Ok, time to try again/Unibox tutorial

[Wilk]

Well after last night I am disgusted with my current sub situation. I had ran outa time, and had gotten fustrated trying to find a workable ported design, and just slammed a RL-p12 in a PE 2 cubic foot box with a 500W bash plate amp.

Well right about the time i get the movie volume where I like it, the boxs starts to reverb so bad that I can't stand it. After several attepmts at sound deading it, it still sounds like I put marbles in the box.

What I was gonna buy and didn't was the PB12-Plus from SVS, It is the biggest thing I could find that fit my space requirements. I haven't bought a speaker in 3 homes in 10 years, and just couldn't do it.

Anyways, I am back trying to find a suitable solution. I would prefer on sticking to a 12" sub still. I got these diminsions to play with do to limitied location, 26" widht, 18 " depth, and approx 28" hight for a cube.

I did show my wife my friends SVS PC_ultra, and she half-ass said yes, so thats good enogh for me. I think the diminsions on that are 16", by 40", with 3, 4" ports, that would be great if there is a resonable way to clone that design. I have heard that sub, and it isn't great for music, but is proabaly the most musical of subs over 10" that I have heard, so its a good compromise in my book.

Is bass box pro a decent peice of software for subs in general. I tried to use Unibox like you suggest earlier, but find it to be a very unfreindly program.

[collo]

WinISD is another popular design program.

Once you've determined the volume and port tuning, you'll need to work out your dimensions.

If you want to build a cylindrical sub, have a look at sonosub.exe
It's been kicked around a bit on AVSForum, but I don't know if it's been mentioned here yet

The SVS subs can have one or two of the three ports blocked to change the tuning frequency. I think you also threw a switch to change the amp's characteristics to suit the tune.

Attached is a sonosub screenshot using the dimensions you gave and with one port blocked....

[ThomasW]

Wilk,

Ok here's the catch-22, the RL-p12" isn't be best driver for HT/music use, it's really designed for high output car audio. That's part of the problem, as is the very small box you have it in.

That said, I certainly think we can create a box or tube that will perform closer to your expectations.... :T

Don't worry about getting BB Pro or anything else. I'll model it for you since I already have the RL-p12" in my UniBox data base.

Do you really want to mess with the 3 port thing or can you choose a particular Fb and we run with that? The reason for asking is that for every port you add inside the box, the outside dimensions get larger.

[Wilk]

No, the three port tuning thing can go, I ain't gonna wanan sit there and retune everytime i wanna listen to soem music. Besides I plan to build a 2.1 system upstairs for my music as soon as I get the HT up to par. Lets just get this as low as resonable with a 12". It does not need to be a Sound Spinter though. If that is not the right direction I will buy a new one, and sell that one to a kid in the neighborhood. I would prefer something that can handle music a little better if that exist. I do still intend to listen to some music down there.

On a side note, I really appreciate the modeling for me for this one, but I don''t wanna be in here bumming designs off your everytime I get the itch to build something. Is there something commercial that you might suggest. (and has a good manual or wiki,)

[---k---]

Wilk,

Thomas and most other people use Unibox: http://home20.inet.tele.dk/kou/ubmodel.html
to model subs. It is a very good program. Actually it is just a Excel spreadsheet. It does a great job. Check it out.

[Wilk]

That sono sub program seems to work pretty good. I have been playing with unibox, and winisd, but have let to get any usefull info outa them. I am pretty good with excel, so I know that I am giving it bad info somewhere, and it is giving me bad info back, I just need to figure out what I am feeding it wrong. Winisd on the other hand was deleted form my computer untill they find time to write a manual for it. From what i can tell soembody has to show you how to use it, or you already know enough that you don't need it anyways. I am deffently in that first catagory threre.

[ThomasW]

OK, BassBox Pro/Lite is the easiest and most user friendly commercial system available. The only difference between the 'Lite' version and the more expensive 'Pro' version is the 'Lite' version doesn't have the database of pre-installed drivers. This mean you put in the T/S parameters for any driver you want to model.

The Pro version has a bizillion driver data base which is updated frequently. Unfortunately it's always behind the newest drivers. That means one has to enter the parameters manually just like the 'Lite' version.

That said Unibox is a really good program. And I'll be glad to tutor you through a couple sims to get you up and running if you want to do that. Someone helped me so I'm just 'paying-it-forward' so to speak by helping someone else.

