what is the recommended radius for port bends or curves in a given diameter port? Planning to use either PVC or cardboard.
Dayton Audio RSS315HF-8 12" Models to 20hz in a 4.6 cu ft (net) closure according to PE using Bass box.
I plan to low pass them around 45hz and will employ a a 10-15hz subsonic filter.
Nominal Diameter 12"
Moving Mass Of Diaphragm (Mmd) 194
Power Handling (RMS) 400 Watts
Power Handling (MAX) 700 Watts
Impedance 8Ω
Frequency Response 25 to 1,500Hz
Sensitivity 85.7dB 2.83V/1m
Voice Coil Diameter 2.58"
Resonant Frequency (Fs) 22.2Hz
DC Resistance (Re) 6.5Ω
Voice Coil Inductance (Le) 1.56mH
Mechanical Q (Qms) 2.5
Electromagnetic Q (Qes) 0.54
Total Q (Qts) 0.45
Compliance Equivalent Volume (Vas) 3.43ft³
Mechanical Compliance of Suspension (Cms) 0.27mm/N
BL Product (BL) 18T·m
Maximum Linear Excursion (Xmax) 14.3mm
Surface Area of Cone (Sd) 506.7cm²
Cone Material Aluminum
Surround Material Rubber
Voice Coil Wire Material Copper
Voice Coil Former Aluminum
Basket / Frame Material Steel
Magnet Material Ferrite
Overall Outside Diameter 12.36"
Baffle Cutout Diameter 11.1"
Depth 5.75"
# Mounting Holes 8
Sealed Volume 1.54ft³
Sealed F3 40Hz
Vented Volume 4.63ft³
Vented F3 20hz
How to get the same FR in a more WAF sized ported 3 cu ft closure? I have some DSP on hand and 500W rms on tap.
how long should the port be assuming 3”, 3.5”, or 4” ID?
Many, many thanks for your help and patience.
Dayton Audio RSS315HF-8 12" Models to 20hz in a 4.6 cu ft (net) closure according to PE using Bass box.
I plan to low pass them around 45hz and will employ a a 10-15hz subsonic filter.
Nominal Diameter 12"
Moving Mass Of Diaphragm (Mmd) 194
Power Handling (RMS) 400 Watts
Power Handling (MAX) 700 Watts
Impedance 8Ω
Frequency Response 25 to 1,500Hz
Sensitivity 85.7dB 2.83V/1m
Voice Coil Diameter 2.58"
Resonant Frequency (Fs) 22.2Hz
DC Resistance (Re) 6.5Ω
Voice Coil Inductance (Le) 1.56mH
Mechanical Q (Qms) 2.5
Electromagnetic Q (Qes) 0.54
Total Q (Qts) 0.45
Compliance Equivalent Volume (Vas) 3.43ft³
Mechanical Compliance of Suspension (Cms) 0.27mm/N
BL Product (BL) 18T·m
Maximum Linear Excursion (Xmax) 14.3mm
Surface Area of Cone (Sd) 506.7cm²
Cone Material Aluminum
Surround Material Rubber
Voice Coil Wire Material Copper
Voice Coil Former Aluminum
Basket / Frame Material Steel
Magnet Material Ferrite
Overall Outside Diameter 12.36"
Baffle Cutout Diameter 11.1"
Depth 5.75"
# Mounting Holes 8
Sealed Volume 1.54ft³
Sealed F3 40Hz
Vented Volume 4.63ft³
Vented F3 20hz
How to get the same FR in a more WAF sized ported 3 cu ft closure? I have some DSP on hand and 500W rms on tap.
how long should the port be assuming 3”, 3.5”, or 4” ID?
Many, many thanks for your help and patience.
Try running winISD. Enter the T/s parameters. Then put in box size and tuning frequency. Then switch to the vent part to find your port dimensions.
WinISD - Linearteam
winisd beta could not be much easier to use.
looks like 3 cu ft tuned to 20hz looks pretty good, f3 ~24hz, but the vent speed with a 4"x26"vent is a little high. a 5"x42" is better. I would personally be fine with the 4" vent.
winisd beta could not be much easier to use.
looks like 3 cu ft tuned to 20hz looks pretty good, f3 ~24hz, but the vent speed with a 4"x26"vent is a little high. a 5"x42" is better. I would personally be fine with the 4" vent.
