Alpine DIY Subwoofer Build for HT (1 Viewer)

[BraveHeart123]

Ironically the part of world I live in, very very very very few people have access to DIY subs and requisite tools and to top it all ..... not even 1% of people know how must an HT sound. And I have to make best use of the available drivers here.
I love the crocodillian approach in sound; one minute the sub is lying dead silent and in a spur of a moment it belts out the shock waves that it knocks the walls down. I literally had my wife bewildered and scream in horror movies.
The sub I built by seeking help from this forum has massive foot print compared to my room size but it completely disappears sonically. You only know the sleeping giant is there in my room when a plane crashes or Kremlin blows up in MI-4. It literally cracks the floor and u feel the shock waves travelling through u. Definitely not for the faint-hearted . And trust me Alpine does rock big time. I have heard REL Stentor and Gibralter in HT setup, but mine does squash them in HT. But still I feel it is a tad crude coz it is a cheap test box made out of chipboard, so um gona do the final build with mdf.

 

[Robert_J]

Ok Thanx Robert. I have re-run audyssey and it is bone-jarringly dreadful bass after tweaking the response in REW and adding some BFD filters. Very accurate with monsterous punch. I will start my final build with 0.75 inch MDF with full cosmetics.
Any chance i can reduce the size to 3.5 cu ft max including driver displacement and port area with the same sonic impact as this one?? The current size (4.8 cu ft gross) is way too huge.

Reducing the enclosure size will give you a slight boost right above tuning by a few DB. There's a +3db slight peak in the 25-30hz range. You also loose about 2db of max output.

 

[Robert_J]

And about "what people are missing". I have an M&K sub that bewilders people in how clean it is...and it is over 20 years old. The mass market crap that passes for subwoofers nowadays has people missing out on what they can really have...
Anyway, great sub and the search for perfection...and then complacency....and the desire for better(vicious cycle isn't it...???)

The small companies have really pushed the envelope over the last few years. Also, modelling has become more and more accurate as additional driver information has been added to the models.
One of the biggest advances was learning how inductance impacted subs - http://www.diy-audio.narod.ru/litr/WooferSpeed.pdf To counteract that, shorting rings were added to the sub motors. I have two of the older Alpine 12's in my garage right now that I've cleaned and prepped for re-coning. I can look in the magnet structure and see the additional copper. In addition to lower inductance, a flat BL (motor to coil strength ratio) has also been found to provide lower distortion. Dan Wiggins had a great idea with his patented technology - http://www.acousticdev.com/cms/index.php?option=com_content&view=section&layout=blog&id=12&Itemid=64 . Around the same time, John J. of AE Speakers and Thilo Stompler of TC Sounds came up with an idea that is exactly opposite of XBL. Instead of a variable magnetic field, they use a coil with variable windings to give you the same flat BL - .

 

[schan1269]

The small companies have really pushed the envelope over the last few years. Also, modelling has become more and more accurate as additional driver information has been added to the models.
One of the biggest advances was learning how inductance impacted subs - http://www.diy-audio.narod.ru/litr/WooferSpeed.pdf To counteract that, shorting rings were added to the sub motors. I have two of the older Alpine 12's in my garage right now that I've cleaned and prepped for re-coning. I can look in the magnet structure and see the additional copper. In addition to lower inductance, a flat BL (motor to coil strength ratio) has also been found to provide lower distortion. Dan Wiggins had a great idea with his patented technology - http://www.acousticdev.com/cms/index.php?option=com_content&view=section&layout=blog&id=12&Itemid=64 . Around the same time, John J. of AE Speakers and Thilo Stompler of TC Sounds came up with an idea that is exactly opposite of XBL. Instead of a variable magnetic field, they use a coil with variable windings to give you the same flat BL - .

You might as well be speaking in "Peanuts parent" voice...
I wonder if Faisal gets the inference...

 

[Robert_J]

I like science behind the sound.

 

[BraveHeart123]

I wonder if Faisal gets the inference

I do but don't like to reinvent the wheel. I prefer using it.

 

[BraveHeart123]

I just recieved Behringer iNuke NU6000 DSP. This will replace crown xls1000 to feed the DIY sub. While hooking up seems straight forward. I have some concerns over its power draw from AC oultet.
It's 110 Volts US model and I have to run it on 230-240 Volts coz that's the voltage we use here. I am already running Crown xls1000 (110 Volts) though a step down transfomer which can bear the load upto 500 Watts. The iNuke user manual shows the power requirments as follows;
Power Consumption @4ohms with 1/8 rated power: 620 watts

• Can I run this amp on my current step down transformer to its full potential?
• Also, there are no power ratings listed for 2 ohm performance. Can I run 2 ohms load on it?? Is it 2 ohms stable??
• The bridged mode power ratings are also not listed; but considering its RMS ratings at 4 ohms (2200 watts) and 8 ohms (1500 watts), should I even care about not being able to bridge??

Any advice on the mentioned issues??

 

[Robert_J]

It's not rated for 2 ohms nor is it bridgable because it is really a pair of iNuke 3000's in a single chassis.
It's odd that it isn't voltage switchable since Behringer is a German company (220v) and it was made in east Asia (220v). Maybe the US version is limited to 110v because of the idiots who switch it to 220v without knowing what they are doing. Your transformer will hopefully handle peaks because the power consumption will vary as the input signal changes. There will only be a few peaks that reach the 620w input level.

