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Old 1st February 2013, 03:02 PM   #1
Matanic is offline Matanic  United States
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Join Date: Oct 2012
Location: Florida
Default Before I start this project....

Hey All,

My Velodyne DEQ-15R fell in the pool (don't ask) and is beyond repair. Okay I'll tell. My wife wanted to move furniture, she moved small stuff like the sub out onto the pool deck while she move the furniture, forgot the sub was there and it was somehow pushed in. Kinda liked that speaker...

That happened right around Christmas and since I have been plotting a replacement. I can work with wood, know what a soldering iron is and have no fear of fire or electrocution so I should figured I will build the our next sub(s).

I found 2 Rockford Fosgate P3D2-12 drivers on Craig's List for $250.00, new in the box, seemed like a deal so I grabbed them and indeed they are unmolested. To drive them I bought a iNuke1000DSP from PE, the amp is a beast just love it. Modded the amp but that is another thread.

So taking one driver I built a 1.1 cu ft sealed box, 3/4" mdf doubled up on all walls stuffed it with pound of Acousta-Stuff. I run the single driver with the two VCs in series, 4 ohm load, amp in bridged mode.

In sort I do not like the sealed box. Not enough below 50Hz without denying the sub all material above 50Hz with the DSP. If I do that it is okay but that is with 15dB boosts at 25 Hz - 40Hz and still it struggles to produce a proper cannon blast (Pirates, At Worlds End) so I am thinking building a vented box next. The Velodyne had to be in the right place to work but once there it was fine, never touched the thing it just worked.

In WinISD 0.44 I come up with a box volume of 3.871 cu ft with a 4" x 15" port for a 21.72 Hz tune while Woofer Box Model 5.0 is at 3.901 cu ft with a 4" x 16.5" port and a 21.2 Hz tune.

So that is what I am planning, build two boxes and run the amp in dual mono. Power output is going to tank going to 4 ohms per channel unless it plays nice with a 1 ohm load but I kind of doubt it will or if I even want to try my luck unless someone has already and it worked, or at least shut down.

Any thoughts or comments before I start on this?

Ciao
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Old 1st February 2013, 04:08 PM   #2
SpirosZ is offline SpirosZ  Greece
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Join Date: Jan 2013
The 1.1Cu.ft box may be fine in a car with so much room gain but at home you need a much bigger box. The 3.9cu.ft recommendation for the ported box shows that.
I bet that if you try sim the sub for a sealed box it will give you a box of at least 2.5 or more cu.ft.
If you want to get an idea how it would sound in a sealed box of 2.2cu.ft just place one driver in the 1.1 cu.ft box like before and the other one on top of it facing each-other. Wire the second one in reverse polarity so they act as push-pull. That configuration is going to give you the performance of a 2.2cu.ft box in the 1.1cu.ft box. That way you will get an idea what happens with a bigger box. The ported box is definitely going to be louder and will probably go lower too but it's good to know how a sealed box of the proper size would work.
The amp you have is stable to 2ohms. I wouldn't do 1ohm.
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Old 1st February 2013, 05:48 PM   #3
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Join Date: Feb 2004
Quote:
Originally Posted by Matanic View Post
Hey All,

My Velodyne DEQ-15R fell in the pool (don't ask) and is beyond repair. Okay I'll tell. My wife wanted to move furniture, she moved small stuff like the sub out onto the pool deck while she move the furniture, forgot the sub was there and it was somehow pushed in. Kinda liked that speaker...

That happened right around Christmas and since I have been plotting a replacement. I can work with wood, know what a soldering iron is and have no fear of fire or electrocution so I should figured I will build the our next sub(s).

I found 2 Rockford Fosgate P3D2-12 drivers on Craig's List for $250.00, new in the box, seemed like a deal so I grabbed them and indeed they are unmolested. To drive them I bought a iNuke1000DSP from PE, the amp is a beast just love it. Modded the amp but that is another thread.

So taking one driver I built a 1.1 cu ft sealed box, 3/4" mdf doubled up on all walls stuffed it with pound of Acousta-Stuff. I run the single driver with the two VCs in series, 4 ohm load, amp in bridged mode.

In sort I do not like the sealed box. Not enough below 50Hz without denying the sub all material above 50Hz with the DSP. If I do that it is okay but that is with 15dB boosts at 25 Hz - 40Hz and still it struggles to produce a proper cannon blast (Pirates, At Worlds End) so I am thinking building a vented box next. The Velodyne had to be in the right place to work but once there it was fine, never touched the thing it just worked.

In WinISD 0.44 I come up with a box volume of 3.871 cu ft with a 4" x 15" port for a 21.72 Hz tune while Woofer Box Model 5.0 is at 3.901 cu ft with a 4" x 16.5" port and a 21.2 Hz tune.

So that is what I am planning, build two boxes and run the amp in dual mono. Power output is going to tank going to 4 ohms per channel unless it plays nice with a 1 ohm load but I kind of doubt it will or if I even want to try my luck unless someone has already and it worked, or at least shut down.

Any thoughts or comments before I start on this?

Ciao
Well, you've gone from a good sized ported 15" to a sealed 12", so there should be a major decrease in output.

Without seeing the models, it sounds like you're on the right track. Just keep an eye on cone excursion at full power.

You do have a problem with the load vs. power situation. What you can do is run a single voice coil on each sub. This will reduce your power handling to 300wrms per sub, which will be fine unless you run test tones at full output. The 380wrms @ 2ohms x 2 rating of the nu1000 will be a perfect match, just keep it out of clipping. Chances are with the larger box you will run out of usable excursion before hitting power limits. Make sure to set a high pass filter, 20hz 8th order butterworth.

Running one vc on a dvc sub

DO NOT RUN 1 OHMS. I've had my nu6000dsp (4 ohms min per channel) plugged into a friend's home install speaker system with some klipsch forte's and other speakers wired in parallel with autoformer volume knobs. This presents a very low impedance and complicated load, the nu6000 was sent into protect for a second, before clipping, during some bass at moderately loud volume (nowhere near the max of the amp). They also wreaked a nu1000dsp running it flat out (red clip lights on solid) for several hours on multiple occasions, and now have an nu3000dsp, which seems to put out plenty of juice, handles the load well and sounds great. lol.

Last edited by turbodawg; 1st February 2013 at 06:01 PM.
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Old 10th February 2013, 02:49 PM   #4
Matanic is offline Matanic  United States
diyAudio Member
 
Join Date: Oct 2012
Location: Florida
So first box is built and it sounds good, I'm happy with it. Like the Velodyne it needs to be in the right place but since there is a second one being built I am guessing that will change room placement.

I have been thinking of a way I can run this amp at full potential with two 2 ohm DVC drivers. I really don't want to run single coils for 2 ohm dual channel loads nor do I want to chance a 2 ohm load in bridged mode so what about this...

I take coil "A" of Driver 1 and Coil "A" of Driver 2 and create 1 ohm load with them in parallel. Then run both "B" coils and the newly created 1 ohm load of the "A" coils in series for a 5 ohm load and leave the iNuke in bridged mode? The coils in the 1 ohm group will dissipate less power, 75% less each the the 2 ohm coils but they will be doing something for the cause right? I mean it has to be better then running the 4 ohm per channel loads @ 200 wpc. I would think 5 ohms in bridge would be good for 700 watts of the 800 of a 4 ohm load in bridged mode.

Thoughts?
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