Miscellaneous Projects

This is my rendering of the Mini-A based on MikeW's PCB. The amp config is single-ended input, dual mono down to the power chord, biased to 1.5 amps. Its output is estimated to be about 17 to 20 watts. There is 72,000mF per rail; each channel has its own bank of supply caps. I did not use air-core coils for filtering. Noise is low, however, not audible from the listening position. I did not by-pass the filter caps yet. The transformers are EI type enclosed rated at 12.6 CT, 8 amps each. There is very little hum coming from them and they do not get warm to the touch. The rail voltage unloaded is 19v and 17v loaded. The circuit itself does not use any exotic parts. The resistors are Vishay-Dale and the caps are hi-temp bi-polars. Non-polarized caps are micas. The HexFets are matched IRF9610 for the input stage and CCS and IRF48n for the output and CCS. The output Fets get very hot to the touch. I can touch them for 1 second. The temp probe shows 60 degrees C for channel 2 and 72 degrees C after 15 minute on time. I need to look at this issue further. After a few hours of playing music, the heat sinks heat evenly and are very warm but not painful to the touch. The heat sinks are handmade. All pieces are milled aluminum. There are no saw cuts! The chassis is 6061 ¼" aluminum and 3/8" plexi-glass for the back panel. Listening: What can I say? It's a terrific little amp. Makes listening to music fun. Thank You! Thanks Nelson Pass for your great generosity! I've been following your designs since I found the Audio Review article on the 20w class A bi-polar design from'77-'78. Thank God for You! Karen- thanks for the chassis advice. Apparently, an aluminum and steel box design is not a problem in this amp. Thanks to everyone at Pass Labs! Thanks to Lou Di Nenna for milling out the heat sink parts and Paul Tashjian for fixing my cutting mistakes with your mill and for all the mechanical design ideas. John Inlow for the DIY heat sink idea. Grey Rollins for putting out your version of the Mini-A. MikeW for the boards and the troubleshooting advice and everyone at DIYAUDIO.COM!!! Thanks, Vince Di Nenna .(JavaScript must be enabled to view this email address)