So, my F5 is built and working beautifully!
The amp is velvety silent and sounds great!
One thing that concerns me - everything is a lovely cool temperature, except the heat-sinks of course, which I can touch for an indefinite time, and even the mosfets I can touch for as long as I like, BUT, the bias resistors, the 3W 0.47R Panasonics, raised off the board to aid cooling, are as hot as hell to the touch. Is this normal?
The amp is velvety silent and sounds great!
One thing that concerns me - everything is a lovely cool temperature, except the heat-sinks of course, which I can touch for an indefinite time, and even the mosfets I can touch for as long as I like, BUT, the bias resistors, the 3W 0.47R Panasonics, raised off the board to aid cooling, are as hot as hell to the touch. Is this normal?
My rectifiers are perfectly luke warm. I am using ST BYW99W200 diodes - well over rated and superb specs. Recommended, if you need to upgrade! Nelson Pass likes them too, so you'd be in good company.
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Yes indeed, you do need sinks - direct connection to 3mm aluminium casing is sufficient, but mica washers and goop required if you do down that road. Big Chief individual sinks are also good, and have intrinsic electrical isolation (unless they touch each other). Are those MUR 820 diodes? Are they under-rated? Are those resistors 3w or greater? They aren't the recommended Panasonic metal film ones, but maybe that's not important. I find that soldering them away from the PCB helps cooling potential considerably.
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O.K., I'll put some on. I'm using Fairchild Stealth. Should those mentioned above be considered an upgrade?
Fairchild Stealth are super-fast. I use them in my DAC. 8A ones should be plenty. It's just that my rectifier diodes, on 3mm aluminium casing, are 42 degrees celcius, barely warmer than me. I guess it's just a case of heat-sinking, but also package size (so to speak - I'm not suggesting I've got a bigger package than you, but...yeah
).
That will be very good in a "sandwich" setup. Nice job!
Four holes should do it! that way each diode is bolted to both sinks.
Great idea for the next PS I build from scratch. . The two I completed will have these, now that I've become informed.
Unfortunately the holes are offset on the PD board
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Hello
I'm a newbie here can any one help me what is the first step to build this amp. and how much is the cost of parts.
THANKS AND MORE POWER!
Here's a good start
http://www.diyaudio.com/forums/pass-labs/188691-illustrated-guide-building-f5.html