deandob said:
1. I'm sure you wouldn't hear it.
2. Yes. The total Q is equal to the "Speaker in the Box" Q times the filter Q.
You do understand that you have to bi-amp here don't you?
I found some T&S graphs that show the transient response between 0.7 and 0.5 to be different but not by huge amounts. However as I'm using the linkwitz transform to equalize the woofer for better low frequency response, this circuit improves the Q from Q=0.7 with the size box I'm using to Q=0.5 with the transform.
So now I have a differential of Q=0.88 for the near field monitors and Q=0.5 for the woofer, which is starting to make a difference in transient response characteristics. For total Q to = 0.5, then I need to adjust the filter Q to be 0.5 / 0.88 = 0.57. I'm using a linkwitz 12db/oct high pass filter for the near field monitor so I'll have to research the Q of this filter (and see if it can be adjusted if needed).
The speakers will be bi-amped, a 200W Class D tripath amp for the (sub)woofer and a stereo LM3875 gainclone for the near field monitors. Maybe because I'm using different amps for the woofer and the near field monitors that will have different characteristics I shouldn't be too bothered with differences in box Q?
Regards,
Dean
So now I have a differential of Q=0.88 for the near field monitors and Q=0.5 for the woofer, which is starting to make a difference in transient response characteristics. For total Q to = 0.5, then I need to adjust the filter Q to be 0.5 / 0.88 = 0.57. I'm using a linkwitz 12db/oct high pass filter for the near field monitor so I'll have to research the Q of this filter (and see if it can be adjusted if needed).
The speakers will be bi-amped, a 200W Class D tripath amp for the (sub)woofer and a stereo LM3875 gainclone for the near field monitors. Maybe because I'm using different amps for the woofer and the near field monitors that will have different characteristics I shouldn't be too bothered with differences in box Q?
Regards,
Dean
Total Q
Doing more research on matching the Q's between the subwoofer enclosure and the near field monitor.
System Q = (driver + enclosure) Q x filter Q
For the near field monitor, WinISD gives me a driver + enclosure Q of 0.88 for a 2.2l cabinet. As I'm using a LR 2nd order filter, it has a Q of 0.5, so the system Q of the near field box is 0.44, close to critically damped.
So to match the Q = 0.44 of the near field monitor, the subwoofer system Q is the Q of the LR transform equalizer circuit x the Q of the 24db/oct LR low pass filter, which has a Q of 0.71. As I can adjust the Q of the equalizer circuit, I need a Q from the equalizer circuit of 0.62. Rod Elliott's site has a handy spreadsheet that allows you to play with the transform parameters including total Q of the equaliser, driver and enclosure, so I can work out the component values in the LR transform equalizer to give me 0.62, for a total system Q for the subwoofer of 0.44.
With this approach I have a close to critically damped system and matching transient responses between the subwoofer and near field monitors. Am I on the right track here?
References:
http://www.linkwitzlab.com/filters.htm
http://www.diyaudio.com/forums/showthread.php?s=&threadid=24230&perpage=10&highlight=&pagenumber=5
Doing more research on matching the Q's between the subwoofer enclosure and the near field monitor.
System Q = (driver + enclosure) Q x filter Q
For the near field monitor, WinISD gives me a driver + enclosure Q of 0.88 for a 2.2l cabinet. As I'm using a LR 2nd order filter, it has a Q of 0.5, so the system Q of the near field box is 0.44, close to critically damped.
So to match the Q = 0.44 of the near field monitor, the subwoofer system Q is the Q of the LR transform equalizer circuit x the Q of the 24db/oct LR low pass filter, which has a Q of 0.71. As I can adjust the Q of the equalizer circuit, I need a Q from the equalizer circuit of 0.62. Rod Elliott's site has a handy spreadsheet that allows you to play with the transform parameters including total Q of the equaliser, driver and enclosure, so I can work out the component values in the LR transform equalizer to give me 0.62, for a total system Q for the subwoofer of 0.44.
With this approach I have a close to critically damped system and matching transient responses between the subwoofer and near field monitors. Am I on the right track here?
References:
http://www.linkwitzlab.com/filters.htm
http://www.diyaudio.com/forums/showthread.php?s=&threadid=24230&perpage=10&highlight=&pagenumber=5
- Status
- Not open for further replies.