[Djleary]

First of all Hey to you all

Ive just orderd 2 10'' mission subwoofers which i am going to build an enclosure for this weeked maybe next, i have seen alot of subwoofer builds on here and they all look great , Just wondering has any one got any tips for me, Box design types (Characteristics) screws, nuts, sealents, paint etc, im going to to build the box out of MDF with a painted finish.

One more question is, inside of Grahams subwoofer build there are lots of wood sections with a hole in the middle, is this just for strength or would it affect the sound?

Thanks v much and look forward to reading your tips

Ill keep this updated

[IronGiant]

They are braces for strength, the bigger the cabinet the more you need

Dave

PS moved the thread for you...

[Djleary]

Ahhh i see, i imagine you would have to calculate the volume of the box they take up?

As for moving the thread, thanks

[IronGiant]

Ideally yes, but in practice people don't tend to (I think). If anyone has hopefully they'll chip in...

Dave

[Moonfly]

Originally Posted by IronGiant

Ideally yes, but in practice people don't tend to (I think). If anyone has hopefully they'll chip in...

Dave

I beg to differ

To get the best from your DIY build you need to know the size of cabinet your sub best works in. To find this out you need the Vas figure of your drivers. For 2 double the figure. The link I've provided will help you calculate the size of cabinet, and it can take account of various cabinet shapes, and will also factor in bracing and driver displacement if you know it. Its best to check the performance of your chosen driver in a cabinet of a given size to monitor driver excursion as well, altering the box size will also alter the amount of excursion your driver is forced to use.

Out of interest, is there a particular reason you want to use 2 10" drivers rather than 1 larger one?

[micb3rd]

Err What? Since when is the drivers Vas value the best for enclosure size?

It all depends on your design wants, the driver Vas value could be totally wrong for the sound and responce you want from the enclosure.

[IronGiant]

Originally Posted by Moonfly

I beg to differ

Cool... Did you all use it?

Dave

[Moonfly]

Originally Posted by micb3rd

Err What? Since when is the drivers Vas value the best for enclosure size?

It all depends on your design wants, the driver Vas value could be totally wrong for the sound and responce you want from the enclosure.

Sorry, I should say, you use it as a guide. Basically, in a general term, more vas means better in a larger box. Correct me if that is wrong or misleading.

Originally Posted by IronGiant

Cool... Did you all use it?

Dave

I did, not sure about Russell and Adam. I provided the same link to Graham which I believe he used, Russell seems to be old school and enjoys working everything out his self so not sure there. I know a heck of a lot of the US DIY'ers use it though.

[IronGiant]

Thanks, I stand corrected

Dave

[Djleary]

Originally Posted by Moonfly

I beg to differ


Out of interest, is there a particular reason you want to use 2 10" drivers rather than 1 larger one?

Cheers folks, correct me if i am wrong but when you use two subwoofers instead of one in a correctly tuned box dont you get a fair bit of "better" sound output as i put it, im not certain on that someone may be able to shed some light, as to the driver specification they are being sent with the speakers so i will have to take a look when they arrive but i will bear that in mind, in general terms is this statement true? "the smaller the box the higher the frequency and you would get a bit more power handling, and the larger the box the lower the frequencys can go but lower power handling, aswell of obviously being too big would result in mechanical failuer of the driver over excursion etc.

Ive seen downword firing subwoofers too, are there any advantages of this sort of design, has any one tried to do an isobaric before?

Thanks again chaps

[Moonfly]

Generally, using two drivers will increase output of the sub by upto +6db, pretty much the same as just having 2 single driver subs. The disadvantage of that is you cant split them up if you want to get the best from room eq'ing, but not everyone is that anal anyway Its worth knowing though that 2 10" drivers are only just more than a single 12", and cant match a single 15" driver for displacement of air. Also, its not possible to force a driver of a given size to go lower without more excursion, which means you get ever closer to the point at which the driver will distort. Basically, multiple drivers will give added volume for each added driver, but not added depth. For that only a larger driver will do.

