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Old 14th August 2006, 11:14 PM   #1
mgriff is offline mgriff  United States
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Default what size capacitors to use?

hi I have two 200 watt amps. I'm in the process of building a power supply for those amps. I allready have the toroidal transformer and the bridge rectifier. the amps need 50V+ and 50V- at about 3 amps max. the question is what size filter caps do I need. Any help would be appreciated!
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Old 15th August 2006, 12:11 AM   #2
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Default here is a start point

http://aussieamplifiers.com/other_prod.htm

Note the pictures and specs for these filter / bridge / capacitor boards ... These are generally used for pairs of ~400 to ~800 watt Class D amps, but the basics all work for just about any DC filtering concept.

(I got two of the above PSU-One units for two 400 watt class d amps ... so I would have "split" supplies and plenty of filtration = overkill, probably.)

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Old 15th August 2006, 01:04 AM   #3
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have you checked this person's web site. It has an excellent article on PS design, caps needed, etc.

http://www.sound.westhost.com/site-map.htm
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Old 15th August 2006, 02:46 AM   #4
mgriff is offline mgriff  United States
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thank you very much for the quick reply!
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Old 16th August 2006, 10:22 AM   #5
AndrewT is online now AndrewT  Scotland
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Hi,
try 2mF to 3mF per Apk of output current.

eg. 200W into 8ohms is 56Vpk into 8r giving a peak current of 7Apk. My recommendation is use at least 2mF/Apk giving +-14mF (14,000uF) per channel. Doing the same numbers for a 4ohm load (@56Vpk) requires >+-28mF/channel
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Old 16th August 2006, 10:58 AM   #6
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I would use a bridge+cap combo per amplifier to get better performance. I'm sure you will find 10000uF per rail fine for what I presume to be your 8 ohm load based on the current figure quoted. If you want to make it better double up on the caps, but try it before first and see what you think.
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Old 16th August 2006, 11:04 AM   #7
AndrewT is online now AndrewT  Scotland
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Hi Richie,
thanks for corroborating the per channel requirement. It is worthwhile.
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