# Looking for some answers on CSS products



## Fishtank

Hello everybody...I'll start with my needs/plans then ask my questions.

I live in a townhouse, so I have neighbors on both sides of me, cement walls however I still won't really be able to run what I build at high levels. The room size will be about 30'x18', with an open hallway about 15' long.

It's going to be used entirely for movies/games... no music.

I'm a huge subwoofer noob, my previous subs were entry level commercial subs (8" psb subzero, 10" velodyne), I've probably never even heard 30hz before. This would be my first build.

I would prefer better sound quality over high output, since I can't go loud anyhow I figure I may as well try to make up for it in quality.

I'm happy to build 2 subs, however I would like to start with 1 sealed sub. Then possibly build another identical sub once I've played with the single sub for a while. 

I would like to stay under $450'sh... so I see my choices as:
Quartet10
Trio12APR15
SDX15 + AMP
Wait for SDX12 kit

Questions:
-What is the XBL motor and how does it really affect the quality?

-Is the SDX15 overkill when you share walls with neighbors? I doubt I would build 2 SDX15's. Would I gain any performance from a pair of quartet10 builds over 1 SDX15 build?

Thanks for any/all input!


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## Mike P.

Welcome, glad to have you with us! A couple of points, you mention wanting to start with a sealed build, yet you listed the Quartet10 and the Trio12-APR15.(the SDX12 has been canceled for the time being) Both those kits use passive radiators which is the same as ported. 

For movies and games a ported or PR design will give you more low end output for your needs, especially in the room size you have. I strongly suggest you consider the SDX15 in a ported design as long as box size isn't an issue.

XBL2 is a motor design that has less distortion than other designs.


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## Fishtank

Woops, Ah yeah I actually know that using PR's is the equivalent of a ported sub, I still get my wording confused. What I meant was I don't need to mess around with tuning the length of a port etc, unless I'm missing something with the PR's. The designs looked straight forward.

So you feel 1 15" SDX15 would actually suit my needs more, which is great, glad I asked. The designs on the CSS website only seem to include a sealed version. I'm looking to keep my first build simple, can you point me towards any previously designed SDX15 ported box so I can compare?

If I need to break out that winisd program and design it all myself I'm willing to do it, I just think for a first build there's some benefit from learning from others!

Any more comments are welcome,


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## Moonfly

Fishtank said:


> Woops, Ah yeah I actually know that using PR's is the equivalent of a ported sub, I still get my wording confused. What I meant was I don't need to mess around with tuning the length of a port etc, unless I'm missing something with the PR's.


You will need to add mass to the pr's to tune them. This isnt usually hard, and the manufacturers of the pr's usually sell the weighting kits that allow you to do this. WinISD will help give you an idea of the mass required to suit your tune.


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## Fishtank

Moonfly said:


> You will need to add mass to the pr's to tune them. This isnt usually hard, and the manufacturers of the pr's usually sell the weighting kits that allow you to do this. WinISD will help give you an idea of the mass required to suit your tune.


yeah the kit comes with the small weighted discs, I assumed they would be the proper amount for the enclosure etc.

The Quartet15 is just way more than I was looking to spend on my first project. So If i was to go with the SDX15, I would be looking to build it with a 500w plate amp, and either sealed (i would just use the design on the CSS website), or if there was a decent ported design out there I would consider following it.


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## mwmkravchenko

Hi Fishtank

What are building skills? Newbie, intermediate, skilled?

That has a lot to do with which designs are available. 

Mark


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## Fishtank

mwmkravchenko said:


> Hi Fishtank
> 
> What are building skills? Newbie, intermediate, skilled?
> 
> That has a lot to do with which designs are available.
> 
> Mark



Hi, beginner to intermediate. I am patient and careful, I am confident I could eventually get through any design/build, however again I do think it's best to keep it as simple as possible for my first project... which is why I was leaning towards sealed subs, since I don't really need the volume or maximum possible output. 

I'm just looking for some great results in a reasonable/standard type build. Get my feet wet in all of this I guess.

Another question... would the 500w BASH amp be enough to power the SDX15 properly in a sealed enclosure?


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## Mike P.

The SDX15 in a ported enclosure with a pair of flared portd would be faily straight forward and cheaper then with PR's, you'll get all the help you need here on the forums. I'll post a graph later on tonight showing you the difference between sealed and ported. There are over a dozen SDX15 builds in the Members DIY Subwoofer Database for you to have a look at. Just click on the link in my signature.


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## Fishtank

Mike P. said:


> The SDX15 in a ported enclosure with a pair of flared portd would be faily straight forward and cheaper then with PR's, you'll get all the help you need here on the forums. I'll post a graph later on tonight showing you the difference between sealed and ported. There are over a dozen SDX15 builds in the Members DIY Subwoofer Database for you to have a look at. Just click on the link in my signature.


