The Mu Monster

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#122
heat

Nelson Pass said:
The maximum voltage times the maximum current rating are not the power
rating of the device.

Also, look at the Safe Operating Area curves of the device. You will usually
find that some of the very high wattage parts do not meet those figures at DC
values. Also, the figures must be derated against temperature, and you will
be anticipating lots of that - The heat sink will be hotter than the ambient,
the case will be hotter than the heat sink and the transistor junction will be
hotter than the case, all in proportion to the dissipated power and the
sum of the thermal resistances of all these heat paths.

How big a heat sink are you anticipating?

😎
Click to expand...

I was planning on .004 C/W but I may do better than that just in case, I can always make the sink temp what I want. I mean I will have 15KW worth of input out of the "plug"... And the usual plates are cheap but a "company" makes special ones, however I can say that there is some entity trying to make this not happen, probably the same one (s) who are rating these posts bad... I think blood pressure pillz are flowing in some others in this audio kingdoom...

So Honestly I wanted 300V rails, and now me thinks the outputs are borderline for my "dream"
Thank you,
Rob
 
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#123
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#127
images
I have too many things going on at once, thermal problems are easily solved, now I am working on re-inventing black powder for my 1851 pietta sherrif. Rewrite the world one day at a time..
Rob
 
#128
Spy's amongst us... Guaranteed.. Between what has happened with MFR'S and low ratings. Yep.. I could tell you stories, but I think it's best that the guy with the pen contacts me in privately, and I do not mean the writer of this post either...
Rob
 
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#129
AndrewT said:
The CCS that you have specified tells us that this is a single ended amplifier with a bias of 5A.
The maximum peak output is also the maximum ClassA output and is 5Apk.

The maximum power into 8ohms will be Ipk²R/2 = 5*5*8/2 = 100W
Click to expand...

Nelson Pass said:
If you are referring to the schematic in post #1, the nominal bias current
is 8 amps, and it will deliver twice that peak, as it is not a CCS.

This gives about 2KW peak into 8 ohms.

😎
Click to expand...
Audiosan in post10 said CCS, You replied to his comment in post11.
But did not point out the error in his statement.

I quoted Audiosan's post10 and corrected his error.

For a push pull output stage, i.e. not with the 14 CCS devices, the ClassA output current would be double the single ended and give 4 (four) times the power.
 
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#130
AudioSan said:
a more doable version could be: 14 IRFP240 gainstage Devices and 14 IRFP240 CCS devices @0.36A pr device for a total of around 5A bias and +/-85VDC rails. thats about 400W class A @8ohm. total consumtion of about 2KW for 2ch. still crazy amount of power.
Click to expand...
AndrewT said:
The CCS that you have specified tells us that this is a single ended amplifier with a bias of 5A.
The maximum peak output is also the maximum ClassA output and is 5Apk.

The maximum power into 8ohms will be Ipk²R/2 = 5*5*8/2 = 100W
Click to expand...

Nelson Pass said:
If you are referring to the schematic in post #1, the nominal bias current
is 8 amps, and it will deliver twice that peak, as it is not a CCS.

This gives about 2KW peak into 8 ohms.

😎
Click to expand...
Audiosan in post10 said CCS, You replied to his comment in post11.
But did not point out the error in his statement.

I quoted Audiosan's post10 and corrected his error.

For a push pull output stage, i.e. not with the 14 CCS devices, the ClassA output current would be double the single ended and give 4 (four) times the power.
 
#132
Yes, a push pull with 2times the ClassA output current compared to a single ended will give 4times the maximum ClassA power.

But that was not the problem, nor the disagreement.

Audiosan said his example was using 14 of his devices as CCS and stated 400W when it was actually only 100W. The 4times error that results from the difference between single ended biasing and push pull biasing.
 
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