I recently acquired a sub cabinet that has 2.3 cubic feet if internal volume and was wondering what drivers would work the best in it. Currently it is set up sealed for a 10 inch driver with no amplifier. I have no problem moving to a 12 or 15 inch sub if that can utilize the space better or adding a port if needed.
I would like to get down to 25hz if possible. I have a few Dayton ST255-8 10 inch woofers sitting around but I don't feel that I can get low enough with them.
This will be used mostly for home theatre if that matters at all.
Thanks in advance,
budzos
I would like to get down to 25hz if possible. I have a few Dayton ST255-8 10 inch woofers sitting around but I don't feel that I can get low enough with them.
This will be used mostly for home theatre if that matters at all.
Thanks in advance,
budzos
Too many variables to work through without simming or at least doing a bit of math, but as a frame of reference using the formula [Vb = 20*Vas*Qts^3.3] where Vb = 2.3 ft^3 - [driver, vent, bracing], then for a maximally flat response, i.e. has the most bass for a given box size, you'll need: 25 Hz Fs, Vas = Vb or a bit less than 2.3 ft^3 tuned to 25 Hz and a Qts = ~0.403.
Most 'sub' drivers for vented alignments are going to have a < ~0.403 Qts, so Vas can be larger and Fs < 25 Hz for a 25 Hz or lower tuning.
The big variable though is how much to reduce the Vb of an already tiny box for a 25 Hz 'sub' since the vent must be large/long, so best to have it outside the box, which often is unacceptable for a variety of reasons; leaving only a sealed alignment, in which case it might be best overall to just cram the biggest driver/highest Xmax with a ~0.7 Qts in it that will either fit and/or meet budget and use a bass controller to EQ it as required/desired in room since HT LFE is all about outputting loud bass below 80-120 Hz.
GM
Most 'sub' drivers for vented alignments are going to have a < ~0.403 Qts, so Vas can be larger and Fs < 25 Hz for a 25 Hz or lower tuning.
The big variable though is how much to reduce the Vb of an already tiny box for a 25 Hz 'sub' since the vent must be large/long, so best to have it outside the box, which often is unacceptable for a variety of reasons; leaving only a sealed alignment, in which case it might be best overall to just cram the biggest driver/highest Xmax with a ~0.7 Qts in it that will either fit and/or meet budget and use a bass controller to EQ it as required/desired in room since HT LFE is all about outputting loud bass below 80-120 Hz.
GM
best sealed box 65 litre performance
Hi Budzos,
If your cabinet can fit an 18 inch driver you can have amazing performance out of 2.3 cubic feet (approx 65 litres) .... Check out the attached sim for the Precision Devices 1850.
Its the lowest power compression (thermal distortion) of any 18 inch driver I have seen.
A few caveats:
You do need a good 1,000 watt power amp.
Driver is expensive.
Driver is heavy.
Hi Budzos,
If your cabinet can fit an 18 inch driver you can have amazing performance out of 2.3 cubic feet (approx 65 litres) .... Check out the attached sim for the Precision Devices 1850.
Its the lowest power compression (thermal distortion) of any 18 inch driver I have seen.
A few caveats:
You do need a good 1,000 watt power amp.
Driver is expensive.
Driver is heavy.
So basically I should go with the largest driver I can in a sealed enclosure. The biggest I can get in there would be a 15 inch since the box is pretty square about 16.5 x 16.5 not including the 3/4 inch on each side for the wall thickness. The face is 1 inch as is the back. I acquired this cabinet when buying a Carver True Sub Junior on Craigs list as part of the deal. Thanks for replying. Its been some time since I put some speakers together and this is my first subwoofer. Now to start scoping out some 15's.
budzos
budzos
15 inch version
Here is the 15 inch version.... Still a great performance.
Happy New Year!
Cheers
Alex.
Here is the 15 inch version.... Still a great performance.
Happy New Year!
Cheers
Alex.
Happy New Year budzos,All
A Layman Program simulation(ajdesigner) that returns a f-3dB= ~110 and 123 Hz to a Sub-Woofer forum= 😱 As not even qualifies for a good Mid-Bass operation ,IMO.
Further, I think your eyes were closed to notice GM's good reply that really is a useful seriously answer.
b 🙂
A Layman Program simulation(ajdesigner) that returns a f-3dB= ~110 and 123 Hz to a Sub-Woofer forum= 😱 As not even qualifies for a good Mid-Bass operation ,IMO.