Thx, I'll read through all those builds tonight, I'm sure I'll have a question or 2 afterwards.


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## mwmkravchenko

> The SDX15 in a ported enclosure with a pair of flared portd would be faily straight forward and cheaper then with PR's, you'll get all the help you need here on the forums. I'll post a graph later on tonight showing you the difference between sealed and ported. There are over a dozen SDX15 builds in the Members DIY Subwoofer Database for you to have a look at.


Bang for the buck as Mike points out a vented enclosure will get you lower in a smaller enclosure. And the 15" driver is indeed a fine specimen of wooferdom. You'll spend a lot more money to get not much more performance.
Binary has a completed build thread that was rather easy to do.

Mark


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## Mike P.

Here's a comparison of the SPL between yellow, sealed and green, ported. Both are powered by a Bash 500 watt amp. The ported has far superior low end output. At 20 hz there would be a 9 db advantage, ideal for movies and games in your room size.


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## mwmkravchenko

Here's my two cents.

All the boxes are with the SDX15. The smallest one uses some voodoo. A second order boost at 20 hz to get the response flat. The gain is that below 20 hz the response falls off very fast acting like a highpass filter. Not bad bass for a 19 inch cube!

Mark


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## Fishtank

Thanks mike! I went ahead and gave that winisd a go, i only read a quick document and slapped in the numbers from the website but we came out pretty similar, at least when I put in similar box sizes as you. I'm not sure why our values are slightly different, I don't think it's too much of a concern though if I continue to play around with it.








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I still have a feeling that the SDX15 is too much sub for me, on the other hand I also think that while the sdx10 setups are more practical, I would never settle for them and in a few months I would be looking at the SDX15 again... might as well start at the top!

Thanks for all the advice so far from everyone, I'm going to play around for a few days and consider my own box designs vs. those nice builds I looked through tonight.

EDIT: I just saw the next post, the smaller the better imo, I would sacrifice some output for size. To be honest I'm going to have to read a bit to understand what you meant by the second order boost. I understand some amps come with boost settings for the lower frequency's to raise the output as they start to drop off, but I'm not sure your talking about the same thing.


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## mwmkravchenko

Hello Mr Tank

Or should I call you Fish?

Ok I'll behave.

Order in loudspeaker roll offs are in 6 db increments. 1st order is 6 db second 12db third I think you can figure out the progression. 

Yes some subwoofer amplifiers have boosts that can accomplish this. But few have a 12 db boost at the frequency you want. I think the Bash amps can have their boost tailored by tweaking a few resistors. Worst case is a small box powered by a 12 volt wallwart with an op-amp two resistors and two capacitors. Not that big a deal really.

Mark


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## Fishtank

Well the more I think about this the more I seem to change my mind.

I'm considering that Behringer EP4000 amplifier for $349. It gives me 1400W x 2, instead of the 1 500w plate amp. I know I'm going to want 2 subs at some point, so it just makes more sense.

I'm also wondering if there is any benefit to maybe building 1 box with 2 SDX10's in it. I'm going to play around with that winisd program again this weekend, but I'm sure you guys have a good opinion about something like that already.


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## mwmkravchenko

Ok Here is the low down on power input.

1-2-4-8-16-32-64-128-256-512-1024-2048 watts

These are all increments which increase the sound level by 3 db.

This is a power output progression showing the power required to raise a signal 33 db. So from about 90db to about 120 db.

The greatest magic in getting things louder happens below 128 watts. Between 128 watts and 2048 watts there is a 12 db rise in sound pressure level. A little over twice as loud acoustically.
From 1 to 128 watts there is a 21 db increase from a 1 watt level in sound pressure. Four times louder to your ears. 3 db is what most people consider a change in loudness. The most acute listener will hear 1 db. Very well trained musicians will hear tenths of a db. Especially when tuning. Yep I was a good musician at one time.

So my advice is this stay at or around 250 watts to 500 watts and save your money for a good driver. Or good drivers. The power amp method quickly runs out of steam and makes very little difference after 500 watts. Doubling drivers will add 3 db at least and possibly another 3 db depending on how the drivers are wired and the power supply capability of the amplifier. 

Enclosures can make an enormous difference in the sound pressure level attainable. There are a couple of them on this forum.

Some are examples that from the start give the driver a 10 db boost in baseline efficiency. WHat they entail is design and construction complexity. No free lunch. But sometimes awesome desert!

Mark

Forgot link to website for sub filter.

http://www.subwoofer-builder.com/subsaver.htm


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## Fishtank

Thank you very much! That was a great post for me to read, easy to understand!

Is there any danger to under-powering a driver? 

If I saved a bit more money and went with a 300W bash amp with the SDX15, are there any problems associated with that? From my understanding it would have more trouble moving the driver enough to properly hit low frequencies, especially in a sealed enclosure.... however you and Mike have talked me into a ported enclosure already. When I change the Watts in winisd it doesn't seem to change the charts much so I might be missing something.


