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Discussion Starter · #1 ·
Hello, this is my first post on what seems to be a forum of plentiful knowledge. I was directed here by THE EAR. I have been a member over at the klipsch and audiokarma forums for a couple years now and have learned a lot, and i hope to here also.


So, anyhow, i would like to possibly get involved in a diy sub. I am looking to stay under $1000. I basically just want to see how involved this gets. I should have the tools for the box, but if not, i guess there are ones you can get preassembled, right? I'm pretty handy, being a carpenter, and understand some electronic concepts. Actually my main concern, at least i don't think, is not putting it all together but what comes after that. Do i need a bunch of measurement tools and software to test it or to properly break it in? Maybe i'm jumping the gun a little bit, but i kind of want a broad aspect of this before i start.


Now, my room is only 11.5'x11'x8'. I know it's relatively small, but there will be a time i will move into a house with bigger rooms, so i want to build for the future. Is there a way to make a 12" or 15" or even 18" sub match well in my room now until then? I was actually looking at the Epik castle and ED A7S-450 for ones to buy, but if i can make a better sub than those and for less or around the same, that would be awesome, which i what i heard was possible, so that's why i am interested, and i like building things. Now, i know i want really deep bass, chest pounding and earth shattering really, yet refined and quick. This will mainly be for HT, but if at all possible it would be cool to hook it up to my 2 channel system as well. Now i guess i just need to get started with what cabinet and driver and amp to decide on. Hopefully what i described limits it down to a few choices so i hope my head won't spin with anymore than that. HAHA. Well, in advance, thanks for your input and suggestions.
 

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i'm on the same quest as you and have been for about a month now. Started by downloading a program called unibox for "modeling" drivers as using the drivers parameters as guide to see performance in different sizes and types of enclosures. Then i started asking these guys about different driver suggestions from their experiences. All in all very helpful people here with very honest opinions. i'm still on the fence as to ported or sealed because my final design needs to be accurate and musical and yet perform well for home theater. Good luck on your journey.
 

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Well, a no-holds barred HT sub is generally a 15-18" driver in a sonotube or HUGE box (like 300-600 liters). You can do something with a 15" and 300L + amp for under 1k, but it will be a significant presence in a ~12x11 room.


If you're okay with taking up that kind of space, one of the easy "budget" massive sub configs I see is a Tempest-X in a 300L sonotube + a Behringer EP 1500 or 2500 amp.


I would think this would be on the upper end of what you'd be looking at for a room like yours, and should stay below $1k without too much issue too. You can search the forum for Tempest-X or Tempest-X + sonotube and find several build threads that should go into adequate detail for you.


If you need it to be smaller, get a maximum size you'd be happy with, and people can recommend some drivers that would do well in a box that size. When you're talking about HT type subs, box size has to be a consideration, because the subs that have high output down to 20Hz generally also require pretty large boxes.


To get a flat in-room response, you will need about $200 in electronics. A mic, mic preamp, access to a computer or laptop, and a Behringer "Feedback Destroyer" (BFD for short, it's designed to offer 20-30 notch filters to keep microphones from giving feedback, but when you put all the filters in a 60-80 Hz range, you end up with an equalizer for subwoofers). Some people opt not to go for equalization. You can look at some of the build threads and see if you want to go this route. It does offer a LOT of flexibility to make your system sound like you want it to.


Room EQ Wizard is the most often used software (because it was designed by an enthusiast and is free).


If you choose the tempest-X / sono route, I think you're looking at ~$200 in equalization electronics, ~$200 for driver, ~$200 for enclosure items and misc items, and ~$300 for amp (EP1500), which leaves $100 wiggle room in your budget.
 

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Quote:
Originally Posted by mayhem13 /forum/post/12902290


I'm still on the fence as to ported or sealed because my final design needs to be accurate and musical and yet perform well for home theater. Good luck on your journey.