Further, I think your eyes were closed to notice GM's good reply that really is a useful seriously answer.
b 🙂
Hello all, Thanks again for the reply's, bjorno you kinda lost me with your reply. I am kinda new at this (first sub build) so maybe if you could simplify your suggestion it may be more useful to me. No insult implied. I am off to work for the evening (Yes On New Years Eve) but I am to old for this celebration stuff anyway but I will check back in the morning. This sub will be replacing a cheapo 10 inch from MCM electronics that cost me
$59.99 so anything should be an improvement. The Sunfire (Carver) True Sub Junior was purchased to go with my digital pc based system and that was a big improvement over the
8 inch Wharfdale SW-8 that was currently being used.
budzos
$59.99 so anything should be an improvement. The Sunfire (Carver) True Sub Junior was purchased to go with my digital pc based system and that was a big improvement over the
8 inch Wharfdale SW-8 that was currently being used.
budzos
Rod Elliot discovered the secret years ago...!
Hi Budzos,
Sub-Woofer Controller
This article is great.... It explains the "ELF" principal in detail... How to build amazing low cost subwoofers (and the physics / maths behind the principal) in small sealed box's.
Its counter intuitive so most guys dont understand the principal ie bjorno who wrongly believes that F3 is limited by box resonance.... The ELF principal is all about driving your subwoofer below box resonance...!
ELF was patented by Bag End Subwoofers (they made millions!) back in the 90's but as long as you dont use the idea to make money you are free to use it. Also Bob Carver use uses variations on the theme.
ELF will outperform any conventional driver box combo on a SPL Vs box size and keeps everything soooooo simple to build.
Hi Budzos,
Sub-Woofer Controller
This article is great.... It explains the "ELF" principal in detail... How to build amazing low cost subwoofers (and the physics / maths behind the principal) in small sealed box's.
Its counter intuitive so most guys dont understand the principal ie bjorno who wrongly believes that F3 is limited by box resonance.... The ELF principal is all about driving your subwoofer below box resonance...!
ELF was patented by Bag End Subwoofers (they made millions!) back in the 90's but as long as you dont use the idea to make money you are free to use it. Also Bob Carver use uses variations on the theme.
ELF will outperform any conventional driver box combo on a SPL Vs box size and keeps everything soooooo simple to build.
Thanks for the info Hydrogen Alex,
I will give it a read after I get some sleep today. I just got home from work after 14 hours and I am beat.
budzos
Hi, there is one huge problem which ruins many diys sub woofer projects: The stability of the surrounding box is seen as something secondary.
You will always hear "sure, I build it extremely solid". Too bad "solid" is a very imprecise parameter.
Basically if your sub box becomes larger than 1 foot or 30cm in any dimension, the panels begin to wobble. Now, if you take the best loudspeaker money can buy and put it in a cabinet, as soon es the speaker cone moves out, the walls move inward, also the wood expands when the cone moves in. So a percentage of the produced sound pressure cancels it self out. People whose interests lie more in electronics than construction of buildings, have some deficits in understanding this, builders that know how flexible, for example, a concrete wall is, understand this better.
This is the most common cause why different builders have very different results, while using the same loudspeaker.
The first approach is usually using thicker panels, but this is only helping with very small boxes. If we look at steel structures, we can learn how you get best stability with lowest weight and costs. A single bar of flat steel wobbles around, a T-bar does not bend. If you take this principle inside a loudspeaker box, you are on the way to good low bass reproduction. Not only for closed box, but even more for vented cabinets.
If you ask for practical advise, brace any panel that is longer than 8” (20cm) with an upright length of wood. it´s height should be 4-5 times the strength of the outer panel. If you do it that way, you will end up with some kind of matrix inside your sub woofer. If you knock on the box, you should feel like it was solid, no hollow feeling or sound.
Especially if you “recycle” loudspeaker constructions, have this in mind and reinforce an old cabinet, it will be the cheapest improvement you can get.
“Sub resonance” constructions need the strongest box you can get or it will not pay of as expected.
PS A good construction glue is a perfect solution if you want to put braces inside an old box, where proper pressing of wood glue is a problem. It sticks like hell and perfectly fills up small gaps you will always have working inside such a tght space. Over night it cures to a vey strong bond.
You will always hear "sure, I build it extremely solid". Too bad "solid" is a very imprecise parameter.
Basically if your sub box becomes larger than 1 foot or 30cm in any dimension, the panels begin to wobble. Now, if you take the best loudspeaker money can buy and put it in a cabinet, as soon es the speaker cone moves out, the walls move inward, also the wood expands when the cone moves in. So a percentage of the produced sound pressure cancels it self out. People whose interests lie more in electronics than construction of buildings, have some deficits in understanding this, builders that know how flexible, for example, a concrete wall is, understand this better.
