I have a headache!

1. 15" It's always better to turn it down that push a sub to the limits to get the volume that you want.
4. What is the maximum size you can live with? Read through the sticky thread at the top. You will see dozens of examples of subs raning from tiny to massive.
2 & 3. Answer number 4.

-Robert

Driver sensitivities vary. Actually a 15" may take less power per amount of spl than a 12" of the same design. A 15" is very little more money than a 12" and has far more capacity for output all else being equal.

I don't see that your receiver is rated into 4 ohms and alot of drivers are nominal 4ohms. This may or may not be a problem. Remember the low frequencies are the ones that require the largest amount of power. I'm not sure how much volume you want but in a 4000cuft room you're going to need more power more than likely.

If you could give people a better idea of volumes you listen to and maybe other subs you've heard it may help.

Odds are good you may need to up your budget or accept less than stellar results. If you want a sub that produces the lowest sounds from a DVD and with good power you'll have to spend more I think. If it's just for music and what I consider low volume on movies then you'll just be ok. Is there any way you can spend more money?

It's possible someone knows of a very sensitive driver and sub design which is inexpensive that may work ok in that large of a room. I really know very little but have spent alot of time doing research before I built my last sub and for 300 and trying to power it with a receiver I'd not do it yet myself. Better to get more money or at least plan on buying an amp. Many people use a Behringer pro amp that's pretty cheap and works well.

Many people like the Dayton 390 HO from Parts Express. They're on sale for 139 dollars with free shipping til I think next Thursday. These are output limited but supposed to be excellent for the money.

I know the HiFi version of the same driver I'm using has amazed me. They're both the same price and my sub cost about 300 to build. That wasn't including the Router, router bit or Jasper Jig I needed to buy. Fortunately I found a dirt cheap router off of Ebay, no doubt made in China, for 40 dollars shipped brand new. Works fine though and for just cutting circles I'm happy. I just bring this up as it's not common to have a router. The router bit cost 20 and the Jasper jig is also on sale from Parts Express for 29 bucks right now.

There's alot of people at http://www.htguide.com/forum/forumdisplay.php4?f=6 that are experts on building subs and will be able to make your project doable. I've only built the one sub but I learned that for 300 bucks you can build an excellent sounding sub. My sub is not really any good as a HT sub though. So I'd go for it if I were you. You'll definitely get way more for your money. Best wishes with your project.

1. With a max of 3cf, you are going to be holding back a 15" sub. A 12" sub would work and you could even go ported.
2. The guy you talked to at the audio store was not well informed. Your receiver's power has nothing to do with running your sub. It will have its own amp. Even if he was talking about pushing your mains to keep up with your sub, then he was wrong. We are all about calibrating and over-engineering. Whether you run a 10" sub or a pair of 15's, neither will overpower a properly calibrated system. We just like building big so you don't push the sub to its limits.

If you are dead set on a your budget, go ahead and mark the BASH 300 amp from PE as something you need for $105 (shipped free). If you could increase the size to 3.5cf (net), you could use a Shiva Classic, a Dayton DVC 12", Ascendant Audio Assassin, Elemental Designs 13Kv.2 or a TC Sounds DB500. Those range from $75 to $150 (some include shipping in the price). That will leave about $100 for building materials and misc. parts.

Have you thought about building tall? Cloning an SVS cylinder sub is always a popular option that saves floor space.

-Robert

I'd like to know if you are planning on powering the sub with your receiver? Also does it have pre outs?

I am actually planning on doing something that is small, sensitive and as small as possible like you. So I'm in the same boat. I do plan to use our HT receiver to power this HT sub in my own house. It was amazing my wife even ok'd it. Even though my receiver is rated into 4 ohms I still won't be shocked if the receiver is too wimpy to supply our HT sub with enough current.

Hopefully someone will chime in with a good answer as I'd like to do the same thing after I'm done with my next one. This is a case btw where the 12" actually will output less volume than the 15" in the same line. In effect you need more power to get equal volume(loudness) from the 12".

