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Need help desining subwoofer enclosure for 2 x 15" subs. - Page 2

post #31 of 128
Your graphs are all of Transfer Function Magnitude.

You will want to click on that, which will give you a drop down.

First select 'Cone Excursion'. If the graph goes way above the red line, you are pushing the driver past xmax. I don't think anybody will disagree that a little past the red line is ok. You can reduce the input power to see how many watts will push the driver to it's limits (or increase the power, if you're not hitting the red line)

Next, select 'Rear Port- Air Velocity'. This is where you can see if you have "chuffing". The rule of thumb I read was to try and keep it below 25 m/s. If it's over that, you need to increase the size of your air port.

Last, select 'SPL'. This will show you the graph everybody wants to see. You can vary the box volume and tuning freq to affect the SPL graph.

Posting the SPL at 1w is usually appreciated by the more learned guys here, so they can compare apples to apples.

In the end, all of the graphs are related. You can massage the different variables to get you where you want to be. Once you play with it-- and understand how everything effects every other thing-- it gets pretty fun.

Tim
post #32 of 128
yeah, you are getting the hang of it.

by making the port longer, the tune will be lower.

you can enter it either way. either change the length
of the port and let winisd tell you what tune it gives or
enter the tune that you want and let winisd calculate
the port length.

all the different types of enclosures are just lower
and lower tunes and different size enclosures. nothing
really special about any of them.

the atmospheric conditions are not something that you
need to ever change. just ignore them.
post #33 of 128
Thread Starter 
Awesome !!!

Thanks again for the help. I'll mess around a bit more and report back. This is cool.


One last question- Two separate boxes? Or one dual 15" box ???
post #34 of 128
that is kind of up to you.

two separate boxes can let you play around with more locations which may help smooth out room response. co-located sources give max spl.
post #35 of 128
Quote:
Originally Posted by Mfusick View Post

Awesome !!!

Thanks again for the help. I'll mess around a bit more and report back. This is cool.


One last question- Two separate boxes? Or one dual 15" box ???

Depends on your scenario.

Dual opposed is nice, but so is having 2 subs you can move around to even out response.

I just played around a bit in WinISD and my results are similar to mrkazador. Large box around the 25Hz region. 10 cf at 26hz is flat within 2db. This is where you start making compromises on size vs performance. Is the extra 2 cu ft worth the marginal improvement over 8cf. You're gonna need a HPF.. I am maxxing out around 350w.

I'm not sure how LTD got such a flat response. I used the same criteria and my SPL chart wasn't nearly as flat.

Tim
post #36 of 128
Thread Starter 
23hz and a bit lower or 26hz and a bit more SPL ???

Vote ?
post #37 of 128
"I'm not sure how LTD got such a flat response."

zero out inductance. winisd doesn't model it properly anyways.
post #38 of 128
Quote:
Originally Posted by LTD02 View Post

"I'm not sure how LTD got such a flat response."

zero out inductance. winisd doesn't model it properly anyways.

Thanks, LTD. I didn't know that winisd exaggerated the effect so much.

Tim
post #39 of 128
Quote:
Originally Posted by Mfusick View Post

23hz and a bit lower or 26hz and a bit more SPL ???

Vote ?

One model drops 3dB, the other 2dB. It's really a personal choice. Balance the size with the output with your equipment with your personality smile.gif

Tim
post #40 of 128
Thread Starter 
What would you do ?
post #41 of 128
Quote:
Originally Posted by Mfusick View Post

What would you do ?


If you built a 24x24x32 cube (outside dimensions) the volume would be just over 8cuft. I would go that route because a sheet of ply is 48x96 and you can cut the pieces with no waste.

First cut the sheet into 3 32x48 pieces, then cut two of those into 24x32 pieces. Cut the last one into 24x24 pieces, and you have some scrap to make braces.

Tim
post #42 of 128
Thread Starter 
Quote:
Originally Posted by Mr.Tim View Post

If you built a 24x24x32 cube (outside dimensions) the volume would be just over 8cuft. I would go that route because a sheet of ply is 48x96 and you can cut the pieces with no waste.

First cut the sheet into 3 32x48 pieces, then cut two of those into 24x32 pieces. Cut the last one into 24x24 pieces, and you have some scrap to make braces.

Tim

Oh eek.gif I like how you think biggrin.gif


What about the port ?
post #43 of 128
Quote:
Originally Posted by Mfusick View Post

Oh eek.gif I like how you think biggrin.gif


What about the port ?

