Does anyone have the Sd for this driver?
Dayton RSS390HF-4 15"
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-468
The T/S parameters they post there lacks them.
I'm thinking of using this driver for an infrasonic subwoofer <30 hz in a TL. (I can always reuse the driver for other subwoofer designs as I have lots of scrap wood. Also this needs to be a infrasonic subwoofer because the >30 hz will eventually be taken care of by dual dipole subs). Any advice or critique? I just started running simulations so I have nothing to post yet though. I am looking for somewhat flat response incorporating room gain down to maybe 5hz (not looking for high spl levels, just audible/feelable levels)
Dayton RSS390HF-4 15"
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-468
The T/S parameters they post there lacks them.
I'm thinking of using this driver for an infrasonic subwoofer <30 hz in a TL. (I can always reuse the driver for other subwoofer designs as I have lots of scrap wood. Also this needs to be a infrasonic subwoofer because the >30 hz will eventually be taken care of by dual dipole subs). Any advice or critique? I just started running simulations so I have nothing to post yet though. I am looking for somewhat flat response incorporating room gain down to maybe 5hz (not looking for high spl levels, just audible/feelable levels)
Greets!
If you download the sample response pdf, it lists measured specs and the diameter as 320 mm, ergo Sd = (32^2*pi)/4 = ~804.248 cm^2.
Anyway, even with room gain, you're looking at a huge corner loaded cab and probably more than one sub driver to generate 5 Hz you can feel.
GM
If you download the sample response pdf, it lists measured specs and the diameter as 320 mm, ergo Sd = (32^2*pi)/4 = ~804.248 cm^2.
Anyway, even with room gain, you're looking at a huge corner loaded cab and probably more than one sub driver to generate 5 Hz you can feel.
GM
Heh... for some reason I was thinking it was 3.2 cm and thus thinking that was the diameter of the dustcap (although I realize now thats way to small).
5 hz is REALLY low... but even if you can barelyl feel it... that would be awesome.
IIRC, 1-5hz is earthquake range and 13hz is around a helicopter.
The room I'm in is small so I believe the room gain should be pretty good, however, due to price, I'm not going multiple drivers. Again, this is more proof of concept than for hifi.
5 hz is REALLY low... but even if you can barelyl feel it... that would be awesome.
IIRC, 1-5hz is earthquake range and 13hz is around a helicopter.
The room I'm in is small so I believe the room gain should be pretty good, however, due to price, I'm not going multiple drivers. Again, this is more proof of concept than for hifi.
Thats actually really nice. I kinda wish the the models showed the response below 10hz. I'm still trying to learn how to use the models. Which worksheet are you using?
Unless I'm missing something, you're not getting too much from such a large TL. Take a look at 325 liters using a 6" diameter port that is 26" in length (~14.8hz tune) with 200 watts per driver. With these drivers, you'll typically want to get two, as they aren't output monsters.
Thanks for the suggestion, if messing around with the worksheets gives me nothing I'll try that (or try both, I have LOTS of scrap plywood).
I think I'm getting the hang of using the TL worksheets, just a matter of following the directions.
I think I'm getting the hang of using the TL worksheets, just a matter of following the directions.
Check out this project:
http://sound.westhost.com/project48.htm
It's a subwoofer designed to operate below the resonant frequency. Since your high end requirements are so low this may be perfect for you. And it keeps the box size reasonable.
http://sound.westhost.com/project48.htm
It's a subwoofer designed to operate below the resonant frequency. Since your high end requirements are so low this may be perfect for you. And it keeps the box size reasonable.
I think that dayton isnt a bad sub to try out on an infrasound project, but remember displacement is key when it comes to putting out low bass.
So two will definately be better than one, but by all means you can add a second later instead of buying them both at once(and if you really are satisfied with one... well I wouldnt think you were sane, but you could just keep it that way)
I'd suggest going with a sealed/ported box. Now if you're going for 5hz sealed is the only way to go, and you're never going to get there with less than 4 of these drivers and serious EQ. Ported boxes would require extremely long and large ports. PRs are an expensive option. TLs arent meant to go that far below a driver's resonance(18hz Fs here I believe).
If you just want to get infrasonic(what i reccomend) build a large ported box tuned to ~16hz. I wouldnt go any lower than 15hz because you're going to loose so much efficiency that the port wont really make a huge difference. I wouldnt go higher than 18hz because this is considered audible and can be at high levels.
The port should be reasonable for 16hz tune unless your enclosure is under ~6.5 cubic feet
So two will definately be better than one, but by all means you can add a second later instead of buying them both at once(and if you really are satisfied with one... well I wouldnt think you were sane, but you could just keep it that way)
I'd suggest going with a sealed/ported box. Now if you're going for 5hz sealed is the only way to go, and you're never going to get there with less than 4 of these drivers and serious EQ. Ported boxes would require extremely long and large ports. PRs are an expensive option. TLs arent meant to go that far below a driver's resonance(18hz Fs here I believe).
