12” BR subs with Faital Pro 12HP1060

Hello,

I’m planing to build two bass-reflex subwoofers to be used for house parties and small gigs, max 100 people. The objective for the design is something that is relatively small, lightweight, portable, and can play down to around 40Hz at the highest output possible.

My plan is to use the Faital 12HP1060 8ohm driver. Each enclosure will have Vb = 35L and will be tuned to Fb = 40Hz, port area = 145cm2, port length = 72,4cm. The two subwoofers will be powered with a Behringer NU6000 amplifier (2 x 1500W 8ohm). At max load the drivers should be within Xmax and will play down to around 40Hz. I have calculated a highpass filter at 34Hz (BW-8) to protect the driver.

I have attached a couple of 3D drawings of my suggested enclosure, which will be made from 15mm highest grade Finnish birch ply.

What do you think of this design? Is my alignment all right? What about the enclosure design? Enough bracing?

Thanks a lot for your help!
 

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TBTL

Member
2013-10-08 12:26 pm
Three things that come to mind:

- Avoid the sharp bend in the port, as it creates wind noise. A smoother port means that a higher air speed is allowable, so it allows for a smaller (area, but therefore also length) port.
- Tune your cabinets higher. 12" subs will struggle to get enough output for parties; bass below 50Hz is not important for most party music anyway.
- Use a less steep highpass filter. Higher order filters tend to ring. Fourth order is sufficient.
 
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Thanks for the input.

- Avoid the sharp bend in the port, as it creates wind noise. A smoother port means that a higher air speed is allowable, so it allows for a smaller (area, but therefore also length) port.
Okay, would it help to add some pieces of wood to the 90 degrees bend as well as router the corner to "smooth out" the path of the port? Even if I were to tune the cabinet higher with a shorter port I don't think I can avoid the 90 degrees bend – unless I change the design and place the driver on the side of the cabinet, however for aesthetic reason I would like to have the driver placed where it is on my drawing.

- Tune your cabinets higher. 12" subs will struggle to get enough output for parties; bass below 50Hz is not important for most party music anyway.
Thanks for the suggestion. I was hoping to be able to use the subs for hifi purposes as well, where I would like lower output. I guess it would be a sort of a compromise.

- Use a less steep highpass filter. Higher order filters tend to ring. Fourth order is sufficient.
Gotcha.
 

TBTL

Member
2013-10-08 12:26 pm
Okay, would it help to add some pieces of wood to the 90 degrees bend as well as router the corner to "smooth out" the path of the port?
Yes that would help. Make the inner radius as large as possible; the 1/4" of a typical router is too small. Here is a suggestion for the 90 degree part.

Thanks for the suggestion. I was hoping to be able to use the subs for hifi purposes as well, where I would like lower output. I guess it would be a sort of a compromise.
Ah, I didn't know you would also use them for hifi. :)
 
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Yes that would help. Make the inner radius as large as possible; the 1/4" of a typical router is too small. Here is a suggestion for the 90 degree part.
Thanks for the link – that's interesting! I will see what I can do to smooth out the path, however I would like to keep the build fairly simple.
I'm planing on building the cabs from 15mm PP laminated birch ply, which I suppose would give less friction in the port (compared to raw wood/mdf). I'm guessing this would reduce compression/port noise?

Ah, I didn't know you would also use them for hifi. :)
Well they will mainly be used for parties, but still I would like to be able to use them for hifi purposes where it would be nice to go below 50Hz.
I actually wrote directly to Faital in Italy and spoke to one of their acoustic engineers about this build. They suggested Vb=30L, Fb=45Hz, and port area=158cm2, so I think this is what I will go for. This alignment gives me 34m/s at Xmax.
 
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I wouldn't worry too much about the vent velocity at extreme power levels at LF. Most music doesn't have that much content that low compared to higher frequencies. Rod Elliott (and friends) analysed a lot of music, and found 40Hz was around 10dB down compared to higher up. So, simulate at 1/10th power and see how your port velocity comes out. Hint - I bet it's absolutely fine.

I know that some music has serious LF content, and there will be port compression playing that sort of music. For 90% of the music out there, you'll be fine.

Chris
 
I wouldn't worry too much about the vent velocity at extreme power levels at LF. Most music doesn't have that much content that low compared to higher frequencies. Rod Elliott (and friends) analysed a lot of music, and found 40Hz was around 10dB down compared to higher up. So, simulate at 1/10th power and see how your port velocity comes out. Hint - I bet it's absolutely fine.

I know that some music has serious LF content, and there will be port compression playing that sort of music. For 90% of the music out there, you'll be fine.

Chris
Thanks for the input. So I guess port velocity shouldn’t be too much of a worry then. However, I have tried to smooth out the 90 degree bend of the port and have added some flare to the port opening. Attached are also the simulations for the alignment suggested by Faital. That was Vb=30L, Fb=45Hz, port area=158cm2, and then they suggested a parametric EQ boost @ 80Hz, 2.5dB, Q 0.707, which is also included in the simulation. I’m getting close to ordering components so I can start building :smash:
 

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Sure. Although I'm more interested in subjective performance. Did it meet expectations?

I realise I forgot to get back to you, but now I was reminded because of the other thread. So I guess the FaitalPRO 12HP1060 met my expectations, it goes quite loud for a 12" and it did play as expected down to 43Hz, which tbh is probably not low enough for my taste. But for the purpose of PA use it worked quite well. I don't use them very often (when I occasionally DJ it's almost always on rented gear). That's why I'm trying to figure out if they the 12HP1060s could be used for a hi-fi 2-way setup crossed to the SEOS12?