Build to suit smile.gif Can go with PVC or you can build a slot.

Tim
post #44 of 128
Thread Starter 
Ok so I played around a little more this morning:

This is 8 cube box versus 10 cube box



Thoughts?

I also did a sealed versus ported


And, I also messed around a little with EQ on sealed versus ported



Thoughts?

Last,

Here is 8 cube feet box with port tune at 20hz versus 23 hz

This seems to be an option (both) that might work well for me. Thoughts?



Is the lower tune of 20hz worth it ?

Would I need a filter to remove content under 20hz? I'd like to avoid that if possible. It is possible to avoid that if I just tune the box lower ? Why would I want to remove sub 20hz signal ? Is there even content that low on movies ?

If I tuned lower @ 20hz and then use EQ to flatten it out would that be my best option ? These won't be my main theater subs but i might use them for "extra" or just show. I have no other use for them, they are 10 year old- and I already have planned a sub build when my theater is done. And- I own a dual 12" MFG made sub that is satisfactory to my needs now anyways.

This is fun to play with though. I think I might have a new hobby.

Thanks for helping me biggrin.gif

Oh,

One last thing:
Quote:
Originally Posted by Mfusick View Post

Is there a special method for mounting the PVC into the MDF ? Can I just drill a hole in the wood and glue it in ?

I never got an answer. I deleted my three posts and combined them into one so the original post is gone but ^ the question remains. How do I incorporate a port into my box and is there a best practice or strategy ?
post #45 of 128

 

The difference between 8cu ft and 10 is pretty small, about 1.5db at 20hz. Personally I would go with 8 cu ft just because its smaller.

 

 

 

Be careful when using EQ. A 6db boost requires four times the amp power! Also need to watch for cone excursion. The graph may look nice when feeding it only 1 watt but once you start to add power you're going to see the cone excursion sky rocket.

 

 

 

I prefer the 23hz tune because its about equal at 20hz but you gain a little spl up top.

 

 

Quote:
Would I need a filter to remove content under 20hz? I'd like to avoid that if possible. It is possible to avoid that if I just tune the box lower ? Why would I want to remove sub 20hz signal ? Is there even content that low on movies ?

 

I think a highpass is absolutely necessary for a ported sub because there is a chance of damaging the driver. A lot of plate amps have a highpass filter so you could use that. Here is an example of a speaker with and without a highpass, notice how cone excursion sky rockets below its tuning (20hz)

 

A lot of movies these days have content below 20hz and if this sub was trying to play those low frequencies, the driver would bottom out and could cause some damage.

I don't know if you're familiar with the waterfall thread but you can SEE how many movies have content below 20hz: http://www.avsforum.com/t/1333462/the-new-master-list-of-bass-in-movies-with-frequency-charts

 

Here is a new movie that has content below 20hz.

http://www.avsforum.com/t/1333462/the-new-master-list-of-bass-in-movies-with-frequency-charts/8800_100#post_23480859

 

 

Quote:
Is there a special method for mounting the PVC into the MDF ? Can I just drill a hole in the wood and glue it in ?

 

Glue would work fine, I don't see how you would do it any other way. Check out this website on how to do flared pvc ports.

http://www.subwoofer-builder.com/port-flares.htm


Edited by Mrkazador - 7/5/13 at 8:06am
post #46 of 128
Thread Starter 
Dude your like a DIY sub box building super hero! Thanks !

Anyone else have a comment or recommendation ? I am leaning towards doing that.

Another question,

Since I am noob to the DIY subs still what kind of performance should I expect from this project?

Is the performance I am going to get way off a DIY sub project I might design from scratch? Or the popular builds people do around here? Is this project worth investing the time and effort into a nice glossy black finish and using in my soon to be built theater?

How do people finish these things? Any advice for painting sanding or finishing the box when I build it ? And special paint or tools or process I should follow ?
post #47 of 128
You can compare different drivers to see how your subs stack up against other popular builds.

Or, you can model them yourself and overlay them in winisd to see.

There's no rule saying you can't take those drivers out and replace them with something better in the future.

Take the same box and model a HO or Ultimax sub in it and see what it looks like.

You have the subs, so why not use them. Plywood is cheap.

Finish is up to you.
post #48 of 128
Thread Starter 
What is a good driver I should model them against ?
post #49 of 128
Quote:
Originally Posted by Mfusick View Post

What is a good driver I should model them against ?