If this driver works out I'll let you know because Parts Express has free shipping right now

Our living room is smaller than yours and I don't expect that single driver to thump the windows but it should be satisfying for my family.

I just tried using WinIsdPro and it's telling me my Qes, Qts and Qms don't make sense.

I'll also look for a small sub to copy for us. There's a thread here called DIY Gallery of subs to copy and one at htguide.com under "missions accomplished". Under that go to Subs. I'll check the thread both here and over there. Be sure to let me know what you find also. It's kind of like a treasure hunt because I feel guilty having to ask other people for so much help. In the end though just take your time and you'll end up with an excellent sub especially for the money spent.

I still can't get over how good of quality of bass the sub that cost me 300 to build. I"ve been into high end audio for 35 years and although there's a ton of subs I've not heard I sure haven't ever heard one that is as accurate as the DIY I just built for under 1500. That's the truth. Like I said I've not heard by far the majority but I've heard subs costing upward of 2 grand that didn't perform as well as my 300 dollar sub The credit however really goes to the people who helped me.

If all else fails we can always call Parts Express or any other driver manufacturer and get their help. With Partsexpress though they're having a great sale that ends Thursday.

If you look at the first post under DIY Gallery you'll find a sub that only cost 275 with a PE plate amp. It's really not bad and I think the plate amp the guy used is on sale. Plus you could get free shipping.

If you're patient I'll try modeling the RSS315HO 12" driver again and see what happens. The Vas is only like 1.62 so it may be a good candidate for a small sub. I've found that at all the different forums the very knowledgeable people have tons of respect for the Dayton Reference Series Drivers. Apparently they're as good or better than the main brand name drivers at a fraction of the cost. You'd still be within budget using it as they're only 40 dollars more than the Quattro.

If you go to the HT Guide Missions Accomplished forum and go to: DIY Subwoofer Showcase you'll find a sub that's small using the RSS315HO. This is on the first page and the guy's username is: WRZ0117.

The sub is only an 18" cube and he claims it goes down to 25hz. If you used a different amp you could save the extra money I think and stay within budget.

Going to 3.5cf (85L), will allow you to port the box with a 3" Aeroport and get a 20hz tune. Any of the 12's listed will work pretty good in this box. Since you are staying on the small side, a 12 in a properly ported box will sound better than squeezing a 15 into a less than optimal box.

And you will only find the Daytons that I listed at Parts Express. You will find the others at their appropriate web sites.
Shiva Classic - www.acoustic-visions.com - $111 shipped
Ascendant Audio Assassin - www.ascendantaudio.com - $90 plus shipping
Elemental Designs 13Kv.2 - www.edesignaudio.com - $75 plus shipping
TC Sounds DB500 - www.tcsounds.com - $135 plus shipping

-Robert

All sub building is a compromise. Put a large sub in a too small box and it will sound boomy. To have a large sub work in a small box, it will need a strong motor. The TC-Sounds TC-3000 will work but it has a 40 pound magnet to push the cone and it costs $400.

Port it and it gets better since it doesn't have to work against the air in the box. But to get a port large enough to not chuff, it will be longer than the box. Also, long ports have a resonance that can become audible.

Passive radiators will work with a small box but they add to the cost.

The Dayton 15" DVC is a less powerful sub but it needs a 104L sealed box to achieve a Qtc of .707.
The ED 16ov.2 only needs 85L for the same Qtc but it costs more.
The TC 3000 15" only needs 30L for the same Qtc but it costs over 3 times the Dayton.

As the size of the box gets smaller, the sub prices increase.

-Robert

If you look on the Parts express site, as others have mentioned, you look under "speaker building", then sub woofer cabinets. In most cases, they tell you what subs and plate amps that work with a particular cabinet.

A heads up, for 4000cuft room, you really need two subs. I use two 15" JBL, in 2.5cuft boxes for a 3100cuft room. I use a Crown K2 amp (800wpc) to power them.

