I am happy with the JBLs and don't want to mess with them, they are experiencing over excursion and this only happens sometimes with certain 808s from songs.
Look at the Eminence and I suggest also looking at these:
Dayton DC250-8
Dayton DC300-8
Dayton DSA270-8
Dayton DA270-8
Peerless 10" 830668 (ignore the fact that it's called a subwoofer - it's specs aren't much different than any of the other drivers you're looking at)
Here's what I now think the selection criteria should be for your woofers (notice that none of them are about driver size):
Price: $85 or less per driver. $340 or less for 4 (based on your acceptance of the DSA315-8, although if you are on a budget, this seems too high to me)
max SPL: minimum 110dB @ 1m
F3: 30Hz-33Hz
Box size: max 150L net, meaning the max volume after you subtract the volume for the port(s), driver, bracing, xo and anything alse that air can't pass through. (again on a budget, I think you should be trying for lower than this)
Impedance: minimum 8ohm since 2 in parallel will result in 4ohm for the amp
Max Power required: if you have to also buy an amp for these, less watts will probably also cost you less. You'll want at least 3dB of headroom beyond your max SPL requirements which means that for the DSA315-8, you'll need about 160W-200W. If you can get away with less, that might also be better. Note that this amp will have to be happy with 4ohm nominal speakers.
In terms of quality, you often get what you pay for but not always. Sometimes less expensive can be better. Not everyone agrees with this, but some feel that the combination of higher Qms and lower Rms woofers can sound better too. Unibox calculates both those parameters for you. Look in the top middle section.
Also, at this point you don't have to decide on 1 driver. It's ok to select 2 or 3 candidates in different sizes and different price ranges that all meet your design criteria. The final choice can be made later.
And a tip: try using the 'Save Graph' tab to compare different response curves at the same time. Hitting 'Save' in the vented box section will save whatever vented FR you have displayed on the 'Speaker Design' tab page at that moment. Label it up top to avoid confusion.
Dayton DC250-8
Dayton DC300-8
Dayton DSA270-8
Dayton DA270-8
Peerless 10" 830668 (ignore the fact that it's called a subwoofer - it's specs aren't much different than any of the other drivers you're looking at)
Here's what I now think the selection criteria should be for your woofers (notice that none of them are about driver size):
Price: $85 or less per driver. $340 or less for 4 (based on your acceptance of the DSA315-8, although if you are on a budget, this seems too high to me)
max SPL: minimum 110dB @ 1m
F3: 30Hz-33Hz
Box size: max 150L net, meaning the max volume after you subtract the volume for the port(s), driver, bracing, xo and anything alse that air can't pass through. (again on a budget, I think you should be trying for lower than this)
Impedance: minimum 8ohm since 2 in parallel will result in 4ohm for the amp
Max Power required: if you have to also buy an amp for these, less watts will probably also cost you less. You'll want at least 3dB of headroom beyond your max SPL requirements which means that for the DSA315-8, you'll need about 160W-200W. If you can get away with less, that might also be better. Note that this amp will have to be happy with 4ohm nominal speakers.
In terms of quality, you often get what you pay for but not always. Sometimes less expensive can be better. Not everyone agrees with this, but some feel that the combination of higher Qms and lower Rms woofers can sound better too. Unibox calculates both those parameters for you. Look in the top middle section.
Also, at this point you don't have to decide on 1 driver. It's ok to select 2 or 3 candidates in different sizes and different price ranges that all meet your design criteria. The final choice can be made later.
And a tip: try using the 'Save Graph' tab to compare different response curves at the same time. Hitting 'Save' in the vented box section will save whatever vented FR you have displayed on the 'Speaker Design' tab page at that moment. Label it up top to avoid confusion.
Last edited:
Also, you'll find the port air speed graph below the cone excursion graph in Unibox. Port air velocity increases with more SPL and more cone excursion. When it gets fast enough, it will start to make chuffing noises. So choose a port diameter that keeps the port air speed below the red line for musical content, which is mostly above 30Hz.
Also, maybe I was unclear re boomy bass. It usually means a peak in the FR so that 1 note ends up much louder than the rest. You think you might want this but you don't. What you want is clean, loud extended bass where all the bass notes play equally loud. With woofers that play down low, a gentle rolloff at about an F3 of 30Hz is exactly what's going to make that happen in an averaged sized room.
Also, maybe I was unclear re boomy bass. It usually means a peak in the FR so that 1 note ends up much louder than the rest. You think you might want this but you don't. What you want is clean, loud extended bass where all the bass notes play equally loud. With woofers that play down low, a gentle rolloff at about an F3 of 30Hz is exactly what's going to make that happen in an averaged sized room.