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## mwmkravchenko

Ok not to leave you out in the cold.

Here is the filter design to get the EQ settings I posted up above from WinISD. 

The TL072 is a dual or two op-amps in one package. So it really one little black package. The resistors and capacitors are each setting a gain stage that acts like a small preamplifier volume setting. It boosts the signal by the required amount shown in the first graph ( 12 db). The other resistors and capacitors tell the op-amp where in the frequency response to boost the signal. If you already understand this I apologize for the very simple explanation. There is more to it than this. But not a whole lot more.

What is missing is the power supply:

http://www.jameco.com/webapp/wcs/st...amecoall&ddkey=http:StoreCatalogDrillDownView

This is a possible ready made solution. There are many other solutions and the Jameco website is full of the parts you might need.



Mark


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## mwmkravchenko

> Thank you very much!


You are very welcome!



> Is there any danger to under-powering a driver?


Yes and no. With a perfect world everything would behave. But amps and drivers are at odds with eah other. Check your impedance curves in WinISD. You will find as you get close to the low end of the drivers response the impedance goes through the roof. Your nice easy 4 Ω load is now what 40 Ω ?

So the power input coming from the amplifier is now also cut by 10 times. That hugely powerful 250 watts is now 25 watts into 40 ohms. 

This is where amps run into trouble. They are being called upon to produce an output signal that will cause your woofer to woof on command. To do this they draw power from your wall outlet, run it through a power supply that changes the Alternating Current voltage to Direct Current voltage ( AC/DC). The amplifier actually modulates the DC voltage as driven by the music. So the music is setting the alternating voltages ( + or - cone in or cone out ) that push and pull the woofer cone back and forth. What the amplifier does is apply a magnification or amplification to the signal source. When that wonderful power supply has given all it has to give you run into a situation where it no longer given a push pull signal. This is called clipping. ( It does not have an infinite amount of power to supply. It is dictated by the wattage available from the transformer in the power supply. This is true even with a switching power supply. ) At this signal level the amplifier is only delivering it's power supply DC voltage. This is not good. The amplifier is either pushing or pulling on the woofer cone. It turns that voice little wound coil of wire inside your speaker motor that is attached to your cone into a stove element. And like a stove element it warms up. So short story we want to stay away from an amplifier clipping. So generally it is better to over size the amp than under size the amp. My advice is pop the extra bucks and get the BASH 500 or the equivalent. You have a greater margin of safety with that size of amplifier. And the amount of extra money is not that much more.

Mark


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## Fishtank

Alright makes sense.

Well back to thinking about a box design that suits me I suppose.


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## Fishtank

Well the SDX15 is ordered, I ordered the mounting kit with it. Pretty excited, time to get a bit more serious about building an enclosure.

I really would like a smaller box, I was playing around with winisd more and I was pretty happy with the results at 6.5-8.5cu, I already have 2 3" flared ports from a different sub I pulled apart a while ago so I was thinking about using those.

Playing around with winisd, there wasn't too many options for ports, if you went to short or to long it screwed up the results pretty significantly, which is fine, I believe 10" 's was where I had the smoothest SPL down to 20hz. 

So my 2 questions:

1. How do you model a slot port? I always thought they looked better, I like the look of them coming out below the sub. I have some idea's that don't seem to hard, however they just might not work properly. Is this a very difficult build? Is there any advantage or disadvantage to building them?

2. I'm 90% sure that the shape of the enclosure doesn't matter. As long as the ports fit in the enclosure, I'm free to make it more of a small profile on the front while being deeper? Are there any circumstances where I need to be careful with the shape of the enclosure?

Thanks for any help!


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## mwmkravchenko

Hi Fishtank

I uploaded a picture showing where to click to change the port shape. If you can't work in metric then click on the field that has the units of measurements and it will change to that is right where it says cm.

Generally you model a slotted port the width of the cabinet. You are correct in your assumption that the shape of the cabinet does not matter. You can do a slotted port with a corner to as you can with a round port. In other words it does not have to be straight. It can have 90 degree or whatever degree bends or corners in it. Just take the length down the center of the port and you will be close enough.

