First DIY project, need help with Subwoofer build - AVS Forum
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post #1 of 21 Old 06-17-2013, 10:07 PM - Thread Starter
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This is an offshoot of my earlier post that you can find here
I was going to purchase a sub in the $700 - $1000 range (HSU, Rythmik, etc…) when jbrown15 suggested building a sub with parts available from parts express. I had ruled out DIY because I didn’t have the resources or skills to build a cabinet myself but with precut cabinets that just need to be assembled, that is a different story.

My question is, can I build an off the shelf type sub (as suggested by jbrown) that will be equal to or better than comparable HSU or PSA offering for less money?
If so, I would consider the TC Sounds LMS-R 15” driver in a 3 cubic ft box; or the Dayton Audio 18” reference HO driver in a 4 cubic ft box
Is it obvious as to which system would be the top performer? My room is large so I am likely to add a second similar or identical sub 6 -12 months later as funds become available. I look forward to your input and advice as I have very little idea of what I’m doing.

Thanks, Garth
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post #2 of 21 Old 06-19-2013, 01:20 PM - Thread Starter
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I spoke with tech support at parts express and he didn't seem too enthused about putting the TC Sounds 15 in driver in one of the three cubic foot boxes on their website. He hinted at the fact that a more sturdy or reinforced cabinet might be in order. Does anyone know of a commercial source for a box that would be suitable for the 15 in LMS driver? Suggestions, opinions??
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post #3 of 21 Old 06-19-2013, 01:30 PM
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The Dayton RS18 or Ultimax 15 in one of the flat pack cabinets is a very good option. You can use an outboard pro amp like a behringer nu3000dsp to power either, and you are left with a second channel to power a second sub when possible. Another great thing about that amp is there's a fully adjustable EQ suite built in, that no commercial sub can touch.
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post #4 of 21 Old 06-20-2013, 06:25 AM - Thread Starter
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Thanks Jay,

Do you think that this option would out perform, under perform or be equal to something like the PSA XS15 or the HSU ULS-15?
Do you think this option would be superior to the TC Sounds LMS 15 inch driver in a 3^3 ft box?

I know that saying one thing is better than the other is a tricky prospect and it is likely to depend on what parameter you are using to judge performance. As I mentioned in my other post, this is for ~ 65% music system with the rest home theater. My goals are: 1. clean, tight, articulate music bass 2. a good mid bass slam for movies 3. sub 20 hz output. In that order. My room is large an I realize that sub 20 hz output will be hard to achieve which is partly why I listed it last.
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post #5 of 21 Old 06-20-2013, 07:20 AM
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The LMSR 15 is definitely a very nice woofer. I'm not sure what the real limits of the driver are, but to make it a worthwhile investment over the Dayton drivers you really need about 2000 watts behind it. This is twice the power that the UM15 can handle in a 3 ft3 box, and will equal 3 db more output for the TC, assuming some of the extra power isnt simply soaked up as power compression... The UM15 also gets about 5 hz lower extension before any EQ is needed.

So you would need the NU6000DSP amp for the TC vs the NU3000DSP for the UM15. So you're spending $233 more for the woofer, and $100 more on the amp for the potential of 3 db more output (you can get the UM15 with cabinet flat pack for $260 also).

There's nothing that leads me to believe the TC sounds better. The UM15 has a low inductance, advanced motor design. It will play cleanly up to several hundred hz and could possibly be used as a woofer in a 3 way speaker.

Both setups would allow you to EQ the response to whatever you desire down to 20hz (the limit of the amps EQ). My guess is the UM15 setup is equal to the ULS15, and the TC has the potential 3 db output advantage.

(Note that you could stack two of the UM15's for the price of 1 TC15. That will yield a true 6 db gain vs a single UM15)
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post #6 of 21 Old 06-20-2013, 09:10 AM - Thread Starter
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Interesting, Thanks for your detailed analysis. However, if I was going with a dayton driver, I had planed to go with the 18 inch Reference HO driver. I had just assumed that the 18 in would give me the best bang for my buck. Do you think otherwise?
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post #7 of 21 Old 06-20-2013, 11:29 AM
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The 18 has a minor output advantage higher up in frequency, but down low the um15 is equal. Given the price and box size difference IMO the 15 makes more sense.
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post #8 of 21 Old 06-21-2013, 07:57 AM - Thread Starter
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I just assumed that the larger woofer would yield more low frequency output and better low frequency extension. But apparently it is also a factor of driver design? Do people use modeling software to make judgements as to how a woofer is going to respond for a given box size and configuration? What free software is good?

Thanks, Garth
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post #9 of 21 Old 06-21-2013, 09:32 AM
 
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The reason the 18 is similar to the LMS-R 15" and the dayton UM15 is because both these 15" drivers have a lot more excursion, the LMS-R with 25.4 mm, UM15 with 19 mm, and the dayton 18" is only 12.75mm.

