27K/16 is traditional. My schematic is "custom" and based upon experimentation, taste,and record of my JTM45 build. The lower the NFB resistor the greater the negative feedback which, in turn, lowers distortion and increases frequency response at the expense of reducing gain. For me, 27K was too much feedback and felt like the amp opened up with less NFB. But start with the traditional NFB and work from there if you desire.This schematic is great but I have one question that perhaps someone can clarify. As I follow the Metroamp instructions/schematic it shows the 27K NFB resistor is connected to the 16 ohm tap of the impedance switch. However, the posted schematic shows the NFB resistor connected to the 8 ohm tap on the impedance switch. Which way is correct??
Here's a MetroAmp build schematic. I used it as a starting point for my amp. The schematic is for my records and MetroAmp is not affiliated with the contents or correctness. So don't blame George for any errors. Scott
http://www.keepandshare.com/doc/1782399 ... 8-66k?da=y