IB makeover..........

**Rodny Alvarez** · **03-16-07, 11:01 PM**

Quote:

SteveCallas wrote:

****, you went for PVC? Nothing at all wrong with that, but as you commented, it's going to be significantly heavier than say 10" Sonotube. Collo's work shows that a 1.5" flare on a 10" port should keep you totally safe. I don't see any problems with having one flare larger than the other - currently my sub only has a flare on the outlet, so you should have no issues.

$20 for two!! to me that was a good deal, I cant find sonotube around here.

**Ilkka** · **03-16-07, 11:12 PM**

Quote:

Rodny Alvarez wrote:

Ilkka, do you think that it matters if there different or not??

You're good to go with asymmetrical flares. I doubt the difference is even easily measurable, not to mention audible.

**SteveCallas** · **03-16-07, 11:20 PM**

Quote:

Rodny wrote:

$20 for two!! to me that was a good deal, I cant find sonotube around here.

Yeah, that is a good deal - looks thick too.

**Sonnie** · **03-17-07, 12:03 AM**

Yeah... great deal! I thought I was gonna have to pay 80 bucks for 6" and then have to cut it with a hack saw... in the rain.

Lucky me and good ole Bradley plumbing saved the day and 80 bucks...

**Rodny Alvarez** · **03-17-07, 10:53 PM**

Left side 80% done!!
I guess I need some batting material or something else??

IMG_3540.JPG

IMG_3543.JPG

IMG_3544.JPG

IMG_3546.JPG

IMG_3547.JPG

This is at the listening position, the blue is SLLT and green IB.
I will do more measurements next week, its late and I need some sleep

, tomorrow we are going to Atlanta

Maybe monday if we get home early I can watch some movies.
This is with the same power (325Watts on each sub), maybe Tuesday I get my other amp.
RedSLLT.jpg

**Sonnie** · **03-17-07, 11:21 PM**

Wow... that's about a 10-12db gain from 10Hz up to about 15Hz. I wonder though, does this mean the sound is generally going to be the same on most material, since there's not a terrible lot below 15Hz anyway.... or will you really notice more of a difference when you crank her on up to normal listening levels. Should be interesting to hear your thoughts... and get more power on the drivers as well.

**SteveCallas** · **03-18-07, 01:04 AM**

NICELY done

That is some significant low end gain, and with no EQ bogging up the excursion down low. Hopefully it works pretty well at blocking out the bass upstairs compared to the IB as well. Looking forward to some impressions with low bass movies.

Can you provide a measurement up to 200hz with the speakers in play as well? Now that I know Sonnie's demo when you guys got the dual RLp-15 LLT running with the Plus/2s was roughly 6-7db hot, the effect you may be after is running your sub a little hot too. With the increase in headroom and decrease in low end distortion the port provides, you can run it blazingly hot if you so desire

**WillyD** · **03-18-07, 08:21 PM**

Stevie got his wish! Someone finally "ported their IB". Who knows Steve, this may be the start of a revolution.

**SteveCallas** · **03-18-07, 09:58 PM**

I won't jump the gun just yet, I'd like to make sure his measurement is repeatable and he gets similar results with #2. Assuming he does, there will still be resistance from the "elders"

who will talk about a rolloff in the single digits being desirable. Based on low end sensitivity however, logic tells us that in the infrasonic range, it is better to stay flat as low as possible and have a sharper rolloff with more headroom rather than rolloff sooner with a shallower one and less headroom. Then you'll still have the faction that believes ports are the devil

But if all goes well, those who value performance more than myth or hype will see the benefits in such a design.

**WillyD** · **03-19-07, 12:19 AM**

Quote:

Then you'll still have the faction that believes ports are the devil

Without a doubt.

So far though, the results look very promising.

**SteveCallas** · **03-19-07, 01:36 AM**

Yeah, and it would seem that as long as one has enough displacement and volume to play around with, it can be tuned wherever the natural -6db point is, even if it's in the single digits.

**Rodny Alvarez** · **03-19-07, 06:24 PM**

Any ideas on acoustic material I need for the box??

I read Collos speaker stuffing....................................................... The walls are high pressure, low velocity zones, so closed-cell foam rubber sheeting can absorb some energy. I used the same rubber that I utilised for the speaker mounting gaskets.

**Sonnie** · **03-19-07, 10:37 PM**

Why not use what I used?

