If I am building a speaker and planning to use 2 8" passive radiators
Is it better to have them front firing or rear for cleaner sound
It seems passive radiator has to produce sound a little our of phase from main woofers.
I understand rear if places by the wall will provide more bass with the help of the wall
But what about phase of bass waves. Which variant will yield more accurate wave arrivals to listeners years
What other pros and cons of front and rear position of the radiators
Is it better to have them front firing or rear for cleaner sound
It seems passive radiator has to produce sound a little our of phase from main woofers.
I understand rear if places by the wall will provide more bass with the help of the wall
But what about phase of bass waves. Which variant will yield more accurate wave arrivals to listeners years
What other pros and cons of front and rear position of the radiators
What about the side... the movements will cancel each other out in terms of vibration. Also you might want to consider floor... apparently it makes it less susceptible to room mods...
Might want to take a cue from how subwoofers are designed. 2× 8 inch I believe should be in a almost subwoofer territory...
Oon
Might want to take a cue from how subwoofers are designed. 2× 8 inch I believe should be in a almost subwoofer territory...
Oon
Last edited:
It's actually a build involving 4 dynaudio 17w75xl drivers 4ohm. Not a subwoofer.
They are designed to be used in vented enclosures.
How will side passive radiators cancel and align in phase.
I originally wanted to use them for maximum crystal clear midrange. 4 drivers in 42L sealed box.
But seems they'll have a pretty low bass. Almost nothing below 70hz
Afraid they won't smoothly work with 15" subwoofer.
Is port noise an. Issue with 6.5" drivers?
I am still undecided to either use 4 passive radiators per speakers or 2 ports per speaker.
Ports will extract more bass. Curve is smoother a little 1.5db bump in 45-100hz region. Flat after that.
Passive radiators are pretty close. Ideal flat response after 50hz. my concern with ports is noise but is it an issue with 6.5" drivers
They are designed to be used in vented enclosures.
How will side passive radiators cancel and align in phase.
I originally wanted to use them for maximum crystal clear midrange. 4 drivers in 42L sealed box.
But seems they'll have a pretty low bass. Almost nothing below 70hz
Afraid they won't smoothly work with 15" subwoofer.
Is port noise an. Issue with 6.5" drivers?
I am still undecided to either use 4 passive radiators per speakers or 2 ports per speaker.
Ports will extract more bass. Curve is smoother a little 1.5db bump in 45-100hz region. Flat after that.
Passive radiators are pretty close. Ideal flat response after 50hz. my concern with ports is noise but is it an issue with 6.5" drivers
I wouldn't say those 17W's should have "almost nothing" below 70 - if you're basing that off my reply in your other thread.
Remember sealed boxes roll off at 12dB/octave rather than the 24dB of vented, so that is somewhat shallower. Plus, depending on room size and where you'd position them, 70Hz could easily be low enough to start getting some help from room gain.
Unless your sub is really optimised for ultra low frequency use (eg 20-40Hz only) then you should be able to integrate the sealed 17W's with it easily enough.
Re Port noise - it is a function of the size of ports you use relative to the SPL you expect to listen at, so driver size on its own is irrelevant - good port design can eliminate port noise even from massive subwoofers, poor port design can exhibit noise even from small midbasses.
Remember sealed boxes roll off at 12dB/octave rather than the 24dB of vented, so that is somewhat shallower. Plus, depending on room size and where you'd position them, 70Hz could easily be low enough to start getting some help from room gain.
Unless your sub is really optimised for ultra low frequency use (eg 20-40Hz only) then you should be able to integrate the sealed 17W's with it easily enough.
Re Port noise - it is a function of the size of ports you use relative to the SPL you expect to listen at, so driver size on its own is irrelevant - good port design can eliminate port noise even from massive subwoofers, poor port design can exhibit noise even from small midbasses.
Ported design is more appealing since I can easily close ports.
I used speaker box lite app for Android to model.
Attached are graphs of closed box, vented, and passive radiator(2 different radiator brands)
Each speaker will consist of 70L box with 4 17w75xl drivers and two 6.5" passive radiators or two ports
Yellow brownish graph is vented design
Blue is closed box
Green is two passive radiators( fs =20hz, qms=6.8, vas =55L)
It's this passive radiator
SB Acoustics SB20PFCR-00 Passive Radiator- ROUND
Red is passive radiators made by Dayton
Dayton Audio DS215-PR 8" Designer Series Passive Radiator
I am leaning to do ported design and replace them with passive radiators if there is a port noise issue. I am planning to use flared round vents around 1.25" diameter. 3cm
What are considered good port designs? I've seen a video of twisted flared ports. But have not seen them sold anywhere
Twisted Flare Port - YouTube
I appreciate your time and advices
I used speaker box lite app for Android to model.
Attached are graphs of closed box, vented, and passive radiator(2 different radiator brands)
Each speaker will consist of 70L box with 4 17w75xl drivers and two 6.5" passive radiators or two ports
Yellow brownish graph is vented design
Blue is closed box
Green is two passive radiators( fs =20hz, qms=6.8, vas =55L)
It's this passive radiator
SB Acoustics SB20PFCR-00 Passive Radiator- ROUND
Red is passive radiators made by Dayton
Dayton Audio DS215-PR 8" Designer Series Passive Radiator
I am leaning to do ported design and replace them with passive radiators if there is a port noise issue. I am planning to use flared round vents around 1.25" diameter. 3cm
What are considered good port designs? I've seen a video of twisted flared ports. But have not seen them sold anywhere
Twisted Flare Port - YouTube
I appreciate your time and advices
Attachments
The first approximation for port design is to turn up the input power in the sim until the drivers reach Xmax (or your max amp power, whichever comes first) then increase the port diameter until the simulated airspeed is no higher than 17m/s.
Flares on the ends of the ports will give lower noise than for straight ports, but I don't know of any definitive conversion from acceptable airspeed in the straight condition to a higher but still acceptable speed with flares. My gut feeling is that you could use about 70% of the cross sectional area and still be ok, based on a few projects I've seen with flares, but I don't have hard data to back that up.
In any case, with or without flares, 2 x 3cm dia ports would be too small IMO - you'd probably want about 2 x 9cm dia to meet the airspeed target for straight vents per WinISD.
That assumes using the box full range, ie without a sub - obviously if you crossover into the sub above the port tuning frequency the ports will be operating at lower SPL and thus lower airspeed. Somewhat smaller ports might therefore be acceptable if you were always going to use the box with your sub.
Flares on the ends of the ports will give lower noise than for straight ports, but I don't know of any definitive conversion from acceptable airspeed in the straight condition to a higher but still acceptable speed with flares. My gut feeling is that you could use about 70% of the cross sectional area and still be ok, based on a few projects I've seen with flares, but I don't have hard data to back that up.
In any case, with or without flares, 2 x 3cm dia ports would be too small IMO - you'd probably want about 2 x 9cm dia to meet the airspeed target for straight vents per WinISD.
That assumes using the box full range, ie without a sub - obviously if you crossover into the sub above the port tuning frequency the ports will be operating at lower SPL and thus lower airspeed. Somewhat smaller ports might therefore be acceptable if you were always going to use the box with your sub.