Active crossover questions

[soongsc]

And a final question before i go to bed.

Why does this circuit http://us1.webpublications.com.au/static/images/articles/i302/30278_5mg.jpg

send the bass output through both the mid LP and the bass LP filters?

It goes to the mid to create part of the bandpass.

Where do you think the bass LP should get it's signal? Something to keep you awake.😀

 

[sachi]

If you have that whole circuit you plan to copy in one box (or one box per channel) then you don't need additional buffers. The design alrady has it in there.

You start needing buffers when you jump from one box to another using interconnects.

Let me clarify: My crossover and amp are in 1 box.

preamp --------- || IP buf > HP > LP > OP buff > LM3975 ||------- Midwoofer

Which of the buffers do I need or not need ?

Now if i keep the xover and the amps in seperate boxes u say that i willl need buffers..
can u please tell me if output buffers can be placed after the xover inside the xpver box or is it better to place input buffers in the amplifier box..
please correct me if i am wrong, but, the circuit in the siliconchip.com does'nt seem to have gain control..
cani implement the gain control alongwith the buffers on a seperate PCB..
I have already given the PCB for etching...

 

[jimbo1968]

It goes to the mid to create part of the bandpass.

Where do you think the bass LP should get it's signal? Something to keep you awake.😀

As it's a single board, the bass LP could take its signal from the input buffer.

 

[soongsc]

Now if i keep the xover and the amps in seperate boxes u say that i willl need buffers..
can u please tell me if output buffers can be placed after the xover inside the xpver box or is it better to place input buffers in the amplifier box..
please correct me if i am wrong, but, the circuit in the siliconchip.com does'nt seem to have gain control..
cani implement the gain control alongwith the buffers on a seperate PCB..
I have already given the PCB for etching...

I think we're getting different designs mixed up. The existing design is okay as long as is it's in one box. If you look at the output buffers there are trim pots (at least there should be acording to the schematics), these control the gain. Once you have them tuned to a specific system, just clos the box and don't worry about them any more.

 

[sachi]

Thank you for that soong..
i'll let u know when i get the PCB..hopefully i should have the PCB populated by end of next week..
Cheers,
Sachi

 

[soongsc]

As it's a single board, the bass LP could take its signal from the input buffer.

If depends on whether the input buffer can drive the load or not with so many things connected.

 

[jimbo1968]

If depends on whether the input buffer can drive the load or not with so many things connected.

The input buffer will either see 2 or 3 filters in parallel. It just seems odd to me to send the signal through 2 filters when one will do.

 

[soongsc]

The input buffer will either see 2 or 3 filters in parallel. It just seems odd to me to send the signal through 2 filters when one will do.

The best way to find out is to do both and see what happens. Nothing more value than hands on experience.😉