It's not really the wrong size, just oversize. Or probably a metric size.
I think this size is used in some higher end speakers. I know I've seen it in a couple popular DIY speakers.
You can hog the hole out and make it fit, if it fits on the baffle.
The $53 FaitalPro 10FE200 gets good reviews for a 10" midwoofer. Look over the extended-flat SPL curve.
The 12" Dayton DSA315-8 is priced at 4-for $306
The-Loudspeaker
If Troels Gavensen's "The-Loudspeaker" build gets your interest, $260 will buy two 18" woofers. JBL dominated recording room monitors with this design. Bi-amping with active LR4/LR4 crossover is popular with this configuration. Passive TM crossover is low cost.
$130 B-52 18-190S 18" Cast Frame Professional Subwoofer 8 Ohm
Model: 18-190S|Part # 299-2302
(8cuft ported tuned to 30Hz)
The 12" Dayton DSA315-8 is priced at 4-for $306
The-Loudspeaker
If Troels Gavensen's "The-Loudspeaker" build gets your interest, $260 will buy two 18" woofers. JBL dominated recording room monitors with this design. Bi-amping with active LR4/LR4 crossover is popular with this configuration. Passive TM crossover is low cost.
$130 B-52 18-190S 18" Cast Frame Professional Subwoofer 8 Ohm
Model: 18-190S|Part # 299-2302
(8cuft ported tuned to 30Hz)
My main design goals include the 12" drivers but I would not even want to look into the 18" driver choices because the boxes would end up being 20 - 22" in width which would not fit on one side of my setup (standing pull up bar is in the way and cannot be moved over bc of the ceiling)
the 3 things that make the graph smoother is Vb Qa and Qi
Qi should be around 30 If I do a good job sealing the box.
I can't find any info on Qa or absorption
[/ATTACH]When Vb is set to a number than smoothens the graph, it makes for a speaker length that is ridiculous and would make the speaker look funny and not right (16" front to back)
Qi should be around 30 If I do a good job sealing the box.
I can't find any info on Qa or absorption
[/ATTACH]When Vb is set to a number than smoothens the graph, it makes for a speaker length that is ridiculous and would make the speaker look funny and not right (16" front to back)
Attachments
I think you've just discovered why the general rule of thumb for a vented box is to just line the walls with insulation - stuffing the box with more and more absorption reduces the output from the vent until you pretty much just end up with something very close to the FR of a closed box of the given Vb. Make the comparison in the closed box section to see.
Typically, the primary purpose of insulation is to absorb the sound energy inside the box coming from the back of the driver, not to change the port output. You actually have to use a lot of insulation in a big box to do that costing you a bit of extra money, when in fact the better way to do it is to simply make the box smaller. Or if you want to change the response after the box is built, simply putting a bit of insulation right inside the port will do the same thing. The thing is, Unibox tells you that extra absorption will change the FR and it will but it doesn't really tell you how much of it and of what density to use. Better to do the standard of just covering the walls and then use the other 2 primary variables to shape the response into what you are looking for.
Ql leakage does affect the FR but it's not really a variable that one plays with. You pretty much always want to make your boxes air tight (except for the port of course). Where you might want to tell the program that there are some minor leaks is when you are using a driver that isn't perfectly sealed, like when it uses a phase plug. Otherwise, keep that variable set to no leaks.
Really, the 2 primary variables that are manipulated in a vented box are box size, Vb and port length. Notice however that in box modeling programs, you cannot directly change the port length - you do so indirectly by changing the box tuning, Fb.
I'm not sure what you mean by making the speaker length ridiculous (please try to start using the word depth, it makes things clearer)? You are pretty much free to choose whatever dimensions you like as long as they give you the correct net volume, and as long as they allow you to fit the drivers (and maybe the port) on the front baffle. And perhaps allow you to fit the length of the port inside the box too, but you do also have the option of putting a right angle in ports as well.
Here's a tip though: it can help to minimize internal standing waves if the interior dimensions of your box follow the golden ratio. There's more info on that in the Dennis Murphy/True Audio link that I gave you earlier. Not absolutely necessary but it certainly helps when the dimensions are not divisible by the same number(s).
Typically, the primary purpose of insulation is to absorb the sound energy inside the box coming from the back of the driver, not to change the port output. You actually have to use a lot of insulation in a big box to do that costing you a bit of extra money, when in fact the better way to do it is to simply make the box smaller. Or if you want to change the response after the box is built, simply putting a bit of insulation right inside the port will do the same thing. The thing is, Unibox tells you that extra absorption will change the FR and it will but it doesn't really tell you how much of it and of what density to use. Better to do the standard of just covering the walls and then use the other 2 primary variables to shape the response into what you are looking for.
