Hi kids

I'm sorry about my barrage of car audio questions lately. Anyways, recieved my new toy today. A lovely immaculate DD2515 subwoofer.

http://www.maccanet.net/gallery/albums/userpics/10003/normal_DSC02967.JPG

Anyways, just get get underway, I need a box for it, and I've decided to go ported. I have never designed or built a ported box, so bear with me. I decided to visit the DD website, and I'ce chosen to go the 3.0cuft, 45.00 sq" vent x 13" long box for my sub, which tunes to about 45Hz (spl freaks)

Now, seeing as though I have a mac, I can't really run much software. I don't completely understand the issue with frequency response curves, tuning, port lengths, areas, etc, etc, blah blah. :doubt:

So, I wouldn't mind a sub that is responsive and still plays low and loud...or something like that. Just be loud, but I'm not going to compete in any competitions. :)

So what are your thoughts on making such a box? better yet, could u reccomend any dimensions and specs to me? :D

Some specs for you:

Fs: 26 Hz
Qts: 0.36
Qes: 0.397
Qms: 4.16
Vas: 77 L
Le mH
Sensitivity: 88 dB

DVC, 4+4 and will be run off a Phoenix Gold, QX900.1d

whats that mr. squiggle wiring looking thing hanging out the side of it?

whats that mr. squiggle wiring looking thing hanging out the side of it?
:bowrofl:


LOL, its speaker wiring..DD are too cheap to provide normal terminals, so they just have a midget in their workshop twisting wires all day... :nuts: it works out cheaper

Its like..16gauge or somthing

Soz been busy at work... lol
check out the dd site...
http://www.ddaudio.com/dd/caraudio/enclosureInfo/boxSize_hiEff.asp

Plug the values into WinISD etc if you can get em onto ur pc.
Otherwise get all the specs and give them to me... I'll need the Qts, Vas, Fs, Re, Le, Xmax, Z, Qms, Qes, SPL, Pe, BL, diameter and Sd. I'll plug em in when I get some time

'You need more port area for a clean sounding, high output system. The DD port formula is this: 16 sqin of port area per cubic foot of box volume... Remember, the port is tuned to the box volume, not the sub(s).'

Peace

Tim

Plug the values into WinISD etc if you can get em onto ur pc.

PC? I don't have a PC, I can't run any program that calculates that stuff :cry:

the ONLY drawback of having a powerbook

lol sounds like a pretty big problem if you can't run programs lol

lol sounds like a pretty big problem if you can't run programs lol

I need to run mac software thats all :badpc: which means your conventional dodgey windows exe programs wont run..

mmkay, so from what i've gathered, if i was aiming for a cleaner, better responding sub, i would increase the port area by a bit?...so instead of 16sq in per cubic foot, i could go..18 and still keep the length 13inches?

only specs i could find are in the first post..

Yep, but remember not to expect miracles. It is an SPL dedicated woofer. Not saying you can't get it sounding good. But it will be much easier to make it sound loud.
With ur ports, since your sub will be moving a lot of air, round off the edges of the ports both inside and out. U can buy pre rounded ports, (or use a metal bowl and heat gun, CAA style) THis just stops weird noises from the air rushing past sharp edges.
Alternatively if you're after more port diameter, use MDF and make a partition instead of plastic ports. Just some food for thought. If you want more length out of ur ports build them out of the box, or inside the box where you can angle them.

Also be aware of reflections off the back off your box and adjust the shape/composition accordingly to stop any cancellation

Brace Brace Brace, and take into account (subtract) any bracing when calculating volume.

This is gonna turn SPL soon. Rear load it with a wall :) Dont forget to shut ur airvents and lean on the back windscreen lol

Tim

hehe, cbf'ed with the pvc pipe heatgun thing..i'll probably end up burning a hole thru my sub with that or something. I'll go with the mdf port coz it adds to bracing and is probably cheaper and takes less effort. probably won't look as good, but meh.

Umm...what do u mean reflections? it is just a box...keep the port areas the same and nice 90 degree bends i should be all good.. :confused:

i'll see, i'll get around to measuring dimensions in the boot n stuff tomorrow..

Umm...what do u mean reflections? it is just a box...keep the port areas the same and nice 90 degree bends i should be all good.. :confused:

The reason why most sub boxes arent square is to minimise direct reflections of soundwaves back at the cone. You can bounce the wave off at a different angle to reduce this, or place a thin layer of dacron or an acoustic tile at the back of the box.

