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PostPosted: Mon Jul 03, 2017 8:52 am 
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Joined: Mon Mar 31, 2008 9:17 am
Posts: 13706
Location: Toronto, ON, CA
There's a bunch here....use the one you like best.

I like this one for the graphs: http://www.micka.de/en/

I used to use BoxPlot. My first one, I had a friend compile the code from Weems' book in QBasic lol.

Times have changed! 8)

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PostPosted: Mon Jul 03, 2017 9:00 am 
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Joined: Fri Dec 12, 2014 5:43 pm
Posts: 159
Location: Pierrefonds, QC, CA
very cool! Will give them a try - thank you!


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PostPosted: Mon Jul 03, 2017 9:22 am 
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Joined: Sun Sep 07, 2008 7:12 am
Posts: 72
Location: Regina, SK, CA
A good free box designer is "Woofer Box Model and Circuit Designer" by Jeff Bagby.

The problem with most of the design tools are they use small signal analysis to determine a box size and tuning. This gives you designs which look fantastic on the computer but sound like garbage in reality. Drivers with low VAS, high QTS and high FS sound best when tuned in the proper range. Anytime you tune below FS with a reasonable box size you run into several problems.

One; the port calculations are not usable. You end up with ports which are too long to fit into the box. So you end up using a smaller diameter port to make it work. This now gives you a really high port velocity which makes it "chuff". The other drawback with the port size is in now interferes with the tuning. Remember the small signal analysis I mentioned? As box pressure increases from high SPL levels the small ports start to become excessively restrictive and the tuning goes out the window, the box starts to act more like a sealed box than a ported box. Computer sims don't tell you this. Bottom line, high SPL subs with 12" drivers should use a 5" diameter port to solve the port drawbacks.

Two; this one the computer will tell you. The group delay gets really really ugly. Anything above 30ms at tuning starts to sound one-note bass. Rule of thumb, box tuning multiplied by group delay at tuning should be less than 400.

Drivers such as the sundown can work if you take into account the limitations of the driver and use it where it will work best. This is why I suggested a passive radiator box with some boost at tuning. The small size helps control the driver when tuned below its FS and the radiators allow for low tuning without the port issues. Many commercial subs use this exact type of design method with very similar drivers. (think Sunfire True Subwoofer here)


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PostPosted: Mon Jul 03, 2017 10:20 am 
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Joined: Fri Dec 12, 2014 5:43 pm
Posts: 159
Location: Pierrefonds, QC, CA
so who wants to design the sub box! lol :P starting to scare me more and more!


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PostPosted: Mon Jul 03, 2017 10:33 am 
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Joined: Sat Jan 11, 2014 12:47 pm
Posts: 27
Location: Montreal, QC, CA
lot of choice as mentioned above!

ive always used Winisd

http://www.linearteam.dk/default.aspx?pageid=winisd

Worked out very well with my builds and tuning/port is on point in my experience, its a bit buggy sometimes though but once you get it working its fine. got lot of options too, cone excursion, impedance, port velocity, SPL, group delay, and also can simulate passive radiator builds. Of course no program will give you 100% accuracy, but gives you good idea

I remember there was one program that cost about 150$ but was very, very detailed and even made for tweeter and woofer design, with xover layout too and all, forgot the name, but no real need for subs, especially since you did have experience with building boxes, im pretty sure you already have a good sense of build.

Passive radiator are fairly simple, as a general rule;
1. PR mass is like "port length"; The more weight (mass) on the PR , usually the cone itself or some models have washers you screw in, the lower tuning... So mass on PR is like "port length"
2. PR size (10", 12", 15", 18") is like "port size"; evey time you add a PR its like adding a second slot port, which makes the tuning naturally higher, so those PR need the have more weight on them to achieve same tuning as less PR
3. Never mount the PR upward or downward unless the actual PR is built for that purpose, it usually isnt.
4. Also, usually, you want to have 2 PR facing outward of each other, so that you cancel off any enclosure stress naturally, or 1 PR at the other end of where you mount the sub, kind of like a sono-tube.


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PostPosted: Mon Jul 03, 2017 1:55 pm 
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Joined: Sun Sep 07, 2008 7:12 am
Posts: 72
Location: Regina, SK, CA
If you want to try ported my first guess would be :

1.8cuft. Build box to about 2cuft and the displacement of port, driver, amp will give you net volume of about 1.8cuft
Single 4" diameter port that is 15" long and rounded at both ends. No need for huge flare.
Lots and I mean lots of dacron or fiberglass fill. take 4 pieces of fiberglass r12 that are each 16"wide by 4' long and roll them up tight into 4 hotdogs and stuff them in the corners of box.

This should net you around a tuning freq of about 30hz and usable in room response down to about 24hz.


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PostPosted: Wed Jul 05, 2017 12:17 pm 
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Joined: Mon Jan 03, 2005 8:43 am
Posts: 936
Location: Burlington, ON, CA
Nice amp just showed up in the classifieds.

Outboard Dayton sub amp - http://www.canuckaudiomart.com/details/649365210-dayton-audio-sa1000-subwoofer-amplifier/

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PostPosted: Wed Jul 05, 2017 3:50 pm 
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Joined: Sat Dec 29, 2012 8:16 pm
Posts: 451
Location: New Westminster, BC, CA
A common thing I've noticed with DIY subs, and have been guilty of myself, is to place too much importance on the numbers, overemphasizing quantity. Quantity, for the most part, is a turn of a knob. Seen quite a few subs tuned for dinosaur stomp seismic events used for music. Most of the calculators and simulators don't take room gain, boundary loading and floor bounce into account. Part of the problem is that many little stand mount speakers optimistically advertise 30 Hz capability and the DIY'er uses that as a reference point. Totally different worlds. Often, a more conservative design is better balanced and easier to integrate.


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PostPosted: Thu Jul 06, 2017 6:52 am 
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Joined: Fri Jan 07, 2011 1:17 pm
Posts: 2398
Location: Not Toronto, ON, CA
If you're not confident in you building, it's gonna be a long tortured road ahead. Nothing ever goes perfectly.

I am building an arcade cabinet that doesn't need anything to be air tight and if there is one thing I can caution... If you don't have the ability to make consistent straight cuts, a strong box with proper joinery etc... Pay someone to build it or buy a flat pack and follow the instructions.

The finished product is most important and requires quality components to go together well. For what a nice flat pack or a few expert cuts costs in addition to wood, it's an either or. There may be a flat pack in the size you need etc.

My subs were built to mimic the Denovo 1.5cubic ft flat packs that PE carries. Solid, heavy and took a lot of glue :lol:

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PostPosted: Thu Jul 06, 2017 7:18 am 
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Joined: Mon Jun 01, 2015 4:49 pm
Posts: 312
Location: Coquitlam, BC, CA
OK, in that situation, I'd sell the 1500 watt car sub and buy a ready-made, pre-engineered subwoofer for home use. Suppose you do all that work and spend more money and it sounds awful, then where will you be? A good used subwoofer should be cheaper than a new plate amp that could actually drive that woofer and likely work a lot better. Also, it's just the right way to do it without trying ten times as hard.


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