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

[SteveCallas]

What's nice is that if for some unexpected reason Rodny doesn't like it (which I see no reason why it should happen), it's very easy to go back to the previous state.

Sonnie wrote:

I'm curious... obviously it appears there will be more output in the lower octaves. How about the quality? Will it be cleaner, about the same, or not significant enough to matter?

The ported version should have significantly less low end distortion at the same outpyt levels, but with four drivers and at such low frequencies, that probably won't be too noticable. I think what will be noticable is a total sense of effortlessness in reproducing even the lowest of lows - the natural FR without EQ should extend deeper and flatter. If he was somehow experiencing any compression previously, like you unknowingly were with even two Plus/2s, that won't be the case anymore. Essentially more raw power on tap.

Also, if he finds he wants to try boosting the 30-50hz range to get more punch, the additional low frequency headroom will definitely be more beneficial as it will be better equipped to keep up.

[Sonnie]

Absolutely not I rather enjoy such debating. I know that neither of us will start name calling, rounding up a posse to try and discredit the other, ask the mods to lock and delete the thread, start including pictures of scantily clad women in an attempt to divert attention from the main issues, or secretly remove previously attached graphs

You mean people actually do this somewhere else???

[Rodny Alvarez]

In terms of the sub's port, that should be fine. In terms of keeping the VR3s away from the front wall, if possible, I'd experiment bringing them out further. The back of my VR3s are 28" out from the front wall - in my experimenting, it gives the soundstage and imaging more depth.

My VRs are 24" from the front wall, how far is your listening position from the VRs???

Don't worry Rodny, me and Steve go way back. A little disagreement won't hurt either of us, isn't that right Stevie?

[SteveCallas]

Sonnie wrote:

You mean people actually do this somewhere else???

Or so I've heard Other tactics? I'm off on a trip, I'll respond to this in 3 weeks (only to never respond to it again), proposing new, unrelated questions in a blatant attempt to get out of the hot seat, questioning the legitimacy of ground plane measurements (cause we all know testing on a 40' pole is the ONLY way to get accurate results ), inferring that an amp's metal casing determines its quality, talking about sick family members to try and gain pitty, talking about drinking martinis to try and seem "cool", talking about how much more money I have than everyone else, and so on and so forth. Each more ridiculous than the next, yet it has become common fare

[SteveCallas]

Rodny wrote:

My VRs are 24" from the front wall, how far is your listening position from the VRs???

Oh, ok, good. I forgot your subs are to the sides of your speakers, not behind If you made a triangle, mine are ~7' apart and the seat is ~9' back. I keep the tweeters pointed at the seats to the right and left of me rather than right at my ears. If things were ideal, I'd have no TV, center tower speaker, or equipment between them, allowing for even better soundstage and imaging. The best I can do is keep the LCD 1' back behind the front of them though. Two discrete rooms - one for stereo music listening and one for HT would be great, but I can't complain for now

[Rodny Alvarez]

My VRs are 9' apart and 10' from my seat and the center CH is 10.5', there is nothing between the mains, the screen is at least 2' back and they are pointing to the side of my head not my ears, I like it this way because even when you seating on the other two side chairs it sounds pretty good.

I love Boston Acoustics, home and car audio!!!!
I see you guys move to Sonnie's arena to

[Sonnie]

I love Boston Acoustics, home and car audio!

There are no telling how many coaxials and separates I've tried in my various vehicles. I always come back to the Boston Pro separates... yet to be topped.


Back to the SLLT... The comparison is between just one IB and one SLLT.... would not the output be even more noticeable since there are TWO SLLT's and there is double the increase in ouput???

[brucek]

He will build it and he can tell us how big of a difference he notices, if any.