The extra surface area makes up for the lack of excursion to give them pretty close displacements.
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post #10 of 21 Old 06-21-2013, 10:28 AM
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http://www.data-bass.com/data?page=driver&id=48

Give this a quick read before looking away from the Dayton 18"

I believe the measurements were taken by Ricci (member name on this forum) and can be trusted.

Plus you can see some info regarding other subs and actual systems and compare output at frequency etc... A fantastic reference source.

XBL-Steelhouse1

"No one wants to fight the naked guy."
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post #11 of 21 Old 06-21-2013, 10:30 AM
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the xmax spec on the dayton is confusing.

it is geometric stroke, not usable xmax.

usable xmax is closer to 20mm.

data-bass.com has measured it and the data seem right to me.

Listen. It's All Good.
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post #12 of 21 Old 06-21-2013, 11:34 AM
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The ultimax was also klippel tested to be in the 22-23 mm range. Why they dont list that I have no idea.
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post #13 of 21 Old 06-21-2013, 11:41 AM
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Quote:
Originally Posted by gakaudio View Post

I just assumed that the larger woofer would yield more low frequency output and better low frequency extension. But apparently it is also a factor of driver design? Do people use modeling software to make judgements as to how a woofer is going to respond for a given box size and configuration? What free software is good?

Thanks, Garth

You make many primitive and simple assumptions. It is almost never as simple as bigger = more output and deeper bass.

Put a massive woofer in the wrong box and it will perform badly. It is almost certain that if you put an 18 inch woofer in a box that is designed for a similar 15 that the 18 inch will have less deep bass, though might play louder. If you choose a vented/ported design you cannot make any assumptions at all.

Even new DIY speaker builders use modeling software. BassBox (not free) is worth every penny.
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post #14 of 21 Old 06-21-2013, 07:39 PM
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For sophisticated box modeling I use SoundEasy but it is not free.

For simple modeling (90% of the time) I use Unibox but you need MS Excel.: http://audio.claub.net/software/kougaard/ubmodel.html

WinISD Pro is also popular free tool: http://www.linearteam.dk/default.aspx?pageid=winisdpro
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post #15 of 21 Old 06-22-2013, 05:23 PM - Thread Starter
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I am struggling with these modeling software packages. Either I don't seem to have all of the parameters required or I am unable to change some of the parameters that are prefilled; frustrating.
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post #16 of 21 Old 06-22-2013, 05:34 PM
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i use winisd alpha pro version.

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

if getting errors when entering new drivers, try this:

make sure all fields are clear, then
enter qes then hit tab, enter qms
hit tab a couple times and let it calculate qts
hit tab a few times to move to mms
enter mms, re, bl, le, sd, xmax, and pe
by using tab after entering each data, it will calculate what it needs to
i no longer get any conflicts
sometimes the specs calculated don't match exactly the manufacturer specs, but its only rounding type errors, so it is not material

Listen. It's All Good.
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post #17 of 21 Old 06-22-2013, 10:41 PM
 
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Quote:
Originally Posted by gakaudio View Post

I am struggling with these modeling software packages. Either I don't seem to have all of the parameters required or I am unable to change some of the parameters that are prefilled; frustrating.

you can just load someones saved drivers into your programs. Just go here http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/14410-downloadable-winisd-pro-files.html and they have like every driver ever made as a downloadable winisd file you can just load for parameters.
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post #18 of 21 Old 06-24-2013, 10:18 PM - Thread Starter
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Thanks for the suggestions and help. I did a comparison between the Dayton Ultimax 15" (white), Dayton Reference HO 18" (yellow) and TC sounds LMS 15" (green). The 18" is in a 4ft^3 box and the 15" drivers are in 3 ft^3 box. Does this model look "right" or correct? If so, it looks to me as though the UM 15" is the most linear with the best low frequency extension. If I did it right and I am interpreting the out put right, it seems like that is the way I am likely to go.

Thanks, Garth
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post #19 of 21 Old 06-24-2013, 10:31 PM - Thread Starter
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The actual figure would help:
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post #20 of 21 Old 06-24-2013, 11:39 PM
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"If so, it looks to me as though the UM 15" is the most linear with the best low frequency extension. If I did it right and I am interpreting the out put right, it seems like that is the way I am likely to go."

hop over to the spl tab.

what is actually happening is the 18ho has higher sensitivity in the top end.
the other plot is normalizing that for all three drivers, which makes the
um15 appear to have "more low end extension".

set xmax on the 18ho to 20mm and the um15 to 22mm and check out the
max spl tab. there you will see the real low end extension possibilies
where the 18ho has about a 2db advantage over the um15 if both are run
with 1000 watts.

Listen. It's All Good.
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post #21 of 21 Old 06-25-2013, 10:12 PM - Thread Starter
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Good point, thanks for the heads up. I made the changes that you suggested. The graphs suggest that the 18ho will have the most output at low frequency extension. Do you think this will have much of an in room difference? One of my goals, in addition to good and accurate musical playback, is as linear a frequency response down to around 20 hz as possible. Do you think that the 18ho is the best option to achieve those goals?

Thanks, Garth
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