The HUGE ported designs are generally keeping the majority of the port noise in the frequency range where mostly you'd be reproducing noise anyway (20-40Hz, generally used for movies making explosions and such). Most real musical information is 40Hz and above, and if you look at something like a 300L enclosure tuned to 15Hz, you'll see that port contribution is down almost 10dB from driver contribution at 40Hz and drops more as frequencies increase.


So in the 'ultimate' ported configuration you really don't lose much musicality, and you gain a significant extension in low end.


I don't see any large SQ drawback to the HUGE ported subs. By keeping the port noise primarily in a frequency range where it doesn't much matter, you get rid of most of the negatives of a ported alignment.


When you start limiting box sizes and forcing yourself into tunes higher than ~15Hz, then the port plays a larger role in the musical range and you end up with some more traditional trade-offs between sealed and ported.


I still think that a lot of the negatives of ported alignments are exaggerated on the internet because people are most experienced with car subs and relatively inexpensive store bought HT subs, that are typically designed for a much different response from DIY HT subs. The store bought subs are catering to consumers who will not take a 5-10 cubic foot box, especially when the costs of such a size are exponential due to packing, shipping and potentially paying best buy or wherever to dedicate some floor space in a demo room.So the boxes are small, and as such, the port tuning higher frequency. You get a peaky response that is not high quality.


When modeling in WinISD or UniBox (free woofer modeling programs) you can run the optimizer, then use a little larger volume and a little lower tuning, and that is what most SQ-type people will tune for. This offers some extension that will roll off more than what the optimizer will choose, but room gain will often bring it right back up in an actual room situation. This also limits the port contribution some. This kind of tuning is very different from store bought subs and auto subs, and is way higher SQ than most people are used to from ported subs.
 

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Discussion Starter · #6 ·
I noticed with that behringer and tempest-x combination, the amp is external, so i guess that means the sub is passive. Is that necessarily better than building an active subwoofer with the amp built in the subs enclosure. Well i guess there's still an amp on the enclosure, it's just passive and you have to run it through the behringer. Is that correct. I also can't seem to find the tempest sub anywhere.
 

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33klfan you use the crossover in your HT receiver (if you have one) via sub out to your Behringer amp . Guys please correct me if i'm wrong.
 

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I don't think any of us use our plate amps crossover, they are rather cheap and its much better to control it all through the receiver.


Don't think of subs as active or passive, all that is indicating is the location of the amp. We design subs to have the right amp for the job, that can be a plate amp or a pro audio amp, but typically we go with pro audio amps for their value.


We can design a sub for you that will outperform the castle, but we need to know how much room you are willing to allow for the sub. For example, many of the builds over here are far larger than the Conquest, castle size subs are a bit rare, but trust me, we can work with you to find something that will suit your needs.
 

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Quote:
Originally Posted by dawg1161 /forum/post/12909474


33klfan you use the crossover in your HT receiver (if you have one) via sub out to your Behringer amp . Guys please correct me if i'm wrong.

Yes, this is the typical use of an HT sub, even plate amp subs. If you use the plate amp crossover, your mains aren't getting a high pass crossover unless it comes from the receiver... and it doesn't really make sense to use the high pass of a receiver and the low pass of a plate amp, you can just use the receiver for both to know that they're matched up.


So, you can use whatever you want to power a sub. If you like plate amps, you can use a plate amp.


I suppose if you used a low pass of a plate amp and a high pass of the receiver you could play with the frequencies a little more and do some semi-EQ type things without having to go with a BFD and such. But you'd still need a mic to be able to see what you're doing to the FR. Keep in mind that receivers are typically 24dB per octave on the low pass and 12 dB per octave on the high pass (they assume some rolloff from the mains will help out here). Plate amps aren't all 24 dB on the low pass, so you have to go grinding into specs and such if you choose to go that route.


and the tempest-x is sold by www.diycable.com . There's also a nice PDF on the page there talking about applications that show how response changes with volume and tuning frequencies.
 