Mark


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## knobert

this should be stickied so that people can use it for a reference to how much power gets you esired db





mwmkravchenko said:


> Ok Here is the low down on power input.
> 
> 1-2-4-8-16-32-64-128-256-512-1024-2048 watts
> 
> These are all increments which increase the sound level by 3 db.
> 
> This is a power output progression showing the power required to raise a signal 33 db. So from about 90db to about 120 db.
> 
> The greatest magic in getting things louder happens below 128 watts. Between 128 watts and 2048 watts there is a 12 db rise in sound pressure level. A little over twice as loud acoustically.
> From 1 to 128 watts there is a 21 db increase from a 1 watt level in sound pressure. Four times louder to your ears. # db is what most people consider a change in loudness. The most acute listener will hear 1 db. Very well trained musicians will hear tenths of a db. Especially when tuning. Yep I was a good musician at one time.
> 
> So my advice is this stay at or around 250 watts to 500 watts and save your money for a good driver. Or good drivers. The power amp method quickly runs out of steam and makes very little difference after 500 watts. Doubling drivers will add 3 db at least and possibly another 3 db depending on how the drivers are wired and the power supply capability of the amplifier.
> 
> Enclosures can make an enormous difference in the sound pressure level attainable. There are a couple of them on this forum.
> 
> Some are examples that from the start give the driver a 10 db boost in baseline efficiency. WHat they entail is design and construction complexity. No free lunch. But sometimes awesome desert!
> 
> Mark
> 
> Forgot link to website for sub filter.
> 
> http://www.subwoofer-builder.com/subsaver.htm


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## dougc

I am new at this too and have some "new guy" info for ya. I have two of the SDX 15s and am working on my build now. First, the subs are amazing - they look perfect and sound great. In regards to the build, I am using them now in two different ported enclosures: a small one tuned to 34 and a md size one tuned to 22. The smaller one is louder for music at higher frequencies, the other louder for movies at lower frequencies. The md size one is better as a Reference sub. The small one doesn't even perform at lower levels. You won't be able to turn it up in the apartment without your neighbors trying to evict you, the stuff you hear that is prefab is a joke in comparison to what you can build yourself. You can also find an EP2500 for around 250 used which is about the same thing as the EP4000, plus 275 for the CDX15, $150 for the build - just under $700 would be what you would spend. If you tune it lower than 20ish, then you will need a subsonic filter like a Reckhorn b2 which is another $90.


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## Fishtank

dougc said:


> I am new at this too and have some "new guy" info for ya. I have two of the SDX 15s and am working on my build now. First, the subs are amazing - they look perfect and sound great. In regards to the build, I am using them now in two different ported enclosures: a small one tuned to 34 and a md size one tuned to 22. The smaller one is louder for music at higher frequencies, the other louder for movies at lower frequencies. The md size one is better as a Reference sub. The small one doesn't even perform at lower levels. You won't be able to turn it up in the apartment without your neighbors trying to evict you, the stuff you hear that is prefab is a joke in comparison to what you can build yourself. You can also find an EP2500 for around 250 used which is about the same thing as the EP4000, plus 275 for the CDX15, $150 for the build - just under $700 would be what you would spend. If you tune it lower than 20ish, then you will need a subsonic filter like a Reckhorn b2 which is another $90.


Cool thanks for the opinions. I have drifted back to getting a pro amp instead of the plate amp, and I have seen a few ebay deals on the 2500. I don't have unlimited amounts of money, and I do like transducers and the possibility of adding another sub in the future which means the flexibility of the 2 channel pro amps seems like the right choice. Plus I don't need to worry about the plate amp in the build. Minor but still a plus.

I'll keep that in mind about the 20 hz tuning, I will have to learn a bit more about that area before i finalize my build.

I don't mind about the eviction part, my neighbors rarely take us into consideration...some payback is due anyhow! Plus I am moving in the spring.

Also thanks again for your input Mark!


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## Fishtank

Alright moving along slowly making some decisions. Unfortunately generating some more beginner questions... 

In the end I want a smaller sub, I will have to give up some low end output for now. From the Enclosure calculator (estimated driver and bracing volume) I will have about 5.4 cu. Basically I made a quick sketchup of the design I was picturing in my head, and I'm curious about any problems with how it will work, because my design was basically just what I thought look cool at this point. It's a quick sketchup so bear with me...I didn't model the wall thickness in the sketchup because I didn't know how! I will sort out bracing once I get some more design details sorted.

2 - 6" x 1" slot ports each 11" long in 5.4cu box will be @ 21hz ... they will be attached directly to the side walls, so they will share one wall with the sides of the enclosure.

I was hoping to just use a smaller addition to the front for extra strength... I don't view this as a problem, There is only 4" 's of space on each side that will have the .75" mdf instead of 1.5", and even the vents will provide some more stability. I have the driver now (it's pretty), as heavy as it is, i can't see this being a problem... 



Questions:
1. Am I going to have trouble with 6 x 1" ports... will the air speed be a problem? I have seen a website on how to model this but I was having some trouble. I've never seen 2 slot ports on a design so I'm wondering if it's just a bad idea.

2. I'm still try to decide between a plate amp and a pro amp... I was settled on a EP4000, but then I was reading about somebody choosing not to because of all the extra add-ins you need with EQ's and filter's. Can anybody tell me all the extra items I will need if I choose an EP4000?

3. Any other problems up to this point? You can be overly critical, it won't hurt my feelings! I would rather have information on potential problems now.


