I finally got all the parts and made my PCB's for my first amplifier project, the pass ZEN. It worked first time without anything going wrong whatsoever. I have a few people on the forum to thank for their help, namely vince and grey. I took greys advice and made the board both ZEN and ZEN revisited compatible so I can substitute values at any time without replacing the board (thanks for the tip). I am presently using the Infineon BUZ350 mosfets for both the CCS and gain stages but I am going to replace them with lower voltage devices (IRF150) in the gain stage to see if I can hear any difference, as lower voltage = less distortion (as is my understanding). I hope to put all of this stuff on a web site soon (-ie- components, PCB layout, findings etc.) but in the mean time I have some questions.
1) How hot is too hot for the heatsinks? The mosfets are rated at 175 deg C junction temperature. Without my pedestal fan pointing at the sinks they get hot very quickly and seem to stabilize after about 5-10 minutes so I can touch them for 2-3 seconds without burning myself. NB: I am using the lower powered original ZEN design at present.
2) I noticed the heat rejection from the CCS mosfet is much less than the gain stage mosfet, does anyone know roughly what the 2 different Power dissipations are for these. I need it for some rough calcs for my case that I am building. At present its a big mess mounted on a sheet of MDF on my lounge room floor.
Thanks once again for your help guys so far this has been a most rewarding project.
Dan
1) How hot is too hot for the heatsinks? The mosfets are rated at 175 deg C junction temperature. Without my pedestal fan pointing at the sinks they get hot very quickly and seem to stabilize after about 5-10 minutes so I can touch them for 2-3 seconds without burning myself. NB: I am using the lower powered original ZEN design at present.
2) I noticed the heat rejection from the CCS mosfet is much less than the gain stage mosfet, does anyone know roughly what the 2 different Power dissipations are for these. I need it for some rough calcs for my case that I am building. At present its a big mess mounted on a sheet of MDF on my lounge room floor.
Thanks once again for your help guys so far this has been a most rewarding project.
Dan