Some years ago , I lost my APT 1 power amp to a severe lightning strike in my apartment. Badly damaged: all output devices fried, most other transistors and some of the resistors as well. I made some inquiries about getting it repaired and trying to locate replacement blank or semi-stuffed PCBs but no luck, so in the corner it went. Did anyone take ownership of the stock of parts, etc. for APT when they went under? Usually, when a company goes belly-up, one of the designers takes the leftovers and at least offers servicing and updates, etc.
Anyways, I found the amp while doing some cleaning a short time ago and decided maybe over the coming holiday, I'd redo the inards myself. So, any good ideas or schematic suggestions from you folks? My caveats are:
1. I want to use the same chassis and not do (much if any) mechanical/metal work
2. The power supply appears to be fine, so I'd like to use it
3. The chassis houses moderate heatsinking for four TO-3 devices. I'd like to continue using that, so Class A is out of the question (I'm saving my "special" heat sinks for my Class A beast in the basement waiting for the "killer schematic" when I settle on it someday
4. I've got enough matched pairs of TO-3 package devices: Hitachi MOSFETs (2SK135/2SJ50) or Motorola Bipolar Transistors MJ21193/MJ21194 to use either as output devices. My last few design have been MOSFET based, so I'm tempted to try bipolar to be a little different this time.
5. There isn't enough space to force fit a pair of Leach Low TIM amp boards (At least I haven't figured out a way yet!). That was my first idea to get something good running quickly with minimal effort. I'm just looking for a quick project to whet my appetite over the coming Holidays - a couple of well deserved weeks off (I won't even have any honey-do list items!). I'm not looking for anything like the 1.5 years I spent building and tuning (aka crafting) my Servo 50.
Thanks in advance!
Michael
Anyways, I found the amp while doing some cleaning a short time ago and decided maybe over the coming holiday, I'd redo the inards myself. So, any good ideas or schematic suggestions from you folks? My caveats are:
1. I want to use the same chassis and not do (much if any) mechanical/metal work
2. The power supply appears to be fine, so I'd like to use it
3. The chassis houses moderate heatsinking for four TO-3 devices. I'd like to continue using that, so Class A is out of the question (I'm saving my "special" heat sinks for my Class A beast in the basement waiting for the "killer schematic" when I settle on it someday
4. I've got enough matched pairs of TO-3 package devices: Hitachi MOSFETs (2SK135/2SJ50) or Motorola Bipolar Transistors MJ21193/MJ21194 to use either as output devices. My last few design have been MOSFET based, so I'm tempted to try bipolar to be a little different this time.
5. There isn't enough space to force fit a pair of Leach Low TIM amp boards (At least I haven't figured out a way yet!). That was my first idea to get something good running quickly with minimal effort. I'm just looking for a quick project to whet my appetite over the coming Holidays - a couple of well deserved weeks off (I won't even have any honey-do list items!). I'm not looking for anything like the 1.5 years I spent building and tuning (aka crafting) my Servo 50.
Thanks in advance!
Michael