Sound Quality of LM3875T

[cwteoh]

I just finish building my LM3875T Amp. Tested, but sound quality is very bad. Is that mean I need to add a preamp or a tune control in front of it?

[Will]

You need to be more specific bout ur problems.

Start with circuit - which config did you build
What PSU caps are used,
Tx configuration
And the sound Q you are hearing.

[cwteoh]

I am using 4 x 10CTQ140 as PSU Bridge with 2 x 10000uF before Vout, Toronoid Transformer 18v-0v-18v 6A

[skyraider]

teoh,
you have to e specific about your problem, does it lacks bass, or does the sound cracks up, or distortion?
a picture of your work will help here..

[RFScheer]

Your time constant on the feedback loop is 10 seconds for the top path and 0.1sec for the bottom. I'm no expert, but what's going on with that?

-Robert

[cwteoh]

OK... The unit is not with me... With the above schematic I am very happy that I can't feel any distortion or cracks up. But I heard bass-less. I can't feel any bass came out from the speaker. If it do so, it sounds like a bang from "an empty box". It doesn't sound solid at the bass level.

[RFScheer]

How about listing the component types.

-Robert

[skyraider]

try taking out r32, c36, and c38

[cwteoh]

I started the circuit excatly like the application circuit in datasheet but it was lack of bass and has ringing on output when I increased the volume. The ringing problem was solved using zobel network at output but still lack of bass. I understand that this LM3875 has lower input impedance and does it mean that I need to add additional opamp stages to make it becomes high impedance?

[jackinnj]

most likely you're overdriving the LM3875 -- go to the National Semiconductor website, pull down the "Overture Design" spreadsheet and determine the input voltage you need for max output (given load, power supply voltage etc.)