I am currently building a pair of dipole speakers similar in design to the Orion.
I am using a Seas L22RNX/P and 10" XLS woofer in a baffle with a width of 300mm and height 1000mm and a MiniDSP for the EQ and x-overs.
I have simulated my baffle design in EDGE, it is my understanding that dipole speakers exhibit a natural roll-off of 12dB/octave.
After I have notched the dipole peak I am left with the dipole roll off and -6dB at 100hz.
Rather than correct for the dipole roll off, could I just let the midrange roll off naturally and apply low pass LR2 to the woofer at 100hz?
Or am I missing something vital?
I am using a Seas L22RNX/P and 10" XLS woofer in a baffle with a width of 300mm and height 1000mm and a MiniDSP for the EQ and x-overs.
I have simulated my baffle design in EDGE, it is my understanding that dipole speakers exhibit a natural roll-off of 12dB/octave.
After I have notched the dipole peak I am left with the dipole roll off and -6dB at 100hz.
Rather than correct for the dipole roll off, could I just let the midrange roll off naturally and apply low pass LR2 to the woofer at 100hz?
Or am I missing something vital?
An externally hosted image should be here but it was not working when we last tested it.
Hi,
Yes you can. You could low pass lower down to extend the bass,
though your not going to get much SPL with 12" wide baffles.
BTW baffle loss is 6dB/octave not 12dB. Your extra roll-
off (not loss) is caused by using very low Qts drivers.
Your Edge sim only shows the baffle loss, 6dB/octave.
Final bass roll-off low down is 18dB/octave, 6dB due
to baffle loss and 12dB due to the drivers roll-off.
rgds, sreten.
Yes you can. You could low pass lower down to extend the bass,
though your not going to get much SPL with 12" wide baffles.
BTW baffle loss is 6dB/octave not 12dB. Your extra roll-
off (not loss) is caused by using very low Qts drivers.
Your Edge sim only shows the baffle loss, 6dB/octave.
Final bass roll-off low down is 18dB/octave, 6dB due
to baffle loss and 12dB due to the drivers roll-off.
rgds, sreten.
Last edited:
It depends on what Q your're happy with, but people usually choose between 0.5-0.7.
Note here that the XLS drivers have a Q of something like 0.18 and a resonance close to 20Hz. These are the numbers you will use when setting the parameters for the LT and you will then pick the desired target fs and Q for it to equalise towards.
If you are wanting the main panels to give you extension down to say 40Hz, then picking a target Q of 0.7 + a target fs of 35Hz would be a good idea. If you combine this with a high pass with a Q of 0.7 and a corner frequency of 35Hz, then you will end up with an overall roll of centred on 35Hz with a Q of 0.5.
Do bare in mind that the XLS' fs and Qts will rise by a small amount when mounted on/in the baffle/frame.
Hi,
Crossed posts.
Rereading your post I've misunderstood your post and no you can't.
You need to model driver responses as well as the baffle loss.
Look at : https://sites.google.com/site/undefinition/diy-sunflowers
A Qts of 0.17 sub in a 12" wide open baffle is a disaster area in all respects.
Baffle loss at 50Hz will turn a 10" driver into no better than a boxed 3" SPL.
Huge amounts of boost and power are required to produce piffling SPL.
rgds, sreten.
Crossed posts.
Rereading your post I've misunderstood your post and no you can't.
You need to model driver responses as well as the baffle loss.
Look at : https://sites.google.com/site/undefinition/diy-sunflowers
A Qts of 0.17 sub in a 12" wide open baffle is a disaster area in all respects.
Baffle loss at 50Hz will turn a 10" driver into no better than a boxed 3" SPL.
Huge amounts of boost and power are required to produce piffling SPL.
rgds, sreten.
Last edited:
Rich,
You can target whatever Q you desire with available EQ tools, like the Linkwitz Transform. 0.5 would probably be an excellent target.