If you just want to get infrasonic(what i reccomend) build a large ported box tuned to ~16hz. I wouldnt go any lower than 15hz because you're going to loose so much efficiency that the port wont really make a huge difference. I wouldnt go higher than 18hz because this is considered audible and can be at high levels.
The port should be reasonable for 16hz tune unless your enclosure is under ~6.5 cubic feet
Great feedback. I'm not really concerned about box size so WAF is not an issue. Still single anyways 🙂
The Sub-Woofer Controller project may not work out in my application simply because its sealed. I'm trying to maximize the low frequency output using as little drivers as possible, afterall, anyone can go as low as they want given any amount of drivers.
Using the xmax, frequency, listening distance, spl equation, a sealed sub of 805 cm^2 at 14 mm travel will give a spl of 91 db at 7hz with a listening distance of 2 meters. By adding output from a port and adding roomgain, I don't see this project being too farfetched.
Its interesting how both BassAwdyO and SteveCallas both recommend a BR. I thought a TL was the best way to gain extension, no matter how ugly the response.
The way I see it, I'm trying to minimize driver displacement relative to an infinite baffle design while keeping spl as high as possible, than equalize room response to reasonably flat.
The Sub-Woofer Controller project may not work out in my application simply because its sealed. I'm trying to maximize the low frequency output using as little drivers as possible, afterall, anyone can go as low as they want given any amount of drivers.
Using the xmax, frequency, listening distance, spl equation, a sealed sub of 805 cm^2 at 14 mm travel will give a spl of 91 db at 7hz with a listening distance of 2 meters. By adding output from a port and adding roomgain, I don't see this project being too farfetched.
Its interesting how both BassAwdyO and SteveCallas both recommend a BR. I thought a TL was the best way to gain extension, no matter how ugly the response.
The way I see it, I'm trying to minimize driver displacement relative to an infinite baffle design while keeping spl as high as possible, than equalize room response to reasonably flat.
Hara said:
Greets!
Unless you live in an underground bunker, the building's construction becomes increasingly transparent with decreasing frequency, so I wouldn't count on much down really low.
Hara said:
Below Fs, TLs tend to roll off based on whatever its Qp is, so just extend the plot/slope to 5 Hz, which will put it somewhat below 60 dB, IOW too low to feel even if your room gain doesn't roll off much.
SteveCallas said:
Not really, to get a wide BW requires trading away efficiency. Your BR will roll off at 24 dB/octave, so at -24 dB/~7.4 Hz it probably won't be enough to feel at 5 Hz.
preiter said:
Agreed, except that one driver doesn't have enough Xmax and probably not enough Xsus even if the distortion winds up being an acceptable trade-off.
Anyway, the only way I see to potentially get it done with a single driver is with a huge bandpass (BP) that drives an entire floor/ceiling corner. Unfortunately, ideally it needs to be tuned to SQRT(5*30) = ~12.25 Hz, so this will require a closet sized cab..........
GM
If you honestly think you're going to get anything usable at 5hz with a single Dayton HiFi15 in any alignment, you're living in a fantasy world. Keep in mind that to maintain the perceivability of subsonic frequencies, you need better than flat response, you need a rising response, as our sensitivity decreases rapidly.
If you really feel like spending enough money to achieve your goal of usable output to 5hz - which again means a rising response to 5hz - you'll need to start stocking up on multiple large drivers, put them in an IB, and EQ the hell out of them. Otherwise, set a more realistic goal of ~15hz.
Hey,
You're right about wanting even decent 5hz response. Looking at the models, its just WAY to low. Response is too crazy, extrapolating beyond 10hz is also unpredictable, and even with the stockpile of wood, the line is just too long. It's just easier if I tune higher.
I think a more realistic goal is output to ~13 hz which is the fundamental of a helicopter. However, now I'm probably wanting up to 40hz, with a much better frequency response.
You're right about wanting even decent 5hz response. Looking at the models, its just WAY to low. Response is too crazy, extrapolating beyond 10hz is also unpredictable, and even with the stockpile of wood, the line is just too long. It's just easier if I tune higher.
I think a more realistic goal is output to ~13 hz which is the fundamental of a helicopter. However, now I'm probably wanting up to 40hz, with a much better frequency response.
SteveCallas said:
Greets!
Being a rather pragmatic sort, I don't have any interest in wasting my time indulging in 'flights of fantasy', especially when trying to help folks meet an audio performance goal, and haven't asserted that it can for sure be done, though from experience with making house shaking bass I postulated how it might happen if the driver's published specs are 'close enough' and the room isn't a complete acoustic sieve down low.
To hear infrasonic frequencies requires a rising response with decreasing frequency, so hearing them below ~16 Hz is pretty much out of reach, but to just 'feel' it we only need to energize the structure, which doesn't necessarily require as much SPL. I literally cosmetically busted up my home from floor to ceiling and structurally damaged it to some extent with BW limited ~16 Hz pipe organ music at ~live levels, but sweeping it with a sinewave generator to find resonant modes didn't consume nearly as much power.
