The diyAudio Firstwatt F6

speaking of mica - it's still easiest to buy T03 ones

I'm routinely using them for T0247 (when I'm short of these) , punching hole and cutting around with scissorrrrrrs

Zen Mod
What a great idea! I have tried using TO3 micas but couldn't figure out a good way to make it work. Would you be able to describe a little more or sketch a simple diagram of what you do?
How do you punch hole? Thanks
 
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What's your choice for resistors for FW amps?

I went for Vishay RN65 (for 1/4W) and CPF (for 3W), with lowest % tolerance and thermal coefficient that were in stock.
I just use Vishay CMF55 25ppm resistors. I have used Vishay Z Foil resistors in the past but when you're building a stack of amps they are way too expensive.
For power resistors I have used 3W Panasonic Metal Oxide Film and Mills wire wound. For high current feedback I use Vishay CPF 3W. I also have 5W Futaba resistors (but not yet used) and in the order I purchased some Vishay BC components metal film resistors instead of Panasonic this time around.
 
I just use Vishay CMF55 25ppm resistors. I have used Vishay Z Foil resistors in the past but when you're building a stack of amps they are way too expensive.
For power resistors I have used 3W Panasonic Metal Oxide Film and Mills wire wound. For high current feedback I use Vishay CPF 3W. I also have 5W Futaba resistors (but not yet used) and in the order I purchased some Vishay BC components metal film resistors instead of Panasonic this time around.


What do you use for the trimpots? I have been using Bourns but they seem very difficult to adjust when the amp is hot.

Nash
 
What do you use for the trimpots? I have been using Bourns but they seem very difficult to adjust when the amp is hot.

Nash
I have used 25 turn pots in the past and single turn pots. Single turn is not enough for my liking. I have now purchased 4 turn bourns pots.
If you select the diode appropriately then everything becomes much easier.
Part of the problem is also due to the temperature coefficient of the devices. Best to set for 0.7A let the heatsinks stabilise in temperature then start fine tuning. It could take 30 minutes for the heatsinks to reach thermal equilibrium.
 
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Don't know if I am too anal about this stuff, but started measuring and selecting all components.

20150929_215108.jpg
 
Nice meter! In the distant past I could look at a carbon comp 5 percent tolerance resistor and knew them by sight . The extra band on modern resistors really caused me a problem . If I have time I measure all resistors for a project to make sure I don't get values mixed up.
 
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