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opor 21st October 2009 02:04 PM

UcD need help for more gain
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?


opor 21st October 2009 02:26 PM

1 Attachment(s)
Sorry ,
Here is my schematic.

Pafi 21st October 2009 03:45 PM

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!)

81bas 25th October 2009 02:38 PM


Originally Posted by Pafi (Post 1956445)
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... :rolleyes:

opor 27th October 2009 03:19 PM

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?

richie00boy 27th October 2009 03:34 PM

Why don't you just turn up the volume dial more? Adding gain just makes more noise.

opor 8th January 2010 05:32 AM

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.

opor 8th January 2010 05:33 AM

1 Attachment(s)
Sorry here is my schematic.

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