**SteveCallas** · **03-20-07, 09:50 PM**

Any impressions yet? Is it working at blocking some of the bass from traveling to the rest of your upstairs? Is the additional low end noticable? Is running the sub hot creating the impact you are after?

**Sonnie** · **03-20-07, 10:28 PM**

Yeah... Rodny... tell'em all what you told me on the phone today. It's juicy!!!

I bet we have some people enclosing their IB's....

**Rodny Alvarez** · **03-20-07, 11:01 PM**

Quote:

SteveCallas wrote:

Any impressions yet? Is it working at blocking some of the bass from traveling to the rest of your upstairs? Is the additional low end noticable? Is running the sub hot creating the impact you are after?

I played some movies and the noise in the living room is a lot better! (less noise)

, watched scenes from Jurassic Park 3 (Plane crash and the dinosaur fight) the bass has more........ punch...impact...feel.., however you can tell were the bass is coming from when listening to the SLLT, with the IB you can't , I don't know if the location of the SLLT, IB has something to do, because they are in opposite sides of the room (left and right)
When I listen to the IB to me it sounds like...... when you have a sub with not enough power,(like is to loose) I don't know if some of you guys agree with this or understand what I'm saying!!

To me a sub sounds a lot better with more power!!

this is coming from my experience with car stereo, I'm little fresh on HT so this maybe different then car stereo

.
Steve, I'm not running the sub hot, don't have the other amp

,( I will tomorrow

)

I need to do a house curve!!

Here is sweep with the mains....
NO/EQ
SLLTMAINSnoEQLposLeft.jpg

W/EQ
MainsSLLTLposLEFT.jpg

Nearfield 12" from the subs/port

Nearfield IB....
NFIBLeft.jpg

Nearfield SLLT sub.....
SubSLLTNFLeft.jpg

Nearfield SLLT port.....
PortNFLeft.jpg

**SteveCallas** · **03-20-07, 11:19 PM**

Quote:

Rodny wrote:

I played some movies and the noise in the living room is a lot better! (less noise)

That's good to hear

Quote:

Rodny wrote:

the bass has more........ punch...impact...feel

Excellent.

Quote:

Rodny wrote:

however you can tell were the bass is coming from when listening to the SLLT, with the IB you can't , I don't know if the location of the SLLT, IB has something to do, because they are in opposite sides of the room (left and right)

Hmm, maybe you do need to line that enclosure space with some batting or foam. I'd imagine that would do the trick.

Quote:

Sonnie wrote:

Rodny... tell'em all what you told me on the phone today. It's juicy!!! I bet we have some people enclosing their IB's...

So I take it so far that it is a noticable improvement?

**Rodny Alvarez** · **03-20-07, 11:29 PM**

Quote:

So I take it so far that it is a noticable improvement?

Its all good!!!!!

can't wait to do the other side

and add the other EP 2500

I need to do the flares and add some acoustic material.

**collo** · **03-21-07, 04:11 AM**

Hi there Rodney,

I just responded to your PM about closed cell foam.

Your cred got an instant bump once I realised you were the dude doing the IB > ported conversion.

This is just the type of before and after analysis that furthers the science for all of us.

Coming in late as it were, I missed the discussion about inner and outer flare sizes. As it happens, I recently did some testing and found:

For speeds below 70% of the core limit, the radius of the inside flare can be 15 - 20% smaller than that of the outside flare

Admittedly this was only tested on small ports, but I think it should extrapolate fairly well to larger ports. The resulting sizes are in line with what you find in the commercial offerings.

I had hoped for a larger difference, but I guess the inrush of air can only mask so much turbulence. I also read a B&W white paper, which apart from the marketing spin, suggested that air that is too turbulent can be sucked back in on the next half cycle, triggering further turbulence.

My experimental notes here

The B&W paper here

regards
Collo

**Rodny Alvarez** · **03-22-07, 09:23 PM**

Just finished installing the amp mono to the SLLT, there was about 6db gain

, this is with only one side, maybe this weekend I can do the other side

.
Look at the dip at 97hz, you guys think I should worry about it or just ignore it until I do the other side?

This is with the mains...............crossover set to 80hz and the mains set to small.

SLLT700L.jpg

**WillyD** · **03-22-07, 09:41 PM**

God that is a nice looking FR.

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