As far as a Dayton driver, the DVC385-88 is a basic driver that performs well for the money. RSS390HO and the new UM15-22 should also model well.

The Kicker C154 may also look good.

Or you can go for it all with the TC Sounds LMS-R.

Tim
post #50 of 128
Quote:
Originally Posted by Mfusick View Post

What is a good driver I should model them against ?

The Stereo Integrity 15" and/or 18".

http://stereointegrity.com/index.php?id=60
post #51 of 128
Quote:
Originally Posted by Mfusick View Post

Dude your like a DIY sub box building super hero! Thanks !

Anyone else have a comment or recommendation ? I am leaning towards doing that.

Another question,

Since I am noob to the DIY subs still what kind of performance should I expect from this project?

If you pick the right driver and amp, exceeding the performance of the like-priced commercial speaker should be a slam dunk.
Quote:
Is the performance I am going to get way off a DIY sub project I might design from scratch?


Good components, workmanship and reasonable use of good design software are all it takes.
Quote:
Or the popular builds people do around here?

That's for you to determine from your survey of the various threads.
Quote:
Is this project worth investing the time and effort into a nice glossy black finish and using in my soon to be built theater?


Yes.
Quote:
How do people finish these things?


Soup to nuts.
Quote:
Any advice for painting sanding or finishing the box when I build it ? And special paint or tools or process I should follow ?

Depends on your preferences. You do have preferences for appearances, I do hope.
post #52 of 128
Thread Starter 
none of those are preprogramed into WinISD but my sub was... lol.

What do I do just input the specs from the MFG site ??
post #53 of 128

You should be able to find the most drivers here. Just download the .wdr file and copy them to the driver folder which is usually located at C:\Program Files (x86)\Linearteam\WinISD Pro\Drivers

http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/14410-downloadable-winisd-pro-files.html

 

For the drivers you cant find you can input the parameters yourself by following this guide

http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/6330-winisd-pro-tutorial-download-detailed-guide-how-use-winisd-pro.html

post #54 of 128
Thread Starter 
Quote:
Originally Posted by Mrkazador View Post

You should be able to find the most drivers here. Just download the .wdr file and copy them to the driver folder which is usually located at C:\Program Files (x86)\Linearteam\WinISD Pro\Drivers
http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/14410-downloadable-winisd-pro-files.html

For the drivers you cant find you can input the parameters yourself by following this guide
http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/6330-winisd-pro-tutorial-download-detailed-guide-how-use-winisd-pro.html

Big thanks again!

Those guys really should just zip all those small files into one zip folder. Clearly PC stuff is not their strong suite. wink.gif I downloaded them all but it was harder than it had to be.

I was going to do it for them with a nice note that said I just joined and here is all of them in a zip folder- but the sign up process was nearly impossible and I could not post yet anways. Wasted my time.

Downloading each individual file instead of all of them as a zip seems silly. You can easily share your user folder from x86 and everyone could have all the specs preloaded, or even update the program to include them.

Oh well,
post #55 of 128
Thread Starter 
Ok so I have basically designed a 8ft cab like Tim explained and I am planning on porting between 20hz and 26hz ( You just trim it for a lower tune right ? ) I might start at 30hz and try it first but I think I want 20hz. I don't need the extreme volume.

That brings me to my question:

Assuming these are not the primary subs in my theater and I don't need max SPL - If I wanted to use them down the road in my theater would it be smarter to make a smaller sealed box? Does a sealed sub sound better?

I always thought from my car audio days that ported could go louder and use less power but that sealed was the most musical and accurate. It also had the best low end extension. It was often easier to get a flat response with a sealed sub too if I recall.

Is that true in a large home theater room ? (30x24 feet) Would a sealed sub sound better ?(excluding volume or max SPL )

Assuming I'd have at least two other subs (one or two front wall behind screen and another in the back near the ceiling or raised up ) and these are just for "extra" or show - would it be easier to EQ them and work them in as a sealed set up ? Would I get better response down to say 10hz ???

I know the port is louder at the tune frequency but if I wanted my theater flat to 15hz it seems like these could help as a sealed system and I doubt I would need more volume since they won't be my main subs.

Just throwing ideas in my head. I might build a sealed and a vented and try them out just for the fun of the project. Love to hear some additional feeback
post #56 of 128
Quote:
Ok so I have basically designed a 8ft cab like Tim explained and I am planning on porting between 20hz and 26hz ( You just trim it for a lower tune right ? ) I might start at 30hz and try it first but I think I want 20hz. I don't need the extreme volume.