You can start out with one, and then built another one at a later time, if you don't want to build both at the same time. You could either buy their boxes or build your own, using their dimensions.
Here is one such combination, there are others.
http://www.partsexpress.com/pe/showd...number=302-822

Manau: If you go here: http://www.htguide.com/forum/forumdisplay.php4?f=39 and then to DIY sub showcase mine is the last one up there. And yes I do sleep but I better start getting in bed before 2 a.m. because I'll have to start going to work again.

I'm not trying to tell you to go with a sealed sub, as a matter of fact a ported sub will be better. Robert ,rlj5242, knows far more about it than I do. I know little even after hours and hours of reading and have only just started on my second sub so listen to him before me. I'd just tried to make sure you don't end up spending your time and money and end up with something that isn't satisfactory for you.

My sub is designed strictly for music reproduction and maximum quality. The box is a sealed 19w x 36h x 28.25d, weighs 165lbs and is not very sensitive so it needs alot of power. Also the 300 dollars I spent didn't include an amplifier as I'm using a Cinenova Grande's third channel which hadn't been being used as the amp is used to power woofers of my stereo speakers in a biamp configuration. The F3, where the output is 3db down, is 30hz with my sub.

In the end though you're going to have a sub far far better than anything you could buy for the same money so be patient.

Robert, So the Dayton 315HO works well in a 3.5cuft box? How small of a ported a box use for the 390HO? I"d like an F3 of 20 if possible. This is for our HT and size is a constraint.

What's funny I was telling me wife about these huge subs and sent her pics and how alot of guys have problems with their wives allowing something that large into their living room. She says "well we don't have that problem". Yeah right, until I'm the one who wants to add a sub.

I'd like to order these parts soon due to the sale prices and free shipping. Thank You

manau: See what Robert comes up with. If he answers my last question you'll also be getting your answer. I need to do the exact same thing because I don't have alot of money to spend on this HT sub for my family nor do we need a killer sub, although if it were just me there would be a bad ass sub in our living room.

Thanks for the compliment on my first diy project. I learned alot. It has been very rewarding especially since for 300 I got a very high quality bass reproducer. I mean that thing is true excellence. It's very large and output capability could be better but it fit my needs well.

When you're looking for an amp to drive a sub or any speaker you need to consider the sensitivity of the speaker and the power of the amplifier. If a speaker is 88db with 1 watt at 1 meter that means it needs double the power of a speaker that is 91db sensitive. In other words for every three db more sensitive the speaker, you only need half the power.

A subwoofer can use alot of power and take alot of power so buy as much as you can afford.

I haven't bought their boxes, just two 1" thick baffles, that already had the hole cut out for a 15" driver.
When I built my boxes, I used two layers of 5/8" mdf, completely glued together. Each side, top, bottom, back was stepped on all edges. In other words, as if I had used 1 1/4" mdf and then rabbited all the edges. So all the pieces interlocked, so to speak, providing plenty of gluing surfaces. The boxes are also braced inside, horizontally and vertically.

As for the sealed or ported thing here is a few facts.
First, as rlj5242 has already stated, for 15" the port's total lengths would longer than the sides of the box. So that would require using "elbows" in the ports to make them long enough. And you would want to use flared ports.
I have had at least one sub in continual use for 28 years. I prefer sealed, for a number of reasons. A sealed box will be smaller than a ported one. I the case of my JBL Sub1500s, they were designed to be used in a sealed box as small as 2.5cuft, or if ported 3.5~5.0.
4 & 5cuft boxes are huge. With ported 4.0 I did gain about 3~4db, but the transient response is better in a sealed box, and I find to be more musical. And in either case I was using the same 800wpc amp.
Also using unfaced fiberglass insulation, or other fill, will increase the virtual volume of the box. So with insulation @ the top, bottom, sides and back will make a 2.5 box considerably bigger.
After you get it built, to get the most from it, place the sub at the main seated location. Run the receiver's internal test tone. While the pink noise is on, walk around the room with a RS signal meter, set to "C", "slow". At the location the meter reads the highest db, that is where you want to place the sub.

No. Sealed, 15L Fb=52hz, F3=53hz, Qtc .698.