 

[BraveHeart123]

I have been running pioneer 800 watts rms sub with voice coil hooked up to 2 ohms parallel configuration with crown xls in 4 ohms bridged mode and it never blew the crown. Do u think inuke can handle 2 ohms load like crown did??
Also what is 1/8 power? If it is 1/8th of 2200 watts rms power at 4 ohms, then it's roughly 270 watts output only.
So, does it mean to get full 600 watts from inuke for the sub to perform at its max the inuke power requirement would go past the 620 watts mark?? And what happens if it does, would the inuke go in protection or would my current stepdown transformer be damaged???

 

[BraveHeart123]

Anyone??

 

[BraveHeart123]

I was trying to make a speakon cable but I am not too sure how it is done. The iNuke has speakon connectors. I have bought a Neutrik Speakon NL4FC plug. It has 4 screw type terminals inside the housing labelled +1, -1, +2, -2. While I understand 4 are for biamping. But I simply want to connect one end of 2 pole wire to connect with speakon jack and other end should be open so I can connect the DIY sub with this cable using positive and negative terminals on the binding post.
Anyone, pls tell me how to do it correctly

 

[BraveHeart123]

Think I figured it out. 1+ for positive wire and 1- for negative. Leave 2+ and 2- as they are for biamping. Pls tell me if I am correct or not.

 

[Robert_J]

I'm not familiar with those connectors so I am of no help there. Same with your power requirements question. I'm not an electrician. I've never researched into power consumption, etc. so I did not answer your question. I would rather stay silent than provide incorrect information.

 

[BraveHeart123]

I'm not familiar with those connectors so I am of no help there. Same with your power requirements question. I'm not an electrician. I've never researched into power consumption, etc. so I did not answer your question. I would rather stay silent than provide incorrect information.

Thanx Robert. U r otherwise a big help and it is well regarded.

 

[BraveHeart123]

Hi everyone. My DIY sub box is 4.8 cu ft gross with great in-room response but it is huge enough to have made my wife hit the roof. Anyway, I modelled it in WinISD again and brought the size down to 2.9 cu ft net and 3.3 gross. I have traded off depth with SPL and tuned it to roughly 24Hz.
The problem is port air velocity. If I bring it down to within 20 m/s by increasing the port dia, the port length increases like anaconda for required 24hz tuning. And if i reduce port length keeping same port dia; the tuning frequency jumps into mid 30s and port velocity hits the roof.
Simply cross-eyed and don't know how to lock genie in the bottle. Any ideas??
Also, WinISD shows only the Rear Port Air Velocity and nothing shows up in Front Port Air Velocity. I will be using Front port. How to do that??

 

[Robert_J]

Flare the ports. Here's how to do a DIY flare. http://www.subwoofer-builder.com/porting/index.htm

 

[BraveHeart123]

Hi Robert. A question about box volume. WinISD suggested box size of 2.9 cu ft net with a 4x18 inch port for 23Hz tuning. Does it mean that for gross volume, I add the (driver displacement + port air volume + bracing volume if any) to 2.9 cu ft and build the box to that dimension??
I mean my port volume is 0.13 cu ft and driver displacement (Vd) is 0.03 cu ft.
So, will the gross volume be 2.9 + 0.13 + 0.03 = 3.06 cu ft? If so, do I dimension the final box to 3.06 cu ft?
One thing more.....is there any rule of thumb for Height, Width, and Depth of the box or does that not matter as long as their product equates to the total volume?? I mean does it matter that the rear wall of the box must be a certain number of inches away from the driver magnet??

 

[Robert_J]

WinISD only gives you net volume. As you stated, you have to add in driver displacement, ports and bracing to determine the gross volume of the enclosure.
The "golden ratio" has no impact on subs because the bass wavelengths are too long. As long as you get your enclosure volume and the driver fits you are good.

 

[BraveHeart123]

Late update I changed the idea of ported and went the easy route with 3.6 cu ft net sealed box (0.58 Qtc) for the final build. Used 24mm mdf all around with double front baffles for flush mount. Box is completed except for the final paint job. Got it made at home from a carpenter friend. Here are the pix

Here is the nearfiled raw response of the sub @ 1 inch from center of the cone. Applied signal is not at max spl.

This is the combined response of Alpine DIY + SW115+ Speakers @ MLP

This is the EQd curve with 5 filters @ MLP. Didnt measure the response but listening is amazing for both music and movies.

Will get the final paint job done in a couple of weeks and post the final pics when it's ready.

 

[Robert_J]

Will get the final paint job done in a couple of weeks and post the final pics when it's ready.

MDF edges soak up paint like a sponge. For mine, I coated all of the edges with sanding sealer, lightly sanded, another layer of sealer and another sanding. Primed the entire box. Painted. If you know a automotive repair guy then you can get some great finishes that way. In fact, that's how Eggleston gets their finishes. It's Porsche paint done at an automotive repair shop nearby. The finish looked like a car that was sitting in the showroom floor. I have taken the easy way out and used Rustoleum Hammered Metal paint. http://www.rustoleum.com/CBGProduct.asp?pid=29