The reason why most sub boxes arent square is to minimise direct reflections of soundwaves back at the cone. You can bounce the wave off at a different angle to reduce this, or place a thin layer of dacron or an acoustic tile at the back of the box.

damn...wedge shaped? haven't seen any cube shaped boxes around yet....wonder if i can use blue fluff instead of dacron :P

you need the power of virtual pc on the mac, then u can run xp :D

Definately go ported, it seems to be a trend with the 35 & 95 series to go for a 4cuft ported enclosure. Just a thought thou. Pity you didnt get a 12inch so you can run against me in Street A, although I will be happy with 140db :doubt: . It will be loud yes, it is hard to get it perfect as you have cabin response etc to worry about so dont worry if it is a little off as you cabin environment will throw a perfect box off anyways ( as calculated on WinISD as no cabin issues are taken into account ).

Apparently DD subs where designed to accurately reproduce music as best as possible.. but then they discovered how loud they are. The are not just for SPL but shyt they can crack windows. :bowrofl:

ok...i don't really have a solid answer...so i take it i'll just follow the reccomendations by DD, but increase the port area a bit to get a little better response?

keep the box wedge shaped...i think i'll face it backwards...but inverse mounted, so pplp can see the chunky frame n stuff of the DD sub :D

reckon i should a good 'connection'...as in airflow between the boot and the cabin? or keep the seperated as much as possible. I think big airflow gives better SPL..

Swap positive and negative wires into the sub. (Reverse the polarity) if you're gonna mount it upside down. Otherwise it will run out of phase and cancel out your fronts... :)

Swap positive and negative wires into the sub. (Reverse the polarity) if you're gonna mount it upside down. Otherwise it will run out of phase and cancel out your fronts... :)

imagine haveing both the voice coils wired up opposite to each other :shock:

would anybody like to confirm the sub-box theory i had above?

Dude the shape of the box will have no issues with the sub, as long as it isnt a cube and the internal volume is correct. Bigger port will only raise or lower the Hz that comes out although to bigger port will sound crap probably so people use 2 ports, which will half the port velocity between them or they use 2 if the port length is to long but you cant tell any of this with out a box program. What Hz do you want you box tuned to? How big will the box be? What would you like your response curve to look like? Peak at XX.XX Hz or flat?

Dude the shape of the box will have no issues with the sub, as long as it isnt a cube and the internal volume is correct. Bigger port will only raise or lower the Hz that comes out although to bigger port will sound crap probably so people use 2 ports, which will half the port velocity between them or they use 2 if the port length is to long but you cant tell any of this with out a box program. What Hz do you want you box tuned to? How big will the box be? What would you like your response curve to look like? Peak at XX.XX Hz or flat?
Shape of the box has many issues. (cube shaped is irrelevent, it could be rectangular and still pose the same problems with internal reflections) If he were to make a horn for instance... Totally changes the dynamcis of the subs response.
Even small things like internal bracing can lower spl by altering the flow of air inside the box...

It may not have many noticable effects to the untrained ear, but I wouldn't say it will not have any issues at all.

I'd say Eek would be after a flat response for sq.

This thing should sound pretty fat after your done Eek... Get it in a comp to see what you can burp it at... I can give you some tips if you wanna get the most out of it...

(You've created a monster!!!) lol

Shape of the box has many issues. (cube shaped is irrelevent, it could be rectangular and still pose the same problems with internal reflections) If he were to make a horn for instance... Totally changes the dynamcis of the subs response.
Even small things like internal bracing can lower spl by altering the flow of air inside the box...

It may not have many noticable effects to the untrained ear, but I wouldn't say it will not have any issues at all.

I'd say Eek would be after a flat response for sq.

This thing should sound pretty fat after your done Eek... Get it in a comp to see what you can burp it at... I can give you some tips if you wanna get the most out of it...

(You've created a monster!!!) lol



AARRRGGHH! I can't decide anymore, lol. Competitions sound interesting, but i still want a system that i can listen to every day without my ears bleeding. I guess i would be looking for a flatish curve.

I guess i would like to have this one around 40hz..? I really cbf'ed using round ports, so this would mean i'll just have to create two slotted ports, instead of one jumbo port. box size..3cu ft is enough, i still need some boot space :P

Alright this is what I got out of the dd site... Not enough info to get exactly what you want but will be good enough.
http://www.ddaudio.com/dd/caraudio/woofers.asp?series=2500
26 Fs (free-air resonance, Hz)
77 Vas (equivalent compliance, litres)
4.16 Qms (Q, mechanical)
0.397 Qes (Q, electrical)
0.36 Qts (total driver Q)
3.6 Re (DC resistance, ohms)
4 Z (nominal impedance, ohms)
88 Efficiency (1W @ 1M, dB)
50 Xmax (one way linear excursion, mm)
500 Pe (continuous power handling, watts)
1000 Peak power handling (music, watts)
etc
etc
Unforunately winisd didnt have your sub, so had to put all this crap in myself.
Now since your not after SPL, we want something nice n flat... With this sub Im sure you wont have a problem with loudness.