Hopefully, there will be an REW response taken before and after, with some sort of standard set of levels and positioning to remove as many real world variables as possible.

brucek

[Sonnie]

brucek wrote:

Hopefully, there will be an REW response taken before and after, with some sort of standard set of levels and positioning to remove as many real world variables as possible.

brucek

I did advise him of this... I suggested a raw unfiltered response from the listening position and a couple of nearfield responses... say 3" and 12" (or whatever you pros deem appropriate)... for each sub type. This is a must IMO!

[SteveCallas]

Sonnie wrote:

The comparison is between just one IB and one SLLT.... would not the output be even more noticeable since there are TWO SLLT's and there is double the increase in ouput???

Yes, this is why the headroom advantage gets up to 10db at some points. Typically, when comparing a single ported sub to a single sealed using the same driver, the ported will have up to a 6db advantage. So the additional low end headroom and power Rodny will gain isn't something to take lightly, it's roughly the equivalent of adding 10-12 more RLp-15s in that range around the tuning frequency.

brucek wrote:

Hopefully, there will be an REW response taken before and after, with some sort of standard set of levels and positioning to remove as many real world variables as possible.

I believe he has a set taken from his seat. From what he showed me, the natural IB response from his seat starts to drop off below 18-19hz.

[Geoff St. Germain]

I'm very interested to see the results of this and hear Rodny's impressions. It looks quite interesting.

[Ilkka]

Sonnie wrote:

There are no telling how many coaxials and separates I've tried in my various vehicles. I always come back to the Boston Pro separates... yet to be topped.


Back to the SLLT... The comparison is between just one IB and one SLLT.... would not the output be even more noticeable since there are TWO SLLT's and there is double the increase in ouput???

So let me get this straight. Rodny has two separate IB subs, each with two 15" drivers? And now he is turning them into SLLTs by boxing and porting them? So no additional drivers?

[Rodny Alvarez]

I'm going to build one side first and compare the measurements with the ones I have now.
There is nothing wrong with my IBs! when I heard Sonnies LLT, to me it sounded better, I know that Sonnies room is better build then mine(solid) he has dual 5/8 sheet rock and mine is only 1/2", some people think this is not an issue, but in my opinion it is, if the room is well insulated it will make a big difference(sound and spl) maybe I'm wrong anyway...the only way to figure this out is to build one of the SLLT
When playing some movies with bass it gets real loud in the attic, you can hear it everywhere, is because the IB plays as loud in the attic then it is in the room, so I'm trying to eliminate some of that sound traveling through the attic

I'm not trying to start a war between people that follow IBs and the ones the follow the LLTs some will be and some will be so by doing this, we will answer a lot of questions.
Here are some measurements ..........

I think this is right!!

Both IBs listening position


Left side IB listening position


Right IB listening position


Left IB Near field 12" from the sub


Right IB Near field 12" from the sub

[Rodny Alvarez]

Ilkka wrote:

So let me get this straight. Rodny has two separate IB subs, each with two 15" drivers? And now he is turning them into SLLT's by boxing and porting them? So no additional drivers?

Yep!! One on each side of the room (Line Arrays) and no additional drivers.

[SteveCallas]

So which side are you doing first? The response from the left one looks like it would be a little easier to work with.

[Rodny Alvarez]

SteveCallas wrote:

So which side are you doing first? The response from the left one looks like it would be a little easier to work with.

Left side first!

[chasw98]

Rodny Alvarez wrote:

I'm going to build one side first and compare the measurements with the ones I have now.
There is nothing wrong with my IBs! when I heard Sonnies LLT, to me it sounded better, I know that Sonnies room is better build then mine(solid) he has dual 5/8 sheet rock and mine is only 1/2", some people think this is not an issue, but in my opinion it is, if the room is well insulated it will make a big difference(sound and spl) maybe I'm wrong anyway...the only way to figure this out is to build one of the SLLT
When playing some movies with bass it gets real loud in the attic, you can hear it everywhere, is because the IB plays as loud in the attic then it is in the room, so I'm trying to eliminate some of that sound traveling through the attic

