I am looking for more and more ways to add subs to my collection. Currently I have two finished. I have a spare 15" pro audio woofer that might get an enclosure. I also have a huge 5.35 cu.ft. enclosure awaiting a little finishing and an Adire DPL12 or Shiva.
My next thought was to use a cheaper PR (maybe a Dayton one from PartsExpress) and a Shiva or DPL12 again. I much prefer 12"-ers to 15's. The idea would be active woofer down-firing with PR up. Would this work well? What are some ways to figure needed enclosure volume and such when using PRs?
Thanks
My next thought was to use a cheaper PR (maybe a Dayton one from PartsExpress) and a Shiva or DPL12 again. I much prefer 12"-ers to 15's. The idea would be active woofer down-firing with PR up. Would this work well? What are some ways to figure needed enclosure volume and such when using PRs?
Thanks
I think that WinISD Pro, has a section for PRs. Also, check the software link on diyaudio, and start poking around for some subwoofer simulatino softare..Once you find something you like, you should be good to go.
Same question
I had the same type of idea, with the Shiva or DPL12 downfiring and an upward facing PR. I almost gave up on the idea because I was gonna use Adire's volume for their EBS PR box (here's the PDF), but with the PR facing up, and I wasn't sure how much weight to add to the PR to tune it and stuff. I figured since gravity was now acting against the PR, it wouldn't need as much, if any, added weight. SO, to reincart this post, I ask the following:
(a) would the net volume be the same in a sonosub with upward-firing PR as with Adire's reference design EBS PR box?
(b) how do I figure out the required mass to add to the PR for tuning (note: I have the Loudspeaker Design Cookbook, and didn't really see a method in there to figure it out, and I tooled around with Adire's LSCAD or whatever but the values were off for the shiva, so I feel I am stuck unless some other freeware program is available that could calculate it)?
(c) would an upward firing DPL12 be better in this situation than a downfiring Shiva (or perhaps a downfiring DPL12 in place of the upward-firing PR...)?
(d) I will go home today, download WinISD Pro and try to figure that out, and since I already put a (d) in front of this, I suppose this has to be a question, so is WinISD Pro your favorite subwoofer program thingy?
I was thinking about using 18" sonotube with a cheapo 350W Rythmik amp. My room is roughly 16'DX20'WX8'H, though I will be moving within the year (and probably won't start building until then). That's all I got for now. Thanks in advance.
I had the same type of idea, with the Shiva or DPL12 downfiring and an upward facing PR. I almost gave up on the idea because I was gonna use Adire's volume for their EBS PR box (here's the PDF), but with the PR facing up, and I wasn't sure how much weight to add to the PR to tune it and stuff. I figured since gravity was now acting against the PR, it wouldn't need as much, if any, added weight. SO, to reincart this post, I ask the following:
(a) would the net volume be the same in a sonosub with upward-firing PR as with Adire's reference design EBS PR box?
(b) how do I figure out the required mass to add to the PR for tuning (note: I have the Loudspeaker Design Cookbook, and didn't really see a method in there to figure it out, and I tooled around with Adire's LSCAD or whatever but the values were off for the shiva, so I feel I am stuck unless some other freeware program is available that could calculate it)?
(c) would an upward firing DPL12 be better in this situation than a downfiring Shiva (or perhaps a downfiring DPL12 in place of the upward-firing PR...)?
(d) I will go home today, download WinISD Pro and try to figure that out, and since I already put a (d) in front of this, I suppose this has to be a question, so is WinISD Pro your favorite subwoofer program thingy?
I was thinking about using 18" sonotube with a cheapo 350W Rythmik amp. My room is roughly 16'DX20'WX8'H, though I will be moving within the year (and probably won't start building until then). That's all I got for now. Thanks in advance.
I'd assume, correct me if I'm wrong, that since the acting force from gravity is working the same as it is in the opp. orientation. Assuming that Xmax/2 would give you your excursion in either way, it wouldn't matter.
hmmm
The PR in the Adire reference design is forward-facing, and gravity will not effect the resting position of the driver, and xmax will be unchanged. In an upward-facing position, gravity will pull the driver down from its resting position, thereby increasing xmax. Adire gives a moving mas of 285 grams (or ~2.8N) and a compliance of 1.25 mm/N, so with no additional mass added, the driver will move down (1.25 mm/N)*(2.8N) = 3.5mm. So, xmax will go from the original 31mm one way to 34.5mm one way. That said, I have no idea what the relationship is between xmax and tuning frequency.
(I think I just got what you were saying - that the total forward and back excursion would be unchanged, and xtotal/2 would be the same. Adire only gives xmax as a one-way number, though.)
WinISD makes a pretty graph with about 90 grams added, though I put the xmax as 31mm. With the xmax as 34.5, the graph does not change. In fact, it doesn't change if I put in 345mm. I feel cheated.
The PR in the Adire reference design is forward-facing, and gravity will not effect the resting position of the driver, and xmax will be unchanged. In an upward-facing position, gravity will pull the driver down from its resting position, thereby increasing xmax. Adire gives a moving mas of 285 grams (or ~2.8N) and a compliance of 1.25 mm/N, so with no additional mass added, the driver will move down (1.25 mm/N)*(2.8N) = 3.5mm. So, xmax will go from the original 31mm one way to 34.5mm one way. That said, I have no idea what the relationship is between xmax and tuning frequency.
(I think I just got what you were saying - that the total forward and back excursion would be unchanged, and xtotal/2 would be the same. Adire only gives xmax as a one-way number, though.)
WinISD makes a pretty graph with about 90 grams added, though I put the xmax as 31mm. With the xmax as 34.5, the graph does not change. In fact, it doesn't change if I put in 345mm. I feel cheated.
A) First, let me say this: I have reservations about mounting any driver with low Fs and long excursion upwards or downwards, regardless of the manufacturer's assurances. The woofer obviously has to have a loose suspension to travel that far. It is hard to imagine that it can stay centered over the course of time.
There is at least one post on this forum where somebody believed the manufacturer's assurance that downward or upward mounting is acceptable, and found that in a couple of years he had a ruined sub. He did not say if this was an Adire sub.
I suppose one consideration might be that the Shiva and Tempest are priced so that replacement every few years would not be an outrageous expense, especially since the Shiva has a foam surround which might need replacement by then anyway. I cannot say for a fact that these Adire subs would need replacement every few years in any case. I am speculating.
B) If you are going to mount it up-or downward firing, I would mount the Drone Cone, (Passive Radiator) down and the woofer up. The reason? Both Ported and Passive Radiator subs are bass reflexes, although the Passive Radiator sub is never referred to as that. They follow the same principles, with the Passive Radiator substituting for the port.
There has been much written on this forum by people who have built downward firing ports on floor mounted ported subs, with the subjective response that it smooths the response quite a bit. Remember, your lowest frequencies are coming from the port or Drone Cone, not the speaker itself. Therefore, I would suggest that you follow the advice that ported sub makers are following and point your Passive Radiator downward and your speaker upward. That is, if you want to take the chance and use the up-and-down mounting.
C) To tune the Passive Radiator, simply decide what Fb you want and add weight until the Minimum impedance is at your desired Fb frequency. Freeware online tone generators are available online, all that would be necessary would be an inexpensive multimeter which is highly borrowable.
There is at least one post on this forum where somebody believed the manufacturer's assurance that downward or upward mounting is acceptable, and found that in a couple of years he had a ruined sub. He did not say if this was an Adire sub.
I suppose one consideration might be that the Shiva and Tempest are priced so that replacement every few years would not be an outrageous expense, especially since the Shiva has a foam surround which might need replacement by then anyway. I cannot say for a fact that these Adire subs would need replacement every few years in any case. I am speculating.
B) If you are going to mount it up-or downward firing, I would mount the Drone Cone, (Passive Radiator) down and the woofer up. The reason? Both Ported and Passive Radiator subs are bass reflexes, although the Passive Radiator sub is never referred to as that. They follow the same principles, with the Passive Radiator substituting for the port.
There has been much written on this forum by people who have built downward firing ports on floor mounted ported subs, with the subjective response that it smooths the response quite a bit. Remember, your lowest frequencies are coming from the port or Drone Cone, not the speaker itself. Therefore, I would suggest that you follow the advice that ported sub makers are following and point your Passive Radiator downward and your speaker upward. That is, if you want to take the chance and use the up-and-down mounting.
C) To tune the Passive Radiator, simply decide what Fb you want and add weight until the Minimum impedance is at your desired Fb frequency. Freeware online tone generators are available online, all that would be necessary would be an inexpensive multimeter which is highly borrowable.
Well, Lots of people have mounted shiva's in downward or upward firing configurations, I have not heard about them being ruined for this reason. All of the speaker programs work pretty much the same for basic enclosure calculations, so whatever works for you should be fine. I downloaded a couple and checked them against each other. One thing im confused about though, why use a PR instead of a port? designing and tuning a port is easier, and the shiva works well ported.
I disagree with you TDruan, you asy that there is a droop in the PR, which I agree with, but why would it's Xmax increase? The droop position or, the position at which Fg is acting creates some negative resistance when the PR is moving upwards (outward) thus creating the droop at rest. I believe that your 3.5mm. should be subtracted from the overall Xmax as the driver is now facing more forces than before. Fnet=Fa(from air inside)-Fg-Faout(air outside). Instead of just Fnet=Fa-Faout
Bose(o) - I'm sure you'll end up being right - I'm just waiting for that "ohhhh, I get it" moment. But for now, I might as well walk the path of the ignorant newbie. Onto the education of Little Tree. 
Ok, the reason I thought xmax would increase is because the upward firing position does not change either the mechanical compliance or the physical limit to how far the cone can travel in the forward (outward) position. If the cone can go X-mm forward when facing forward, it is able to go X-mm when facing upwards. So I figured xmax would increase because it is now able to move the original amount that it would if it were forward facing, plus the amount it lost to droop. As to the air pressure forces you mention, I don't see how those will come into play since the chamber isn't (de)pressurized before it's sealed up, so the air pressures will cancel. So from what I can tell, there is only the force due to gravity acting to push the PR down, and the force of the spider acting to push it up. But since xmax does not seem to matter much to WinISD, I am still confused as to its role in frequency response. I guess this question is really, "Why does a Passive Radiator need to move roughly twice the air as the powerd driver?"
kelticwizard - I agree with you on the downward firing issue, I never got why you would want to blast a speaker into the floor. I guess with a sub it would sort of help with the perceived omnidirectionality of the sound since it's not facing the listening position, but who knows. Up/Downward firing does produce forces that the speaker is designed to take while making sound, and the force on the driver is more symmetric than a forward facing driver since the sag is axial rather than radial, so over time I would actually prefer an up/down set-up as it seems to imply a decreased lifespan of the driver as opposed to a possible distortion of the sound of the driver over time. Anyway, like you said, the Adire stuff is relatively cheap, so whatever. I like the idea of downfiring the PR if it would produce better results. I was planning on a top and bottom "cap" over the drivers anyway, so flipping it would probably not do a whole lot (changes resting position of cone and adds a lot more surface area to the cap, perhaps giving it more of a horn-like jive to it?).
kevyjo - As to the Passive Radiator versus the vent, I threw it in WinISD and the curves are similar, but the vent one got louder at frequencies around 20Hz as opposed to being flat and dropping off at around 20 Hz. (this is with a 4.9ft^3 box tuned to 16.66Hz and a 22" long 4" dia. vent). Nothing dramatically different from the PR, just not as flat. I guess the vent would be cheaper, but I hear stuff about wind noise and pipe resonance and think PR would pose fewer such issues. Is a vent this size problem-prone?
Ok, the reason I thought xmax would increase is because the upward firing position does not change either the mechanical compliance or the physical limit to how far the cone can travel in the forward (outward) position. If the cone can go X-mm forward when facing forward, it is able to go X-mm when facing upwards. So I figured xmax would increase because it is now able to move the original amount that it would if it were forward facing, plus the amount it lost to droop. As to the air pressure forces you mention, I don't see how those will come into play since the chamber isn't (de)pressurized before it's sealed up, so the air pressures will cancel. So from what I can tell, there is only the force due to gravity acting to push the PR down, and the force of the spider acting to push it up. But since xmax does not seem to matter much to WinISD, I am still confused as to its role in frequency response. I guess this question is really, "Why does a Passive Radiator need to move roughly twice the air as the powerd driver?"
kelticwizard - I agree with you on the downward firing issue, I never got why you would want to blast a speaker into the floor. I guess with a sub it would sort of help with the perceived omnidirectionality of the sound since it's not facing the listening position, but who knows. Up/Downward firing does produce forces that the speaker is designed to take while making sound, and the force on the driver is more symmetric than a forward facing driver since the sag is axial rather than radial, so over time I would actually prefer an up/down set-up as it seems to imply a decreased lifespan of the driver as opposed to a possible distortion of the sound of the driver over time. Anyway, like you said, the Adire stuff is relatively cheap, so whatever. I like the idea of downfiring the PR if it would produce better results. I was planning on a top and bottom "cap" over the drivers anyway, so flipping it would probably not do a whole lot (changes resting position of cone and adds a lot more surface area to the cap, perhaps giving it more of a horn-like jive to it?).
kevyjo - As to the Passive Radiator versus the vent, I threw it in WinISD and the curves are similar, but the vent one got louder at frequencies around 20Hz as opposed to being flat and dropping off at around 20 Hz. (this is with a 4.9ft^3 box tuned to 16.66Hz and a 22" long 4" dia. vent). Nothing dramatically different from the PR, just not as flat. I guess the vent would be cheaper, but I hear stuff about wind noise and pipe resonance and think PR would pose fewer such issues. Is a vent this size problem-prone?
By the way, do you already have an amp for this sub? Apexjr has a 400w amp along with the sae1205 (very similar to the shiva) for only 250, which is the combo i used, and the amp and the driver are of excellent quality. If you want to go with a higher quality driver, you might want to check out stryke audio, there av12 is a beast for only 120.
Port noise is simply an issue of air speed though the port which is lowered the bigger the port is. 4" is pushing the lower end I'd say, my sub is roughly a copy of the old HSU 12 sub in a 24" sonotube (both port and driver face down so it makes a nice table). The HSU used two 4" ports, which had to be curved around to get the proper tuning. I used a single 5" driver because I was able to fit a single tube in with the proper port tuning (around 17hz in my case), and it was very simple and cheap (free actually, the port is a cardboard tube from a carpet store they gave me). I get NO port noise at all. A single 4" port would probably work, there would likely be some port noise, but would likely be small enough to be totally masked by music/movies playing. (pay attention to the "mach" speed of the port, there are various links out there discussing what is an acceptable mach speed, there should be a mach speed calculation in youre box program).
As far as the pr vs. port, I'm sure either way would work, I like ports better because its very simple, cheap, and you have total control of the tuning. Also, as far as the frequency hump at 20hz, if its a small one its not likely to be noticable, and might even be helpful in the subs performace. Play around with various combinations of port size/lenghths on the program! I tweaked mine until i got a design with no port noise and totally flat response to 17hz. As far as the driver placement goes, excellent subs have been built with drivers facing up, port down, driver down and port up, both driver and port down and both driver and port up (sub would need to be very tall in that configuration), all designs will work, they just need to be tweaked differently as far as placement goes (my design with both driver and port down I think is the fussyest to place properly, but delivers the most viceral bass once you have it tweaked). Also, these designs i think work best if you are using the sub as really a SUB, only covering the very lowest frequencies, with pretty much full range R and L speakers (my front speakers go down solidly to about 35hz, so my sub was really optimized just to cover the 15 to 35 hz range, which i think the downward facing design is really good for)
Port noise is simply an issue of air speed though the port which is lowered the bigger the port is. 4" is pushing the lower end I'd say, my sub is roughly a copy of the old HSU 12 sub in a 24" sonotube (both port and driver face down so it makes a nice table). The HSU used two 4" ports, which had to be curved around to get the proper tuning. I used a single 5" driver because I was able to fit a single tube in with the proper port tuning (around 17hz in my case), and it was very simple and cheap (free actually, the port is a cardboard tube from a carpet store they gave me). I get NO port noise at all. A single 4" port would probably work, there would likely be some port noise, but would likely be small enough to be totally masked by music/movies playing. (pay attention to the "mach" speed of the port, there are various links out there discussing what is an acceptable mach speed, there should be a mach speed calculation in youre box program).
As far as the pr vs. port, I'm sure either way would work, I like ports better because its very simple, cheap, and you have total control of the tuning. Also, as far as the frequency hump at 20hz, if its a small one its not likely to be noticable, and might even be helpful in the subs performace. Play around with various combinations of port size/lenghths on the program! I tweaked mine until i got a design with no port noise and totally flat response to 17hz. As far as the driver placement goes, excellent subs have been built with drivers facing up, port down, driver down and port up, both driver and port down and both driver and port up (sub would need to be very tall in that configuration), all designs will work, they just need to be tweaked differently as far as placement goes (my design with both driver and port down I think is the fussyest to place properly, but delivers the most viceral bass once you have it tweaked). Also, these designs i think work best if you are using the sub as really a SUB, only covering the very lowest frequencies, with pretty much full range R and L speakers (my front speakers go down solidly to about 35hz, so my sub was really optimized just to cover the 15 to 35 hz range, which i think the downward facing design is really good for)
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