FET Audio | Hi-End Audio & Electronics DIY Electronics & Repair

This is a clone kit from China.  It is a class AB amp and the clone is only for the power amp part.  The measured result shows a very good design amplifier!

1. Gain: 18x
2. Supply Voltage +/-50V; with 36V x 2 AC transformer
3. Distortion at 1W 8.2ohm: 0.0044% 30kBW
4. Current drain at idle: 160/153mA.
5. Current drain at 1W output: 260/253mA
6. Op-amp: 4.5mA
7. 470 ohm resistor: 1.75mA
8. 33 ohm resistor: 24mA
9. Output offset: 0.8mV
10. Current diode is 2mA 100V, metal can

[Show as slideshow]

1W 8 ohm fft with hp ps

50W 8 ohm fft with 500va

MBL distortion vs input level

Related Images:

This is a photo type for a Ipod amplifier.  It use 6DJ8 with supply at about +44V as input buffer and then drive a LM1876 IC power amplifier.

[Show as slideshow]

Circuit

Related Images:

This is another Borbely Erno design op-amp using all jfets.  This is the most complicated one with high gain and thus a servo is required to maintain the output at near 0Vdc.  I have tried this op-amp but I have not make it up to the best sound.  As of 2009, I think the all jfet buffer line amp sound the best.

[Show as slideshow]

All Jfet op-amp Circuit

Related Images: