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Discussion Starter · #1 ·
I have an Image Dynamics IDMAX 12" V3 D2 subwoofer. Specs are listed below:


IMP 1 / 4 ohms

Re .7 / 2.8 Ohms

Fs 20.2hz

Qes .424

Qms 2.05

Qts .350

Vas 5.71 cuft (162 liters)

Xmax 24.6mm

Sd 545 cm2

Spl 93.2dB/88.1dB

Pwr 1000 RMS power


The driver is designed for a car environment, but could I theoretically make this into a home build? If so what would be the recommended ported enclosure dimensions, and what amplifier should I use for the dual 2 ohm coils?


I have no idea what I'm getting myself into, but considering doing it.


Any help would be greatly appreciated. Do you guys need more info? Here is a link to where i found the specs:

http://www.imagedynamicsusa.com/manu...DMax12D2V3.pdf


-Chad
 

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You would wire the VC's in series for a 4ohm load. No problem for most amps out there.


I've modeled it just a little bit for you. This isn't a bad driver at all. Most car drivers are useless in a HT environment but this one seems to have the goods to get HT done well. I am not sure what kind of performance you are looking for though...


Small, large? Sealed, vented? $$$ or amp restrictions?
 

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Discussion Starter · #3 ·

Quote:
Originally Posted by Scott Simonian /forum/post/15477545


You would wire the VC's in series for a 4ohm load. No problem for most amps out there.


I've modeled it just a little bit for you. This isn't a bad driver at all. Most car drivers are useless in a HT environment but this one seems to have the goods to get HT done well. I am not sure what kind of performance you are looking for though...


Small, large? Sealed, vented? $$$ or amp restrictions?

Scott,


I have been trying to sell the driver on the used market for about a month and a half now without success for the price I want for it. I am thinking maybe I can just experiment, and my costs are minimized due to the fact I already own the driver



I currently own an Epik Tower, so this would be a second subwoofer to complement the Epik I already have. My room is about 10,000 cu. ft (17 foot ceilings suck) so I could use the additional output. Size is a small factor, although I'm not sure how much of one. Another sub the size of the Tower would be fine, and it's around 30x27x20. I'm assuming I could go much smaller with this driver since that's around 9 cu. ft. if I'm doing my math correctly. Vented would be ideal in this case to go along with the Epik.


Money is not necessarily a restriction in this case. Materials for the box and amp would be the primary considerations. Good amp with solid power and efficiency are always a plus, but I don't want to overspend. Meaning when I buy amplifiers I like the Rotels and Emotiva's of the world, but not the Meridians, Krells, etc. You get the idea
 

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Ouch! 10,000 cu ft?! Are you sure you don't just want to build a quad 18 setup?



The addition of this single 12 inch subwoofer will not make a huge contribution to the SPL in the room. It will be able to smooth out the frequency response some what. Depends on where you and the subs are and how good it is already.


Building a box around the size of your Tower is a good idea. It will extract the most performance from the sub driver. Something around the area of 170-200 liters is pretty decent. A tune from 18-22hz gets the most extension without making a port tube stick out one side of the box.
Or you could always get a couple of passive radiators but that would increase the budget a good deal. Although the ports will be long in a design like this so maybe you might want to look into PR's if that's an affordable option for you.


A box of this magnitude would be very affordable, btw. A single sheet of MDF, maybe two sheets total. That's about $50 right there. As for what amp to use...oh boy, there are so many. First one I think to use would be one of those BASH plate amps from Parts Express. Pretty cheap and they have a 300w and a 500w. Either of which will run the IDMAX well enough.
 

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Discussion Starter · #5 ·

Quote:
Originally Posted by Scott Simonian /forum/post/15478247


Ouch! 10,000 cu ft?! Are you sure you don't just want to build a quad 18 setup?



The addition of this single 12 inch subwoofer will not make a huge contribution to the SPL in the room. It will be able to smooth out the frequency response some what. Depends on where you and the subs are and how good it is already.


Building a box around the size of your Tower is a good idea. It will extract the most performance from the sub driver. Something around the area of 170-200 liters is pretty decent. A tune from 18-22hz gets the most extension without making a port tube stick out one side of the box.
Or you could always get a couple of passive radiators but that would increase the budget a good deal. Although the ports will be long in a design like this so maybe you might want to look into PR's if that's an affordable option for you.


A box of this magnitude would be very affordable, btw. A single sheet of MDF, maybe two sheets total. That's about $50 right there. As for what amp to use...oh boy, there are so many. First one I think to use would be one of those BASH plate amps from Parts Express. Pretty cheap and they have a 300w and a 500w. Either of which will run the IDMAX well enough.