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Discussion Starter · #10 ·
Well, i am kind of running out room with my chorus ii's and everything else in my room. I always surprise myself with what i can fit into my room, so i'll just consider this my next challenge. Where i have my klipsch rw-8 now, is behind all of my equipment, so i wouldn't be able to go to much bigger there, which it's around 10"w, 18" deep, 16" high. If i keep it that size i prolly won't be able to get the sub i want or can i. If i take this Eagles mini locker out of my room, i could fit a nice size sub there which would be to the right of my left speaker. Here's the thing too. I know sub placement is crucial and i don't have much room for playing around with that. I also have my hd tuner sitting on the Eagles locker, so should i figure on putting nothing on my sub? I can possibly have a sub 24" to 30" high, 20" to 24" deep, and 16 to 18" wide. Anything under that or around that should work. Ok, yeah i can do it with that behringer. Now i understand that aspect. So how does the subwoofer enclosure hook up to the amp. Do i just connect the speaker cable from the sub to the amp or our there rca's on the enclosure and then there's a connection from my receiver to the amp? Thanks
 

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Quote:
Originally Posted by 33klfan /forum/post/12910068


Well, i am kind of running out room with my chorus ii's and everything else in my room. I always surprise myself with what i can fit into my room, so i'll just consider this my next challenge. Where i have my klipsch rw-8 now, is behind all of my equipment, so i wouldn't be able to go to much bigger there, which it's around 10"w, 18" deep, 16" high. If i keep it that size i prolly won't be able to get the sub i want or can i. If i take this Eagles mini locker out of my room, i could fit a nice size sub there which would be to the right of my left speaker. Here's the thing too. I know sub placement is crucial and i don't have much room for playing around with that. I also have my hd tuner sitting on the Eagles locker, so should i figure on putting nothing on my sub? I can possibly have a sub 24" to 30" high, 20" to 24" deep, and 16 to 18" wide. Anything under that or around that should work. Ok, yeah i can do it with that behringer. Now i understand that aspect. So how does the subwoofer enclosure hook up to the amp. Do i just connect the speaker cable from the sub to the amp or our there rca's on the enclosure and then there's a connection from my receiver to the amp? Thanks

33klfan, I had similar dimensional constraints as you. With those dimensions you're looking at around 4-4.5 cuft. This will typically allow for a 12" ported design, or a 15" sealed. Take a look at the sub I just built, it's tall with a small footprint, and sounds like it's similar to what you're looking for.

http://www.avsforum.com/avs-vb/showt...3#post12510443
 

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If you build the sub with a plate amp, an RCA interconnect goes straight to the plate amp from your receiver.

If you build the sub with binding posts just like speakers and use an external amp, then an RCA goes from your receiver to the amp and speaker wire from the amp to the binding posts on your sub.


In the case of pro audio amps, they all take balanced inputs, and RCA interconnects are unbalanced, so you need a converter (like $4 at Radio Shack, or can often be ordered at wherever you buy the amp). The converter basically looks like a 1/4" headphone plug and has a female RCA jack on the end to plug a normal subwoofer RCA into.


You can put stuff on your sub, if it's built right it won't vibrate until everything in the room is vibrating anyway.


looks like somewhere around 4 cubic feet internal volume is where you will end up for those dimensions (which is around 110-115 liters). With a box like that you may be limited in how low you could tune a ported box just due to port length, so a 12" or 15" sealed may be right for you. If you do ported, since your long length is height, you may need to put it up on feet and put the port downfiring.
 

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Discussion Starter · #13 ·
What dimension to i have to look for if i wanted to do ported. How will the sealed sound compared to the ported. Does it sound like this sub will be equivalent to the epik castle or so or better.
 

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Port length:


Model the Ficaraudio Q15, and you'll see it likes around a 4 cubic foot ported enclosure with a reasonably low tune (25Hz, maybe lower, let's use 25Hz). With a 6" port at 25Hz, the port length is over 22 inches. Since you generally want to leave a distance equal to port diameter between the port and the wall of the sub, to get that tune, you have a few options:

1) run the port downfiring, this will fit, but you have to put the sub on stilts, eating into your acceptable height.