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## mwmkravchenko

> Am I going to have trouble with 6 x 1" ports... will the air speed be a problem? I have seen a website on how to model this but I was having some trouble. I've never seen 2 slot ports on a design so I'm wondering if it's just a bad idea.


Go to Graph types explained in the WinIsd Help file. The crux of the answer is keep the vent air speed below 17 meters per second. That will require a vent 2.5" high 13.5" wide 76" long. That is at 100 watts input or 112 db loud. Real loud! How do you do a port that long? Wrap it around the box internally.



> I'm still try to decide between a plate amp and a pro amp... I was settled on a EP4000, but then I was reading about somebody choosing not to because of all the extra add-ins you need with EQ's and filter's. Can anybody tell me all the extra items I will need if I choose an EP4000?


Get Bob's EQ it is the biggest band for the buck period. It is also probably the simplest way to get reasonably flat response in your room. It is very useful considering it only has a few buttons to push.



> 3. Any other problems up to this point? You can be overly critical, it won't hurt my feelings! I would rather have information on potential problems now.


If you want the smallest box possible I modeled you a rough estimate on port length already. A box that size needs some EQ assistance to bring up the low end roll off. The downside is you have to make an EQ. It is not really hard. If you are game I can nudge you along the way if you want.

Your choice of amplifier is excellent. Don't take to many peoples opinions into count when you are reading stuff on the net. There are a great many baseless opinions out there. Common sense will usually make sense no matter who it comes from. That includes me 

Mark


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## Mike P.

> That will require a vent 2.5" high 13.5" wide 76" long.


Mark, that would be 2 ports. One port 2.5 high x 14" wide x 35" long would keep the air speed to 22 m/s if a Hi-Pass filter is used at 16 hz to keep the sub within its Xmax. (1000 watts input power)


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## mwmkravchenko

Hey Mike

I modeled the numbers in a 3 cubic foot enclosure. Input power was 100 watts or 112 db 2Pi or about 116db in room response. Pretty loud. But the box is as small as I would dare make it with a port. You get weird non-linear air pressure fluctuations when you go with a small box and try to port it down low. You are better off sealing the box and using the DSpeaker unit to flatten the response. I personally think that's the easiest way to knock off a decently flat subwoofer in a small box. That's what Velodyne does. I used to do consulting work with a guy who made their woofers. They mass loaded them so they would be able to perform well in a small box. And yes you can mass load a woofer yourself. It's called lead solder and some silicone caulking. You will loose a few db in efficiency but the driver will perform much better in a small box. It's quite easy to model in WinISD 

If you model port noise for 1000 watts it is almost useless. We will never listen that loud at any sustained length of time. Even the 100 watt rating I gave is ludicrous. The 1000 watt input will only sound twice as loud as the 100 watts to. And the port volume will be almost be equal to half of the speaker box! So a balance is needed between what is practical and what is necessary.

Anybody getting peaks in room close to 120 db is going to be a happy camper. A well done box can get you there with around 250 watts and some port noise. Most of the time with a decently designed port this will be masked by the music or effects being generated. 

Maybe I'd better post a well modeled box and see if it is acceptable. I don't mind. But I would like to have an idea of maximum wanted size. From that point all can be calculated. 

Mark


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## Mike P.

I modeled 5.4 cu.ft. as stated in post #26.


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## Fishtank

I have to admit I'm a bit confused now. 

I understand (I think) that the wider a port, the slower the air will pass through, and it will need to be longer to hold a desired tune. Having 2 ports, is the same as having 1 larger port, so both ports will need to be longer.

I'm not sure why you guys posted such huge port sizes required. I assume it's to keep the air speed down, because it wasn't what winisd was indicating when I was playing around... however they seem abnormally large vs the normal circular ports you find on subs, is it only the shape that matters?? Or am I missing something very simple...

Just so I'm clear I am quite happy with a 24" cubed box, it doesn't need to be any smaller, but I really can't have it any bigger...


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## Mike P.

> that the wider a port, the slower the air will pass through,


It's not the wider the port, it's the amount of cross sectional area a port has. The more area the lower the air speed. A 24" cube would have a net volume around 5.4 cu.ft. Two 1" x 6'" ports has the same area as one 4" round port. Tuned to 21 hz with 1000 watts input and a Hi-pass filter at 16 hz the air speed would be 63 m/s which would sound like a freight train. A 2.5 high x 14" wide port would have the same area of 2.5 4" round ports, and a lower air speed. (22 m/s)


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## Fishtank

I understood that, my "wider" was a poor choice of words compared to "area".

I did not know that it would be pushing air through 3 times too fast however! When I'm not so tired I will play with the actual calculations I just went and found till I understand it better.

I clicked on your googlemap avatar there, I grew up in Fort St John, in northern BC... practically neighbors! Actually I live in kitchener Ontario now....close to Mark who's been helping me as well in this thread.

