DIY Sub - This seems to be a trend

[xboxweasel]

At what span do you typically add bracing? I was thinking along the lines by replicating the face (with a ~14" hole in the middle) as a brace piece.

Just out of curiosity, why aren't you considering a sealed option?

Not sure. I guess because my current sub is ported and I wanted to go that route. It's only 5 inches small all around. For a vented box I get a flatter response. With a sudden drop at around 30Hz. With a sealed box the drop [which is not as sudden] starts at 80Hz. If you use WinISD I can send you the data files.

No $ex to upset mommy and the kiddies on this site incase they're looking over your shoulder.

Why is that? Other links work. Why not these? Conflict of interest? But Audioholics does not sell any perchandise.

I just checked the sealed box specs with WinISD vs Parts express. PE=2.2 ft^3. WinISD=3.2 ft^3. Wonder why there is that much difference?

 

[xboxweasel]

sealed vs vented

I can get a much lower F3 with a vented box (44.4 vs 20.7Hz). And it's not that much bigger.

 

[xboxweasel]

Canadian Distributor

Does anyone know of a Canadian Distributor for DIY speaker projects, similar to Parts Express?

Preferably in the great Toronto, Ontario area.

Thanks.

 

[genesound]

I put two of these in 2.2 cu ft sealed boxes of 1" MDF. They're relatively small, very powerful, not too expensive, and give good response to 16Hz according to SmaartLive. Also, due to the servo, tuning is not necessary. And since the boxes are so small and given the 1" MDF, bracing seemed unnecessary.

A little parametric eq tuning for room resonance and blammo, good to go!

 

[annunaki]

With the example *********** uses the f3 is 25.71Hz which is the -3db point, with the example I gave the f3 is ~21.5Hz, so you can see just from that, what a difference box size makes. With a port size of 6" x 21.6" long. Or you could use 2 tubes at 3" x 10.8" long

As far as mine, I used the 500 watt bash amp that they sell, it's not as good as their 1000 watt monster, but it works for me. As far as setting it up I just let the reciever take care of that, though I'm still screwing around with placement because I just moved it to my basement were I'm building a dedicated [more or less] home theater.

Actually, to yield the same tuning frequency, the ports must remain the same length. Two 3" ports do not equal one 6" port either. To get the same amount of port surface area 4, yes FOUR, 3" ports would be needed at 21.6" long.

 

[annunaki]

Thanks. I missed that. I was looking at the PDFs for the driver specs.

I've been playing with winISD a bit. I came up with a vented ~181L (6.4 cubic foot) box with a tunning frequency (Fb) of 21.19Hz. The port is ~4"OD x 8"long. Outside dimensions of enclosure are ~24" cube. This off course will increase as I will be making a seperate compartment off the back for the amp. Adding another 7"-8" in depth.

I would do a larger diameter port with a low tuned enclosure for a 15" driver. You may have serious port noise issues at low frequencies. Besides you would only be tuning to around 25hz-27hz. With an enclosure that large, I would use two 4" aero ports at about 20" long tuning to about 20hz.

 

[annunaki]

I just checked the sealed box specs with WinISD vs Parts express. PE=2.2 ft^3. WinISD=3.2 ft^3. Wonder why there is that much difference?

I know for a fact that WinISD plots are based on anechoic response. I would be willing to be Parts Express is taking into account average room gain. That would definitely account for a larger enclosure.

 

[xboxweasel]

Two 3" ports do not equal one 6" port either. To get the same amount of port surface area 4, yes FOUR, 3" ports would be needed at 21.6" long.

Area = pi r ^ 2. I understand that.

However, what is the relationship between port length and port diameter? Are we talking volumn?

I know for a fact that WinISD plots are based on anechoic response. I would be willing to _bet_ Parts Express is taking into account average room gain. That would definitely account for a larger enclosure.

Parts Express was using a small box design than WinISD (2/3 what WinISD comes up with). I'll run through WinISD again. What is anechoic response?

Do you mind going over my WinISD project file to see if I am doing anything wrong? The great thing about a project like this is you can always make a new enclosure for minimal cost. The driver and amp are re-usable.

TIA.

 

[annunaki]

Area = pi r ^ 2. I understand that.

However, what is the relationship between port length and port diameter? Are we talking volumn?

For a given enclosure volume, as port surface area (diameter) increases so does port length. A set tuning frequency can be achieved with any number o different sized ports.

Remember that any ports used must be figured into the total port surface area. For instance If a person had four 3" ports it would yield the same tuning frequency as a single 6" port assuming the lengths were all equal.

