where to place active filters? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

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 21st October 2004, 07:10 PM   #1
AndrewT is online now AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
Default where to place active filters?

Hi all listeners(readers?),
what are the pros & cons for locating the active filters for a 4 way stereo speaker system.
a. one big box with 8 filters, psu, interference suppression etc, located next to the preamp.
b. 2 boxes each contained half stereo set as above but located near the monoblock power amps behind the speakers.
c. 4 little boxes with one filter in each plus one psu box, all five located at the back of their respective power amps. & repeat for other channel.
d. psu & filter inside each power amp with two inputs, flat and filtered.
I'm inclined to opt for d. but most manufacturers sell a.
are there any better options I have missed?
regards Andrew T.
  Reply With Quote
Old 22nd October 2004, 12:14 AM   #2
sek is offline sek  Germany
diyAudio Member
sek's Avatar
Join Date: May 2003
Location: Berlin

Regarding sound quality, I'd recommend keeping the number of interconnects/leads between (to and from) filter stages as low as possible, as they are prone to picking up noise and hum. This applies to audio signal lines as well as power supply wiring, so a single unit would be preferable.

Regarding cost, the number of enclosures and transformers is what greatly dominates the total project costs, so a single unit would also be the most economic.

This would opt for solution (a).

Solution (b) with only one case and one PSU more is 'nearly' as inexpensive and integrated as (a), but looks more beautiful.

Solution (c) is the one with the highest number of enclosures, and I would consider the single PSU to be more difficult to integrate into the system (thick wiring is difficult to get reliable, inexpensive and noise free at the same time).

Solution (d) is superior to (c) but a little difficult to get started, I think. You would have to fit a PSU and the filter into each amp enclosure, so that neither of them interferes with the other. Other than that, the maximum number of PSUs also doesn't let it appear attractive to me...

That said, of course most manufacturers sell (a).
Why should they offer 8 boxes and a PSU when customers only want a single functionality (have you ever seen someone selling a 'desintegrated' preamp with plenty of gear to modify, just because it connects to more than one source)? And of course using a single and readily prepared external unit is the only way for them to keep safety and warranty issues under control.

As a general rule in active filters, it is wise to keep noise away from low pass filter circuits (as induced noise is never filtered any more past the LPF.) and hum away from high pass filter circuits (as imposed hum is never filtered anymore past the HPF stage). Depending on your filter topology and circuit it could be overly complicated to separate LPF and HPF from each other, which could increase complexity (and thus cost and size) and bad influences on the signal path due to the 'too' many opamps (or whatever).

Both solutions (a) and (b) should be good - assuming proper design and construction - with (a) being the most economic and (b) the more beautiful if you don't want to have another unit under or next to your preamp.

Indeed, you could design the xovers matching your monoblock amps...

Just my couple of cents...

Which filter circuit do actually you want to use?

  Reply With Quote


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Might speaker filters be in the wrong place? beamnet Tubes / Valves 14 9th December 2007 07:52 PM
Active notch filters neutron7 Full Range 2 19th November 2006 11:51 AM
preamp active filters DD_Davo Solid State 29 7th April 2006 01:23 AM
active filters: which resistors to buy akunec Chip Amps 11 13th March 2005 01:09 PM
Which op amps do you use for active filters?? zx3chris Parts 4 25th April 2003 06:42 AM

New To Site? Need Help?

All times are GMT. The time now is 10:02 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2