In general terms, how high a frequency your sub reaches is a moot point, as all will reach above the 80hz generally considered the limit for sub bass. So unless you want an unusual crossover you dont need to worry about your subs upper limit really. Depth is important. Larger boxes go deeper with less effort, but again there are other factors that must be considered so you cant just get any driver and stick it in a huge box for mega depth.

There are 3 main factors that come in to play when considering a sub. Size, price and performance. You can only choose 2 and will have to take a hit on the other at some point.

Power handling is a moot point really in relation to box size. Your driver will have a limit it can handle, and power doesnt always dictate how much excursion your driver will have to deal with, box size will affect this as well. These are things you need to keep an eye on when designing your sub really, and simulation software really is there to remove the need to build several boxes and designs to find which will work best.

Generally speaking though, the larger you build the easier it will be to get more performance, or rather depth out of the box. The more compact the sub the more difficult, and this is where the price comes in. It is possible to get smaller boxes to perform beyond what they really should, but it starts to cost a lot and get more difficult.

DF and FF subs are really a matter of choice. Some say that a DF model will suffer from driver sag over time, but Ive yet to come across someone really concerned with that, certainly the manufacturers arent. As for Isobaric designs, they are the best way to get a smaller box to outperform its physical limits. The problem with these is your paying for an extra driver and gaining no extra output volume wise and you need twice the amp power because you have twice the drivers. Isobaric does however make sure the drivers are very accurate and its said that this design will give the best bass from a small box. Due to cost, and the fact large boxes will go deeper for much less money, its a design people dont seem to bother with.

For more info on sub types see here.

[gperkins1973]

Dan,

Mine was price.

cheers

Graham

[AngelEyes]

I used WinISD to calculate rough volumes and then trigonometry for the braces etc. Using Google Sketchup is a great way to visualise volumes.

As I can't (refuse) to do imperial, the HTS calculator just gave me headache.

Russell swears by Unibox.

Adam

[Moonfly]

Originally Posted by AngelEyes

I used WinISD to calculate rough volumes and then trigonometry for the braces etc. Using Google Sketchup is a great way to visualise volumes.

As I can't (refuse) to do imperial, the HTS calculator just gave me headache.

Russell swears by Unibox.

Adam

There is a converter at the bottom of the page on HTS

[Russell.Williams]

Originally Posted by Moonfly

I did, not sure about Russell and Adam. I provided the same link to Graham which I believe he used, Russell seems to be old school and enjoys working everything out his self so not sure there. I know a heck of a lot of the US DIY'ers use it though.

I couldn't be bothered to keep converting everything into feet/inches, so I did just run the calcs and do the maths on paper. A cubic centimetre is a millilitre, so keeping it all in cm is much easier.

Russell

[IronGiant]

unless you end up 2mm out, when 80 thousands of an inch sounds much smaller.

Dave

[Moonfly]

Originally Posted by Russell.Williams

I couldn't be bothered to keep converting everything into feet/inches, so I did just run the calcs and do the maths on paper. A cubic centimetre is a millilitre, so keeping it all in cm is much easier.

Russell

Strange how we work, converting didnt bother me at all, yet I couldnt be bothered getting to grips with google sketchup

[AngelEyes]

Originally Posted by Moonfly

There is a converter at the bottom of the page on HTS

I noticed.

Originally Posted by Russell.Williams

I couldn't be bothered to keep converting everything into feet/inches, so I did just run the calcs and do the maths on paper. A cubic centimetre is a millilitre, so keeping it all in cm is much easier.

Russell

+1

Adam

[Moonfly]

Originally Posted by IronGiant

unless you end up 2mm out, when 80 thousands of an inch sounds much smaller.

Dave

80 thousand sound smaller than 2

Sorry, I'll get my coat.

[gperkins1973]

Hi chaps

I went down the route of what was the biggest size box I could fit in my space or could get away with, wrote down the measurements in mm. Job done. Got the mdf cut to size and built it. I think considering that I didn't take into account the vas etc... of the drivers I should get a really good result.

