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Old 21st October 2009, 03:04 PM   #1
opor is offline opor  Thailand
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Question UcD need help for more gain

Hello,
I am quite new in class D. I have build my first class D amp base on Ucd. Sound is great. But seem that it give less sound level compare to other class AB . Please look into my schematic .Have I done somthing wrong? How to get more gain from this amp?

BR
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Old 21st October 2009, 03:26 PM   #2
opor is offline opor  Thailand
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Sorry ,
Here is my schematic.
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File Type: pdf classd.pdf (122.3 KB, 166 views)
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Old 21st October 2009, 04:45 PM   #3
Pafi is offline Pafi  Hungary
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Gain is approximately (R36/R101+1) * R35/(R32+R35) = (8.2/1+1) * 8.2/(1.8+8.2) = 9.3 * 0.82 = 7.626

Increase R36! (And decrease C18!)
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Old 25th October 2009, 03:38 PM   #4
81bas is offline 81bas  Germany
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Quote:
Originally Posted by Pafi View Post
Increase R36! (And decrease C18!)
Please, do not forget to do the same with R35 and C17...

Also, I would like simply use the additional opamp at the input with required gain. Hypex does the same, by the way...
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Old 27th October 2009, 04:19 PM   #5
opor is offline opor  Thailand
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With this formular, I have increased R36 to 22K and reduce R101 to 470 ohm.Also reduce C18 to 220pF .So gain is 39.196 .
How does it effect to the performance of the amp? Is it the noise ? Or any others? What is the good solution between increasing the gain of the amp and increasing the gain of balance receiver?
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Old 27th October 2009, 04:34 PM   #6
Did it Himself
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Why don't you just turn up the volume dial more? Adding gain just makes more noise.
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Old 8th January 2010, 06:32 AM   #7
opor is offline opor  Thailand
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This is my new schematic . I have build it .And I found some oscillation that make sound dirty . In this schematic there are balance line reciever and bridge adapter. Either I connect signal to balance section or direct to the amp there is still oscillation.
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Old 8th January 2010, 06:33 AM   #8
opor is offline opor  Thailand
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Sorry here is my schematic.
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File Type: pdf ClassD Beta32.pdf (133.1 KB, 68 views)
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