UcD need help for more gain

opor · 21st October 2009, 02:04 PM

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

opor · 21st October 2009, 02:26 PM

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

Quote:

Originally Posted by Pafi

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...

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

Sorry here is my schematic.

21st October 2009, 02:04 PM	#1
opor diyAudio Member Join Date: Nov 2005	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

27th October 2009, 03:34 PM	#6
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Why don't you just turn up the volume dial more? Adding gain just makes more noise. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

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21st October 2009, 03:45 PM	#3
Pafi diyAudio Member Join Date: May 2004 Location: Budapest	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!)

27th October 2009, 03:19 PM	#5
opor diyAudio Member Join Date: Nov 2005	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?

8th January 2010, 05:32 AM	#7
opor diyAudio Member Join Date: Nov 2005	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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