electrical or cone damping - Page 3 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

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
Reply
 
Thread Tools Search this Thread
Old 3rd January 2003, 08:04 PM   #21
diyAudio Member
 
Pjotr's Avatar
 
Join Date: Nov 2002
Location: Netherlands
Quote:
BTW: Q=0.5 is only true for 2.order (12dB) LR-filter whereas 4.order LR-filter(24dB) is nothing less than two cascaded 2.order Butterworth filters (Q=0.7)
Hi Cocolino,

If you put two Butterworth filters with a Q of 0.71 in cascade you will end up with an overall Q of 0.5 isn’t it? But in general I agree, x-overs involve much more than only the x-over filter characteristics. It is the total response that counts.
_____________________________________


Hi Bjed,

Think I understand what you mean. But my “Dutch English” is of help maybe

I did a lot of experimenting with taming the Qb of closed boxes with electronic filtering. I have found that for small living rooms of say 4m x 6m a gentle bass roll-off (Qb =< 0.5) gives me the most natural bass reproduction. Then room modes/resonance’s are less aggressive exited: If you don’t put the energy in it can’t come out.

Even if the bass starts to drop at say 60 Hz but it drops gentle and 20 Hz is more than 15 dB down, then that 20 Hz can be heard, or better “perceived”, quite natural. Although it will not shake your stomach. To me this sounds more natural than a ruler flat response to 30 Hz and then dropping steeply as with some BR alignments. There is also something like natural “bass amplification” of the volume of the room itself that needs to be taken into account. I have put a small and quick engineering note about the background of filtering closed boxes online HERE for download as a .zip file. But please don’t blame for typo and grammar errors. It also contains an Excel sheet to calculate the filter response and values for a wanted target response. With the filter you can even make Qb as low as 0.25 but lower than 0.5 gives a rather thin bass.

Cheers
  Reply With Quote
Old 3rd January 2003, 10:19 PM   #22
diyAudio Member
 
cocolino's Avatar
 
Join Date: May 2002
Location: Bavaria (south of veal sausage equator)
Quote:
If you put two Butterworth filters with a Q of 0.71 in cascade you will end up with an overall Q of 0.5 isn’t it?
Pjotr:
I assumed the reason behind Your (unfounded) claiming that Butterworth filter were no good for high quality audio and that LR-filters would be a better choice was related to the more "smooth-shaped/ better pulse response thing" rather for just the level of attenuation (what IMO makes even less a point regarding this ) hence I wanted to explain that 4.order LR-filter actually = two 2.order Butterworth in series. Of course You`re right in that the 4.order LR-filter has 6dB (Q=0.5) attenuation at fx-over.


I fully second what You said about taming with electronic filtering!
Due to room gain at low frequencies speakers with flat low-frequency free-field response tend to sound boomy (particular in smaller rooms).
Electronic manipulation with a LR-transform circuit together with high-pass filtering is a very handy tool in compensating this effect and to achieve more natural though deeper bass.
Most people tend to believe the electronic manipulation will yield to huge amplification factors and need monster amps. Not so when applied accordingly and reasonable (eventually in conjunction with a subsonic-filter for protecting against weird ultra-low frequency effects). Taken into account the filters compensating slope for the room gain, in fact the power demand for such electronic filtered designs do not neccesarily have to exceed the unfiltered/unequalized by such a big amount (and besides this, most of the recorded music rarely contains really low frequency/ high level information).
__________________
Christoph
STEAL the BEST - INVENT the REST
  Reply With Quote

Reply


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
Loudspeaker electrical damping zebra100 Multi-Way 1 7th July 2009 09:48 PM
Cone weight vs Cone stiffness musgofasa Full Range 9 25th July 2008 08:16 PM
Loss of electrical damping for bass drivers powered by current drive 454Casull Multi-Way 38 6th February 2005 05:28 PM
Driver Cone and Surround Damping Paint mrfeedback Multi-Way 0 22nd July 2002 03:30 AM


New To Site? Need Help?

All times are GMT. The time now is 08:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2