Ql leakage does affect the FR but it's not really a variable that one plays with. You pretty much always want to make your boxes air tight (except for the port of course). Where you might want to tell the program that there are some minor leaks is when you are using a driver that isn't perfectly sealed, like when it uses a phase plug. Otherwise, keep that variable set to no leaks.
Really, the 2 primary variables that are manipulated in a vented box are box size, Vb and port length. Notice however that in box modeling programs, you cannot directly change the port length - you do so indirectly by changing the box tuning, Fb.
I'm not sure what you mean by making the speaker length ridiculous (please try to start using the word depth, it makes things clearer)? You are pretty much free to choose whatever dimensions you like as long as they give you the correct net volume, and as long as they allow you to fit the drivers (and maybe the port) on the front baffle. And perhaps allow you to fit the length of the port inside the box too, but you do also have the option of putting a right angle in ports as well.
Here's a tip though: it can help to minimize internal standing waves if the interior dimensions of your box follow the golden ratio. There's more info on that in the Dennis Murphy/True Audio link that I gave you earlier. Not absolutely necessary but it certainly helps when the dimensions are not divisible by the same number(s).
Last edited:
Qi makes a big difference in the graph but if I'm not supposed to play with it then what should it be by default? Having a lot of insulation means high number absorption like 100 or low numbers like 1 (which makes the graph smoother)? Also I don't see any places to put box depth, only a place to put volume.
What I meant was if I don't have 1 or 2 on QI or QA, then the only way to make the graph smoother is having low volume and when I do that the depth of the box becomes really short(Like less than the width)
What I meant was if I don't have 1 or 2 on QI or QA, then the only way to make the graph smoother is having low volume and when I do that the depth of the box becomes really short(Like less than the width)
So for a vented box, choose 'Walls covered' (Qa=20) and for leakage choose 'No leaks' (Ql=30). If you use the little drop down menus, you may need to select something different 1st and then select one you want to get the right value loaded.
The program only tells you the net volume required. Again, it's up to you to decide which dimensions will make that work out.
Ok, I think I get what you mean about the depth, but I suggest you re-check your box calculations because mine show that you have all kinds of depth to play with - a box with interior 12" x 33" x 12" will give you 77.9L. You can go all the way to a depth of 23" before the gross volume will be 149.3L with those dimensions, just for example.
The program only tells you the net volume required. Again, it's up to you to decide which dimensions will make that work out.
Ok, I think I get what you mean about the depth, but I suggest you re-check your box calculations because mine show that you have all kinds of depth to play with - a box with interior 12" x 33" x 12" will give you 77.9L. You can go all the way to a depth of 23" before the gross volume will be 149.3L with those dimensions, just for example.
Not sure which drop down menu you are referring to...
I was going off an exterior width of around 16" making the interior 14.5" the height of the woofer box would be around 27.625" (interior) so the area of the face is 400.5625". You said that the graph needs to be smooth and in order to do so the Vb needs to be put at around 100L. With 100L of space and those previous calculations, the depth would be 15" which would look funny and not right. If I make that depth ~20" that would cause a higher volume resulting in a sharper graph...
I was going off an exterior width of around 16" making the interior 14.5" the height of the woofer box would be around 27.625" (interior) so the area of the face is 400.5625". You said that the graph needs to be smooth and in order to do so the Vb needs to be put at around 100L. With 100L of space and those previous calculations, the depth would be 15" which would look funny and not right. If I make that depth ~20" that would cause a higher volume resulting in a sharper graph...
Will, see attached for what are called the dropdown menus in Excel.
Go back and check my posts. What I said was that you want a slightly more gentle rolloff. You are not trying to smooth it out so much that it's more or less just about the same as the sealed response. If you go back to post #182, I said your goal should be an F3 of between 30Hz-33Hz. Your F3 with 2 of the SDA315-8 in 100L tuned to 28Hz will be 37Hz. That's not going to work. Looks to me like 100L is too small for 2 of those drivers.
I'm not sure if I'm not explaining this well enough or if you aren't getting it. So let's try this. You've tried 150L with Fb at 28Hz giving an F3 of about 30Hz, so that 1 works. Now see how much smaller you can make the box and still keep F3 below 33Hz. You can change Fb up or down too to see if that makes any difference. Attached below is probably what's going to work out at the bottom end of the criteria. Vb is 130L tuned to 28Hz with F3 just under 33Hz. So it looks like with these drivers, anything between 150L and 130L tuned to 28Hz, probably plus or minus 1 or 2Hz, will fit the design criteria. If you prefer the larger cab, then go with that. If you want it smaller, go with 130L. Or go with something in between. That is the designer's prerogative.