Anyhow thanks for answering some more easy questions.


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## Moonfly

mwmkravchenko said:


> The crux of the answer is keep the vent air speed below 17 meters per second.
> 
> Mark


Dont forget to monitor port resonances as you play with the port. Generally, altering the port to lower port air speed has the effect of bringing the port resonance down as well. You just need to keep an eye on it so it doesnt fall in to the frequency range you'll be using.


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## Fishtank

Moonfly said:


> Dont forget to monitor port resonances as you play with the port. Generally, altering the port to lower port air speed has the effect of bringing the port resonance down as well. You just need to keep an eye on it so it doesnt fall in to the frequency range you'll be using.


Ah brand new information... alright it's on the list of things to double check.


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## Moonfly

Fishtank said:


> Ah brand new information... alright it's on the list of things to double check.


Well if you find it becoming a concern, dont forget that altering the box size also has an affect on the port resonance, so you need to play with the tune, port size, and box size when modelling.


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## Fishtank

Alright, as you can probably tell I don't get a lot of time on this, mostly weekends even to do some reading, but I think i'm a little bit further along.

I think I'm going to stick with my design (for now), I took the advice about making sure the vents were big enough an long enough, and I wound up with this... hopefully it's fine this time! You should be able to see the settings in the winisd screen cap. The current box size is 28" x 22" x 24", with estimated port/bracing/driver volume I think I"m around 6cu now. I know I keep saying it won't get any bigger...this time it won't!



Below are the obvious choices for the ports, the pictures are from the back of the sub. I don't think the shape matters, I was going to choose the one that's folded over itself, however I figured I should ask.




Assuming the above is fine, I was moving onto the high pass filter. I know what it does, and why I need it... however I'm not exactly sure what you would choose to use with an ep4000. I've seen a few options out there and I believe that the ep4000 comes with a 30 or 50hz low cut filter. I believe that's basically the same thing as a high pass filter, however I know I need this down at 18hz based on my current settings in winisd. 

Do you guys buy or build these? I'm also not opposed to sorting out a boost as mark has suggested to deal with that fairly noticeable drop from 30-20hz. I'm fine with sorting through woodworking but I'm sure it's apparent that I have limited knowledge of the electronics side. So I'm looking for simpler solutions to these problems, however I'll learn anything with enough time and help! I realize certain plate amps are probably the simpler solution but I would really like the flexibility of these 2 channel amps.

Thanks again for all the help here guys, I'll be sure to pass it along moving forward.


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## mwmkravchenko

Hi Fishtank

Your numbers look good. 

If you want help on a high pass board give me an email at

mwmkravchenko at gmail dot com

I can set you up with a couple of methods of making one depending on what you feel comfortable with. The high pass available on the amps will not be of much use to you. When you need a high pass that is needed at a custom frequency there is not much else to do other than buy a EQ that will do it or make one. If you are going the DSPeaker route from Bob it already has the requisite high pass filter built in.

Mark


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## Fishtank

Hey Mark, a little more looking and I found the Reckhorn B1 and B2 units will sort this out for me for $60-90. 

I was expecting a $2-300 solutions for some reason but I'm ok with spending under $100. It should leave me with options if I decide to build a new sub later on. 

Sooo I guess I have something that will let me boost the signal around 20. I guess I'm going to play around winisd some more and see if I can sort out modeling. A quick fix was a 4db boost at 20 and tune it to 18hz made the SPL nice and flat, however the cone excursion went crazy in between 20-30hz. 

So I might be looking at more of a re-design but that's ok, with all the help I've gotten so far it's going to go much better!

It seems pretty straight forward but I guess I should ask if using a boost will introduce any problems that a beginner like me wouldn't anticipate?

EDIT: After reading more, it seems that I might be too worried about the cone excursion. I had my input power up at 1400w just as a best guess between getting on EP4000 or EP2500. Even down at 1000w it doesn't look like an issue so I think it's ok. I don't assume that it's going to be pushing 1400w into the sub at all times however I'm not exactly clear on this area yet.

If someone has an opinion about this stuff I would love to hear it. I'm going to keep reading in the meantime.


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## mwmkravchenko

> Hey Mark, a little more looking and I found the Reckhorn B1 and B2 units will sort this out for me for $60-90.


The price on his website is 60 euros or about $85 plus shipping. It is a crossover only with an infrasonic cut. Subsonic is not the right word. I know I'm nit picking but it drives me nuts! We all went to school at one time or another right!

Ok rant over. 

If you want purpose designed it is cheap. The parts I showed away back for a lift and highpass circuit are less than $12. The enclosure is about $10 if you want to make a neat wood box then it is almost free. To power it you need two 12 volt wall warts about another $10 or the dual supply I showed you. So if your not to scared I can guide you through it. It starts off with perf board you push the I.C. into and then you bend and push the capacitors into the perf board at the right places wrap them on to the correct pins on the I.C. and you install the resistors the same way. I probably have all the parts in stock right now. I probably even have the wall warts! If you want to go purchased then choose as you will. 