[Wilk]

Bass box pro will get ordered this week, as we go throught this project, I'll attempt to duplicate your unibox info on my side, and ask questions when it tells me my port needs to be 1 in diameter, and 30 ft long again.

Any Sub MFR I should go research to replace the sound splinter? I am thinking 80% HT use, 20% Music, but just casual listening. Like I said, I am gonna move/build more reference type stuff upstairs.

[ThomasW]

I'll model your RL-p12" and do screen shots as attachments to guide the process. This will take a few minutes to get started.

[ThomasW]

Ok back again had a typo. (thanks bent.... :T ) Here's your driver in a 7.56cu ft sealed box heavy fill.

[ThomasW]

Always hit the update boxes after every change to see the effects on the plot

[ThomasW]

Here's the same 7.56 cu ft box, with a single 4" dual-flared port. I didn't choose the Fb I just took the box size, flare diameter and let the program do it's thing, so the Fb was 25Hz.

Does this make sense so far?

[ThomasW]

If we leave everything the same but change the Fb to 18Hz this is what we get.....

[ThomasW]

If we leave the port tuning at 18Hz and the same port diameter but drop the box size to 6 cu ft this is want we get

[Wilk]

I am gonna try to match these plots tommorrow morning for learnings sake, but i only have about 5 cubic feet to work with. And that is if I go with a sono tube 18X40".

Ok here's the catch-22, the RL-p12" isn't be best driver for HT/music use, it's really designed for high output car audio. That's part of the problem, as is the very small box you have it in.

Should we just scrap the Sound Splinter and move to a bettter suited driver? ANy suggestions?

[ThomasW]

Dropping again to 4 cu ft but retaining the same Fb and port diameter we get.....

[ThomasW]

Ok here's 5 cu ft 18Hz tuning and the same 4" port. This is actually looking better than I remember. So you might keep the driver...We'll look at the Mach numbers tomorrow

[Marzen]

...Besides I plan to build a 2.1 system upstairs for my music as soon as I get the HT up to par.

I would say hang on to that sealed 2cu/ft PE enclosure and try the Dayton 12" (RSS315HF) in it for this system. I run a pair of these for music and they're quite fast & blend really well with my MTM mains. For movies I can turn on a larger ported sub.

Is bass box pro a decent peice of software for subs in general.

It's ok for what it does. It has the advantage of very good integrated help files and has possibly the best enclosure calculator on the market. I use SoundEasy primarily, but still use BassBox Pro for cabinet sizing because of it's ease of use.
If you're going to do more than this one speaker then it's worth it.
-Ward

[Wilk]

Thomas I think 5 Cubic foot is right about where I am looking 18 X 40" tube, and that plot looks fine to me. Not prefect, but completley workable, unless you know something I don't. ( I am sure you do ). Lets stick to that approx model, and throw some differnet drivers at it for sound qaulity's sake, I will start bright and early tommorow, couple to many beers for me tonight to keep up, you work very quickly.

Is there anything else i need to worry about since i am going below you standard 15" sub design that i see in the forums? I quess I am looking for a the possiblility of HP filter, and or PEQ reguirements? Just quessing?

[Wilk]

Quote:
Originally Posted by Wilk
Is bass box pro a decent peice of software for subs in general.

It's ok for what it does. It has the advantage of very good integrated help files and has possibly the best enclosure calculator on the market. I use SoundEasy primarily, but still use BassBox Pro for cabinet sizing because of it's ease of use.
If you're going to do more than this one speaker then it's worth it.
-Ward

Thats exactly what I am looking for. Something with a good manual to get me started in the low freq side of things I am a RF/Microwave calibration tech by trade. Anything under about 10 MHz is DC noise from my veiw professionally. I generally work in the range of 1 to 50 GHz. From a math standpoint 20 Hz is strange to deal with. No offense, any frequncy is hard to deal with in open air, I understand that. 50 GHz is actully easier to predict in common enviroment, becasue it just travels though everything. So control of a 20 Hz sine is a very different thing than i am used to. Some of the numbers i get on speaker design programs may be completly correct, and just look very impossible to me due to the difference in what I am used to working with in my job. The difference between 20KHz, and 20Hz, for Volume. and material interaction is amazing, try 50 Ghz to 20 Hz. the numbers just start to look like lies. With no true expereince, the lies and the answers are very hard to tell apart.