 

You need to make the port longer to lower the tune. You also need a way to add a highpass at these different tunes. An inuke 3000 with DSP would work well for this experiment.

 

Quote:
If I wanted to use them down the road in my theater would it be smarter to make a smaller sealed box? Does a sealed sub sound better?

 

People have recommended that you don't mix a ported and sealed sub, something to do with the phase response being totally different. I don't know if a sealed subs sounds any better than a properly designed ported sub.

 

 

Quote:
Is that true in a large home theater room ? (30x24 feet) Would a sealed sub sound better ?(excluding volume or max SPL )

 

30x24 is a HUGE room to fill. If you decide to go sealed then you would need at least 4 subs, 18" drivers of course biggrin.gif

post #57 of 128
Thread Starter 
Quote:
Originally Posted by Mrkazador View Post

You need to make the port longer to lower the tune. You also need a way to add a highpass at these different tunes. An inuke 3000 with DSP would work well for this experiment.


Yeah I had my eyes on that amp but I am on a HT gear spending freeze at the moment until the house is done. I can pull off this project because wifey won't notice $35 for MDF on my next home depot run biggrin.gif
I own a Crown 402 that I am also doing nothing with. It's the older one. I got it on ebay many years ago cheap because it was dented, but it works perfectly. I use it for some PA/DJ speakers at parties or when I jam in my basement and want to crank up the amps and the music to the level of the drums. I don't really play anymore so the amp just collects dust much like these Soundstream subs have been doing for the last 10 years. I found them in my dads garage. They play fine infinite baffle it seems. I hooked them up without a box and all seems fine. They are over engineered compared to most I've seen. The weight, the strength of the basket is admirable even by today's standards.

Quote:
Originally Posted by Mrkazador View Post

People have recommended that you don't mix a ported and sealed sub, something to do with the phase response being totally different. I don't know if a sealed subs sounds any better than a properly designed ported sub.


Is that on the same amp ? Or just in the same room? On the same amp that makes sense. But in the same room I'm not seeing it. I'd love to understand though. If anyone can shed light on this it would be appreciated ?


Quote:
Originally Posted by Mrkazador View Post

30x24 is a HUGE room to fill. If you decide to go sealed then you would need at least 4 subs, 18" drivers of course biggrin.gif

Actually when I model the 18" they don't seem much better than the 15" Am I doing something wrong ?



Theoretically I was planning on 4 subs for best performance inside my soon to be built theater... two or three subs in front behind the screen and one or two near the back of the theater. I wanted to raise one or two up near the ceiling too - so it would cancel out the ones on the floor. I already own two MFG made subwoofers I bought back when I was a store manager of Circuit City on the employee accomodation program. I think they are a PSW650 and a PSW1200 but I forgot that was also almost 10 years ago. I also wanted to build a little mike F20 or a THT Tuba like project too just because it seems cool as well. What is the appropriate amount of subwoofers? Is there a such thing as too many ? I've seen some freaks around here eek.gif I really want to just make 4 awesome ones and set them up right eventually but I have a feeling over the next two years I will play around before I settle down.


Quote:
Originally Posted by Mr.Tim View Post



Or you can go for it all with the TC Sounds LMS-R.

Tim

So I have been modeling different stuff in my attempt to learn this stuff. I did 1 watt, no EQ, same 8 foot box and same 20hz tune just to get an idea of how these decade old pigs I pulled from the top shelf of my dads garage with dust all over them perform. I did not expect this Soundstreams to be so formidable.

I paid $290 each for them back in 1998 I think.

Does this look right to you ?




Now I know my subs will probably top out around a few hundred watts and the TC-Sounds is going to take more wattage but even at 400 watts on the Soundstreams and 1000watts on the TC-sounds the SPL is close. The TC-sounds is flatter (a good thing) but only because the SPL-170's just want to make stupid noise. I did not cut at 80hz either, but obviously would cut them somewhere between 75-95 hz is my guess. The sound streams look like you could cut a bit sooner since they get going at 80hz it seems.

If I tuned them to 30hz and ran two in the corners with only my existing spare Crown 402 I am pretty sure I could damage my sheetrock it seems. It would be over 125db at 30hz eek.gif I am a bit noob but that seems pretty loud inside a home.