Yeah the room is roughly 18' x 18' x 17'h. Then the kitchen opens directly on the back which is probably 12' x 12' x 8'h and I cannot close it off as there is no door. Then there is an upstairs bedroom, downstairs bedroom/bathroom attached and I don't typically close those doors either. I'm probably exaggerating by 2-3,000 cu. ft but 7,000 cu. ft. is realistic for the space I have. I'm actually pretty impressed with the Tower in the room as it is now. I was thinking that by adding the second subwoofer I could at least add 3-5db in total output. Do you think I'm off in that thinking?


Thanks so much for the help Scott! I was thinking of BASH plate amplifiers as well since so many manufacturers use them.
 

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Oh yes. You can expect a gain around what you mentioned. I really depends on where you are in the room and where the subs will be and how they all interact. Since you already have the sub driver, this situation is a 'no-brainer' and adding this to the system should provide some extra oomph. Just not as much as a 2nd Tower would provide which is what I meant to say.


With a 6cuft box and a 20hz tune, a single 6 inch port that's 25-26 inches long will get you flat response down to 20hz with a system F3 @ 19hz. All at 110dB with 350w. Not bad at all. Use either of those BASH amps (500w would be best) and there you have it.
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by Scott Simonian /forum/post/15478569


Oh yes. You can expect a gain around what you mentioned. I really depends on where you are in the room and where the subs will be and how they all interact. Since you already have the sub driver, this situation is a 'no-brainer' and adding this to the system should provide some extra oomph. Just not as much as a 2nd Tower would provide which is what I meant to say.


With a 6cuft box and a 20hz tune, a single 6 inch port that's 25-26 inches long will get you flat response down to 20hz with a system F3 @ 19hz. All at 110dB with 350w. Not bad at all. Use either of those BASH amps (500w would be best) and there you have it.

So the actual dimensions of the box wouldn't matter so much as the port length? What material does one use as a port? Or are ports sold? Sorry for all the questions just curious on this one if port size matters as well.


I also realize output wouldn't match another Tower.
 

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Discussion Starter · #8 ·
Can anyone else offer any more specific comments as to the box, dimensions, port size, and what i would make the port out of? Are these available off the shelf? Can someone build a box for me if I don't want to/can't? I know Mr. Marv used to do it, just don't know if he is anymore.
 

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The dimensions aren't important for a subwoofer, only the internal volume. The internal volume, port area, and port length will determine what frequency the box is tuned to. Ports can be purchased (parts express, etc) but most here use PVC for 4" or smaller ports and sonotube for 6" or larger ports. I've seen quite a few people using slot ports lately, likely due to the elimination of the cost of buying a port (maybe?).


If you haven't done so yet you should download Unibox or WinISD and do some modeling to get an idea of what size box, tuning, and port size to use.


If you don't want to build the box yourself I hear elemental designs does custom built boxes at a very fair price.


One thought, I noticed on the site you linked for the driver it shows a simulated FR of a sealed and ported box with a caption stating "Sealed enclosures are very strongly suggested for most listeners". Although the graph they show is pretty outragious... they show it down 3dB (to 97dB) at 10Hz in a 1.3 cuft enclosure!?!?
 

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Discussion Starter · #10 ·

Quote:
Originally Posted by lennon_68 /forum/post/15490522


The dimensions aren't important for a subwoofer, only the internal volume. The internal volume, port area, and port length will determine what frequency the box is tuned to. Ports can be purchased (parts express, etc) but most here use PVC for 4" or smaller ports and sonotube for 6" or larger ports. I've seen quite a few people using slot ports lately, likely due to the elimination of the cost of buying a port (maybe?).


If you haven't done so yet you should download Unibox or WinISD and do some modeling to get an idea of what size box, tuning, and port size to use.


If you don't want to build the box yourself I hear elemental designs does custom built boxes at a very fair price.


One thought, I noticed on the site you linked for the driver it shows a simulated FR of a sealed and ported box with a caption stating "Sealed enclosures are very strongly suggested for most listeners". Although the graph they show is pretty outragious... they show it down 3dB (to 97dB) at 10Hz in a 1.3 cuft enclosure!?!?

Likely measurements taken in a car. In a space that's 150 cu. ft. a lot of different things can happen
I've seen less than capable drivers that can produce 10hz frequencies in a car due to the car itself resonating. So a lot of factors come into play there. I know the IDMAX can play down to 20hz with authority which is my main interest. My Epik Tower can handle duties down from there



Thanks for the suggestions on WinISD and Unibox. I don't have a modeling software so I'll grab one of those.
 
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