[ThomasW]

I have BassBox Pro, LspCAD, Unibox, and others...

For accurate and fast box models I use Unibox. Once you understand what involved in creating the model, and learn the Unibox interface, it's operation becomes second nature. Once I learned Unibox I completely stopped using BassBox Pro.

Jon and I have compared box sims made with Unibox against those made with LspCAD Pro ($980). The models are for all intents and purposes identical. Since Unibox is freeware, IMO it's the program of choice..

[---k---]

Oooh, I see a Archived Reference Thread!
Thomas, great to see you taking the time to put those screen shots together. I might also mention that with Unibox, if you click on the "Help" tab, it has a conversion of the metric to imperial. This always helps me.

I was wondering what you were going to suggest. I modeled that driver earlier in a 100L box with a ~17-18hz tune, and it didn't look too bad, except for the port speed (mach numbers). I guess I'll look forward to your answer tomorrow for that one.

[Dennis H]

Will, I think you are making this way too hard. With your technical background, a little time poking around with WinISD or Unibox should make them easy enough to understand. The only thing they don't tell you is what your target response should be and that's why forums like this exist. Room gain will boost LF so, if the software is giving you a gradual rolloff below 80Hz or so, that's about right. With WinISD, the EBS -3dB ported alignment is a good place to start. That gives you box size and tuning frequency. Then adjust port diameter to 6" to keep port velocity low (no chuffing) and that will give you a port length.

[ThomasW]

Just for fun here's your 5 cu ft box/tube Fb 18Hz, with a 6" port flared on one end. The Mach number with 500 watts input are a bit higher than the theoretical ideal. Personally I don't think it's a problem. What is a problem is the port length, which is longer than your tube is tall ....

[Wilk]

Ok, I have been able to catch up to you except for one small problem Thomas. On most of yor SPL graphs the response tens to head back down in the 130 Hz and up range. All of my graphs flatline at 100 Hz and up. I am getting the same plots as you from 10 Hz to 100 Hz though. I am doing somenthing dumb here, just not sure what.

Ok here's 5 cu ft 18Hz tuning and the same 4" port. This is actually looking better than I remember. So you might keep the driver...We'll look at the Mach numbers tomorrow

I liked the looks of this untill I saw the port speed numbers. That seems a little high to me, but I would like to hear what you gotta say on this.

Just for fun here's your 5 cu ft box/tube Fb 18Hz, with a 6" port flared on one end. The Mach number with 500 watts input are a bit higher than the theoretical ideal. Personally I don't think it's a problem. What is a problem is the port length, which is longer than your tube is tall ....
Attached Thumbnails

That does look decent if I could jam the port in the tube. Never seen anyone try, but is there anything stopin me from down fireing the port also, and running the port all the way up the tube, and bending it back down the other side? I have seen very close to this in a down fireing cube, tube shoundn't be an issue. Bracing the thing just became a real nightmare though.

I am goign to go try to find some 12" that require a little less volume. That should help make thing simpler I think?

[JonMarsh]

Ok, I have been able to catch up to you except for one small problem Thomas. On most of yor SPL graphs the response tens to head back down in the 130 Hz and up range. All of my graphs flatline at 100 Hz and up. I am getting the same plots as you from 10 Hz to 100 Hz though. I am doing somenthing dumb here, just not sure what.



I liked the looks of this untill I saw the port speed numbers. That seems a little high to me, but I would like to hear what you gotta say on this.



That does look decent if I could jam the port in the tube. Never seen anyone try, but is there anything stopin me from down fireing the port also, and running the port all the way up the tube, and bending it back down the other side? I have seen very close to this in a down fireing cube, tube shoundn't be an issue. Bracing the thing just became a real nightmare though.

I am goign to go try to find some 12" that require a little less volume. That should help make thing simpler I think?

Your modeling isn't including the effect of voice coil inductance, Le. This has a significant impact, depending on the driver design- many subwoofers start rolling off in the top end at 75 Hz.

[Wilk]

I'll check on where, and why I am missing that.

[Bent]

You need to select it in a check box in the Unibox user interface.

[ThomasW]

I liked the looks of this untill I saw the port speed numbers. That seems a little high to me, but I would like to hear what you gotta say on this.