So I think I have decided to tune them to 20hz in favor of a lower extention at the expense of max SPL. It seems smart if I want to use them in my theater along with other subs. I won't need the SPL and it would be nice to be flat to under 20hz @ 120db I think.

I have decided to build the boxes. 8 cubic feet ported at 20hz. I will make the box tall so it can fit behind my 30" screen wall. I might do 36" for my screen wall actually. I am debating that now. I think 3.5 feet from the wall for my mains means I can cross over my mains at 80hz and not have any problems. Closer to the wall I get some issues and need a higher crossover point I think. 36" might be a nice compromise - I think 3.5 feet is too much for a false screen wall, even though it's the theoretical best choice allowing my speakers 3.5' from wall.

Wish me luck !
post #58 of 128
Quote:
Originally Posted by Mfusick View Post

Is that on the same amp ? Or just in the same room? On the same amp that makes sense. But in the same room I'm not seeing it. I'd love to understand though. If anyone can shed light on this it would be appreciated ?

It has to do with phase shift. Model a sealed box, then model a vented box in winisd. Then overlay the Transfer Function Phase. You will see them start to move in opposite directions at low frequencies. It's not impossible to mix, but that will show you the problem.
Quote:
Actually when I model the 18" they don't seem much better than the 15" Am I doing something wrong ?

18s would typically roll off at a lower frequency. Briefly looking, I think you'd have to highpass the Soundstream at 20Hz, where you could get away with 15hz on an 18. The 18 will also give about another 6dB at 15Hz, which would equate to two of the soundstreams. If you want flat to 15Hz the 18s would get you there faster.
Quote:
Does this look right to you ?




Now I know my subs will probably top out around a few hundred watts and the TC-Sounds is going to take more wattage but even at 400 watts on the Soundstreams and 1000watts on the TC-sounds the SPL is close. The TC-sounds is flatter (a good thing) but only because the SPL-170's just want to make stupid noise. I did not cut at 80hz either, but obviously would cut them somewhere between 75-95 hz is my guess. The sound streams look like you could cut a bit sooner since they get going at 80hz it seems.

If I tuned them to 30hz and ran two in the corners with only my existing spare Crown 402 I am pretty sure I could damage my sheetrock it seems. It would be over 125db at 30hz eek.gif I am a bit noob but that seems pretty loud inside a home.

So I think I have decided to tune them to 20hz in favor of a lower extention at the expense of max SPL. It seems smart if I want to use them in my theater along with other subs. I won't need the SPL and it would be nice to be flat to under 20hz @ 120db I think.

I have decided to build the boxes. 8 cubic feet ported at 20hz. I will make the box tall so it can fit behind my 30" screen wall. I might do 36" for my screen wall actually. I am debating that now. I think 3.5 feet from the wall for my mains means I can cross over my mains at 80hz and not have any problems. Closer to the wall I get some issues and need a higher crossover point I think. 36" might be a nice compromise - I think 3.5 feet is too much for a false screen wall, even though it's the theoretical best choice allowing my speakers 3.5' from wall.

Wish me luck !
In my amateur opinion I think the Soundstreams model very well. My graphs are showing the driver past excursion at 300w. That said, they are pushing decent SPL at 300w.


So now that you've compared them to the $400+ TC Sounds driver, how do you think they stack up against the other popular drivers? Looks pretty good to me.

Tim
post #59 of 128
Thread Starter 
Thanks again for all your input and your reply biggrin.gif

I'll probably build the boxes this weekend. I'll try to update with a picture if I can.

One last question,

WIthout buying an iNuke or something- what is the easiest way to cut them at say 19hz to protect them ? Can I do that how ? Is there an easy way ? I was going to use an existing amp I have that does not have that ability. Some day I might buy an amp that can do it. Is there a cross over or something I can make to protect them ?
post #60 of 128
Quote:
Originally Posted by Mfusick View Post

Thanks again for all your input and your reply biggrin.gif

I'll probably build the boxes this weekend. I'll try to update with a picture if I can.

One last question,

WIthout buying an iNuke or something- what is the easiest way to cut them at say 19hz to protect them ? Can I do that how ? Is there an easy way ? I was going to use an existing amp I have that does not have that ability. Some day I might buy an amp that can do it. Is there a cross over or something I can make to protect them ?

Either a MiniDSP or a plate amp that will cost the same amount ($100). Maybe your receiver also has a HPF?

Or you could just watch the power you are sending to them. The amount of SPL these would put out at max excursion is freakin LOUD (at least to my ears).

Tim
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