Ported, 40L, Fb 22hz, F3 31hz. It pairs up well with the BASH 300 in this alignment. The only problem is porting it. It's almost impossible. A 3" port is over 2 feet long. This is where the compromise comes in. You can put a port in that twists and turns or use a passive radiator.

The PE sub I mentioned above is the DVC385-88.


120L (4.24cf net). Fb=20hz, F3=19.95hz. With 300w, you can get an estimated max output of 110db. Use a 4" port 42.61 cm (16.7") long. The 4" Aeroport from PE would work PERFECT. With the BASH300, this would be a killer sub for under $300 in parts.

-Robert

Thank you very much Sir!

I'm trying to learn to do this myself but for obvious reasons am still in a steep learning curve. I just finished trying to model another HT sub with two RL-P 15's. I don't know if I did it right or not. I posted it on another forum and hopefully someone will tell me if it's correct or not. It's a gift for my best friend and I'm trying to get him the most kick ass sub for his room I can. I don't know how his wife is going to like this 3'x4'x20" box in their living room. I already tried with my wife and she'll only accept a small one that we can hide

I've been into high end audio for 35 years and for various reasons am completely bored with it. DIY is easily the most enjoyable part of the hobby. I wish I got the tail out from between my legs a long time ago.

Manau: at bare minimum you want a double thickness of mdf on your front baffle. You'll also want some cross braces too. These with the back of the driver can take up some of the volume and should be accounted for.

I don't know how far you're pushing your budget but a subwoofer can eat up power in a hurry. One thing I hadn't mentioned earlier is that music and movies have dynamic peaks that can require the amp to put out a hundred times the normal amount it's running at for dialogue. In other words if you're averaging 3 watts at a nominal listening level and an explosion or car crash occurs it could need 300 watts. In my opinion the bigger amp may be the wise choice in the long run especially in a 4,000 cuft room.

Through the years I learned to anticipate a budget higher than I'd guessed on things I didn't know much about. In the long run it's better to spend a little more money in the first place rather than be disappointed I didn't. In this case I think it's really a necessity, it would be for us. You'll need every decibel you can get out of that sub for your room, assuming it can take the power of the larger amp.

1-6 are all good options. #1 will move the most air, giving you the most output. Option 6 is my 2nd favorite.

7. More power that is overkill on some of those designs. Plus you would have to change some resistors on the circuit board since the sub-sonic filter on the 500 is set too high. Soldering is required.

Like warnerwh said, all of the enclosure sizes are net. You have to account for the sub, bracing, amp and volume taken up by the port. You treat the port as if it were a solid object.

-Robert

I'd go with 1 or 6, and I'd get the 500W amp for either. They can both use the extra power.

Considering your budget, the size of your room, and the primary use..you should definitely build a ported sub.

On paper the two drivers are pretty much equal in output. I'd go with the Dayton because of the small savings. Either one would be a fine choice.

Go with 500W.

Willd is correct that more power is better. The 500w amp will push all of those subs except for the db500 past their limits in most enclosures. Also, the 500w amp requires de-soldering and soldering of a pair of resistors to change the sub-sonic filter. The factory setting is set way too high.

-Robert

I know I make mistakes sometimes with modeling, but the 500w amp most certainly does not drive the RSS390 HO past its limits.

and he would want to change the hipass regardless of what amp he gets, for optimum performance.


No, there is zero risk. He must be thinking of the HF model.



No you can't.

And there are at least a few guys on here who have changed the resistors..and I believe a few threads were made.

The BASH 500 filters out the bass below 30hz. The BASH 300 filters out bass below 20hz. You want the bass below 30hz. Depending on the box you choose, you may want the bass below 20hz as well.

The process requires identifying 2 resistors on a circuit board. You have instructions with the amp as well as pictures here to find them. De-solder and remove them. Add the two new ones that correspond with your new filter/boost values. We can even help you with the values that you need. The removal and replacement are all up to you.

And I may have modeled the wrong sub. When I get time later today, I'll go back to Unibox and see what I came up with.

-Robert