building sub....... please help a first timer (1 Viewer)

[Joe Meissner]

In a previous post http://www.hometheaterforum.com/htfo...threadid=60956
I asked about building a sub. well here is the dimmensions i have come up with that will work in my living room
18Wx14Dx25.5H = 3.17^3 using 3/4 inch mdf correct?
so with some bracing what would be a good driver for this setup a dvc15 front firing or a 12 inch shiva down firing.
also i am not good with the software so what would the port length need to be to get in the 20hz zone with each driver. I will be using a 120watt plate amp for now until i can afford the pe250 watt amp.
would 120 watts be enough power to get the dvc15 in a sealed box of that size down in the 20hz range?
is it even worth building before i can afford the pe250?
thanks
Joe

 

[Dave Poehlman]

18Wx14Dx25.5H = 3.17^3 using 3/4 inch mdf correct?

Well, if those measurements are internal.. it would actually be 3.71 cuft. If those are external measurements, the internal space (w/ 3/4" MDF) would be 2.86 cuft.

If you are going to introduce bracing and a port, you need to account for those taking up space inside your enclosure.

FYI: Just plugging the driver specs into ISD online, I see a sealed enclosure @ 3.71 cuft yields a slightly flatter response as a 3.71 ported enclosure with very little sacrifice in bass extension.

 

[Joe Meissner]

O.K. i just started puting my box together. right now the inside dimensions are 16.5w X 15d X 24.5h = 3.51^3 correct?
I am wondering what the formula is for figuring out the ^3 when you add bracing, 4" port & the driver.
here is the driver i will be using. a freind is selling me this driver for $50. is this a good deal for home theater or should i just wait and get a shiva? any input would be great.

specs
Frequency Response (Hz) 25-500
Sensitivity (2.83v/1m) 96 dB
Impedance (nominal Z, ohms) 2
Rated Program Power, Watts 800
Fs (Hz) 28
Qts .33
Qms 7.82
Qes .35
Vas (ft3) 7.24
Vas (liters) 205
Vas (m3) .205
Cms (um/N) 183
DCR (ohms) 2.01
Levc (mH) @ 1 KHz .67
BL (Tesla m) 13.3
Sd (in2) 131.0
Sd (m2) .0845
Sd (cm2) 845
X max; one way (linear mm) 10.0
X max; one way (peak mm) 22
Vd (linear cm3) 845
Vd (peak cm3) 1859
Vd (linear m3) 0.000845
Vd (peak m3) 0.001859
Mms (grams) 173
Magnet Assembly (oz) 345
Magnet Weight (oz) 157
Vf (volume of frame, in3) 385
Coil length (mm) 28.6

 

[Joe Meissner]

I will be powering this with the adire 250watt plate amp.

 

[Patrick Sun]

There's no magic to finding the final internal volume, just start subtracting the volume of everything that occupies space inside the enclosure. Do some geometry calculations, and the proper conversion to ft^3 and you'll find your answer.

 

[ThomasW]

That's a 2 ohm driver. You better check with Adire to see if the amp is rated to drive to ohm loads....

 

[Joe Meissner]

its a dvc so i think i can run it at 4 ohms? i hope:frowning:

 

[Robert_Gaither]

It doesn't look like a dvc, it would have a second pair of binding posts if it did (all I see in the pic is one pair of binding posts not two pairs). I would advise not buying this woofer for home use as well due to the 2 ohm rating of this driver will give many amps fits trying to drive this (the type of amps to drive this type of load, it would be cheaper buying some other driver such as the Shiva, Stryke Lamdas, ACI SV12, BPD1201, etc and a plate amp).

On this site somewhere there are people getting rid of their old SVS woofers pretty cheap and I'd recommend building a sub based on this woofer instead as you can get it for a little more than what your friend is trying to sell you this woofer for (btw, is the basket on this woofer plastic? The photo looks this way to me).

 

[Joe Meissner]

It says in the brochure that is a dual voice coil

no its not plastic..... it is cast aluminum.

this is a $300 driver. so i will check and see for sure if it is a dvc. if it is, is it worth it to use for ht? do the specs look good? in the brochure it gives some recommendation's for HT. it says between 3.0 & 4.0^3 ported.