In fact, if you need a subwoofer for a smaller box, look at Dayton's Reference HO (high output) and HE (high excursion) which can do well in smaller boxes. Those might be a better fit to hit lower in a certain size box.
Please consider my desired F3 is the 20hz of the 4.6 cu ft closure. My goal is the same F3 in a 3’ closure.
When I get a windows platform computer I’ll give WinISD ago. Haven’t used it in years. Didn’t know I could use it to model this driver in 3’ closure w/20hz F3.
Please recommend a bend radius for a 4” ID PVC port though I expect I’ll hafta start w/a 4’ gross closure to allow room for that big, long port for a net ~3’
Thanks for all your help
When I get a windows platform computer I’ll give WinISD ago. Haven’t used it in years. Didn’t know I could use it to model this driver in 3’ closure w/20hz F3.
Please recommend a bend radius for a 4” ID PVC port though I expect I’ll hafta start w/a 4’ gross closure to allow room for that big, long port for a net ~3’
Thanks for all your help
f3 of 20 hz or 24hz is pretty immaterial especial in room. 3.5 cubes should be plenty to account for a 4" port and bracing. The more gradual the better for port curve.
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Also, I'm in the mountains, so I have changed the air pressure which effects how close the speaker is to XMAX (it hits it sooner). If it works in the mountains (just under a mile up), then it will work at sea level and all in between.
I don't think it's really possible to do this in a 3cuft with this driver, it's cutting at 23Hz F3 in that space.
But for that tuning, 2x4" diameter ports of 53.25" will work. If it's practical is an other question. If you don't have the drivers yet, get other drivers that are more suited for reflex, as this is mainly ment for sealed cabs i think.
Edit: i would actually use that driver sealed and use linkwitz transform eq (as you got dsp) to get to the wanted response. That works in 3cuft with that driver to an max dB on 20Hz of 98dB before running out of xmax (it can probally go further but with added distortion as excursion is not linear anymore.
But for that tuning, 2x4" diameter ports of 53.25" will work. If it's practical is an other question. If you don't have the drivers yet, get other drivers that are more suited for reflex, as this is mainly ment for sealed cabs i think.
Edit: i would actually use that driver sealed and use linkwitz transform eq (as you got dsp) to get to the wanted response. That works in 3cuft with that driver to an max dB on 20Hz of 98dB before running out of xmax (it can probally go further but with added distortion as excursion is not linear anymore.
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I am so very sorry I’m so bad at expressing myself. A side note: I want a finished (stereo) pair for 2 ch and HT. Each will reside next to my LR* covering below 40-45hz. I’m pleased at how well they* cover to the low 30s in-room.
Seems consensus is: a 20hz F3 demands a 4.6’ net* closure (per Bass box.) Too much DSP in a smaller closure will exceed this driver limits and capabilities.
What about a ported isobaric? Smaller w/twice the power handling?
Having read David Weems’ book, assembled a few projects (back then*) and messed around w/this stuff on and off since the 80s* I understand closure size directly connects to F3, efficiency, etc.
*when I was single
“Doing the voodoo” that SVS, HSU, and Sunfire* etc “do” to achieve larger closure FR from a smaller one using DSP etc is their domain - not for diy hobbyist. Maybe this is the “Mt Everest” I can’t climb - senior citizen.
* my LFE is a Sunfire True Subwoofer Signature
From the PE Q&A etc on this driver, it will perform well at that F3 in 4.63’. Another Diyaudio thread agrees based upon his experience and that driver’s construction.
I’m sorry for wasting the precious experience & skills of you gifted craftsman that could better serve others instead my fools crusade.
Thanks for trying. I’ll return after messing w/WinISD. Tony
Seems consensus is: a 20hz F3 demands a 4.6’ net* closure (per Bass box.) Too much DSP in a smaller closure will exceed this driver limits and capabilities.
What about a ported isobaric? Smaller w/twice the power handling?
Having read David Weems’ book, assembled a few projects (back then*) and messed around w/this stuff on and off since the 80s* I understand closure size directly connects to F3, efficiency, etc.
