Help with SonoSub Calculations

[Newfiestang50]

Guys before I get started here with my request for help with my DIY Sonosub, I would first like to say that I have read all the info that I can find on here but couldn't find anything specific to my application. This is my first DIY attempt so all help is appreciated. I plan on building one or two 12" Sub/s and I would first like your thoughts on the Driver selection, I am considering at this point:

1. Soundsplinter RL-p 12
2. Suggestions
3. Suggestions

I am open to sugestions on other units, I only ask that you keep in mind that I will probably be temperarly powering these with a spare NAD C272 (150 w/chan). Will this amp be capable of driving these subs on a temp. basis or am i wasteing my time to think so? While we are on the Amp topic, if you guys could suggest a more suitable amp I would greatly appriciate it also. Also which coil config should i get 2 or 4 ohm?

Next topic I guess is the actual tube construction, I am capable of building this enclosure but have not actually seen any info on how to connect the end caps in the tube, are they just glued in? if so what type of glue is best?

I have just started using WinISD Pro Alpha and would appreciated if someone could run some numbers for me to compare using a 17hz tune with the SS RL-p12. I seem to find that a 155 cubic litre enclosure seems to work ok but would like to know what some of you more experienced builders might think.

Guys I should also mention that I plan on using this Sub for 80% music and 20% movies in a room about 20' x 17'. I presently have a B&W ASW675 and it goes without saying that I am not satisified with this sub and I want to build something that would totally put the B&W to shame. Also, I did consider buying the Axiom EP-600 or HSU 3HO, will this DIY be comparable to either on of those units and if not what DIY Sub would?
Finally, do anyone know of a free program that I could download to draw sub enclosures, just to expermint with, something that has dimentions would be prefered. Thanks for the patience in reading such al long post.

[Newfiestang50]

Come on guys, I need your input here, I have posted this on three different forums with little input from either, someone has got to have some oppinions!

[ThomasW]

There are numerous threads posted here that are quite detailed with regard to the basics of the construction of a tube sub. The search function will reveal lot of information helpful to your project.

Decide on 1 or 2 drivers and the budget, we'll go from there.

[Newfiestang50]

As I mentioned earlier, I have read alot of the info and have decided on twin Sonotubes and I am considering using a single SS RL-p12 in each but would like everyones thoughts on this setup. Also I am new to WinISD and would like someone with more experience with this software to run the numbers to see if I am in the ballpark, just a simple request. I came up with a 155 ^m enclosure tuned to 17Hz, the port being 4" X 16.8" long mounted in a piece of sonotube cut to 41.6" using the Sonotube calaculator I found on this forum. Also I asked before, will the NAD C272 be capable of running these subs temporarily or not? Also, what version of the drivers should I puchase, the dual 2ohm or 4ohm? As for the budget, lets just aim for $1500 Cdn, if the NAD amp does not cut it then I will have to buy another so we will have to factor this in aswell. Thanks.

[Dotay]

The most common way I've seen people attaching end caps is to use some sort of fastener to tack the endcaps on (think brad nailer) and then use something like liquid nails around the seams to make it air tight.

For the most part choosing dual 2 or dual 4 will depend on what you are planning on driving them with. If you are planning on running two subs off something like one of the often recommended two channel pro amps (Nady, Behringer, Crown etc) I would get the dual two so you can wire the VC in series to get a 4 ohm load. You could bridge the amp if you're only running one or you could buy two subs and just run them off each channel of the amp.

Do you have any size limitations on the sub? Any particular reason you are looking at 12's instead of 15's? With a budget of ~$1250 you could get two SS rl-p 15's at ~$270/per and pick up a Behringer EP2500 for ~$300. Throw in a BFD at ~$100 and add in materials cost (sonosubs don't cost a ton to build) and you're still under or around your budget. Just something to think about.

[ThomasW]

As a temporary fix the amp will work. Eventually you'll probably want something with more balls. Can you live with the noise of a fan cooled amp? If so there are some nice ones out there.

