Hi Ninfendo,
A ported mid will naturally roll off at 24dB/oct, a sealed will roll off at 12dB/oct. If you are going to try and match the sub to a ported roll off you will probably need a 'phase' dial to help line up the 2 drivers (group delay on the mid)
You will not need a high pass with the ported mid (what you are suggesting will yield a 36 dB/oct highpass), you'll only need a 12dB/oct highpass on a sealed mid, if you include its natural roll off.(what I suggested at ~130Hz)
The linkwitz transform I referred to is a 'eq' type circuit which can move the roll off of a driver downwards - ie from the 130Hz to 80Hz, at the expense of needing more power, lower spl.
http://web.archive.org/web/20031009102907/linkwitzlab.com/thor-eq.htm
Cheers,
Rob
A ported mid will naturally roll off at 24dB/oct, a sealed will roll off at 12dB/oct. If you are going to try and match the sub to a ported roll off you will probably need a 'phase' dial to help line up the 2 drivers (group delay on the mid)
You will not need a high pass with the ported mid (what you are suggesting will yield a 36 dB/oct highpass), you'll only need a 12dB/oct highpass on a sealed mid, if you include its natural roll off.(what I suggested at ~130Hz)
The linkwitz transform I referred to is a 'eq' type circuit which can move the roll off of a driver downwards - ie from the 130Hz to 80Hz, at the expense of needing more power, lower spl.
http://web.archive.org/web/20031009102907/linkwitzlab.com/thor-eq.htm
Cheers,
Rob
No no no! I really wasn't suggesting adding anything to a ported roll off.
If this was my project I'd go sealed mids. I'd try using the mids natural roll off, with a 12dB oct lowpass on the jbl. If the mids strained at good volumes I'd then try adding a 12dB/oct highpass to the mids, and using a 24dB/oct lowpass on the sub.
I would never consider ported mids. - ever - . Even my subs are sealed.
If you are *desperate* to cross at 80, rather than 130. (about 4 keys on a piano difference) then use the digital xo to eq the mids flat to 80Hz. then add a 12dB/oct highpass to them. Just beware of the power levels. You'd need to add about 6dB of boost.
If your mids were using 40w on peaks, now they'll need 160w to do the same levels.
It may be better to find some mid drivers that give you your 80Hz f3, rather than pushing these ones.
Cheers,
Rob
Hi Rob,
My initial idea was to use a sealed box. When I discussed it with Stig Erik Tangen, this was his response:
"My choice for midrange cabinets in your case would be to use a rather
large bass reflex box tuned an octave or so below the crossover point,
and use 4th order crossover. Your 5 liter example is good. Also make
sure the bass reflex boxes are properly damped, so that you dont get any
resonances. You could safely fill 50-70% f the box volume with damping material."
It was then I decided to to go for the ported alternative. Later Tangen suggested that a 2nd order Linkwitz should be used at 80Hz. The initial plan was however to x-over at around 100Hz.
My initial idea was to use a sealed box. When I discussed it with Stig Erik Tangen, this was his response:
"My choice for midrange cabinets in your case would be to use a rather
large bass reflex box tuned an octave or so below the crossover point,
and use 4th order crossover. Your 5 liter example is good. Also make
sure the bass reflex boxes are properly damped, so that you dont get any
resonances. You could safely fill 50-70% f the box volume with damping material."
It was then I decided to to go for the ported alternative. Later Tangen suggested that a 2nd order Linkwitz should be used at 80Hz. The initial plan was however to x-over at around 100Hz.
So if you tuned the mids to 75Hz, then you'd crossover 24dB/oct at 150Hz ?
I'm getting lost here...
Rob
btw, damping the box that much (50-70%) should be pushing towards daves aperiodic stuff.. the stuffing works against the port.
""It was then I decided to to go for the ported alternative. Later Tangen suggested that a 2nd order Linkwitz should be used at 80Hz.""
Is that still with a ported mid ?
I'm getting lost here...
Rob
btw, damping the box that much (50-70%) should be pushing towards daves aperiodic stuff.. the stuffing works against the port.
""It was then I decided to to go for the ported alternative. Later Tangen suggested that a 2nd order Linkwitz should be used at 80Hz.""
Is that still with a ported mid ?
RobWells said:So if you tuned the mids to 75Hz, then you'd crossover 24dB/oct at 150Hz ?
I'm getting lost here...
Rob
btw, damping the box that much (50-70%) should be pushing towards daves aperiodic stuff.. the stuffing works against the port.
Sorry, using 4th order filters at 150Hz was the initial plan! Tangen later suggested using a 2nd order at 80Hz would work as well. This is my aim at the moment.
The mid boxes are currently filled with lambwool, however it is not in the way of the ports at the moment.
I can't see how a 12dB/oct highpass at 80Hz could work with that midrange either sealed or ported.
Of note, My speakers were designed to have exactly what you are proposing. The 5.5" mids roll off exactly at 80Hz in a sealed box. I put a 12dB/oct high on them to make a 24dB slope. They're crossed to 2x10".
You can see them here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=55509&perpage=10&pagenumber=1
After some use I found that the mids couldn't keep up with the 10's. They're now crossed at 254Hz.
I really wouldn't be worrying over the difference between 80 and 130Hz , I'd just do it right for the drivers you're using.
Cheers,
Rob
Of note, My speakers were designed to have exactly what you are proposing. The 5.5" mids roll off exactly at 80Hz in a sealed box. I put a 12dB/oct high on them to make a 24dB slope. They're crossed to 2x10".
You can see them here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=55509&perpage=10&pagenumber=1
After some use I found that the mids couldn't keep up with the 10's. They're now crossed at 254Hz.
I really wouldn't be worrying over the difference between 80 and 130Hz , I'd just do it right for the drivers you're using.
Cheers,
Rob
planet10 said:
I think you have me convinced. I will initially go for the 130Hz 4th order x-over. I will probably keep the box ported in the beginning at least, or else the midrange will start to falloff at 200Hz if in a sealed box.
Also I would like to get hold of some measurement equipment; microphone, software and probably a good soundcard, any ideas???
Ninfendo said:
The midrange has to start rolling off at 200 in order to cross it at 130Hz. If you keep it ported then put a 24dB high pass on it at 130Hz, the slope will look the same as adding a 12dB 130Hz highpass to the sealed box (Almost - the port will 'interfere' a bit with the mids roll off an octave down). ie will start falling at ~200Hz.
Do a search for "measurement software" (try "RTA") aswell. Theres a lot of info here already.
Speaker workshop , trueRTA, lspCAD etc..
Cheers,
Rob
Those posts where over 6 years ago. Where have you been?
It should be easy to locate a link to the Behringer DCX2496.
SpeakerBuilding.com - Almighty Subwoofers, Page 1 for the Sig Sub.
Ariel Speaker Page Worked fine for me and I'm not registered?
It should be easy to locate a link to the Behringer DCX2496.
SpeakerBuilding.com - Almighty Subwoofers, Page 1 for the Sig Sub.
Ariel Speaker Page Worked fine for me and I'm not registered?
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