Lm3886 Bpa

[jaudio]

Originally posted by thomasfw
Dear Jaudio,



By the way, I have just made a tube buffer for my friend.
It connect in between DVD player (Made in China, HKD499) and
a AV amp.
You can't belive how great it is !!!!!!


Thomas

Ok I cant resist. Can you Email the schematics to me?



Thanks

[thomasfw]

Dear Jaudio,
How can I get your e-mail ?

Thomas

[jaudio]

In the upper left hand column of each post there is an authors name: click the name

[jkraxi]

please help me. I desperately need a schematic of JR model 12-concentra.
pls.mail me at jkraxi@yahoo.com
thx, JAY

[Mrpong]

Originally posted by jaudio
No buffer needed.

The caps go bewteen drv134 output and input resistor of each lm3886. Be sure to match all resistor as close as possible

Hi JAUDIO,

For the circuit you shown in #62, can I replace the 10uf cap with 1uf? I think the purpose of 10uf is to block DC. Correct?

[jaudio]

HI

That cap also act as part of a high pass filter. If you use a 1uf cap with the same resistor value then the cutoff frequency will be

159155/(R*frequency)=C(Capacitor value)

for a 20hz cutoff frequency,you should divend by 4.

5Hz would be your target

[Mrpong]

Originally posted by jaudio
HI

That cap also act as part of a high pass filter. If you use a 1uf cap with the same resistor value then the cutoff frequency will be

159155/(R*frequency)=C(Capacitor value)

for a 20hz cutoff frequency,you should divend by 4.

5Hz would be your target

Thank a lot JAUDIO, I think I may misunderstand something
With R=3900, C=1uF, this equation would give
the cutoff freq = 159155/(3900x0.000001) Hz????????

[jaudio]

Hello

For a 1uf cap and a resistor value of 3.9k, the cutoff frequency is 40Hz, which is much too high.

Let say you want a cutoff frequency of 15hz

1. 15Hz/4=3.75Hz

2. 159155/(3900*3.75)=11.3uf

R is the resistor on the inverted input
Remember,I used 3.9k on the schematic
for an example,your value may be different.

[Mrpong]

According to this original BPA200 schematic, I think we can use trimpots at the + input PINs of U3 and U4. However how can we use trimpot at U1 and U2?

[jaudio]

Originally posted by Mrpong
According to this original BPA200 schematic, I think we can use trimpots at the + input PINs of U3 and U4. However how can we use trimpot at U1 and U2?

Add trimpots the U1 and U2 wont work, the impedance in the chip is too high.

In the schematic, I posted all the chips are in the inverted mode.

If you use the original BPA200 schematic, you won’t be able to adjust the dc offset. There are a few things you can do to minimize the offset

Increase the output resistor value to .3 to.5 ohms

Use chips with similar dc offset (You will have to buy more chips to match them)

servo s

You should use the original Bpa200 schematic or the schematic I posted. I don’t think the schematics can be mixed together