Parts Express was using a small box design than WinISD (2/3 what WinISD comes up with). I'll run through WinISD again. What is anechoic response?

Do you mind going over my WinISD project file to see if I am doing anything wrong? The great thing about a project like this is you can always make a new enclosure for minimal cost. The driver and amp are re-usable.

TIA.

Anechoic response shows truly what the enclosure is capable of with no room gain or loss figured in. In other words, it would be like listening to the sub and it's enclosure with no outside source to affect response. Without knowing how a particular room, and particular placement within said room will affect response, anechoic plots will typically yield best results.


If you wish to send it (WinISD file) to me that would be fine, I can look it over.

 

[xboxweasel]

WinISD

Cannot find a way to attach a file to a PM. I'll do it the hard way.

Specs for Dayton 15" Titanic:
Qts: 0.38
Vas: 7.790 ft^3
Fs: 19.93Hz
Re: 3.68 ohm
Le: 3.84
Xmax: 0.83 in
Z: 4.00 ohm
Qms: 5.89
Qes: 0.41
SPL: 88.28dB
Pe: 800W
BL: 3.55
dia: 15.00inch
Sd: 113.15 inch^2

In a 6.395 ft^3 (24.41x24.41x24.02) vented enclosure. The tuning frequency is 21.47. Ql=7.00. One 6"OD x 20.95"long vent.

The graph is flat until 30Hz @ 0dB at which point starts to drop.
20Hz @ -4.44dB
15Hz @ -12.71dB

If I enter the tunning frequency (25Hz) you mentioned then there is a huge hump in the graph.

Thanks.

 

[xboxweasel]

Another question:

Is there any way to limit an amplifiers output? ie: I plan on getting the 1000W Dayton amplifier along with the Dayton 15" Titanic HKIII. But what if I want to try a different driver down the road. Since I have the power available, can I dial it down to 850W? 500W? 400W? 300W? That would be real nice. If not, is there much concern in pairing the 1000W amp with a 400W driver?

 

[annunaki]

Cannot find a way to attach a file to a PM. I'll do it the hard way.

Specs for Dayton 15" Titanic:
Qts: 0.38
Vas: 7.790 ft^3
Fs: 19.93Hz
Re: 3.68 ohm
Le: 3.84
Xmax: 0.83 in
Z: 4.00 ohm
Qms: 5.89
Qes: 0.41
SPL: 88.28dB
Pe: 800W
BL: 3.55
dia: 15.00inch
Sd: 113.15 inch^2

In a 6.395 ft^3 (24.41x24.41x24.02) vented enclosure. The tuning frequency is 21.47. Ql=7.00. One 6"OD x 20.95"long vent.

The graph is flat until 30Hz @ 0dB at which point starts to drop.
20Hz @ -4.44dB
15Hz @ -12.71dB

If I enter the tunning frequency (25Hz) you mentioned then there is a huge hump in the graph.

Thanks.

Your Bl number is not correct, it should be 15.79 Tm.

I received the following information for the driver (Dayton Titanic MKIII TIT-400C-4) in question:

Net enclosure volume 6.52 ft^3

2, 4" ports 23.0" (use aero ports)

Tuning frequency 20hz

F3 of 20.55hz

Dimensions (internal) 27" D x 19.5" W x 23" H This will give you a net volume of 6.52 ft^3 after woofer and port displacement. A 23" internal cube would work as well. Though you would have to use a slot vent, as the ports would not fit inside the enclosure.

One would not really notice the difference between 6.395 ft^3 and 6.5 ft^3 in terms of physical size, unless specifically looking for it with the two enclosures next to each other.

 

[xboxweasel]

Thanks annunaki.

Does anyone know what the Ql for a box stands for? In my current design it comes up with 7.00 (using WinISD). And just to clarify, is F3 of approx 21.5Hz good or bad?

I'm planning on starting this project sometime end of February / beggining of March 2006. Got to pay down the old plastic first.

 

[annunaki]

Another question:

Is there any way to limit an amplifiers output? ie: I plan on getting the 1000W Dayton amplifier along with the Dayton 15" Titanic HKIII. But what if I want to try a different driver down the road. Since I have the power available, can I dial it down to 850W? 500W? 400W? 300W? That would be real nice. If not, is there much concern in pairing the 1000W amp with a 400W driver?

The only real way to dial back the power is to do it with impedance, or the driver's resistance. It will depend on what the amplifier does for power at a given nominal impedance.