This is the most common cause why different builders have very different results, while using the same loudspeaker.
The first approach is usually using thicker panels, but this is only helping with very small boxes. If we look at steel structures, we can learn how you get best stability with lowest weight and costs. A single bar of flat steel wobbles around, a T-bar does not bend. If you take this principle inside a loudspeaker box, you are on the way to good low bass reproduction. Not only for closed box, but even more for vented cabinets.
If you ask for practical advise, brace any panel that is longer than 8” (20cm) with an upright length of wood. it´s height should be 4-5 times the strength of the outer panel. If you do it that way, you will end up with some kind of matrix inside your sub woofer. If you knock on the box, you should feel like it was solid, no hollow feeling or sound.
Especially if you “recycle” loudspeaker constructions, have this in mind and reinforce an old cabinet, it will be the cheapest improvement you can get.
“Sub resonance” constructions need the strongest box you can get or it will not pay of as expected.
PS A good construction glue is a perfect solution if you want to put braces inside an old box, where proper pressing of wood glue is a problem. It sticks like hell and perfectly fills up small gaps you will always have working inside such a tght space. Over night it cures to a vey strong bond.
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Hi,
you mentioned these two Dayton drivers you have. They are sub woofers, not with extreme cone movement (+-5.5mm linear), but decend. Ultra high x-max sub drivers dont sound better automatically, they only play louder. Consider using these Daytons with your cabinet, they are good diys quality, compared to average industry build powered subwoofers even high end 🙂
I don´t know how your existing box looks like, but placing them at opposite sides would have a very positive impact, as the moving masses cancel each other out. The sub does not move in this configuration, even pushed hard. Concider to double up existing holes with a new panel, which takes mounting holes for the new loudspeakers.
They are 8 ohms, so in parallel good food for a 500 watts sub amp. Two 8" chassis are not good simulating an earthquake in a large hall, but in a average living room can do some nice bass. They move a lot more air than a single 12" driver!
If you want to go with a closed box, this would be worth a try. But you need some kind of frequency adjuster, like the ELF or a Linkwitz transformer plus a really stable amp. Not 500 Watts "musik power", but true, clean rms at 4 Ohms. A too smal amp can easily damage a speaker, as you don´t hear distortion at very low frequncy until it is too late.
Otherwise, you could go vented. A nice way to ad the port to an existing cabinet, is to build it under the box, like it was meant to be there as a stand. This way you don´t loose volume, but, in fact, can add some (to a closed box, as well!).
There are some very good simulation programs around, most simulate with two identical woofers. The results are perfect, if the input is perfect too and the cabinet solid. If you simulate right, there is no try and error, you will get what you see on the computer. Anyway, with low frequncy, the room is influencing the sound much more than any imperfection of a simulation.
you mentioned these two Dayton drivers you have. They are sub woofers, not with extreme cone movement (+-5.5mm linear), but decend. Ultra high x-max sub drivers dont sound better automatically, they only play louder. Consider using these Daytons with your cabinet, they are good diys quality, compared to average industry build powered subwoofers even high end 🙂
I don´t know how your existing box looks like, but placing them at opposite sides would have a very positive impact, as the moving masses cancel each other out. The sub does not move in this configuration, even pushed hard. Concider to double up existing holes with a new panel, which takes mounting holes for the new loudspeakers.
They are 8 ohms, so in parallel good food for a 500 watts sub amp. Two 8" chassis are not good simulating an earthquake in a large hall, but in a average living room can do some nice bass. They move a lot more air than a single 12" driver!
If you want to go with a closed box, this would be worth a try. But you need some kind of frequency adjuster, like the ELF or a Linkwitz transformer plus a really stable amp. Not 500 Watts "musik power", but true, clean rms at 4 Ohms. A too smal amp can easily damage a speaker, as you don´t hear distortion at very low frequncy until it is too late.
Otherwise, you could go vented. A nice way to ad the port to an existing cabinet, is to build it under the box, like it was meant to be there as a stand. This way you don´t loose volume, but, in fact, can add some (to a closed box, as well!).
There are some very good simulation programs around, most simulate with two identical woofers. The results are perfect, if the input is perfect too and the cabinet solid. If you simulate right, there is no try and error, you will get what you see on the computer. Anyway, with low frequncy, the room is influencing the sound much more than any imperfection of a simulation.
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Thats something I never considered. Would 1 Dayton combined with 2 passives be an option? My room setup seems to get better performance with a front firing sub.
budzos
budzos
An 8 inch driver has a surface area (Sd) of approx 220 square cm, so a pair will have approx 440 square cm.