2) Make a box with a larger footprint

3) Make a shorter port and change the tuning frequency higher

4) use a smaller diameter port... a 4" port would only need to be 9.5" long to get a 25Hz tune. However it has some downsides. While a 6" port will handle 500+W with no detectable air noise, a 4" port exceeds the generally accepted max air speed at 500W at 35 Hz and below (8% of speed of sound is generally accepted max). a 5" port exceeds at 25 Hz and below.


You can use less power and get less output, and this reduces air speed down to something inaudible... at 250W, a 5" port is no longer above 8%, and a 4" port drops down to about 28 Hz before it pushes past 8%.


It's a trade-off, which is what designing is all about. Understand the trade-offs and compromise where it will affect you least. The great thing about DIY is that you decide what matters and what doesn't instead of someone making those decisions for you. The downside is that you have to do some learning to make the right decisions for you, or you just have to trust the right people.


In your case you probably won't need 500W in a 12x11 room, and you can likely downsize a port without issue, assuming you won't play it loud enough that the box size and port size become a huge issue. For example, a Tempest-X in 4 cubic feet with a 4" port at 20Hz tune. This isn't too bad, with -3 dB at 28Hz and room gain should add a bit so you're reasonably close to flat around 20 Hz... This is probably already flatter than most manufacturer claims of being flat to 20 Hz.


Then your restriction becomes some port noise if you play it REALLY loud, generally louder than you could probably stand in a 12x11 room.


When and if you move, and the sub will be in a larger room, then you can rebuild into a larger box. You already have the amp for more juice, and you essentially upgrade your sub without actually spending much money, just build a box about twice as large and buy a new 6" port with a tune for something like 15Hz. Now you are able to put more power through it without port noise issues, and you move to a more gentle rolloff at really low frequency, one that should basically match with room gain well enough that you can EQ a completely flat response.
 

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Quote:
Originally Posted by Concillian /forum/post/12910526


If you build the sub with a plate amp, an RCA interconnect goes straight to the plate amp from your receiver.

If you build the sub with binding posts just like speakers and use an external amp, then an RCA goes from your receiver to the amp and speaker wire from the amp to the binding posts on your sub.


In the case of pro audio amps, they all take balanced inputs, and RCA interconnects are unbalanced, so you need a converter (like $4 at Radio Shack, or can often be ordered at wherever you buy the amp). The converter basically looks like a 1/4" headphone plug and has a female RCA jack on the end to plug a normal subwoofer RCA into.


You can put stuff on your sub, if it's built right it won't vibrate until everything in the room is vibrating anyway.


looks like somewhere around 4 cubic feet internal volume is where you will end up for those dimensions (which is around 110-115 liters). With a box like that you may be limited in how low you could tune a ported box just due to port length, so a 12" or 15" sealed may be right for you. If you do ported, since your long length is height, you may need to put it up on feet and put the port downfiring.



yes but we are looking to beat a castle here, its gonna take one heck of a ported 12 to do that. You need a VERY nice ported 15 or decent 18 I'd say, perhaps an ED 18" sub on a tall ported box, not super big, maybe around 10 cubic feet.
 

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Really take a look at http://rythmikaudio.com/ . Brian sells a good product and as you will see you he has kits designed for enclosures of 1.5 cubic feet and up. Check out the site-lots of info to help you select a model and Brian is very helpful.


His servo kit cost me way, way, less than my mains, but I am very happy with the results.
 

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Quote:
Originally Posted by armystud0911 /forum/post/12911971


yes but we are looking to beat a castle here, its gonna take one heck of a ported 12 to do that.

A Shiva-x in 4 cubic feet tuned to 15Hz is as flat as you could want response to be. The Castle may beat it in pure volume, but this guy is in a pretty small room, a 12 will be plenty loud.


It also looks manageable with a 3" port. I'm with the guy who built the Shiva box, this looks like the way I'd go if I were in your shoes.
 

