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Old 21st July 2012, 10:25 AM   #191
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Jay View Post
19V single ended for 5W...
ahh
been looking at this regulated power supply, not knowing what to do with it
a friend dropped it on my doorstep
0-24V, 10A
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Old 21st July 2012, 10:38 AM   #192
tinitus is offline tinitus  Europe
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14db gain, 5watt me think compression driver
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Old 21st July 2012, 11:59 AM   #193
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Thanks Mr. Pass for the explanation and the rigorous and exact calculations. Mine was very simplistic [Ohm's Law]. I can't even say what's a couple of unaccounted Ohms among DIYers? A lot in this power application.
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Old 21st July 2012, 02:38 PM   #194
LBHajdu is offline LBHajdu  United States
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Woow it seems like finding the output Imp. is pretty complicated.
Steps
1)find the transconductance at your biased current
2) calculate your theoretical expected open loop gain
3) measure actual open loop gain
4) calculate missing gain and equivalent resistance end then output impedance
5) calculate for correction of feedback
The amp camp amp is working already, I'm learning something new.
Thank you Mr. Pass
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Old 21st July 2012, 03:02 PM   #195
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Quote:
Originally Posted by LBHajdu View Post
Woow it seems like finding the output Imp. is pretty complicated.
Steps
1)find the transconductance at your biased current
2) calculate your theoretical expected open loop gain
3) measure actual open loop gain
4) calculate missing gain and equivalent resistance end then output impedance
5) calculate for correction of feedback
The amp camp amp is working already, I'm learning something new.
Thank you Mr. Pass
If I may add to the above in the abscence of loop feedback. The Resistance of the gain MOSFET = 9.5 V divided by 1 Amp = 9.5 Ohms. The upper MOSFET [mu follower] is a constant current source of very high impedance; i.e. >>>10 Ohms. After all, we all believe [and grew up with the concept] that a CCS defies Ohm's law; but appears to be intrinsically very high resistance. It does not count here relative to 9.5 Ohms. So, looking in the output node, two resistive paths are evident in parallel: 9.5 Ohms//may be 1000 Ohms for example [ignore it]. One is left with 9.5 Ohms or 10 Ohms [1 significant figure]; like the calculated result of Mr. Pass.
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Old 21st July 2012, 04:51 PM   #196
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The mu follower has a relatively high DC impedance, but it is an active
component with an AC negative resistance. It contributes to raising the
apparent output impedance of the amplifier.

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Old 21st July 2012, 05:06 PM   #197
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Thanks again Mr. Pass for your explanation.
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Old 21st July 2012, 08:56 PM   #198
Variac is offline Variac  United States
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Well this does point out that the amps are so small and cheap that multi-amping might be a great strategy. Especially with active or passive crossovers at the amp inputs- the amp only "sees" the one driver.

Its looking like a classic... thinking of some crazy idea? Make a couple of ACA's and try it out!
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Originally Posted by tinitus View Post
14db gain, 5watt me think compression driver

Last edited by Variac; 21st July 2012 at 09:45 PM.
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Old 21st July 2012, 09:10 PM   #199
tinitus is offline tinitus  Europe
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Originally Posted by Variac View Post
Its looking like a classic... thinking of some crazy idea? Make a couple of ACA's and try it out!
also have some 'smaller' heatsinks

ehh, schematic shows + output at ground
I suppose it means phase inverting output
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Old 21st July 2012, 09:36 PM   #200
Variac is offline Variac  United States
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inverting, true. But was easily fixed as you mention..
And its cheap also because of the smaller required heatsinks. Most of us have some the appropriate size sitting around.
Although the power supplies are really a bargain!

Last edited by Variac; 21st July 2012 at 09:46 PM.
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