A40 Amplifier.pls help.

tone · 4th March 2003, 04:06 AM

hi all,
i have omitted the Q11 transistor..replaced with a 10k value resistor..

im getting loud hum..according to a diyer..to reduce the hum..or noise..he adviced to connects a polarity caps parallel between the resistor.

.how do i connect the cap to reduce the noise..i have tried to put a cap(positive) at base of Q3 and the negative to grd..but im experience distortion when power up and during large load required..(ea: deep bass)..

>the caps valued 100uf/100volts..

>when i replace Q11 to resistor..should i remove the R9?

>currently i didnt remove it..(R9).

>thanks for the advice..

rgds
tone.

Mambo · 4th March 2003, 09:27 AM

If you want to do this remove Q11 along with R9, connect two 5K resistors in series between the base of q3 and the ground, the cap negative between the two resistor and the positive to ground.

A good supply filtering can also greatly reduce the level of noise try a CRC filter with 1Ohm as R.

Check also ground connections

tone · 4th March 2003, 10:06 AM

mambo:
u are saying to remove Q11 AND R9?
>so i would have to do is :

>base Q11 ---> 5k ---> 5k---> Grd.
^--> negative caps to grd.

>what would be the required cap value between the 5 k resistor.
>pls confirm this..thank you mambo.

rgds,
tone

Mambo · 4th March 2003, 10:27 AM

Sorry for my last reply, I made a mistake on the cap connection.
I attached an image with the correct configuration.

You can remove R9

4th March 2003, 04:06 AM	#1
tone diyAudio Member Join Date: Aug 2002 Location: Malaysia	A40 Amplifier.pls help. hi all, i have omitted the Q11 transistor..replaced with a 10k value resistor.. im getting loud hum..according to a diyer..to reduce the hum..or noise..he adviced to connects a polarity caps parallel between the resistor. .how do i connect the cap to reduce the noise..i have tried to put a cap(positive) at base of Q3 and the negative to grd..but im experience distortion when power up and during large load required..(ea: deep bass).. >the caps valued 100uf/100volts.. >when i replace Q11 to resistor..should i remove the R9? >currently i didnt remove it..(R9). >thanks for the advice.. rgds tone.

4th March 2003, 10:06 AM	#3
tone diyAudio Member Join Date: Aug 2002 Location: Malaysia	att: Mambo (A40) mambo: u are saying to remove Q11 AND R9? >so i would have to do is : >base Q11 ---> 5k ---> 5k---> Grd. ^--> negative caps to grd. >what would be the required cap value between the 5 k resistor. >pls confirm this..thank you mambo. rgds, tone

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4th March 2003, 09:27 AM	#2
Mambo diyAudio Member Join Date: Feb 2002 Location: Italy	If you want to do this remove Q11 along with R9, connect two 5K resistors in series between the base of q3 and the ground, the cap negative between the two resistor and the positive to ground. A good supply filtering can also greatly reduce the level of noise try a CRC filter with 1Ohm as R. Check also ground connections

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