If the woofer you are looking at handles only 400 watts, make sure it is 8 ohms. The specific amplifier you are looking at will do about 500 watts into 8 ohms. The Dayton amplifier will only output 1,000 + watts at impedances of 4 ohms or so.

One can also try to keep the dial turned down on the level control, but it is not a guarantee of keeping the power within your desired level.

 

[annunaki]

Thanks annunaki.

Does anyone know what the Ql for a box stands for? In my current design it comes up with 7.00 (using WinISD). And just to clarify, is F3 of approx 21.5Hz good or bad?

I'm planning on starting this project sometime end of February / beggining of March 2006. Got to pay down the old plastic first.

Why not do the enclosure I suggested? It will give you an anechoic F3 of 20.55 hz. You should have usable response down to about 14hz or so, if not lower, depending upon your room.

Where are you seeing the Ql at? In advanced? I would not worry about this at all. It is not going to be of any real significance.

An F3 of 21.5hz is definitely not bad. That would mean in an anechoic chamber, the output is only -3db below the fundamental at 21.5hz at reference. With the enclosure I gave you it pushes the -3db point to 20.55hz. This would most likely be inaudible though. With either enclosure you will have very usable output below 20hz in your room.

 

[Feanor]

I've got Bassbox and like it

... Bassbox is a lot less money, $180. Someone also made an Excel spreadsheet to help figure out cabinet sizes. I have not tried this one yet.

I also have X-over Pro. They both are very easy to use and seem valid and reliable -- that is, so far since I haven't done a lot of projects yet.

 

[Ozbradw]

Hi All

My first DIY audio project was a Sub. I ended up with 3 x 12" Shivas in a sealed tower arrangement with active Eq, 8 band constant Q graphic equaliser powered by a class D amp module. Subs make good DIY projects IMHO, and sealed subs are probably 'easier' for the novice than a ported design.

This said, when I started researching I found this web site to be invaluable source of info. http://sound.westhost.com/

I also found WINisd to be a good program, it just takes a bit to get the hang of It. The new version can model Xmax, SPL and Excursion which are inportant considerations with eq'd sealed subs.

I suggest any first time sub builders contemplating building their own sub look thru the above site before starting (including buying amps, drivers etc). It will only take a couple of days to read the relevant parts and will possibly save some money.

One thing that I have noticed in this thread for instance is quoted large watt plate amps. The required output of the amp may be much smaller than 1000w dependent on driver selection, enclosure configuration and target SPL and frequency response of the sub. From reading the relevant info on the above site you may find that smaller (cheaper) amps are all that is required dependent on your final design.

Some things that are interdependent (in a sealed design anyway) that i didn't notice in this thread (or I missed) are Xmax and SPL and Fb. These are inportant considerations in designing enclosures to suit drivers when targeting the lower frequency range.

IMHO an f3 of 20hz in room for most applications is sufficient. Not to say a target of 15hz cannot be achieved and if thats what tickles your fancy, what the hell

Good luck with the project xboxweasel

Brad

 

[xboxweasel]

Thanks Ozbradw. I'll keep that in mind. My DIY sub is kind of set back at the moment. $1000 for parts for a 1000W sub was/is a little much. Maybe I will take your recomendations and go with something smaller. I just wanted something to best my current sub. No sense waisting any time or money if I is not a step up. Ask me to define "step up" and you'll have to get in line. I'm still waiting for that answer myself.

 

[BassHead]

According to Pardigms site the specs for your sub show it going down to 23Hz. If you're only getting 30Hz. Maybe there's a problem with your sub. If so Paradigm should have a good warranty. See what they will do for you. 23Hz should be enought for all but the most demanding systems.

yes he may have a problem with that sub,i like to know how he has it hooked up to start with ,second what his settings are,third what hes has his eq at in reciever and forth what his settings are on - + level,the 2100 is a killer sub and reached 21 hz in a 20x23 room

 

[xboxweasel]

i like to know how he has it hooked up to start with ,second what his settings are,third what hes has his eq at in reciever and forth what his settings are on - + level,the 2100 is a killer sub and reached 21 hz in a 20x23 room

1) sub connected via pre out from receiver
2) sub settings: phase = 0, crossover = 150Hz, volumn = approx 50%
3) crossover settings in receiver = 80Hz
4) gain settings in receiver = -3dB

I can see the driving moving at 25Hz when playing back the sample from the Rives Test CD 2. But no sound or reading on my SPL meter. Nothing at 21Hz. At 31.5Hz, and up, I get something.