I don't have time this AM to recheck you model. I will have time later today.

Any particular reason why you choose 2-12"s as opposed to a single 15"?

and you're still under or around your budget. Just something to think about

Not since he lives in Canada

[Dotay]

Not since he lives in Canada

Do they get nailed on duties or shipping or something else if they order parts from here? Based on the conversion his budget is $1285.

[ThomasW]

Do they get nailed on duties or shipping or something else if they order parts from here?

Yep...

[Newfiestang50]

As a temporary fix the amp will work. Eventually you'll probably want something with more balls. Can you live with the noise of a fan cooled amp? If so there are some nice ones out there.

I don't have time this AM to recheck you model. I will have time later today.

Any particular reason why you choose 2-12"s as opposed to a single 15"?

Not since he lives in Canada

Ok so the NAD wil work for a while, thanks.

I choose two 12's thinking it would be better for approx. 80% music listening, do you think otherwise, a single 15 would be better?

Also Thomas, did you have time to check my model yet?

[ThomasW]

Sorry no I haven't double checked your model, here's why.....

Jonmarsh and I recently had a fairly long discussion regarding the SS drivers. And the conclusion is that the RL-p15" is the best design they offer. The RL-p12" among other things has higher Ls and Lp numbers, and therefore isn't an optimally designed woofer like the 15". So the only benefit to a pair of the 12"s is that they'll play louder, but the SQ won't be better.

Given the minimal price difference between the 12" and the 15", if you want more output buy a second 15".

[Newfiestang50]

Sorry no I haven't double checked your model, here's why.....

Jonmarsh and I recently had a fairly long discussion regarding the SS drivers. And the conclusion is that the RL-p15" is the best design they offer. The RL-p12" among other things has higher Ls and Lp numbers, and therefore isn't an optimally designed woofer like the 15". So the only benefit to a pair of the 12"s is that they'll play louder, but the SQ won't be better.

Given the minimal price difference between the 12" and the 15", if you want more output buy a second 15".

I think two 15's will just be too big, therefore I will be sticking with the 12's unless you guys can convince me why one 15 will be better. If someone could just check my model using the data i provided above to see if i am close to the correct size enclosure than i will probably start planning this project, please, please,please??? He He

[ThomasW]

Here's a plot of the Mach numbers (port speed) of your design. For the sub to sound good the dark blue line should stay between the red and brown lines. For your design the Mach numbers are WAY, WAY, too high.

If you look at the output vs excursion plot (red line crosses dark blue) the driver runs out of excursion at 25Hz, with 350 watts input. That's 1/2 the rated power of the driver

BTW, it's not my job to convince you of anything. I've been designing and building high performance subs for more than 25yrs. So FWIW the RL-p 15 is a better designed driver than the 12". This means the 15" will sound better than the 12". How use this info is up to you.

[Newfiestang50]

Here's a plot of the Mach numbers (port speed) of your design. For the sub to sound good the dark blue line should stay between the red and brown lines. For your design the Mach numbers are WAY, WAY, too high.

If you look at the output vs excursion plot (red line crosses dark blue) the driver runs out of excursion at 25Hz, with 350 watts input. That's 1/2 the rated power of the driver

BTW, it's not my job to convince you of anything. I've been designing and building high performance subs for more than 25yrs. So FWIW the RL-p 15 is a better designed driver than the 12". This means the 15" will sound better than the 12". How use this info is up to you.

Thanks Thomas, so does this mean that the 155^Litre enclosure is to big or too small or is it more to do with the port dimentions? Also, what software is that you are using to produce these plots and where could I get it? I guess WinISD only provides the basics and maybe info that is not entirely acurate for the purpose of box design since that is the program i used to come up with those numbers.

