Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Subwoofer filter
Subwoofer filter
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 4th January 2011, 02:47 AM   #1
rockgardenlove is offline rockgardenlove  United States
diyAudio Member
Join Date: Sep 2008
Default Subwoofer filter

Hey all,
Just looking for a basic sub filter. I wired up an LM3886 chipamp and need a preamp module that prep a signal for the subwoofer.
How does something basic like this look?
Subwoofer Filter Circuit

I would probably only build the low-pass element circuit meant to drive the sub. I would send the unfiltered full signal to my L/R satellites instead of passing it through a high pass filter as this circuit does.

This is intended for musical use, btw. If you have better suggestions lemme know.

Thanks for anybody who can help!
  Reply With Quote
Old 4th January 2011, 10:00 AM   #2
AndrewT is offline AndrewT  Scotland
Join Date: Jul 2004
Location: Scottish Borders
passing unfiltered wide band music to the satellites will force the satellite amplifier and the satellite speaker to try to reproduce the bass frequencies. This potentially is setting your satellites up to fail in quality stakes and ultimately damage the drivers trying to handle the bass signal.

The Low Pass section is OK for the bass only channel.
The left and right signals need the two 4k7 before the first summing opamp.
But, this will load the signal source with a 4k7 load in parallel with the input impedance of the satellite amplifier.
Either adopt a much higher impedance for the summing opamp and accept a tiny bit of extra noise. The bass won't reproduce much of it anyway.
Or buffer the signal source to give four high current outputs that go on to feed the summer and the two satellites.

If you look up MFB filter you will find it forms the first summing opamp's function and the next f2pole filter opamp in one section.
But note the summing opamp and the MFB are inverting topology. Where are you going to correct the phase?
regards Andrew T.
  Reply With Quote
Old 7th January 2011, 05:47 AM   #3
Ian Finch is offline Ian Finch  Australia
diyAudio Member
Join Date: Apr 2010
Location: Coffs Harbour, NSW
'Not questioning the analysis, but trying to listen to a 24 dB filtered response without its reciprocal form is going to be very...well, difficult to call decent audio. Assuming your proposed drivers cover the crossover frequencies adequately, I would second using all the adapter sections presented as a full crossover. Otherwise, use a much lower (perhaps only 12dB) subwoofer rolloff in a rough attempt to track the natural rolloff of the satellites.

Perhaps the final sub. filter stage attenuator and a downstream sub. amp level control may have been intended to correct the overall gain?
If only I had listened....
  Reply With Quote


Subwoofer filterHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Subwoofer Filter Galexjav Chip Amps 2 13th September 2010 10:21 AM
Subwoofer Filter Translation coolet Subwoofers 2 18th June 2010 05:10 AM
Sub-filter for N-ripole subwoofer Antonio Tucci Subwoofers 0 18th March 2005 04:29 AM
subwoofer filter kinser Subwoofers 32 12th August 2004 10:40 PM
Subsonic filter for a SubWoofer guylemar Subwoofers 10 28th March 2003 01:38 AM

New To Site? Need Help?

All times are GMT. The time now is 08:17 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio