I am currently in the process of building a pair of Zaph ZRT. And at the same time, I've got a mind towards the subwoofer that I will pair with them. And honestly, I've been all over the place, and am full of indecision.
What I think I like: T/L or Passive Radiator.
Why do I like those? I like the small size of the PR, with the combined qualities of both a sealed and ported box. T/L I like, due to the shallow roll-off. I find the potential size of a T/L worrisome.
I have (3) SoundSplinter 15" woofers available, of which one would be the candidate for the PR sub. If I were to go with a T/L, I'd use either a 10" Dayton HO, or (2) 8" Dayton HO. (with a mind to build a second unit later, if I liked the sound)
Intended purpose: Music - anything from classical instrumental to modern rock, some TV/Movies, and a general multi-purpose (but high quality) sound stage.
My room is approximately 12' X 20', with the listening layout spanning the shorter dimension.
I don't want to do giant ported subs. No sonotubes. I'm not really a fan of strictly sealed boxes.
Just want some opinions from those who know the (2) types of subs that I've laid out, or who know of an alternative that would give me a better listening experience than I deserve.
THank you.
What I think I like: T/L or Passive Radiator.
Why do I like those? I like the small size of the PR, with the combined qualities of both a sealed and ported box. T/L I like, due to the shallow roll-off. I find the potential size of a T/L worrisome.
I have (3) SoundSplinter 15" woofers available, of which one would be the candidate for the PR sub. If I were to go with a T/L, I'd use either a 10" Dayton HO, or (2) 8" Dayton HO. (with a mind to build a second unit later, if I liked the sound)
Intended purpose: Music - anything from classical instrumental to modern rock, some TV/Movies, and a general multi-purpose (but high quality) sound stage.
My room is approximately 12' X 20', with the listening layout spanning the shorter dimension.
I don't want to do giant ported subs. No sonotubes. I'm not really a fan of strictly sealed boxes.
Just want some opinions from those who know the (2) types of subs that I've laid out, or who know of an alternative that would give me a better listening experience than I deserve.
THank you.
Which sound splinter 15s do you have?
Looking at the rl p15 dual 4ohm driver the specs seem like it would work well in a transmission line. Unable to simulate here.
For clarification sake, a PR box should be treated the same as a ported box. The PR just serves rear wave output instead of a port. Same size enclosure will be needed.
A TL can be done, assuming needed path length and taper rate will fit, in a box generally around the size of a sealed enclosure.
I don't see any reason not to use the drivers you have on hand, a few technical details and I'm sure others would be happy to help
Looking at the rl p15 dual 4ohm driver the specs seem like it would work well in a transmission line. Unable to simulate here.
For clarification sake, a PR box should be treated the same as a ported box. The PR just serves rear wave output instead of a port. Same size enclosure will be needed.
A TL can be done, assuming needed path length and taper rate will fit, in a box generally around the size of a sealed enclosure.
I don't see any reason not to use the drivers you have on hand, a few technical details and I'm sure others would be happy to help
I have the RL-P15. I think that's a bit large for a transmission line. I see that cabinet being ridiculously huge. If I use a transmission line, I would almost certainly use one of the Dayton variety. Contrary to what you've posted, every model that I've ever seen or attempted for a PR is more along the size of a sealed. Before he passed, MikeP at the Home Theater Shack, gave me a model for these woofers in 5 cu. feet, with 2 passive radiators, tuned to 23 Hz. The ported size for these is 10 cu. ft.
I'd be interested to see a model of T/L for the 15, along with the tuning and cabinet size. If it were just the right size of huge - but not too huge, huge, I could do (2) of them, and lay it over vertically, and make it into a piece of furniture at the front of my listening room.
I'd be interested to see a model of T/L for the 15, along with the tuning and cabinet size. If it were just the right size of huge - but not too huge, huge, I could do (2) of them, and lay it over vertically, and make it into a piece of furniture at the front of my listening room.
The Subwoofer DIY page v1.1 - Transmission Line Systems
The Subwoofer DIY Page - Passive Radiator Systems
I'd have to simulate what you propose above, but unable to right now.
I'd suspect the choice of PRs was to prevent vent noise at high power due to the size of vent to achieve tuning.
Specs for those that may be able to help
Dual 2 Ohm Dual 4 Ohm Measurements
Qts: 0.333 Qts: 0.447 Mounting Depth: 17.5 cm
Qes: 0.363 Qes: 0.508 Total Depth: 18.5 cm
Qms: 4.032 Qms: 3.728 Outside Diameter: 31.8 cm
Fs: 23.426 Hz Fs: 27.487 Hz Weight: 35 lbs
Re: 3.66 Ohm Re: 6.1 Ohm Magnet Width: 18.8 cm
Ls: 5.236 mH Ls: 5.303 mH Mounting Cutout: 35.5 cm
Rp: 10.46 Rp: 12.39 Displacement: 0.18 cu ft
Vas: 163.0 L Vas: 148.8 L
Mms: 290.9 g Mms: 231.4 g
Cms: 158.6 u Cms: 144.8 u
Bl: 20.76 T*m Bl: 21.90 T*m
SPL: 89.43 dB SPL: 89.67 dB
Sd: 0.0806 m^2 Sd: 0.0806 m^2
Xmax: 24.6 mm Xmax: 24.6 mm
The Subwoofer DIY Page - Passive Radiator Systems
I'd have to simulate what you propose above, but unable to right now.
I'd suspect the choice of PRs was to prevent vent noise at high power due to the size of vent to achieve tuning.
Specs for those that may be able to help
Dual 2 Ohm Dual 4 Ohm Measurements
Qts: 0.333 Qts: 0.447 Mounting Depth: 17.5 cm
Qes: 0.363 Qes: 0.508 Total Depth: 18.5 cm
Qms: 4.032 Qms: 3.728 Outside Diameter: 31.8 cm
Fs: 23.426 Hz Fs: 27.487 Hz Weight: 35 lbs
Re: 3.66 Ohm Re: 6.1 Ohm Magnet Width: 18.8 cm
Ls: 5.236 mH Ls: 5.303 mH Mounting Cutout: 35.5 cm
Rp: 10.46 Rp: 12.39 Displacement: 0.18 cu ft
Vas: 163.0 L Vas: 148.8 L
Mms: 290.9 g Mms: 231.4 g
Cms: 158.6 u Cms: 144.8 u
Bl: 20.76 T*m Bl: 21.90 T*m
SPL: 89.43 dB SPL: 89.67 dB
Sd: 0.0806 m^2 Sd: 0.0806 m^2
Xmax: 24.6 mm Xmax: 24.6 mm
Technically - yes the PR is treated the same as a port.
But where a PR shines - is letting you take a woofer that would work really well ported, but the box is too small to fit the port. i.e. 1/ft3 box, but needs a 4"x20" port to tune it to 25-Hz - impossible.
However, using a PR and now you can use that small box and easily tune the PR to 25-Hz.
So while the same - a PR has PROS that you don't get with a port, with the biggest CON being cost.
I would go for 15" and either sealed, or ported/PR - only because of size of box. the 15" will give you everything you would need musically, especially if XO at <100-Hz.
But where a PR shines - is letting you take a woofer that would work really well ported, but the box is too small to fit the port. i.e. 1/ft3 box, but needs a 4"x20" port to tune it to 25-Hz - impossible.
However, using a PR and now you can use that small box and easily tune the PR to 25-Hz.
So while the same - a PR has PROS that you don't get with a port, with the biggest CON being cost.
I would go for 15" and either sealed, or ported/PR - only because of size of box. the 15" will give you everything you would need musically, especially if XO at <100-Hz.
3 cubic foot box - Ported or PR's after allowance for sub and amp
Ported - 4" Precision Port 20" long (won't fit in the 20" square box I modelled, but you could change height and width and depth to accomodate.
PR's - 2 CSS 12" PR's (tuned to 22-Hz with 450g added mass)
Both modelled with a 500 watt amp will get you:
F6 of 21-Hz - which will be even lower in an actual room with room gain
Should produce about 114db - again before room gain with 500 watts
Excursion is about 60% in this design - so you could go up to a 1000 watt amp and still be within specs, except at very explosive tracks.
Remember 500 vs 1000 watt is on 3db - IMO speaker safety is more important, go with the 500 watt.
As I mentioned earlier - 3 cubic foot box for a 15" sub - not that big especially to get into the 20's. But the PR's run $80/ea. where the port is $25.
Quick model - but gives you an idea of what the sub is capable of in a pretty small cabinet.
Ported - 4" Precision Port 20" long (won't fit in the 20" square box I modelled, but you could change height and width and depth to accomodate.
PR's - 2 CSS 12" PR's (tuned to 22-Hz with 450g added mass)
Both modelled with a 500 watt amp will get you:
F6 of 21-Hz - which will be even lower in an actual room with room gain
Should produce about 114db - again before room gain with 500 watts
Excursion is about 60% in this design - so you could go up to a 1000 watt amp and still be within specs, except at very explosive tracks.
Remember 500 vs 1000 watt is on 3db - IMO speaker safety is more important, go with the 500 watt.
As I mentioned earlier - 3 cubic foot box for a 15" sub - not that big especially to get into the 20's. But the PR's run $80/ea. where the port is $25.
Quick model - but gives you an idea of what the sub is capable of in a pretty small cabinet.
I used the T/S parameters that were included a few posts up.
Quick model - you could certainly spend hours trying to squeeze every last drop out of those very capable woofers, which would probably lead to a larger box and lower tune.
But you will only get so much more increasing the box size and IMO sub safety and margin for peaks in music/HT are more important than going 10-Hz lower in a 2-3 times larger cabinet. YMMV.
Quick model - you could certainly spend hours trying to squeeze every last drop out of those very capable woofers, which would probably lead to a larger box and lower tune.
But you will only get so much more increasing the box size and IMO sub safety and margin for peaks in music/HT are more important than going 10-Hz lower in a 2-3 times larger cabinet. YMMV.
If you truly want the highest SQ, you will keep each in a separate cabinet, so you can place them in different locations throughout the room. This will allow you to offset each of their nulls they will create in the average room.
Of course not necessary if you plan to (already have) treatments throughout the room.
IMO - 3 15" subs will over power your ZRT's and most any other audiophile speaker, because they aren't typically made to produce 120db and have 300 watts run through them for any period of time. HT/PA speakers are they only ones designed for that type of long term (ab)use.
Of course not necessary if you plan to (already have) treatments throughout the room.
IMO - 3 15" subs will over power your ZRT's and most any other audiophile speaker, because they aren't typically made to produce 120db and have 300 watts run through them for any period of time. HT/PA speakers are they only ones designed for that type of long term (ab)use.
So I did some follow-up to this, and found some online calculators. I don't really trust free online tools all that much - which is why I did some comparison modeling at about 10 different sites. Most of them gave similar results. It was the few that didn't that raised questions.
For example: Most of the tools are calculating a single sealed box size of 1.64 cu. ft. OK, that's really smallish. But a couple of them calculate exactly the 4.6 cu. ft. size recommended as optimum by SoundSplinter.
So, here's the question... There is what graphs show in the modeling phase - and what the ears hear during the reality phase. Most sealed box models show frequency response being very close to the same, for all box sizes, up until we get into infinite baffle territory - 10000L and up. Then, there's a huge difference. But it's insignificant at the normal human size enclosure.
So, what's the net effect of going with a "smaller than optimum" box size? Assume that I end up with (2) subwoofers out of this venture. What's the trade-off for going with a 3-ish cubic foot box?
For example: Most of the tools are calculating a single sealed box size of 1.64 cu. ft. OK, that's really smallish. But a couple of them calculate exactly the 4.6 cu. ft. size recommended as optimum by SoundSplinter.
So, here's the question... There is what graphs show in the modeling phase - and what the ears hear during the reality phase. Most sealed box models show frequency response being very close to the same, for all box sizes, up until we get into infinite baffle territory - 10000L and up. Then, there's a huge difference. But it's insignificant at the normal human size enclosure.
So, what's the net effect of going with a "smaller than optimum" box size? Assume that I end up with (2) subwoofers out of this venture. What's the trade-off for going with a 3-ish cubic foot box?
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