Mark


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## Fishtank

Well I would order it from CSS and it looks like he still has the B1's in stock for $75'sh shipped, I think they are just old B2's... B2's are supposedly slightly more accurate and black...

Like most things in the DIY space, I'm sure you could walk me through building something better and cheaper. However this entire build is new enough for me, that I think for this part at least I would like to keep it simple and I would feel a bit more confident in the B1 vs my skills in this area.

Thank you very much for the offer though.


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## mwmkravchenko

> Well I would order it from CSS and it looks like he still has the B1's in stock for $75'sh shipped


That's hard to beat!



> I would feel a bit more confident in the B1 vs my skills in this area.


It's not really hard. It's like burning yourself with a soldering iron. Once you do it you never forget.

I'm self taught from a great many years ago. Through sheer cheap skateness uh determination. I learned from some of the best designers who would put their ideas down on paper and I kept reading and researching until all the questions I had were answered. Then I went for it. Nobody held my hand and I wish there was somebody I could have asked back then. I vaguely remember my first power supply blowing up. A bit of amnesia from that episode.:whistling: But what I have learned is priceless. 

Your on a track that will keep you entertained for a long time. I think you are doing it the right way. Mike has a wealth of experience to offer and so does Moonfly. Add us all up and I'm sure you get at least a full brain! :rofl2:

Mark


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## Fishtank

yeah I've learnt a lot already from you guys and I really appreciate it... but I still manage to find more beginner questions!

Like this one... earlier in the thread when talking about port velocity, you and mike were talking about input power. What do I model with in winisd? Some people say RMS of the amp, I've read someone say peak... mike modeled one with 1000W input and you modeled it once with 100W and it seriously changes the size and length of port needed.

To be honest I don't actually understand how much power a sub draws and how it relates to the level I run the sub at. I don't assume that my sub is going to be pulling 1400W @ 4ohms at all times from that EP4000 I'm looking at.... especially at the level's I'll be using in a townhouse!

Any advice anyone?


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## mwmkravchenko

> What do I model with in winisd? Some people say RMS of the amp, I've read someone say peak... mike modeled one with 1000W input and you modeled it once with 100W and it seriously changes the size and length of port needed.


Mike modeled under highest strain conditions. Which is exactly that. Battleship engineering. Dreadnaught actually. I modeled under more normal loud conditions. Both have their valid points. In WinISD you just change the signal level and see what port velocity you end up with. But keep this in mind the difference in loudness from 100 watts to 1000 watts is just under 10 db or twice as loud. There are conditions where if you are pushing your sub a bit you will pour in 500 to 800 watts in a blink of an eye. I have measured this quite regularly. But those are peaks not steady state. Subs when really kicking use around 100 watts and then on great transients peak out in the higher range of power. When they are that loud there are masking effects that will cover over the port noise as the transients that are reproduced are quite short so to the post noises. So the moral behind all this typing is that you won't really hear it if you model to keep port noise down to decent levels between 100 and 150 watts.

Power to sub out put works like this. Depends on the music you like. Take an orchestra a 500 person choir and a big bad pipe organ in Mahlers 8th symphony. Loud. 105 db a couple of rows back. To get your sub that loud you need 150watts. Not bad. You want heavy metal concert levels or pipe organ at concert levels you have to bump that up to 120 db. Your sub can't pull that off for long but it can get close. 800 watts will take you to 118 db. So the amplifier choice can have some bearing on maximum sound pressure level. Keep in mind that the SDX15 can take peak power levels for a short period of time that it cannot withstand steady state. So the 800 watt rating is most definitely meant to be a transient peak not steady state power input.

Mark


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## Fishtank

Nice thanks, straight forward enough.

Well I'm starting to run out of things to consider, I feel pretty comfortable with winisd now... Bracing seems straightforward enough with plenty of examples out there.

I think I'll take a few days to look around at some more designs and consider if I really want those slot ports, if they are worth the extra weight/volume they will consume compared to just round plastic ports. 

thanks again for all the help, I'm sure I'll come across another question, but I'm going on a vacation in a few days so I might not be around for a bit.


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## mwmkravchenko

Happy vacation Fishy

Mark


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## Fishtank

Hey I'm back. I'm in the final stages of my planning here and will probably get cracking next week some time. While I've been gone I made a few stands for my new Ascend Acoustics. I've never used MDF so I just built them out of the 3/4" mdf I'll be using for the sub. Speakers sound amazing, compared to my PSB's I let go to try them out.

