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Old 24th April 2013, 12:32 AM   #81
Junm is offline Junm  Philippines
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Can you post and share your pcb layout and updated schematics with the ccs you used. I planning to build another one since i have plenty of power mosfet to use...
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Old 16th May 2013, 08:49 PM   #82
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Did some THD measurements on the amplifier. Measurements were done with a juli@ soundcard the amplifier was loaded with 8ohms and a uni-t 61E was used to ascertain voltage levels.

Sorry no 60W measure as i ran out of attenuation range.
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Old 16th August 2013, 05:43 PM   #83
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Originally Posted by Junm View Post
Can you post and share your pcb layout and updated schematics with the ccs you used. I planning to build another one since i have plenty of power mosfet to use...
Ditto on the schematics and pcb layout. Do you have any boards left? Maybe there's enough interest for a group buy of boards and/or components?
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Old 20th April 2016, 03:02 PM   #84
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I strongly advice Replacing R1 with a current source for the input diff pair.

Its obvious now when you look at the schematic that the input diff pair cannot control the VAS when the voltage across R1 is less then half the supply voltage, due the resistive load R2 (sized to split the current equally in the diff pair at normal operation)

Simply put when the supply voltage bellow about half the supply voltage Q3 is turned off and R3 and R4 acts as pull up on the Q6 putting what is left in the reservoir caps across the speakers...
I'm sourcing transistors for my boards. Is there a recommended Hfe range to specify when purchasing the 2SA970's? How tightly should I request matching of each pair?
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Old 20th April 2016, 05:53 PM   #85
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They don't require much in the way of matching.

That doesn't keep people from going for tight matches anyway...

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Old 20th April 2016, 06:09 PM   #86
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They don't require much in the way of matching.

That doesn't keep people from going for tight matches anyway...

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