FYI, the Orion system does not use a Linkwitz Transform anywhere in the design. Q correction of the woofers is handled by a simple 6db/octave shelving filter.
Cheers,
Dave.
You can target whatever Q you desire with available EQ tools, like the Linkwitz Transform. 0.5 would probably be an excellent target.
FYI, the Orion system does not use a Linkwitz Transform anywhere in the design. Q correction of the woofers is handled by a simple 6db/octave shelving filter.
Cheers,
Dave.
I forgot to mention, the 10" woofer will be mounted in an H-frame similar dimensions as the Orion.
I think I need to get outside and measure the responce of the baffle/driver and work out the shelf filter for the midrange and H-frame.
So there is no problem in using LT on the woofer then to achive a target of 35hz, Q=0.5 and a 6db/octave correction?
I think I need to get outside and measure the responce of the baffle/driver and work out the shelf filter for the midrange and H-frame.
So there is no problem in using LT on the woofer then to achive a target of 35hz, Q=0.5 and a 6db/octave correction?
Technically, you are correct. But, I'm just saying, the Orion uses only a 6db/octave shelving filter for Q "correction" in the ASP architecture.
You're probably confused because of the ASP capabilities. The ASP circuit board design does allow you to implement a full bi-quad (LT) stage, if needed for some other usage. But it is not configured that way in the Orion design.
Cheers,
Dave.
You're probably confused because of the ASP capabilities. The ASP circuit board design does allow you to implement a full bi-quad (LT) stage, if needed for some other usage. But it is not configured that way in the Orion design.
Cheers,
Dave.
http://www.linkwitzlab.com/images/graphics/orion-asp2.jpg
Is what I am referring to, where clearly an LT is used on the woofers along with a shelving section.
Is what I am referring to, where clearly an LT is used on the woofers along with a shelving section.
While labeled LT2, it is not an LT. It is a 20-110 1st order shelf. That is, the gain is 110/20 and the poles are at 20 and 110 Hz. The way this is done with the original woofers is that the 20-110 shelf shifts the low Q pole at 110 Hz to 20 Hz. Dipole EQ would in theory extend from 305 Hz to DC. However there is also another (stealth) shelf to shift the woofer pole below 20 Hz up to 20 Hz. This shelf would be a cut, not a boost. As I recall it would have poles at about 5 Hz and 20 Hz. But this pole shifter is the inverse of the dipole eq below 20 Hz so by stopping the dipole eq at 20 the second pole shifter can be omitted and the same result is achieved down to 5 Hz. Below 5 Hz the woofer would roll off 3rd order.
That's interesting as LW himself describes the LT2 circuit as a 12dB/oct biquad which is clearly not a simple shelving network. On his website he also describes how one can compensate for a low Q woofer on an OB by using a special biquad circuit, which links to the LT with a description of how to use it.
LW may have used different filters that arrive at the same end result, but it is certainly misleading for him to write two things that indicate that an LT is used and then to not actually use one.
LW may have used different filters that arrive at the same end result, but it is certainly misleading for him to write two things that indicate that an LT is used and then to not actually use one.
He's not misleading anyone.
The designations on the block diagram you posted are correct. Items in parentheses are capabilities the ASP circuit boards have, but that are not used in the Orion design. You'll note there are others as well.....such as a 200Hz notch filter in the woofer circuit. There is no 200Hz notch filter in the Orion design, but the boards have the capability to implement one should an experienced user/designer be using them for some other purpose.
Dave.
The designations on the block diagram you posted are correct. Items in parentheses are capabilities the ASP circuit boards have, but that are not used in the Orion design. You'll note there are others as well.....such as a 200Hz notch filter in the woofer circuit. There is no 200Hz notch filter in the Orion design, but the boards have the capability to implement one should an experienced user/designer be using them for some other purpose.
Dave.
Missing something vital. Unlike a sealed box that falling acoustic output doesn't mean excursion is falling.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.