.
The circuit is based on two part:

1. V-I converter
2. 6 time current multiplier

In other words, the amplification is due a mirroring of the the original signal and this allow to the circuit a very low distortion without feedback.

Comments and advice are welcome

 

[EUVL]

Take a look at this, and also the listening impressions.
Current Drive for Headphones & The Super Linear Transconductance Amplifier


Patrick

 

[Mark Tillotson]

R7 needs a capacitor across it to short out its thermal noise.

 

[Aiace]

Hello a few update:
1) As suggested by Mark added a capacitor across R7
2) replace the mosfet to IRFP9240 because it has less thermal resistance
3) increased R16 for better performance on distorsion, now estimated at 0,007%

 

[Aiace]

Circuit arrived.

 

[hagtech]

Zener diodes are generally noisy, but you don't have any filter capacitance on them.

 

[Aiace]

The circuit has been mounted and tested. Work fine with all load

 

[Aiace]

MercuryEngine is complete.
In the picture you can see it inside its 3d printed box. It's connected between the HTPC and the 800 ohm philips speakers.
I'm very happy about the result