You've already discovered 1 thing that makes a difference to you - how it looks. Here's another - if you draw up all the cuts that are going to be needed for the 2 cabs from a 4' x 8' sheet of wood, you may find that certain dimensions are going to make the difference between 1 or 2 sheets. Or probably in your case with larger speakers, the difference between 2 or 3 sheets. Maybe more, I'm not sure. Just something else to think about when you're on a budget.
Now I don't know if this is going to help or confuse things more but also attached below is an estimate of the gain you get in an averaged sized room (17' long) with 60% losses (it might be less if the room were build of cement blocks). It's this response plus the 1 you are modeling in Unibox that when combined together should be more or less flat down to a good 30Hz or so if possible. Notice what the exact dB increase is at 30Hz. That's about how much down your Unibox FR should be at that same frequency.
In terms of box dimensions, I've mentioned a couple of times that you need to think in terms of net volume. So your real box volume is going to have to be larger by probably at least 5L or so (or 5-10% depending) to account for the driver volume, port, bracing etc. Just guessing on that though. As the design becomes more finalized, I would start to do the actual volume calculations for most of those other things that will be in the cabinet too.
Also, if you're still not getting enough depth, maybe choose a smaller width. Check the driver spec diagram - you actually only need a 10.7" diameter cutout to fit the DSA 315-8 which means an interior width of about 12" is perfectly acceptable. And you'll need even less than that if you went with a smaller driver.
Go back and check my posts. What I said was that you want a slightly more gentle rolloff. You are not trying to smooth it out so much that it's more or less just about the same as the sealed response. If you go back to post #182, I said your goal should be an F3 of between 30Hz-33Hz. Your F3 with 2 of the SDA315-8 in 100L tuned to 28Hz will be 37Hz. That's not going to work. Looks to me like 100L is too small for 2 of those drivers.
I'm not sure if I'm not explaining this well enough or if you aren't getting it. So let's try this. You've tried 150L with Fb at 28Hz giving an F3 of about 30Hz, so that 1 works. Now see how much smaller you can make the box and still keep F3 below 33Hz. You can change Fb up or down too to see if that makes any difference. Attached below is probably what's going to work out at the bottom end of the criteria. Vb is 130L tuned to 28Hz with F3 just under 33Hz. So it looks like with these drivers, anything between 150L and 130L tuned to 28Hz, probably plus or minus 1 or 2Hz, will fit the design criteria. If you prefer the larger cab, then go with that. If you want it smaller, go with 130L. Or go with something in between. That is the designer's prerogative.
You've already discovered 1 thing that makes a difference to you - how it looks. Here's another - if you draw up all the cuts that are going to be needed for the 2 cabs from a 4' x 8' sheet of wood, you may find that certain dimensions are going to make the difference between 1 or 2 sheets. Or probably in your case with larger speakers, the difference between 2 or 3 sheets. Maybe more, I'm not sure. Just something else to think about when you're on a budget.
Now I don't know if this is going to help or confuse things more but also attached below is an estimate of the gain you get in an averaged sized room (17' long) with 60% losses (it might be less if the room were build of cement blocks). It's this response plus the 1 you are modeling in Unibox that when combined together should be more or less flat down to a good 30Hz or so if possible. Notice what the exact dB increase is at 30Hz. That's about how much down your Unibox FR should be at that same frequency.
In terms of box dimensions, I've mentioned a couple of times that you need to think in terms of net volume. So your real box volume is going to have to be larger by probably at least 5L or so (or 5-10% depending) to account for the driver volume, port, bracing etc. Just guessing on that though. As the design becomes more finalized, I would start to do the actual volume calculations for most of those other things that will be in the cabinet too.
Also, if you're still not getting enough depth, maybe choose a smaller width. Check the driver spec diagram - you actually only need a 10.7" diameter cutout to fit the DSA 315-8 which means an interior width of about 12" is perfectly acceptable. And you'll need even less than that if you went with a smaller driver.
Attachments
Yeah changing Fb to 23Hz makes the drop down more gentle. I experimented with all the inputs though, I must not have put in the right numbers to know that Fb changes the graph...Btw I wasn't talking really about how it looks, just that I know 15" in depth is too short from my experience of what speakers look like (yes it would look weird too but that wasn't my main concern)
I should have some time later tonight to thoroughly read through some things again and try the eminence low frequency driver even though I think im going to go with the Dayton.
