Hello. I'm planning on building a small-ish sealed sub with the Dayton RSS315HF-4. When using WinISD to model a box, I have come up with this:
This seems very peculiar that this would be possible with this configuration. What am I missing? When I input the amount of power (I'll be using a Behringer EP1500, can go to 1400W @ 4ohm) to 500W, the apparent load spikes to over 60k VA. I'm not sure if this is supposed to be this way and that my sub design is completely pointless due to ridiculous power requirements, or if I am inputting data and misinterpreting the graphs.
If I am able to build a sub that is nearly flat to 20hz and good to about 14 in an enclosure of only 1.94ft^3, this is incredible. However this doesn't seem possible given Hoffman's Iron Law. Please help me understand what I'm doing wrong in designing this sub. Thanks!
This seems very peculiar that this would be possible with this configuration. What am I missing? When I input the amount of power (I'll be using a Behringer EP1500, can go to 1400W @ 4ohm) to 500W, the apparent load spikes to over 60k VA. I'm not sure if this is supposed to be this way and that my sub design is completely pointless due to ridiculous power requirements, or if I am inputting data and misinterpreting the graphs.
If I am able to build a sub that is nearly flat to 20hz and good to about 14 in an enclosure of only 1.94ft^3, this is incredible. However this doesn't seem possible given Hoffman's Iron Law. Please help me understand what I'm doing wrong in designing this sub. Thanks!
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You'll need to look at how much electrical gain that circuit is giving, my guess is a LOT. Look at the Transfer funtion magnitude (EQ/Filter). Over 10dB is kind of pushing it as a general rule.
Cone excursion will show you the excurion at different power inputs. Observe what switching the LT in and out does to the trace. Scary?
The Max SPL trace will show you how much SPL you can actually achieve at different frequencies, taking into account thermal handling and xmax limits. You'll need to decide if this driver in this enclosure can produce suffient SPL at such low frequencies. I doubt on paper that it will, however you have room gain to help you.
My choice would be to LT to only 25-30Hz and rely on room gain to extend the response further. So little content below these frequencies that it doesn't seem worth the extra power and potential driver damage to try to make this 'flat' to 14Hz.
Cone excursion will show you the excurion at different power inputs. Observe what switching the LT in and out does to the trace. Scary?
The Max SPL trace will show you how much SPL you can actually achieve at different frequencies, taking into account thermal handling and xmax limits. You'll need to decide if this driver in this enclosure can produce suffient SPL at such low frequencies. I doubt on paper that it will, however you have room gain to help you.
My choice would be to LT to only 25-30Hz and rely on room gain to extend the response further. So little content below these frequencies that it doesn't seem worth the extra power and potential driver damage to try to make this 'flat' to 14Hz.
When designing a sub so that the cone doesn't reach its max excursion, do you model it so that it never crosses Xmax or so that it doesn't cross at a certain frequency. I'm finding that when I put the LT at 25Hz, I'm able to put in 45W and have it reach Xmax at about 12Hz. Will this be fine?
Also, I'll be in a pretty small room (1500ft^3). Do you think the room gain in a room this small will be enough to drop me to around 20Hz? SPL at 45W gets me 96dB in WinISD. Here are the graphs:
Also, I'll be in a pretty small room (1500ft^3). Do you think the room gain in a room this small will be enough to drop me to around 20Hz? SPL at 45W gets me 96dB in WinISD. Here are the graphs:
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Reduce the Qtp to 0.5, and relax the extension requirements. With decreasing frequency comes increasing power. With increasing level, comes even more power. You've tried to use a lot of both, so yes, 60k VA probably isn't far off.
What SPL is ideal for a) listening to music and b) watching movies/playing games? I've tweaked this design a bit and have a very good response in everything except SPL, which is nearly flat at 98dB until 21Hz, at which point it has a nice even slope. 15Hz is 90dB and 10Hz is 83.5dB. Will 98dB be enough? It seems like 98dB is quite a large number, and I don't think I'll be listening that loud. Then again, I've never measured my speakers before. What do you think?
Also, what would happen if I build two of these subs and put them on opposite sides of the room? I imagine SPL would increase as well as low freq. response, but I've never tried having two subs before.
Also, what would happen if I build two of these subs and put them on opposite sides of the room? I imagine SPL would increase as well as low freq. response, but I've never tried having two subs before.
The design is entirely reasonable and is patterned after the classic AR1W which has a system 3db point at 42 hz with a Q of .707. The free are resonance of that driver is around 19 hz. The heavy mass, high compliance, long excursion, high power handling capacity, and equalizable 12db per octave falloff make this one of the best designs ever. To improve it, put two in a double sized enclosure (Teledyne AR9 is an example.) BTW, Parts Express offers both the single and double driver versions as kits. Don't forget the stuffing. Having it in the right amount is critical, it controls the damping factor Q. THD should also be very low. I think you'll be pleased with the results.
Would it be better to put two in the same box or to have two separate boxes? I suppose two in the same box will be much easier to power. It's just going to be quite large and difficult to fit in my small dorm room. My room mate is into this stuff too, but I'd like to have somewhere to sleep as well. Could you offer some rough dimensions that would get me in the right direction?
