Rerurn to Romy the Cat's Site

The greatest thing that happened to my Yamaha B2 amp was the fact that I got rid of my MiniMe ported bass section. The MiniMe is truly nice now and I operate in the highly desirable not annoying status. That all made me to pay more attention to what Yamaha B2 does. 

It had to say what Yamaha B2 does – it sounds in the way how it sounds as I have absolutely no problem with it sound.  It has no annoying SS character and it sound very soft and lash, though the fact the I own the tweeter that B2 driver might have a lot of to do with this fact. I put in the B2’s input a 24 step-attenuator with 250K impedance to fight the huge B2’s gain. All together it turned out to be a nice amp. It has a great protection circuit that does work VERY well and it’s outputs are perfectly shortable – I do not like when they are not.

I did play with Yamaha B2’s bias. The service manual insists 40mA. Still I asked me what would be the right bias for my specific load. My fist sentiment was to get max power to my specific speaker. The amp has much more power then I even need for my room. They I decided to go not for power but for LF character at high volume.  Experimenting with bias I feel that the amp sound more polite with much higher bias. I do not know why – I presume that the amp is running at higher power before it switched to class B – I did not measure it. Still, juts purely by listening I end up with 120mA bias – 3 times higher than it was designed for.

Now my B2 runs quite hot, that is not end of the world for winter. I decided to not risk the B2’s unique V-FET transistors and put the forced cooling in the game. I put atop of B2 two of my favorite Antec 200mm "Big Boy" fans. I am huge fun of the Big Boy fan. It is large 7.8 inch, thin, DC, low spin that at low voltage is absolutely silent with very food air flow. Even at higher spin it has very pleasant LF harmonics. So, I put two of them above each transistor heat sink and powered from a high resolution thermosensor . After the calibration of the thermosensor it begins to work very well. The amp starts and run for 10 munutes with no fans spinning. Then the fans very slowly to pick up rotation and at 65 degree Celsius the funs run at ~200RPM with no sound of any kind. The temperature is stabilized with surprising stability. I took 8R power resistor and drove the amp for a half hour at fill power. The fun spins faster but still far from it max 800RPM speed. Very cool.

Rerurn to Romy the Cat's Site