*when I was single
“Doing the voodoo” that SVS, HSU, and Sunfire* etc “do” to achieve larger closure FR from a smaller one using DSP etc is their domain - not for diy hobbyist. Maybe this is the “Mt Everest” I can’t climb - senior citizen.
* my LFE is a Sunfire True Subwoofer Signature
From the PE Q&A etc on this driver, it will perform well at that F3 in 4.63’. Another Diyaudio thread agrees based upon his experience and that driver’s construction.
I’m sorry for wasting the precious experience & skills of you gifted craftsman that could better serve others instead my fools crusade.
Thanks for trying. I’ll return after messing w/WinISD. Tony
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HUGE thanks for these formulae��. Yes I plan to brace, Brace, BRACE!
And what does “… with voice coil inductance turned on,” mean?
Yeah, I make a number of formulae depending on what I am doing with the box or bracing for each design, that way to calculate the volume of different areas that are not counted toward the volume needed for the drivers.
For ports and vents, the length is measured from the center of the port, not the edge. So, when you are doing bends, you need to account for those with more math, but doing the volume of a cylinder will at least help figure out the volume you have to account for in the design. If doing a circular port, you should look to common sized PVC and ABS for sewage, etc., as that will likely be the easiest to find lengths and elbows, whereas for a shelf style vent, it is just a different math problem.
For voice coil inductance, it means how the inductance of the voice coil effects or shapes a subwoofer's frequency response curve. It is something to help compensate for in the design stage, including a crossover point and any filters you will want to apply in the crossover itself.
Ok, you use an inductor, a copper coil, in order to make a low pass filter. It drops the frequency depending on the characteristics of the coil.
With a transducer (a driver), the voice coil is a magnetic copper coil. As such, to varying degrees, it has inductance properties and can cause a drop at certain frequencies. When you model for voice coil inductance, you are taking into account the natural drop off of the driver, at which frequencies, and how to compensate for its effects on usable frequency response.
Eventually you will find out how long a port will need to be
to get such low tuning and reasonable velocity.
have fun its going to be looooooooong
point is your going to need some sort of calculator
nobody's going to do the work for you.
and you will have to decide what is a realistic sound pressure level.
and what trade offs you can manage to get a reasonable port velocity
and not have a port that is 5 feet long.
to get such low tuning and reasonable velocity.
have fun its going to be looooooooong
point is your going to need some sort of calculator
nobody's going to do the work for you.
and you will have to decide what is a realistic sound pressure level.
and what trade offs you can manage to get a reasonable port velocity
and not have a port that is 5 feet long.
Do I still need to take the above into account?
I have DSP filtering at my disposal to manage XO duties and to do what I call soundshaping; a plethora of slopes (1st, 2nd, 3rd, & 4th) and types (LR & BW) and PEQs
Thnx so much for your input
Tony
Others answered what induction is, but that may not have been your question.
In winISD, you can either include the effects of induction in the model, or ignore it. It makes for a more accurate model if you do include it, so you should always turn it on if you have the information.
(in the T/S parameters, it's called (lowercase) 'LE', and measured in millihenrys. Car audio manufacturers for example sometimes don't even give a measurement for it.) It doesn't hurt anything to turn it on if you don't have a number there; it just won't change anything. Honestly I don't know why it isn't on by default.
By 'turn it on' they meant turn on the option in winISD. Not that one can turn on or off the induction in the actual driver 🙂
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A small, high performance box with a low tuning will end up balancing the length of the ports vs the air speeds flowing in them. It can take up a surprising amount of volume, or get unreasonably long (ports have their own resonance based on their length; around three feet is a hard maximum for most subs; because it will put the resonance inside the frequencies you want to hear. The resonance is displayed in winISD, and should be at least an octave above your low pass cutoff)
A passive radiator trades all of the length and volume of a port, for money. Effectively it's a zero length, zero volume port, with very few downsides other than cost. As long as you stay within the excursion capacity of the PR's, all issues with chuffing and air speeds disappear.
If one were building a 'Large Low Tuned', the box is so large that even massive & deep tuned ports may be only a foot or so long (so no resonance issues) and only take up a few percent of the box volume, so there's very little benefit to moving to a PR. A tiny box, on the other hand, may nearly require one, because the necessary sized port won't fit!
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