Would you please explain where you're getting 3500W from? Yes, I have considered ported, however they are large and I've had trouble designing one that won't eat up my precious space.
a dorm room... hu... 98db at 30hz will be enough to ****-off everyone on your floor.
I was responding to a your design above, never mind, you've changed it.
So 98dB will be enough? That's what I had figured but most sub designs I see are up around 104dB. Obviously I won't be running it that high, I was just curious as to what most people shoot for.
I think I'll start by just building the single sub. If someday down the road I decide I need more, I can always build another or make the dual version. I just don't need that much bass right now.
Time to start enclosure design. .75" MDF or 1" MDF? I'll be bracing the living crap out of it on the insides, if it matters. Cube or rectangular? I'm thinking cube. I'll have to model everything in a CAD program to find out the actual internal volume, but I'm thinking somewhere around 18" with 1" MDF. Overkill do you think? I'm planning on having it front-firing.
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If you're going to use a LT... 1" at least. you can't overbuild. Have you tried boxnotes? Boxnotes - Free Speaker Design Software
I build my personal system to handle 25db transient peaks over 85db avg. (110db) to eliminate music compression via reproduction. which is enough to actually induce a fight or flight response in most people when the "boom" hits in some movies. but i'm also in a dedicated bunker / man-cave.
I build my personal system to handle 25db transient peaks over 85db avg. (110db) to eliminate music compression via reproduction. which is enough to actually induce a fight or flight response in most people when the "boom" hits in some movies. but i'm also in a dedicated bunker / man-cave.
I haven't used Boxnotes before, but after tinkering it looks to be a very useful program. Is it better to plug in my volume and let it do the math? When I do that, I get a rectangular box, not a cube. Is this ideal? The graph at the bottom has the resonances all spaced out when it is a rectangular prism, whereas they are condensed into just three frequencies when I alter the sides to be a cube. Which is better? I like the look of cubes more but I'll build a rectangular prism if it makes a difference acoustically.
With sub's the shape dosen't really matter as long as none of the sides are really long so as the resonance of the pannel isn't in the frequency range of the sounds it will be producing, or the first harmonics. (above 200hz and you're good)
I'd plug in the internal volume you want then fiddle with the dimensions to get it as cube like as you want. pay head to the working volume (bottom right of screen in blue) That is the volume you want to match up to your simulation in winISD.
edit: when you are putting numbers in the dimensions section, If you click on the box once you can enter a parameter if you click twice it will auto calculate from the last changed box, say, you make the volume larger then double click on one of the other dimension boxes it will change that box to the correct dimension for the volume entered.
I'd plug in the internal volume you want then fiddle with the dimensions to get it as cube like as you want. pay head to the working volume (bottom right of screen in blue) That is the volume you want to match up to your simulation in winISD.
edit: when you are putting numbers in the dimensions section, If you click on the box once you can enter a parameter if you click twice it will auto calculate from the last changed box, say, you make the volume larger then double click on one of the other dimension boxes it will change that box to the correct dimension for the volume entered.
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Hi,
The Apparent Load tab on winISD is the power output required of the amp when an un-eq'd part of the response is at 1 watt (or whatever power input you specify).
So, set the input power to 45w, check under apparent load to see how much you're actually hitting the driver with.
If you go for a final Q of 0.5, you'll find a smoother response to being placed up against the wall, and less eq is actually needed, reducing the demand on the driver etc.
Chris
The Apparent Load tab on winISD is the power output required of the amp when an un-eq'd part of the response is at 1 watt (or whatever power input you specify).
So, set the input power to 45w, check under apparent load to see how much you're actually hitting the driver with.
If you go for a final Q of 0.5, you'll find a smoother response to being placed up against the wall, and less eq is actually needed, reducing the demand on the driver etc.
Chris
Two in a double sized box will beat two in two single boxes. The system F3 resonance drops froom 42 hz to 28 hz between AR1W and its descendants and Teledyne AR9. The result is wall and floor shaking, window shattering if you're not careful and chest thumping. It can be forced to produce the same thumpy lumpy false bass that is actually upper bass exaggeration that lesser systems produce but when properly used, it will simply extend an octave or more below what you're used to. It seems to just be getting started where other systems quit.
Such wide range systems do have drawbacks though. You will hear rumble on turntables and records, even cds that are silent with lesser woofers, there will be acoustic feedback for many if not most turntables, and you will excite every room resonance you've got. The temptation to use its capability is certainly there and if you rent and have a lease you could wind up breaking it.
The latest Parts Express kit with two of these drivers probably will produce bass comparable to Teledyne AR9. One caution, placement of side firing woofers is critical. Against a back wall and move it left and right until you reach an optimal spot. Two such systems are recommended, I never liked the one subwoofer idea.
BTW, the AR12" woofer was impulse tested by HH Labs to handle over 1KW without distorting. This driver might handle even more. Don't worry about the air pressure inside the box (the enclosure must be very sturdy made of 3/4" MDF or stronger and internally braced) IMO you will be hard pressed to find a better subwoofer than this variant at any price. I think the Parts Express kits with amplifiers are about $1000 per double sided unit.
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