After I have a good understanding of how I'm going to build my woofer box I want to discuss the deal with mid range and tweeter, weather I should use 12" 10" or 8" mid range because I was getting a lot of interfering recommendations on that.
-I can't find the graph that mentions Room Pressurization etc...
How would the volume increase when accounting for things like the driver, wouldn't it become smaller? Also I think I am going to build a small compartment that is closed off for all the wiring below the whole thing so I would need to account for the volume that takes up.
How would the volume increase when accounting for things like the driver, wouldn't it become smaller? Also I think I am going to build a small compartment that is closed off for all the wiring below the whole thing so I would need to account for the volume that takes up.
Put some tech thought and budget analysis into bi-amping, and bi-amping with active W + TM crossovers. woofer plate amp?
PE has limited time sale on a proven tweeter + horn. Free ship on $100 + $10 discount code 18CRC5 might favor a small purchase now.
$13 B-52 PHRN-1014 1" Horn 10" x 14" Bolt-On waveguide
Model: PHRN-1014|Part # 299-2303
$34 Selenium 1" compression driver 2/3 Bolt . ( Proven Xover ckt available)
Selenium 8 Ohm Model: D220Ti-OMF-8 |Part # 299-2321
PE has limited time sale on a proven tweeter + horn. Free ship on $100 + $10 discount code 18CRC5 might favor a small purchase now.
$13 B-52 PHRN-1014 1" Horn 10" x 14" Bolt-On waveguide
Model: PHRN-1014|Part # 299-2303
$34 Selenium 1" compression driver 2/3 Bolt . ( Proven Xover ckt available)
Selenium 8 Ohm Model: D220Ti-OMF-8 |Part # 299-2321
Will, I would really appreciate it if you follow through with my suggestions from Post #182 and model more drivers. Include LineSource's suggestion too from his post #185, he's someone else who really knows what he's talking about. The more drivers you model, the better you are going be at it and the more you are going to understand. But mostly I want you to see that your driver choices should be based on their performances (well, and price too), not on their size. In the end, it's fine if you select a 12" woofer because you want a 12" woofer (this is 1 of the things that diy is about - you get to design something exactly the way you want to) but I want you to learn that woofer LF extension and max SPL are not solely dependent on cone size and that you should be selecting drivers for their performance and how they meet your design criteria first and then for any other reasons second.
Once you got a few more woofers compared, the next thing I wanted to do with you was to establish your overall design goals. We really haven't done that yet. In particular, I really need to know what your overall budget is so we can start breaking it down into different categories. I mean I really have no clue whether you can spend $500 or $1000 or what.
After that we can move on to tweeter and mid selection, probably in that order but it'll help if you understand the concepts of spacial loading, baffle diffraction, baffle step loss and beaming/off-axis response. Look in the True Audio link I posted previously for most of that to start off with.
Room pressurization gain (or just room gain for short) is from another program. I didn't want to introduce another program for you to try until I felt you had a solid handle on the 1st one.
About box volume, read what I wrote again - you need to increase the gross volume of the box in order to account for the extra solids (and well, for the port volume too) that you put in it and so that the net volume comes out to what Unibox is telling you.
An extra compartment on the bottom or on the back is a good idea. Again for an excellent source on what good cabinet construction and more looks like, have a look at Troels Gravesen DIY site.
Once you got a few more woofers compared, the next thing I wanted to do with you was to establish your overall design goals. We really haven't done that yet. In particular, I really need to know what your overall budget is so we can start breaking it down into different categories. I mean I really have no clue whether you can spend $500 or $1000 or what.
After that we can move on to tweeter and mid selection, probably in that order but it'll help if you understand the concepts of spacial loading, baffle diffraction, baffle step loss and beaming/off-axis response. Look in the True Audio link I posted previously for most of that to start off with.
Room pressurization gain (or just room gain for short) is from another program. I didn't want to introduce another program for you to try until I felt you had a solid handle on the 1st one.
About box volume, read what I wrote again - you need to increase the gross volume of the box in order to account for the extra solids (and well, for the port volume too) that you put in it and so that the net volume comes out to what Unibox is telling you.
An extra compartment on the bottom or on the back is a good idea. Again for an excellent source on what good cabinet construction and more looks like, have a look at Troels Gravesen DIY site.
I want to understand the woofer box before I move on. I also am not buying anything till October so unfortunately I won't be able to benefit from that sale.
Maybe I made you think I was trying to move on but I was just trying to understand how to manipulate the graph and understand the inputs to the program. Of course I was going to try more drivers!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.