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Old 28th October 2013, 08:55 PM   #1441
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switcher is probably weakest one you can use

choke - think big - just one winding , iron core

didn't check but I think at least 30mH per channel PSU

those you linked are for different purpose
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Old 28th October 2013, 09:24 PM   #1442
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30mH?! That will be big and expensive!
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Old 28th October 2013, 09:37 PM   #1443
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name of the game ..... putuporshutup!



make it as good as you can pay ...... and enjoy

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Old 28th October 2013, 09:43 PM   #1444
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Got it :-). Just making more of a toy for computer than a serious amp, that's why I am so ... What is the word... cheap :-)
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Old 28th October 2013, 09:48 PM   #1445
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I'm always ......... cheap :-)
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Old 28th October 2013, 10:03 PM   #1446
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Cheap switching and C-R-C? :-)
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Old 28th October 2013, 10:21 PM   #1447
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Some switchers won't like the big capacitive load, they'll act like the output is shorted and shut off. They may eventually run if the caps can get charged up. You'll just have to try it, but it might kill the supply.
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Old 28th October 2013, 10:33 PM   #1448
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what with Zen Art.3 regulated psu.

I`ve done it this way.

22000F - regulator - 22000F for me that worked fine

not the cheapest but regulated
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Old 31st October 2013, 02:00 PM   #1449
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Default val

Quote:
Originally Posted by Loudthud View Post
It looks like all the transistors are functioning correctly. The problem must be that one or more of R1, R2, R3, R4 are not the correct value, or current is flowing through C1 to the speaker.

The voltage from the Drain of Q1 to the plus side of C1 should be 0.366V and 0.253V from the plus side of C1 to the Source of Q2. A low voltage on one side points to which side has too low a resistance. If the sum of the voltages is not 0.62V, some current is flowing in C1 or somewhere else.

With no signal, the DC voltage at the speaker (-Out on the schematic) should be very close to zero volts. Verify that the polarity of the capacitor is correct. I made a mistake on one of my builds. I connected the +Out to +19V instead of ground.

Note that it's a good idea to mount transistors low on the heatsink for best cooling efficiency. The top of a heat sink is usually several degrees warmer. I suggest about 1/3 the length from the bottom.
hi
these values ​​are valid for P.S. 13 volts and 4 ohms loudspekers?
thanks
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Old 31st October 2013, 04:51 PM   #1450
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I experimented with the ACA on the bench with a 13.3V rail and a 4 ohm load. There was a raise in distortion at 1 Watt. The cure for that was to increase the idle current in Q1 and Q2. What I did was solder and additional 0.47 ohm resistor in parallel R1, R2 and an additional 0.68 ohm resistor in parallel with R3, R4. That moved the distortion curve down near the stock ACA with a 19V rail and an 8 ohm load.

Adjusting the pot affects the distortion. With a 13V rail, about 7V will give the most headroom. I posted a graph somewhere in this thread for different ouput voltages with a 19V rail.
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