3 cu ft eh??? ~= 85 litres
If I throw this straight it some quick specs... (one optimal box)
Width: 482 mm
Height: 749 mm
Depth: 303 mm
(18mm thick mdf)
If you give me some specs, distances that you want it to fit eg: a height and length and depth, I can calculate the other side... (You are going to go wedge yeah??) In fact give me any lengths and it will calculate the remaining unknown side(s)

This is using 18 mm mdf. What do you plan on building it with? (how thick?) I can plug all this in too.

It's tuned to just under 30 Hz... Nice n low. 29.21Hz in case you were wondering.

Port size, I didnt get to play around with much, if you want two square ports
70mm x 70mm each the should be 350 mm long. (Do you mind if your ports go outside the box?)
this'll give you a vent mach of around 0.10...

All that will give you this (*inserts blurry graphs) Well not quite I couldnt find enough TS specs to get it accurate... But u get the idea...

Gimme more details.

Peace (I charge by the hour)

Tim

hey, yeah, i will build it with 18mm mdf, and as for ports going out of the box...arent i able to bend them into the box? It doesn't bother me really. Umm, as for dimensions, i did a rough measure on how big it would approximately be (TF magna boot) 900wide, 37high...any bigger than this than it wouldn't fit in between wheel arches, and would probably hit those bars on the ceiling of the boot. then from the vol, the depth can be figured out.

Seems like a very helpful program that winisd...if only i could grab virtual pc off someone/somewhere *cough*torrent*cough*

What a coinciedence! I charge by the hour too..perhaps i could give you an eek's special!! :badgrin: ...whatever that is :nuts:

ok, i am back, seeing as though i can't run winisd on my computer, i used the online one.

after punching the values for my sub into the program, i clicked on optimum, and it gave me a nice flat looking graph, and

Vb was 52.88(assuming its in litres)
Fb was 29.12

Now, i went on to that port length calculator thing....this is where it got a little tricky, coz there was that value down the bottom, where you needed to get less than 0.16 to prevent whisteling.

I am going to build a box using only square shaped ports. Now, if i was to go with the optimal values, it would mean i needed a diameter of about 22.5cm and a length of 514.3cm with two ports.

Is there a difference between a circular, square, rect. port as long as the area is the same? Also, it says on the DD website, taht a 15" sub is optimised for a 3cu ft. box. Now, if i was to throw the sub in a 3.1cu ft box, the port diameter/area would have to be the same, but only 303cm long.

Does this sound right to you? A 3 cu ft box doesn't give as flat of a curve as the 52.88(~1.87cu ft) one did. Do thse figures sound about right? :s

There is an option there for square / circular... etc. Tick that, u can also add multiple ports.
Remember the port can bend inside the box, or come out of the box. Try and round the edges to stop any noise from airflow. But test it out first and see if you have a problem.

Always gonna be a tradeoff between perfect and practical as well...

so u reckon i should still go with the 3 cu ft instead of the 'optimal' 1.86? yeh, port bending isn't a problem for me. 29hz..should be ok..i think.

I wouldn't go below the 2 cu ft. Slightly bigger if anything. I put those figures in and got the same optimal size in terms frequency response. But changed it up to make it 85 litres...

Seeing that it is going to be very loud anyway and you're not after spl go with the smaller box. Make sure you match the port size as best as you can though according to what it said.

ok, 2.1cu ft (59.47L) at 30Hz, with two 6cm ports at 27.56cm.

winisd online doesn't seem to have a button where u can change from square to circular

:doubt:

Calculate the equivalent area from Pi r ^2 etc... It is the area/length that is important. >2-2.5 cu ft will be sweet (no smaller), ~40 hz will go nuts, but 30 hz should be better for what you want.

hrmm, it seems u have neglected to put those pictures up u said u were goin 2 :D i wanna see it eek

hrmm, it seems u have neglected to put those pictures up u said u were goin 2 :D i wanna see it eek

shuddup fool! I don't feel like making a complete fool of myself yet...the box is done, just need to put in the vinyled side panels and somehow stick the ports in and she's all good :badgrin:

oh and for u ppl out there, the box is 2.43cu ft, 3 50x248mm ports tuned to 30Hz

Should sound sweet.... Brace Brace Brace...

Should sound sweet.... Brace Brace Brace...

hehe, yeah gonna stick the circle i cut out, and some bits and pieces on the inside edges and the back wall....

side panels in...need to cut up vinyl and stick the ports in...and bracing...just waiting for glue n stuff to dry a bit more