My IB Adventure (lots of pics)

**Darren** · **06-22-06, 10:39 AM**

Hi Guys, I've had a few requests to share my experience building my IB subwoofer. I'm currently beta testing the Silver Iris B.A.D 15" IB drivers for Darrel at Hawthorne Audio and will be posting my thoughts on them in the coming week or so. There is more information at my website www.garagehobbies.com/ib.aspx.

Here are the details:
-4 X IB subwoofer
-testing 2 and then 4 Hawthorne Audio Silver Iris IB B.A.D 15 drivers
-Powered by a Behringer EP1500
-Manifold opening is 14.5" X 14.5" inside dimensions

Here is a shot of my home theater room / family room from just behind the listening position before the IB install. The IB will be located in the ceiling above the plasma and behind the center channel. The distance from the screen to the listening position is about 13'. The camera makes it look much farther than it is.

And here is where the hole will be cut

This is a shot of my right rear corner with my AV1RS surrounds and my previous AV15 PR'd subwoofer (An incredible box sub).

The following are shots of the manifold construction

The manifold is built of two layers of 3/4" MDF laminated as an inner box and outer box. I built the inner box first then build the outer box to fit precisely.

And I had to radius the corners being the woodworker that I am.

A shot of the manifold ready for the holes to be cut. I initially built it to house 8 drivers but decided 4 was the ticket, I didn't want them stacked anyway so I'll be cutting this manifold down to size.

I'll be cutting the manifold at the ruler closest to the driver

Here I have cut it down and am routing the recesses for the drivers

The driver holes all cut out

And the top plug glued in place

After texturing the inside I painted it white to match the ceiling. I'll be framing the opening but no grill will be used. I like the look that way.

Here is the mounting hardware, I've mounted two plugs so I can test two drivers vs 4.

Ok, heading into the attic... I have to walk on a 2 X 12 for about 20 feet to get to the other side with this 130 pound manifold in my arms. I almost ended up in the family room below twice

Here is the view right after entering... the second lantern on the far side is my destination and the 2 X 12 I have to navigate is right under the vent duct at the bottom right of the picture. I have to dodge that 2X4 strut as well. The hump to the left is the tray ceiling from the theater room below.

Here I am at ground zero. The cleared out spot is where I'll mount the beast. The box on the left in the insulation is the center channel.

Here I have the birch plywood (cabinet grade for strength) spans in place. I secured them with pocket hole screws and support blocks underneath. I can jump up and down on one of them without any flex and I weigh about 165. They'll hold.

A close up of the pocket screws, two on one side of each end and 3 on the other side of each end. 5 total per side with support blocks under each end as well.

Let the cutting begin!

Here she is in place!

And with drivers all wired and ready to go!

Here is what it looks like from the business end

I'll be finishing the opening out as soon as I've finished testing the Hawthorne drivers. It was a rough start after installing. Lots of testing, configuring, and listening to get it dialed in right for my less than desireable room and dimensions. After much tuning my impressions are quite good for IB in general. The two drivers go much much lower than my box sub as expected. I've been able to EQ the IB to the point of being quite adequate for my 3,200 cubic foot room (also open to the rest of the house) and am expecting two more drivers to arrive soon so I'll be able to test 4. I expect 4 will be incredible.

You can find out more about Darrel's drivers at http://www.hometheatershack.com/foru...rne-audio.html or visit my site that shows some pics of them and the specs at http://www.garagehobbies.com/ib.aspx?Section=Drivers

Stay tuned!

**Ayreonaut** · **06-22-06, 01:22 PM**

Where is your head? Don't you know it's required?

This is a great write up. I can't wait to read your "subjective" impressions.
Will you have a religious experience?

**JCD** · **06-22-06, 01:23 PM**

My cup runneth over in jealousy, envy and admiration..

JCD

**Darren** · **06-22-06, 01:26 PM**

Yeah, I would have done the "head" shot but I already had the plugs in and forgot to before I installed the drivers

. I'll get one when I install the second pair.

My review will definately be subjective but more importantly it will be impartial and based mostly on how it performs in my eyes. I won't be able to compare it to any other IB driver as I've never heard another driver in an IB configuration.

It should be fun!

Oh, religious experience? I have one every time I play my Bass Mechanik tone sweep! Love the 10Hz house shaking!

**brucek** · **06-22-06, 02:28 PM**

Really interesting.....

What is the decibel level in an attic when set up this way. No sound or really loud?

brucek

**FlashJim** · **06-22-06, 02:28 PM**

Add me to the jealous list. Congrats on the IB!

**Ayreonaut** · **06-22-06, 02:31 PM**

Quote:

brucek wrote:

...What is the decibel level in an attic when set up this way. No sound or really loud?...

The back wave into the attic should be about equal to the front wave into the listening room. All that insulation may dampen it a little quicker.

**Darren** · **06-22-06, 02:34 PM**

Quote:

FlashJim wrote:

Add me to the jealous list. Congrats on the IB!

Thanks!

Quote:

brucek wrote:

Really interesting.....