They turned out well, and I got some practice with the table saw/router/finishing nailer I'm going to be using. Ignore the current movie room, I am still moving out of the 2-bedroom apartment in a few months so I can set up a proper room soon. I should be able to build this sub to blend right in with those speakers/stands.




























Anyhow I do have another question...I'm trying to really nail down the volume of my box... and while I do want the slot ports, 2 - 1" x 18" high x 48" long ports made out of 3/4" mdf is a ton of weight and seems like wasted volume. Cylinder ports use narrow light PVC etc... can I skimp on the slot port material and use 1/2" or even 1/4" MDF? I should be able to secure it quite well if I build my bracing around it...

Also i haven't found exactly how much volume the SDX15 itself chews up. Does anyone know the exact number?


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## Mike P.

I wouldn't use less then 1/2" and it would need to be well secured so it doesn't vibrate. 

The SDX15 displaces 7 liters.


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## Fishtank

awesome, maybe I will just keep the 3/4" mdf and make the box an inch wider.

I'm not going to be able to pick the thing up by myself either way...

thanks for the quick response!


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## mwmkravchenko

Lookin Spanky!

Your wood working skills are definitely up to par to make the box you desire.

Mark


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## Fishtank

Well this is pretty much a re-design. I think it's complete though... very easy to build...I think the bracing is more than enough but it seems a bit different than most people. The port is a significant chunk of the bracing which helps with the internal volume. 










*Size/Volume*:
I do still need the box to be fairly small, so right now I'm at 24" x 25.5" x 25.5".
Port Volume including the 3/4" wood is 3" x 17.25" x 65" = 3363 cu"
Bracing Volume is only 330 cu"
I wind up with a 5.1 liter box.

*WINISD Values*:
I still might not fully understand the implications of what I model, so let me know!

Used 500w input
Box size 5.1
Tuned to 16hz
1 - 2.25" x 15" x 65" slot
6db boost at 20hz











The only problem I can see for myself is I'm pretty much closing the box off. Because of how it fits together the only piece I could make removable is the back. And that would only give me a 3" slot at each side right at the back. Is this a big problem?

If I ran each voice coil to the back of the box in separate runs, I could still change the wiring to series or parallel from outside the box right?


Anyhow, i just threw this together today, if I managed to still overlook something please let me know... is 1st Port Resonance considered to low at 104?


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## mwmkravchenko

Ok now for some opinion.

You don't have to make anything removable. You have a big driver hole to work in if you want to.

Your idea about running both coils to the back is good. You can even get Bi-wire cups to help you out.

Now for a question:

What are you using to get you your bass boost?

Mark


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## Mike P.

With 500 watts input power you would need a 2000 watt amp to have 6 db of boost without the amp clipping. What amp are you going to use? Also your port is too long, you'll have a first port resonance issue.


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## Fishtank

Ha, there is always something else... I thought I was getting a bit greedy and the graph's looked to good to be true for the box size!

Mark - I'm still just going the easy route with the reckhorn.

Mike - I was worried about that first port number, but to be honest I have no idea what is too low. Doing some reading now I guess it matters as to where your crossover is set, as well as how many bends are in your port, if it's a slot or not... I've read a few people say 150 is fine, others 190 or it depends. Do you guys have any opinions on it?

Cutting the port back to 45" 's gives me 150 for 1st port and tunes the box to 19hz, I lose a bit in the 16-21hz range however I'm sure that's why people build bigger box's and I'm hitting a limitation I can't do much about.

Unfortunately I didn't put it together for myself, but I do understand that I would need to double the watts needed twice to accommodate 6db because of what Mark mentioned earlier in this thread, so thanks for pointing that out.

Also lets just assume that I have an ep4000, which I really will get sometime soon...what would you set as the input power in winisd? If you put in even 1000w it gets very hard to control the excursions and port velocity. The way I understood it earlier was a couple hundred watts is normally plenty... so I thought I was safe using 500w and keeping the numbers in line. Can you guys clarify what I should be using there?


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## Mike P.

Here's what I come up with with your box size and amp combination. 5.7 cu.ft. tuned to 18 hz with a slot port 2.25 high x 15" wide and 44" long. 3 db of boost at 20 hz and a HPF at 15 hz. Maximum air speed is under 28 m/s. Both ends of the port should be rounded over.

Here's the project file.

View attachment 20682


View attachment 20680


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## Fishtank

alright, I'm building it!

I really don't want this box any bigger, so it will have to do! At this point I just want to build it... I'll probably be building another in a year or so anyhow.

Thanks for all the help in this thread. I suppose I will start a build thread shortly!

If you guys have anything else to add that's great.


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## Fishtank

Thanks for all the help guys, I got started for better or worse this weekend...I couldn't wait any longer, was great weather.

If it doesn't turn out I'm happy to build another, had some fun this weekend.

Here is the build thread.

http://www.hometheatershack.com/for...k-build-5-5l-ported-first-diy.html#post255272


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