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Quote:
Originally Posted by Concillian /forum/post/12902629


The HUGE ported designs are generally keeping the majority of the port noise in the frequency range where mostly you'd be reproducing noise anyway (20-40Hz, generally used for movies making explosions and such). Most real musical information is 40Hz and above, and if you look at something like a 300L enclosure tuned to 15Hz, you'll see that port contribution is down almost 10dB from driver contribution at 40Hz and drops more as frequencies increase.


So in the 'ultimate' ported configuration you really don't lose much musicality, and you gain a significant extension in low end.


I don't see any large SQ drawback to the HUGE ported subs. By keeping the port noise primarily in a frequency range where it doesn't much matter, you get rid of most of the negatives of a ported alignment.


When you start limiting box sizes and forcing yourself into tunes higher than ~15Hz, then the port plays a larger role in the musical range and you end up with some more traditional trade-offs between sealed and ported.


I still think that a lot of the negatives of ported alignments are exaggerated on the internet because people are most experienced with car subs and relatively inexpensive store bought HT subs, that are typically designed for a much different response from DIY HT subs. The store bought subs are catering to consumers who will not take a 5-10 cubic foot box, especially when the costs of such a size are exponential due to packing, shipping and potentially paying best buy or wherever to dedicate some floor space in a demo room.So the boxes are small, and as such, the port tuning higher frequency. You get a peaky response that is not high quality.


When modeling in WinISD or UniBox (free woofer modeling programs) you can run the optimizer, then use a little larger volume and a little lower tuning, and that is what most SQ-type people will tune for. This offers some extension that will roll off more than what the optimizer will choose, but room gain will often bring it right back up in an actual room situation. This also limits the port contribution some. This kind of tuning is very different from store bought subs and auto subs, and is way higher SQ than most people are used to from ported subs.

I agreee, and i will add...


I thinik a lot of non-diy customers on the "113" ( http://www.avsforum.com/avs-vb/forumdisplay.php?f=113 No pun intended... honestly thats the real name of that board! lol) instantly recommend sealed boxes when the "musicality" (evil word) word is brought up, but i think this stems from mfr habits of the old and marketed driven ways of developing subwoofers with very high Q (cheapo drivers) in very small, and in-appropriate ported boxes with lousy responses. You can't hardly lose if you design a well ported box and the low end efficiency is generally 3 fold that of a sealed design where the high end efficiency and response is virtually the same (not even distinguishable)... implying unless size/cost is a problem, you're probably better off finding a lower Q woofer and doing up a ported design, especially if you intend to have bass below 30Hz. Even with ultra high linear high excursion drivers, at 20Hz with lots of Eq, the distortion is generally high and the SPL is not very impressive next to a lesser displacement driver in a resonator type system.
 

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With only 4.5-6ft of volume to play with I think it might be worthwhile to go with a PR system. Maybe based off an SDX15? If that's more complicated than desired just go with a sealed 18.
 

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Quote:
Originally Posted by KyleLee /forum/post/12913611


I agreee, and i will add...


I thinik a lot of non-diy customers on the "113" ( http://www.avsforum.com/avs-vb/forumdisplay.php?f=113 No pun intended... honestly thats the real name of that board! lol) instantly recommend sealed boxes when the "musicality" (evil word) word is brought up, but i think this stems from mfr habits of the old and marketed driven ways of developing subwoofers with very high Q (cheapo drivers) in very small, and in-appropriate ported boxes with lousy responses. You can't hardly lose if you design a well ported box and the low end efficiency is generally 3 fold that of a sealed design where the high end efficiency and response is virtually the same (not even distinguishable)... implying unless size/cost is a problem, you're probably better off finding a lower Q woofer and doing up a ported design, especially if you intend to have bass below 30Hz. Even with ultra high linear high excursion drivers, at 20Hz with lots of Eq, the distortion is generally high and the SPL is not very impressive next to a lesser displacement driver in a resonator type system.

Indeed.
 
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