What is the decibel level in an attic when set up this way. No sound or really loud?

brucek

Significantly less than in the listening room. The insulation really absorbs the sound. I have one wall in the attic that is all batted insulation and the entire floor of the attic has 13" of loose insulation throughout. It makes noise up there, it is far from silent but not nearly as enforced as below. Adjacent rooms to the attic space are no more affected by the IB than they were by the box sub before. Outside the house the subwoofer is nearly silent.

**Sonnie** · **06-22-06, 10:09 PM**

Absolutely incredible... so this is how it's done huh. WOW! I am impressed beyond words Darren. Add to all the jealously, envy! I almost wish you hadn't even shown us this... now I know I'm gonna end up trying this sooner or later... okay now add angry to the list too... you makin' me spend money. This is just remarkable. I guess I've never seen it layed out quite like you've shown us here. I appreciate you doing this for us all.

I'm really interested in seeing some response graphs on these subs too.

At least I can get through my attic a tad easier.

How do you determine where to mount it? I could see me mounting mine in a similar location as yours.

Off topic... that's pretty neat how you did the center channel. How does the dialogue sound with it coming from so far above the screen... or is it as far as it looks?

**Darren** · **06-23-06, 12:01 AM**

He he, thanks for the compliments.

It's best to have the IB centered between the mains or two IB's, one next to each main. The best way to "check" your IB location to be sure the seating area isn't in a null etc... is to put a box sub where you'll be sitting and then measure the response from the location you intend to put the IB. Mine measured decently but not as good as other parts of the room. I opted for the prime location between the mains even though the response was a little weaker than other places. I have been able to overcome the weakness of that spot with EQ though.

The center channel is only about 2.5' above the screen and slightly forward. The dialogue sounds just as if it is coming from the screen, the only problem is there is little to no baffle step loss so some frequencies are a bit enforced which can cause certain voices to sound a bit tinny. I'll be upgrading the network on the center to account for no step loss which should bring the voices back to normal. Really though, it is not all that noticeable. I'm just a bit of obsessed with getting things as good as I can get them.

I have several response graphs but am in the middle of more tweaking. I'll post my updated graphs soon!

**SteveCallas** · **06-23-06, 12:15 AM**

Looking forward to some measurements from the seating position.

**Sonnie** · **06-24-06, 12:08 AM**

Yeah... where are those graphs? lol... Okay, it ain't funny I know.

We certainly want to see them again Darren... sorry about that goof up. I had made a post requesting if you could to show us the response down to 10hz.

**Darren** · **06-24-06, 12:51 AM**

I swear I posted graphs...where did they go? I answered questions about them and everything...Was I smoking crack? Do I need professional help?

I don't currently have any final EQ'd graphs showing down to 10Hz but it is relatively flat to 10Hz, it has a small hump actually. I'll try and get new measurements showing 10Hz, my estimate is that I have decent output down to 5Hz easily.

Here is one graph I have showing 10Hz that is a failed attempt at EQ... my first measurement. I put too much boost after 20Hz.

Here is the latest graph for home theater from the seating position...

And the one I prefer for music:

**Sonnie** · **06-24-06, 01:08 AM**

Quote:

Darren wrote:

I swear I posted graphs...where did they go?

Quote:

I answered questions about them and everything...Was I smoking crack?

Quote:

Do I need professional help?

Quote:

I don't currently have a graph showing down to 10Hz but it is relatively flat to 10Hz, it has a small hump actually. I'll try and get new measurements showing 10Hz, my estimate is that I have response within 3db to 5Hz easily.

You should be able to change your axis setting to 10hz and save it... if you saved your measurement data file.

Quote:

my estimate is that I have response within 3db to 5Hz easily.

**Darren** · **06-24-06, 09:34 AM**

Of course do you think I was smart enough to save my measurement data file? Heck no! I'll take more measurements...planned on it anyway

Might have that in a couple days.

**Darrel Hawthorne** · **06-24-06, 09:48 AM**

Hey Darren,

Listen....... What is that sound? That far off low rumble ..... It's getting closer, ever closer.
Should I run?..... It must be huge.....My heart is pounding , my knees are getting weak....

WARNING... you only have two more days

" I'd turn back now if I were you"

-Darrel

**Darren** · **06-24-06, 09:49 AM**

Quote:

Darrel Hawthorne wrote:

Hey Darren,

Listen....... What is that sound? That far off low rumble ..... It's getting closer, ever closer.
Should I run?..... It must be huge.....My heart is pounding , my knees are getting weak....

WARNING... you only have two more days

" I'd turn back now if I were you"

-Darrel

Ahhhhh, the sound of two drivers arriving by delivery van!

**Darren** · **06-25-06, 11:17 AM**

Here is my music plot EQ'd showing 10Hz:

**Sonnie** · **06-25-06, 02:20 PM**

Impressive.... now we need JohnM to get us REW with a sweep and graph down to 5hz.

**Darren** · **06-25-06, 06:49 PM**

It's crazy but there is some information there in certain movies. My plot is far from smooth but I find I like the sound much better when it is a bit irratic like it is shown above. When I smooth the response out it becomes kinda boring to me. I'm quite happy with the IB concept though. Huge WAF, deeper and cleaner bass and the cool factor is huge.

I'll be getting the second pair tomorrow and of course will have to drop them in after I get home from work. At that point the real adventure will begin.

Advertisement