F5 power amplifier

[udailey]

I imagine that it could also be a function of heatsink efficiency. So when we bias up we get 'better' sound. So is this because the mosfet sounds better at a certain temp or is it because of the bias point. Maybe you bias it up to 2amps and it sounds great but is that because of the temp of the device or the current? Can we tune a heatsink to get better sound rather than biasing a mosfet to the point of destruction?
Uriah

[Magura]

Nope, it's because of the current. No free lunch there.


I just have the luxury of loads of hefty heatsinks available, hence the tests and results.


Magura

[Renron]

Originally posted by Magura

Till they go bang that is.
Magura

--------------> Then back off a little


Ron

[udailey]

Not to be argumentative, I certainly appreciate the conversation. It just isnt working out with what I have heard yet. See TeaBag brought his F5 over and it took about an hour, little less, to sound good. So to me that meant that the heatsink had to get to certain temp. Following that logic I figured that the mosfet sounds best at a certain temp or at least above a certain temp.
Whats happening here?
Uriah

[Magura]

Originally posted by udailey
Not to be argumentative, I certainly appreciate the conversation. It just isnt working out with what I have heard yet. See TeaBag brought his F5 over and it took about an hour, little less, to sound good. So to me that meant that the heatsink had to get to certain temp. Following that logic I figured that the mosfet sounds best at a certain temp or at least above a certain temp.
Whats happening here?
Uriah

What you see there, is most likely that everything settles in the right parameters, which in the first place had been adjusted at full working temperature.

If you measure the circuit when it's cold, many measurements would be off target.


Magura

EDIT: BTW that's not being argumentative, I call that curiosity

[Magura]

Originally posted by Renron



--------------> Then back off a little


Ron

Almost

Back off a little, till it takes a while for them to go bang


Magura

[Peter Daniel]

Originally posted by udailey
See TeaBag brought his F5 over and it took about an hour, little less, to sound good. So to me that meant that the heatsink had to get to certain temp. Following that logic I figured that the mosfet sounds best at a certain temp or at least above a certain temp.
Whats happening here?
Uriah

I wouldn't be coming to such conclusion yet. There are many other low power circuits, that do not feature mosfets or need heatsinks, yet they are also claimed to sound better after an hour or so of warm up.

[tinitus]

Someone said that the high temperature will lower impedance
But where I dont know

Another one claimed that classA works better with power supply with a bit higher resistance

Both very professional people

[Nelson Pass]

Originally posted by Magura
What you see there, is most likely that everything settles in the right parameters, which in the first place had been adjusted at full working temperature.

If you measure the circuit when it's cold, many measurements would be off target.

That's pretty much the case. Almost always the bias goes up with
temperature and the performance improves over an hour or so.

[udailey]

Just got back from a swim with my daughter.
Thanks for all the answers guys. I really appreciate it.
Uriah