Anyway, I just 'ran the numbers' for a straight taper TL to see if my experience based 'postulation' had any merit and with the above caveats and further assuming MJK's WS is reasonably accurate down this low (it's 'close enough' IMO), I'm satisfied that I'm somewhat more firmly 'planted' in the real world WRT this driver/app than you.
L = 341.56"
CSA = 306.25"^2
zdriver = 7.5"
At ~60.54 ft^3 net, it's ~ the size of the average closet (at least where I live) and calcs nominally flat from ~5 - 30 Hz/90 dB min. half space sens, so when folded up so both the driver and terminus are together at the bottom, then once the optimum distance is found from the corner's apex to complete the BP there should in theory be enough in-room acoustic sens to offset the driver's otherwise mechanically limited gain in the 10-25 Hz BW and enough peaking at Fp to excite 5 Hz. Only one way to know for sure though..............
GM
Attachments
Hara said:
Greets!
Then a MLTL tuned to 13 Hz is your best option IMO, though at ~12 ft^3 net it's still going to be pretty big by most folk's standards.
GM
GM,
Wow... you actually came up with the curve I was originally looking for. I'm still trying to gain some intuition using these models. The insight I learned so far was that widening CSA usually lowers average spl, lowers the extension, and somewhat flattens the response while tightening does the opposite. I have been experimenting with somewhat of a large port for a MLTL and was able to shorten the line a bit given a different set of design goals.
I'm glad at least the curves shows the somewhat viability of using TLs for really low extension, but rather than pursuing this pipe dream, I now am raising the tuning frequency in order to have real world usability.
What kind of subs are you using?
BTW, I'm trying to simulate the super low sub with your parameters. A CSA of 306.25 "^2 is 1974 cm^2 and thus 2.48 * Sd of 805 cm right? Also, zdriver would be driver offset so the center of the driver is 7.5 " below the closed end?
For some reason my graph shows a downward sloping response starting at 30hz maintaining a 5db increase relative to the IB model.
Sorry, I'm unfamiliar with the acronym BP. What does it mean in this context?
EDIT: BP stands for Bandpass
Thank you for your postulations and advice. I really appreciate it. I learn a lot just trying to design something even if the design isn't eventually used. Hopefully these posts will be of some use to others.
Wow... you actually came up with the curve I was originally looking for. I'm still trying to gain some intuition using these models. The insight I learned so far was that widening CSA usually lowers average spl, lowers the extension, and somewhat flattens the response while tightening does the opposite. I have been experimenting with somewhat of a large port for a MLTL and was able to shorten the line a bit given a different set of design goals.
I'm glad at least the curves shows the somewhat viability of using TLs for really low extension, but rather than pursuing this pipe dream, I now am raising the tuning frequency in order to have real world usability.
What kind of subs are you using?BTW, I'm trying to simulate the super low sub with your parameters. A CSA of 306.25 "^2 is 1974 cm^2 and thus 2.48 * Sd of 805 cm right? Also, zdriver would be driver offset so the center of the driver is 7.5 " below the closed end?
For some reason my graph shows a downward sloping response starting at 30hz maintaining a 5db increase relative to the IB model.
Sorry, I'm unfamiliar with the acronym BP. What does it mean in this context?
EDIT: BP stands for Bandpass
Thank you for your postulations and advice. I really appreciate it. I learn a lot just trying to design something even if the design isn't eventually used. Hopefully these posts will be of some use to others.
That size is acceptable in my case, but anything significantly larger is not (for the new design goals).
Greets!
You're welcome!
I had a 'stereo' pair of corner loaded ServoDrive Contrabass subs, but had to sell them as part of a 'fire' sale to help support the greedy medical cartel. Now I'm back to the 'subs' I built back in '69, which are ~20 ft^3 MLTLs loaded with '50s era Altec 515B cinema horn drivers (see pic).
I use Convert.exe, which calcs 306.25"^2 = 1975.803 cm^2/804.248 cm^2 = ~2.4567*Sd.
Right, 'zdriver' is just half the driver's overall diameter (o.d.), which is acoustically the same as end loaded, putting it right at floor level for max boundary gain.
Don't know why you're not getting the same plot. I used the measured specs on the pdf plus the 'Sd' I posted.
GM
You're welcome!
I had a 'stereo' pair of corner loaded ServoDrive Contrabass subs, but had to sell them as part of a 'fire' sale to help support the greedy medical cartel. Now I'm back to the 'subs' I built back in '69, which are ~20 ft^3 MLTLs loaded with '50s era Altec 515B cinema horn drivers (see pic).
I use Convert.exe, which calcs 306.25"^2 = 1975.803 cm^2/804.248 cm^2 = ~2.4567*Sd.
Right, 'zdriver' is just half the driver's overall diameter (o.d.), which is acoustically the same as end loaded, putting it right at floor level for max boundary gain.
Don't know why you're not getting the same plot. I used the measured specs on the pdf plus the 'Sd' I posted.
GM
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