 

[Joe Meissner]

this is from the brochure

DESIGN FEATURES

· Long Excursion Design -- The SPL woofers use high performance components and the

New Ultra-Excursion Surround to achieve extra long excursion for high output and deep

bass.

· Heavy Cast Aluminum Basket on the SPL160 and Heavy Gauge Steel Basket on the

SPL15 provide extra rigidity and damping.

· Textured Blue Powder Coating ensures durability and lasting superb good looks.

· Ultra-High power handling Voice Coil with Glass Polymide Former increases power

handling and performance. Aerospace grade adhesives and materials insure longevity and

high performance.

· Dual Voice Coil Inputs for increased flexibility in optimizing installations.

· Computer Numerically Controlled (CNC) machined magnet plates and pole piece

precisely focus the magnet energy for optimum performance.

· High Emissivity Coatings on pole and top plates improve power handling.

· Double Magnet Structures for powerful, well-controlled output.

· Vented Pole Piece for greater voice coil cooling.

· Custom-designed High Strength Spider controls the long travel cone assembly.

· Gold Plated 8 Gauge Terminals ensure consistently outstanding connectivity for cable

2

and home theater applications.

 

[Jack Gilvey]

Looks like a standard car audio woof. High 28Hz Fs, unimpressive Xmax of 10mm linear. $300 list price for that is a joke.

 

[Dan Hine]

I agree with Jack about the price. For $300 you could get dual tempests! Though, I admit that dual tempests would need a much larger enclosure than you are building. So be patient, save some money and order a Shiva or Dayton DVC (are the new Titanic's available yet?). I currently have the Dayton and it definitely rocks for its price.
Regards,
Dan Hine

 

[Joe Meissner]

so wich would be better.....

the dayton dvc15.....

or the shiva.......

or an old SVS driver

they are around the same price except the svs

 

[Joe Meissner]

also i have an older 120watt 8ohm plate amp i could use to power it until i can afford a pe250 watter

 

[Dustin B]

All three of those are excellent drivers. And you've already listed them in order of their output capabilities. 15" Dayton has a 2.4L Vd, the Shiva 1.55L and the SVS has been guessed at around 1.1-1.3L. They are also in reverse order to the size of enclosure required.

So it becomes an enclosure size/cost/output capability decision that only you can make.

 

[Joe Meissner]

i have already started the box. its size is interior 24.5 X 16.5 X 15 with bracing should end up being around 3.15^3 i dont have ms excel so i cant use the unibox software. how will the dayton do in this size box? with the dayton should i go with a ported box or go sealed? this will mainly be used for HT. and about 30% music. mainly i want good impact for movies, i dont listen at loud levels but i want to be able to feel some bass. im not a critical music listener so that is secondary.
right now i have an old optimus 10" sub that just doesnt cut it. My co-worker just got an SVS 20-39pci and i want something to sound close to that. but he doesnt have a wife or kids, so he gets all that money to himself. i have a very tight budget and need to build a sub cheaply. thats why i would like to use the amp off my optimus for now. thats why the soundstream sounded good for 50 bucks that way i could buy a pe 250 amp. so if i have to buy the dayton driver i would have to power it with what i have for now.
thanks for all the help so far. you guys are great.
Joe

 

[Dustin B]

That being the case I'd get the Dayton DVC 12" driver, and put a pair of 19.5" long 3" diameter ports or a single 19.5" long 4" diameter port in your box.

Then I'd get the PE 300-792 amp to power it. But you'll have to mod the boost on that amp. It's really not all that hard to do though.

 

[Joe Meissner]

so you think the dayton twelve over the shiva in that size box?

what if the dayton dvc15 goes on sale for $99? would that be good or would my box size not work for that?

thanks

 

[Dustin B]

The Vas on the 15" is too high, and the box is too small to fit enough port for the displacment of that 15" driver.

The enclosure would have to be twice the size of the one you built before I'd consider putting the 15" DVC in it with a port.

Sealed you could do it, but the Q would be pretty high. For that size of box the 12"DVC would be best.

 

[Kyle Richardson]

Dustin is right use a Shiva, Dayton 12" DVC, or the new Dayton Titanic MkII. 3 cu ft is perfect for either of those drivers.