A 12 inch driver has a surface area of 550cm square cm.
Hi Alex, you are not right, you picked a wrong Dayton data sheet from a 8".
The PA255-8 10" Pro Woofer 8 Ohm has a cone area of 346.4 cm², you took the 8 Ohm for 8".
So two of them make close to 700 cm², more than one 12"
The PA255-8 10" Pro Woofer 8 Ohm has a cone area of 346.4 cm², you took the 8 Ohm for 8".
So two of them make close to 700 cm², more than one 12"
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@Buzos
We are talking about 80 Hz and below. The soundwaves at these low frequncy are not direktional. So your room does not care about woofers left and right or front facing. Not even a bit.
You might get this impression, because to small woofer produce higher order frequencys, that are, by the brain, recomposed to bass. This will not happen with a correctly desigend and adjusted Sub of 10", 12" or 15".
Sometimes "downfire" subs are able to make the floor vibrate more than "normal" loudspeakers. But this is more a fault than a feature.
We are talking about 80 Hz and below. The soundwaves at these low frequncy are not direktional. So your room does not care about woofers left and right or front facing. Not even a bit.
You might get this impression, because to small woofer produce higher order frequencys, that are, by the brain, recomposed to bass. This will not happen with a correctly desigend and adjusted Sub of 10", 12" or 15".
Sometimes "downfire" subs are able to make the floor vibrate more than "normal" loudspeakers. But this is more a fault than a feature.
Alex replied to your incorrect statement in post #12:
"Two 8" chassis are not good simulating an earthquake in a large hall, but in a average living room can do some nice bass. They move a lot more air than a single 12" driver!"
At any rate, a pair of 8" generally have more Sd than a 10", but less than a 12" :^).
My fault, I only thougt of the speakers that are already there! Sorry! Can´t edit it any more. Meant 10".
Passive radiators are only a way to replace a port of a vented box by a membrane. Often a very good option, if a port would get to long to fit in a box. You will not get more sound pressure out of them, because you still only power one voice coil. Two passives will not change this.
Maybe you have not fully understood the idea of the "ELF" principle. To make it very simple:
The most important factor for bass is the air moved by the cone. So it is area x stroke. In a small box the air, which acts like a spring, restricts the cone movement. The ELF installation ignores this and overcomes the restriction by giving the woofer more power, the lower it plays. So a 12" woofers cone in a small box moves just in the same way as it would in a large one. Only negative effect, you need a lot more power. But today, with "D" amps, you can join a SMPS and an amp circuit board and have a 500W amp for under 100$.
This also explains, why the enclosure for the ELF sub has to be stronger than usual, as the air pressure inside is much higher than in the large box.
Passive radiators are only a way to replace a port of a vented box by a membrane. Often a very good option, if a port would get to long to fit in a box. You will not get more sound pressure out of them, because you still only power one voice coil. Two passives will not change this.
Maybe you have not fully understood the idea of the "ELF" principle. To make it very simple:
The most important factor for bass is the air moved by the cone. So it is area x stroke. In a small box the air, which acts like a spring, restricts the cone movement. The ELF installation ignores this and overcomes the restriction by giving the woofer more power, the lower it plays. So a 12" woofers cone in a small box moves just in the same way as it would in a large one. Only negative effect, you need a lot more power. But today, with "D" amps, you can join a SMPS and an amp circuit board and have a 500W amp for under 100$.
This also explains, why the enclosure for the ELF sub has to be stronger than usual, as the air pressure inside is much higher than in the large box.
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So what if I mounted 3 of the 10 inch in the box? I actually have 5 of them.
Would that be an option? Also I included the data sheet for the woofers I have.
Also here is the old Parts Express page Dayton Audio ST255-8 10" Series II Woofer
budzos
Would that be an option? Also I included the data sheet for the woofers I have.
Also here is the old Parts Express page Dayton Audio ST255-8 10" Series II Woofer
budzos
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If you want to experiment, best is if you use a simulation prog. There are many around, even for free.
The best is "AJ Horn" it´s predictions allways fit perfectly. But only closed box in the Demo version and one driver.
Maybe someone can give a hint to a good, easy to use speaker simulations.
At first sight, 3 drivers could fit, but you need a lot of amp power with that, please don´t forget. Even low listening level will need a few hundred watts!
The best is "AJ Horn" it´s predictions allways fit perfectly. But only closed box in the Demo version and one driver.
Maybe someone can give a hint to a good, easy to use speaker simulations.
At first sight, 3 drivers could fit, but you need a lot of amp power with that, please don´t forget. Even low listening level will need a few hundred watts!