Do I need a LPF?

Dxvideo · 3rd March 2004, 09:17 AM

Hi all,

I want to build a simple 5.1 gainclone with 2 TDA7370s... Each channel (except subwoofer) will be 7W (%10THD) and sub will be 24W. That gc will be used for a cheap DVD's analog 5.1 output.

The question is; do I need a low pass filter and/or a preamplifier for subwoofer input?

Thanks for your interest in advance..

abid_rehan · 7th March 2004, 12:47 PM

Quote:

That gc will be used for a cheap DVD's analog 5.1 output.

Well I guess in such a case you wont be needing a LPF as DVD's analogue out at subwoofer has already LPF.

matjans · 7th March 2004, 02:37 PM

it does have a LPF but often it's filtered way to high...

I used a passive 100Hz LPF and that sounds way better...

Dxvideo · 8th March 2004, 06:25 AM

Thank you very much.... I will finish the project in this week. The main problem is volume control... I guess I will use four seperated pot..

macboy · 8th March 2004, 01:15 PM

For volume control, try the National LM1036. This IC controls the volume, bass, treble, and balance of 2 channels using DC voltages to control each of those parameters. You can use three of them for 6 channels, using the same voltage to to control the volume on all of them. This chip will add a very small amount of distortion, but it doesn't seem like you are shooting for stellar sound quality to begin with.

3rd March 2004, 09:17 AM	#1
Dxvideo diyAudio Member Join Date: Nov 2003 Location: Turkey	Do I need a LPF? Hi all, I want to build a simple 5.1 gainclone with 2 TDA7370s... Each channel (except subwoofer) will be 7W (%10THD) and sub will be 24W. That gc will be used for a cheap DVD's analog 5.1 output. The question is; do I need a low pass filter and/or a preamplifier for subwoofer input? Thanks for your interest in advance..

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7th March 2004, 02:37 PM	#3
matjans diyAudio Member Join Date: Aug 2003 Location: Utrecht, NL	it does have a LPF but often it's filtered way to high... I used a passive 100Hz LPF and that sounds way better...

8th March 2004, 06:25 AM	#4
Dxvideo diyAudio Member Join Date: Nov 2003 Location: Turkey	Thank you very much.... I will finish the project in this week. The main problem is volume control... I guess I will use four seperated pot..

8th March 2004, 01:15 PM	#5
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	For volume control, try the National LM1036. This IC controls the volume, bass, treble, and balance of 2 channels using DC voltages to control each of those parameters. You can use three of them for 6 channels, using the same voltage to to control the volume on all of them. This chip will add a very small amount of distortion, but it doesn't seem like you are shooting for stellar sound quality to begin with.

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