Rodny:
I have a very similar situation to you. I am now running 4 RLp-15's in a manifold for an IB. Yes, the sound will now go through the attic and around the house just like you describe. (That works to my advantage cause I tell the kids to go to sleep and turn off the system at night). When I first built the IB, I got advice on the cult and was mostly told that you don't need as much power as a sealed or ported sub to get the same level. I found out that was not true. My IB with 4 drivers did not play as loud as my tube sub with 1 driver! I used to run my tube sub with 1200 watts per voice coil. I had extra amps so I put them to use and purchased another amp to bring the 4 drivers up to the equivalent of 1200 watts per voice coil. Now the IB plays much louder and sounds better than the tube. After wondering why and asking some questions, people asked about my room, so I took pictures and showed them. Sure enough, all were in agreement and said lossy room. I went, huh? Basically once a room gets to a point that it will not hold sound (not sure of the right terminology) because of windows, opening to other rooms, thin sheetrock, etc. the difference must be made up somehow. Either more drivers or more power to the existing drivers if they will handle it. I can now hit 120 db peaks in the 15 to 80 Hz range and the amps don't clip and it is very, well shall we say, enveloping. I never listen at that level but do have the capability. Have you ever thought of putting battens across your attic to slow down the annoying back sound off the drivers that your wife complains about? 3 rows of insulation hanging across the attic would knock the db down enough to be acceptable to the rest of the house and you would still get your IB.

Rodny Alvarez wrote:

I'm not trying to start a war between people that follow IBs and the ones the follow the LLTs some will be and some will be so by doing this, we will answer a lot of questions.
Here are some measurements ..........

I don't think you are allowed to start a war at the shack because General Sonnie just won't tolerate that behavior, but spirited factual discussion will ensue!

Here is my install.............







And I am still working on tuning it.

Chuck

[Rodny Alvarez]

I have the 10" pvc cut to 33", this thing is "BIG" and heavy, I have all the wood cut ready to be install, I don't know if I have time to finish the left side this weekend work tomorrow and going to the Atlanta aquarium on Sunday with the family.
One question..... do I need to make both flares the same or can I make the front bigger then the back? is this going to affect the tuning or............ ??

[Geoff St. Germain]

Rodny Alvarez wrote:

I have the 10" pvc cut to 33", this thing is "BIG" and heavy, I have all the wood cut ready to be install, I don't know if I have time to finish the left side this weekend work tomorrow and going to the Atlanta aquarium on Sunday with the family.
One question..... do I need to make both flares the same or can I make the front bigger then the back? is this going to affect the tuning or............ ??

I seem to recall reading that having the two flares of different radii in the manner you describe was better.

Ok, here it is, it's out of the Loudspeaker Design Cookbook.

"Asymmetrical inlet and exhaust ports with a shallow radius on the inlet end and a larger radius on the exhaust end provide the best balance of lowering distortion and compression."

[Ilkka]

Geoff St. Germain wrote:

I seem to recall reading that having the two flares of different radii in the manner you describe was better.

Ok, here it is, it's out of the Loudspeaker Design Cookbook.

"Asymmetrical inlet and exhaust ports with a shallow radius on the inlet end and a larger radius on the exhaust end provide the best balance of lowering distortion and compression."

Since the air will be constantly resonating in the port (moving in both directions), it would be interesting to learn why Vance says asymmetrical flares would be better...?

[Rodny Alvarez]

Thanks Geoff!!!
I was thinking on a 1" on the inside and 2" or 3" on the outside.


Here is the port .......

[Geoff St. Germain]

That's one of a port.

[Rodny Alvarez]

Ilkka wrote:

Since the air will be constantly resonating in the port (moving in both directions), it would be interesting to learn why Vance says asymmetrical flares would be better...?

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

[Bent]

It's funny, tubes we'd use for subwoofers a couple years ago are becoming the ports for subwoofers tomorrow...

That being said, I have a couple of 12" wide X 60" long PVC tubes just lyin' around.

[SteveCallas]

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.