[Brian Bunge]

That's Unibox, and it's a much better program for box modeling than even WinISD Pro, IMHO. There are only 2 (well, maybe 3) catches with Unibox. First, you have to have Excel on your computer in order to run it. Second, everything is in Metric, but if you have a little patience it's very easy to use. And third, it does not spit out an "optimum box" like WinISD does. I used to use WinISD until I got more adept at box design. Since then I've used Unibox and never looked back.

[ThomasW]

As Brian said those are Unibox simulations. I like it a lot. And use it more than my copy of LspCAD. You can download it from the link below. It's a Excel spreadsheet that uses marcos, so it's necessary to open Excel and enable those before loading the spreadsheet.

http://home20.inet.tele.dk/kou/ubmodel.html

[chasw98]

Will this amp be capable of driving these subs on a temp. basis or am i wasteing my time to think so? While we are on the Amp topic, if you guys could suggest a more suitable amp I would greatly appriciate it also. Also which coil config should i get 2 or 4 ohm?

The amp will drive the speakers at a 4 ohm load just fine. Not much headroom and not super loud. You should plan on buying a larger amp in the near future such as a Crown, QSC, Behringer, Nady.

Next topic I guess is the actual tube construction, I am capable of building this enclosure but have not actually seen any info on how to connect the end caps in the tube, are they just glued in? if so what type of glue is best?

If you buld the end caps carefully they will fit in the tube very tightly and all you have to do is use liquid nails around the interior of the joint to make it airtight. Some have just used pressure fit.


Guys I should also mention that I plan on using this Sub for 80% music and 20% movies in a room about 20' x 17'.

I am using my sub in a 24 X 16 room and am finding it very nice for music. Since building my sub I have returned to listening to a lot more music than I used to. It is quite nice.

You can read about my sub here. http://www.cwitt.com/htpage.htm
I ended up using the RL-p15 and have found it to be a very nice driver.

[Dennis H]

I'll be a contrarian and say, without having heard one, I like the specs of the single-spider 12" TC9 which I think is what SS is selling. It has the best looking Dumax curves, BL and Kms, of any of the TC drivers I've seen - better than the 12" TC2 and the 15" TC9. The Le would limit its HF use but the bass should be outstanding. The 15" TC9 in particular has a very asymmetric BL curve which could lead to distortion if you push it. Of course those are just generic TC drivers and the ones O-audio and Soundsplinter are selling are customized a certain amount.

http://www.tcsounds.com/TC9_12_2568.htm

http://www.tcsounds.com/TC9_15_2570.htm

http://www.tcsounds.com/TC2plus_12_2578.htm

[ThomasW]

From what I can tell the SoundSplinter RL-p12 and the RL-p15 have a very similar motor structure (3" VC, dual spiders, etc.) The 15" has a 4lb larger magnet. Depending on the version the Cms of the 12" is 2-3 times higher than the 15". And it's design is highly overdamped. So I'll stick with my original recommendation .....:wink:

Evil Twin likes the look of 12" for one of his special slot loaded designs. Perhaps we can prod him into showing the world one of these. The last one disappeared when Audax stopped production of a VERY low Qts prosound 15". The design is quite unique, a very small sealed box, that maintains a Qtc 0.50 without the need for equalization ..... :T

[Newfiestang50]

Ok guys thanks for all the info but due to space I am going to be pushing it with twin 12's so 15's are out. Are there better 12" drivers on the market than the SS ones?

Also, Thomas or anyone else, what do I have to do to correct the above mentioned problem with my driver bottoming out near the 23Hz region in the model along with the excessive portspeed?

[Dennis H]

Depending on the version the Cms of the 12" is 2-3 times higher than the 15".

Yeah and a lower Fs as well. That was what made me think it has a single spider. Probably they figure 12" doesn't need dual spiders like the 15". Basically it looks like a pumped up version of the O-audio TC2+ which we all know is excellent so I wouldn't hesitate to use it. It might be really sweet in an IB -- get the dual 4 ohm version and just drive one coil for a Qt a bit over .4 and Fs around 19 Hz. Spendy way to do 12 Shivas dancing though.