Lots of forum bandwidth is dedicated to the idea that slightly higher Mach number are something terrible. That's nonsense. First most of the time if one is using a decent sized port the effects of the higher Mach number are drowned out by the music coming from the sub. Also look at the input power being used in the sim. Are you really going to be driving this thing with 500 watts continuous?

Also if you run the numbers for my AS-15 design, the Mach numbers are significantly higher that what 'current trends' recommend. Oddly enough when it's playing at literally house shaking output levels, there's no audible effects from those higher Mach number.

So there's a difference between the theoretical 'ideal' numbers, and what's actually needed to make a good sounding sub

I am goign to go try to find some 12" that require a little less volume. That should help make thing simpler I think?

You have a low Vas driver now. That's what car subs are all about.

I have to run to do errands so I'll check back in a few hours

Thomas

[Wilk]

yep, you guys where right on the LE, LE2, RE2 check box.

I have been experimenting with some different drivers, and got some interesting results for the Dayton RSS315HF-12.

I am running the model based on 141.5 liters, 18 Hz tune with 3 4" ports at 24.5 ".(At least I think I am). All the numbers look great except it looks like I can't get more than about 250W on it before I exceed xmax.

First question is am I just a retard that can't make unibox work correctly, or am I pretty close here?

Next question is considering that I am running a Denon 3806 120X7, and it has never seen more than about 3/4 of that, and my existing sub has never seen more than 1/2 of the 500W bash plate amp behind it, Isn't 250W or so on a 12" in that much air goingto be loader than I actually ever wanna play it anyways?

[ThomasW]

First question is am I just a retard that can't make unibox work correctly, or am I pretty close here?

I can't comment on this.....

Below is what I get when I put in 3-4" ports. Note the port length. 144.24=56.78"

Next question is considering that I am running a Denon 3806 120X7, and it has never seen more than about 3/4 of that, and my existing sub has never seen more than 1/2 of the 500W bash plate amp behind it, Isn't 250W or so on a 12" in that much air goingto be loader than I actually ever wanna play it anyways?

Unless you measured it that "never used 1/2 of 500 watts" may not be accurate. Frequently a knocking noise can be the result of an amp clipping.

[Wilk]

Ok, you unfortanly answered my retard question as I figured that 144.24 was the total port lenght, and the individual ports were approx 19".

Back to the drwing board

[ThomasW]

Don't worry, it's not that you don't understand the program, you're just a bit behind the learning curve for how one designs a sub. Regardless of what you pay or don't pay, none of the programs create the design for you. They all assume the user understands the basics of box design.

[Wilk]

Ok, teacher this is what I have learned today. After I have spent most of the day screwing with the following subs. in a 18, or 20" sono tube about 40-45" tall. (140-200 liters)

My exisitng RL-p12
a 12" TC-1000
a 12" assasin
Dayton HF 12"
a couple of 15" just for learnings sake.

A 6" port will not be a easy thing to do unless I make the Sonotube 60 + inches tall.

With a 18Hz tune a 4" port fits well on most subs, but may have some port noise issues.

I am going to be limited to approx 300 watts on most of the subs listed do to over excursion.

Going to need some kinda High pass filter for some Movies

Due to the size retrictions, 15" ore pretty much not a option.

The TC sounds, and the Assasin seemed to model the best in a 145 liter volume. The TC sounds appears to be the best option due to Power handling/excursion advantage on the assasin.

Can anyone give me an opinion on this being a resonable compromise between what I want, and what I got the room for. I know this is way below the standard build here, but is this going to handle regular Family HT respectfully enough to make stop cussing at my sub woofer? This is after all as big as all but the largest SVS tube sub.

[PMazz]

I always wanted to try a nested tube for a ported alignment, ala Adire's Sadhara. Seems like you should be able to achieve quite a low tune and still have plenty of port area. I have a suspicion that standard models would only get you close to the actual tuning but I've never tried or measured one.

Pete

[Bent]

Pete, I'd considered that as well.
even posted about it a while ago...

http://www.htguide.com/forum/showthread.php4?t=22577

Dennis H was even nice enough to run some numbers for me

alas, time ran short and so did my patience, so I put it on the back burner even before my saw came out.

I'd bet this is a great opportunity to do it vicariously.

