Steinchen
HeadWizerJoined: Oct. 12, 2005
Locale: Germany
Total Posts: 260 |  posted 01-01-2007 11:11 AM CST (US)   |  | 
concerning offset: I replaced the poorly matching J201 JFETS with J503 CRDs on one channel, but the dc offset at the output was still 30mV. Then I replaced the 2sk170/2sj74 with a very tightly matched quad match and the offset can now easily be set to below one mV. The IDSSs of the first set of trannies was 6.9mA / 7.2mA for the n-channels and 7.25mA / 7.4mA for the p-channels. Apparently that wasn't good enough, though within a 0.5mA range. Matching the input JFETS tighly is a basic requirement. J201 suck though  I've never come across JFETs grouping that awfully.Finally I got my β22 running and cased up, pictures are online at my gallery. So how does it sound ? Pretty darn good I must say. First thing that stands out is the clarity of the sound. Everything is tight, well defined and under control. I guess that's because of the very low distortion of the amp. I'd call the sound smooth yet lively. I'd say it's a little on the warm side, personally I find that very pleasing, particularly with older or flawed recordings. Nevertheless the amp delivers a lot of detail. Last but not least you easily feel the plethora of power this (ch)amp got and it drives the cans as confident as the Dynahi does. The β22 does not reach the remorseless titanic impact of the Dynahi, but it plays more cultured and analytical. (I think I better come to an end now since I start using prose). To cut a long story short, the β22 is a first class high end amp and a must build for every headamp maniac. |