[Newfiestang50]

Ok guys, I have been playing around with Unibox and seemed to have figured out my port speed problem (See above post by Thomas) but still can't solve the problem of the driver reaching its Xmax prematurely.....any hints from the Unibox experts.

Also, what is the deal with increasing the port diameter, I was expecting the port length to decrease as dia increased but it more than doubled in length, in fact it is now longer than my planned Sonotube length from end to end, is there a way to resolve this besides making the complete sub enclosure longer?

[ThomasW]

Actually I screwed up, you're ok for the output at 25Hz, I posted that comment while waiting for migraine meds to kick in (so seeing a black and white pattern on the PC monitor) and referenced the wrong line. It's the thin black line, not the blue one.

To lower the Mach number you need a larger diameter port and probably a bigger box given the interaction between port size and box size.

The larger the diameter the longer the port.

A 6" port in a 200L box is just under 32" long and the mach within reason for 350 watts. Note that the Mach numbers will climb again if you use more than 350 watts.

For a reference the second attachment is ideally what the Mach number should look like...

[Newfiestang50]

Actually you're ok for the output at 25Hz, I posted that comment while waiting for migraine meds to kick in (so seeing a black and white pattern on the PC monitor) and referenced the wrong line. It's the thin black line, not the blue one.

To lower the Mach number you need a larger diameter port and probably a bigger box given the interaction between port size and box size.

The larger the diameter the longer the port.

A 6" port in a 200L box is just under 32" long and the mach within reason for 350 watts. Note that the Mach numbers will climb again if you use more than 350 watts.

Ok, I changed my port size to 6" and the plot for port speed looks ok.

I'm sure glad you found a mistake in your previous post because I have been punching in some pretty crazy numbers trying to get the Xmax to slip by the overall SPL, HA HA.

Thomas, how come when you change to two ports nothing much seems to happen within the model SPL plots?

Now, if only I could find the sonotube calculator on here I will be in business.

[Brian Bunge]

volume of a cylinder: (Pi*r^2)*L, where L is the length/height of the cylinder.

Assuming you are using inches for r and L, divide your answer above by 1728 to convert from cubic inches to cubic feet and multiply that answer by 28.3 to convert that to liters.

[ThomasW]

how come when you change to two ports nothing much seems to happen within the model SPL plots?

The port only effects output at the tuning frequency, it has no effect anywhere else in the FR. The benefit of doubling the number of ports is that it cuts the Mach numbers in half.

Here's a tube sub calculator.

http://www.online-calculators.co.uk/volumetric/cylindervolume.php

[Newfiestang50]

The port only effects output at the tuning frequency, it has no effect anywhere else in the FR. The benefit of doubling the number of ports is that it cuts the Mach numbers in half.

Ok, but given a fixed size sub enclosure volume, and lets say the model indicates that your port should be a 6" dia by 26" long, if I wanted to keep my sub enclosure at the same volume, (ie: not having to increase the length/diameter for the sake of a longer port model length) could I simply just add an additional port to compensate, possibly two 3" ports 13" long or does it work like that?

Also, I keep seeing the term "Mach", but I don't see this term mentioned in the Unibox software, could you please explain this term a little further, I assume it is something to do with the port speed maybe, but not sure.

[opt-e]

Assuming you are using inches for r and L, divide your answer above by 1728 to convert from cubic inches to cubic feet and multiply that answer by 28.3 to convert that to liters.

Quick tip: you can use Google to convert units. For example, to convert 3843 cubic inches to litres you can do a 'search' for "3843 cubic inches in litres" and Google will spit out an answer. You can also use Google as a calculator in the same way.

I find this extremely useful for quick calculations since I always have a browser open and I'm far too lazy to open up a caculator app.

[ThomasW]

if I wanted to keep my sub enclosure at the same volume, (ie: not having to increase the length/diameter for the sake of a longer port model length) could I simply just add an additional port to compensate, possibly two 3" ports 13" long or does it work like that

Nope doesn't work that way. You can't keep a fixed enclosure size and change things with the ports if you want the tuning point to remain the same. And 2-13" ports create a completely different model compared to a single 3"-26" port.