[ThomasW]

I'd go ahead and build the sub with your existing driver. With ported alignments it's not a big deal to swap out one driver for another. So doing that is always an option

Listen to the new alignment, you're probably going to find it sounds pretty good (certainly better than the current box.) If you aren't pleased we can revisit the situation and make the whatever adjustments are needed.

[Wilk]

Cool, I am still trying to fight with the wife over how tall I can get away with building this thing. I am just gonna order up like a 18' diameter by 60" height sono tube, and some 4" port supplies. Hopefully I can get a couple extra inches by her before I get to cutting on things. Any extra volume will only help from what I am learning. Regardless It's gonna be way better than the current situation. Been watchin a simular thread where Steve Callas has a 120 liter, and 185 liter model with a simular driver that are both good in my book. Mine should fit nicely in there somewhere.

Thanks for all the help. I am far from understanding unibox, but at least I can fight my way through it now.

[ThomasW]

Unless you're going for really high SPL, I don't think you'll have issues with a single 4" dual-flared port. Do buy one of the PNP flare kits. The DIY router round-over flares don't 'flow' air as well as the factory made flares..

It's more than understanding Unibox or any other modeling program, it's knowing how to design the box. Once you understand the principles involved with that, the box program itself becomes second nature.

The reason it looks easy for Dennis, Jon, myself, etc is just a function of experience. I'm pretty sure I'd look like a complete fool trying to run the system you use to calibrate mics...:wink:

[Wilk]

I am not tryign to change my design up, but I have ben modeling diffent size drivers in unibox again, just trying to get confident to using it.

I modeled the TC Sounds dB-500 10" that just showed up on their website. I had to quess about 300cm2 for SD based on a simular Soundsplinter design.

Anyways the model in my existing 141.5 liter box seems to actually be alot better match. Simular SPL in across the whole frequency plot. I also have a lot more room to play with the diameter on the port, and how low I can tune it. My port speed numbers are about the same as the 12".

Am I doing somethiing wrong again, or is this just a better fit due to the small volume I am dealing with and the large XMAX, and power handling on that 10"

[ThomasW]

Not sure that it models that much better....don't know where they get their power rating this can't take 300 watts in your box, so the 200-700 watt thing seems odd. It's lower Le and Fs will make the sim look better. That's usually a non-issue when room gain does it's job.

[Wilk]

Well, I have just finished listining to my almost finished sono tube for the first time. I have everything done except for the "sock" or whatever the offical term for that is. I have not found what I want to cover the tube yet. Looking at the standard strechy black fabric, and basically vennering it with a thick leather. I'll post some picks as soon as i get that done, and get my gallery page on my webserver working correctly again.

It is a smallish 18" diameter 3 and a 1/2 ft tall sonotube. Finished the thing is just shy of 4ft tall. It is at 145 liters, and tuned to about 23 Hz. I had it tuned a little lower, but it was making a sound like a guy gasping for breath. I don't think it was quite audible from the primary listing postion, but it was creepy sounding from the chair closest to it, so I cut it the port back a little.

I have only listened to music at standard volumes so far, and sounds suprising good to me as I was a little sceptical of how it would preform quality wise. I have always been a sealed 10" sub guy up untill now. This maintains a level of qaulity that suprised me. I was seriously afaird it was gonig to sound like the back of a 16 year old kids car. I know this is a wimpy sub compared to most here, but I have very good hearing, and listen to things a relitivley low volumes compared to most. I think this is going to work out just fine for what I am actually going to be doing with it. Not sure if the wife is going to let me keep it or not in the long run. The thing is twice the size of anything we would have considered before, but its going to be fun in the meantime, and was well worht the knowledge i gained in building it.

Going to run a few movies though it, and see if it will bottom, out anywhere at regular listining levels.

Thomas,
Thank you for all the help, and tutoring.

[Wilk]

Nope, it doesn't seem like it is going to bottom out at the volumes I am going to listen to. The only thing I have noticed that I am not sure about is that it seems to hold on to certain tones to long. Not really sure how to describe this correctly, and I am being very picky to even bring it up, so it may just be my ears. Has anyone else heard anything like that with a sonotube sub before?

I'll have to bring some equipment home to get some measurements done next weekend hopefully

I am goign to test the leather wrap on the left over tube on tuesday night I think.

[ThomasW]

It's got nothing to do with the enclosure being a tube. The transient response of most ported subs isn't as good as that of a seal sub.