I just put my sub into WinISD, worked out what my size box was in cu ft, see what spl, cone excursion etc... and that was it. I personally don't think unless you are a real boff you need to go in to deep as all you are going to do is confuse yourself.

cheers

Graham

[AngelEyes]

Originally Posted by gperkins1973

Hi chaps

I went down the route of what was the biggest size box I could fit in my space or could get away with, wrote down the measurements in mm. Job done. Got the mdf cut to size and built it. I think considering that I didn't take into account the vas etc... of the drivers I should get a really good result.

I just put my sub into WinISD, worked out what my size box was in cu ft, see what spl, cone excursion etc... and that was it. I personally don't think unless you are a real boff you need to go in to deep as all you are going to do is confuse yourself.

cheers

Graham

I somewhat amazed you built the sub before entering the calculations in WinISD?

If you don't do your calculations you could end up with something that at best sounds very mediocre and at worst, end up with no appreciable output below 50hz or even blow your driver(s).

The whole point of DIY is to get the utmost out of your expenditure and that requires a bit of head scratching before you start IMO.

Adam

[gperkins1973]

Adam,

I don't think I made myself clear. I measured the area I had available in the space where the sub will go, then I chose the drivers I wanted, then downloaded the wdr file to put into WinISD, told it how many watts I would be putting in and then from the dimensions I had for the sub worked out what that was in cu ft, inputed that into WinISD and it then gave me the information with regards to spl, cone excursion etc... I then took some out based on the bracing I had put in. I did have help from Am and FI and Scott at FI as they worked out the information I gave to them and both of them told me my box would be pretty impressive based on the information supplied, hence I feel confident that I will have a very potent toy with lots of power.

cheers

Graham

[AngelEyes]

Yes that is much clearer

Adam

[IronGiant]

Well I'm still confused, yeah, yeah, I know, it happens a lot

Did WinISD tell you what size box to build, or did you use WinISD to tell you what performance you would get from the box you already had in mind ?

Thanks,

Dave

[gperkins1973]

Dave,

I already had the box size in mind. I modelled everything around the box dimensions I wanted to use. I couldn't go any bigger but I dont think I needed to. I then put the cu ft size into WinISD told it what drivers I was using added the power input and presto! Even running with this set up I will be no where near full excursion at 2400 watts, I will have plenty of spl so all should be fine. The proof will be in the pudding on saturday when I fire it up but I have had alot of positive feedback from alot of peeps on the hometheatershack forum and the people from FI and to be honest if the suppliers of these subs thinks my box will be great that's good enough for me. After all this is what they do for a living and my subs are CUSTOM built and not just off the shelf so they have been designed with all my information and specification in mind. FI have taken on board all this and tweaked what they need to do so the TS parameters will be different from the normal FI Q18's.

You will see the graphs tomorrow.

cheers

Graham

[IronGiant]

That's fine, no complaints here I was just trying to get it clear in my mind.

I'm looking forward to it

Dave

[Djleary]

Cheers for the info guys, im still waiting on the drivers/specs so i will keep you updated

[Djleary]

The drivers came through today , ill put some pics up when i register with photo bucket or something similar,im going to go for a sealed box i have decided, reason being is just to keep this build simple then i may change it if it doesnt work out properly, the drivers reckon optimum enclosure volume would be 1.2cu.ft to 1.8 cu.ft so im going to build a 3.3 cu.ft enclosure for the both of them to go in, this sound about right to any one?
Thanks

[Moonfly]

Sounds good to me, but if you have the correct TS specs, why not run it through a sim and check.

[Djleary]

Sweet , i ran it through a program called "ajsealed" and came up with a box volume of roughly 1.6 cu.ft so it should be ok, just got the wood orderd from "mdf cut to size" if anyone has ever heard of them not a bad price in all, both of the subs appear to be magnetically sheilded not that it matters just seems odd to me , putting wadding in a sealed box sort of "tricks" the driver into thinking its playing into a bigger enclosure doesnt it? or something similar anyhow thanks guys