Remember you must subtract the volume of air displaced by the port from the volume of the enclosure. The box models only show the net volume of the enclosure after subtracting for the port, the driver, bracing etc. Adding a second port means you double the amount subtracted.

Mach numbers refer to the air speed in the port. The reference is of course Mach 1 being the speed of sound, tec...

[dyazdani]

if I wanted to keep my sub enclosure at the same volume, (ie: not having to increase the length/diameter for the sake of a longer port model length) could I simply just add an additional port to compensate, possibly two 3" ports 13" long or does it work like that

Nope doesn't work that way. You can't keep a fixed enclosure size and change things with the ports if you want the tuning point to remain the same.

The only way to do that (I think) would be to extend part of your port externally. That way, the "internal volume" of the port (that which takes up gross enclosure volume, would stay the same. Now, for looks, I'm not sure that's the optimum...

[SteveCallas]

For good performance, "small" and "ported" don't really go together. As has been said, if you want more port area without taking away more internal volume, you'll need the port to go extrenal. Doesn't look very good - look at the HSU turbo for an example - I guess another design could look like an old wood burning furnace

My suggestion would be to go small and sealed using the RLp 15, as has been done by many here. When you limit yourself to a small enclosure, sealed will almost always be the better option.

[Newfiestang50]

For good performance, "small" and "ported" don't really go together. As has been said, if you want more port area without taking away more internal volume, you'll need the port to go extrenal. Doesn't look very good - look at the HSU turbo for an example - I guess another design could look like an old wood burning furnace

My suggestion would be to go small and sealed using the RLp 15, as has been done by many here. When you limit yourself to a small enclosure, sealed will almost always be the better option.

I did consider sealed but I cannot achieve the sub 20Hz freq. that I want, unless someone can tell me how.

So as a rule, is it safe to say that the bigger that you can go the better the sound with ported subs?

[ThomasW]

The bigger you can go the 'better' with any alignment.

Here are the trade-offs for sealed vs ported.

With ported you get a boost in ouput at the tuning frequency, BUT given the current crop of movies with REALLY LOW frequencies (3Hz for example) one must have a subsonic filter to protect the driver. Subsonic filters are active and are in the $50-$100 range depending on how finished looking you want the product. They are a DIY only device unless you pay $600 for something like the Velo SMS-1.

Sealed don't have the output boost at the tuning frequency. But the box itself acts as an acoustic filter rolling off the extremely low frequencies, this protects the driver and means there's no need for a subsonic filter.

Ported are slightly more efficient, but in this day of really cheap amplifier power that's not a big plus.

Sealed you can boost the lower end with different kinds of EQ, everything from a simple parametric to something as fancy as a Linkwitz transform circuit.

[Newfiestang50]

The bigger you can go the 'better' with any alignment.

Here are the trade-offs for sealed vs ported.

With ported you get a boost in ouput at the tuning frequency, BUT given the current crop of movies with REALLY LOW frequencies (3Hz for example) one must have a subsonic filter to protect the driver. Subsonic filters are active and are in the $50-$100 range depending on how finished looking you want the product. They are a DIY only device unless you pay $600 for something like the Velo SMS-1.

Sealed don't have the output boost at the tuning frequency. But the box itself acts as an acoustic filter rolling off the extremely low frequencies, this protects the driver and means there's no need for a subsonic filter.

Ported are slightly more efficient, but in this day of really cheap amplifier power that's not a big plus.

Sealed you can boost the lower end with different kinds of EQ, everything from a simple parametric to something as fancy as a Linkwitz transform circuit.

Ok, that makes sense, but can a well built sealed unit hit 20Hz, and if so, how much power would it need to play.....lets say at 90db?

I have been trying to decide between ported or sealed since I have started this DIY kick but have really up until now only spent any serious time at modeling the ported version and I have finally found a happy medium that will work (I think)

Vb= 165 L
Fb= 18Hz
Port dia= 15.24cm
Port Length= 89.5cm

Please see attachments and let me know if I am close to something that will sound good, Ha Ha. Thanks.

[SteveCallas]

I did consider sealed but I cannot achieve the sub 20Hz freq. that I want, unless someone can tell me how.

Well either way you are going to have compromises - you definitely can't get it all with a 12" driver in a 150 liter enclosure. With your size limits, sealed is the better option. Use a 15" driver in that same enclosure with enough power and some EQ and then you are actually approaching a pretty solid performer.

So as a rule, is it safe to say that the bigger that you can go the better the sound with ported subs?

Up to a point. You have to find just the right balance taking all factors into consideration with a ported design. Too big and overall output takes a hit, you get a big bump in output at the tuning frequency, and group delay skyrockets down low. I find an optimal volume and tune for a specific driver and then adjust power and port variables until it all comes together. Typically it ends up being a fair amount larger than most commercial ported subs.

[Newfiestang50]

Well either way you are going to have compromises - you definitely can't get it all with a 12" driver in a 150 liter enclosure. With your size limits, sealed is the better option. Use a 15" driver in that same enclosure with enough power and some EQ and then you are actually approaching a pretty solid performer.


Up to a point. You have to find just the right balance taking all factors into consideration with a ported design. Too big and overall output takes a hit, you get a big bump in output at the tuning frequency, and group delay skyrockets down low. I find an optimal volume and tune for a specific driver and then adjust power and port variables until it all comes together. Typically it ends up being a fair amount larger than most commercial ported subs.

Steve, I forgot to mention that i am planning on building two of the above mentioned units.

So what do you think of the above numbers? Will it work, now that you know that there will be two.

[SteveCallas]

I put that data into WinISD and what I'm seeing doesn't look too good. -3db at 88hz leading into a wide valley and then a big bump near the tuning. The room plays a big role in in-room FR, but don't make it impossible for yourself Group delay is really bad near tuning, a giant spike, and the first port resonance is a bit lower than what I would feel safe with. You want the port output to blend in as seemlessly as possible.

This is an odd driver that looks to work best ported with a really small enclosure - something like 40 liters tuned to 20hz with 1000 watts. Only problem is port velocity will be huge or first port resonance will be way too low.

My advice is still the RLp 15 in a small sealed enclosure.

[ThomasW]

This is what I've been saying all along. The RL-p12" is a strange driver, and I think's it's use for this kind of project is problematic.

The RL-p 15" can be placed in a 3 cubic ft sealed box, (this is smaller than the 155L design originally proposed). With a nice big amp and some EQ it will kick butt.

[Newfiestang50]

Ok, you guys are beginning to move me over to the RL-p15, I will play with some numbers, its just that without the port it just seems to really fall off as it approaches 20Hz.

[ThomasW]

its just that without the port it just seems to really fall off as it approaches 20Hz.

It does in the computer models since they don't show the effects of room gain. Below are measurements of my small IB sub (IB subs are very large sealed boxes). The blue line is nearfield, the magenta line is the same sub measured 13' away. There is no EQ. The boost in output is simply from the interaction of the sub with the room.

[Newfiestang50]

It does in the computer models since they don't show the effects of room gain. Below are measurements of my small IB sub (IB subs are very large sealed boxes). The blue line is nearfield, the magenta line is the same sub measured 13' away. There is no EQ. The boost in output is simply from the interaction of the sub with the room.

Ok, well that actually looks pretty good. So what is the size of the box in the above plot, I was just playing around with a 100L enclosure which seems to look ok.

What does the IB stand for?

[ThomasW]

IB stands for infinite baffle (min size 10 times driver's Vas ) google will give you lot's of info about them. Room gain has nothing to do with the alignment. Ported, sealed, IB, bandpass, etc., all benefit from room gain