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Discussion Starter · #1 ·
Hey everyone - I'm an old school guy who hasn't kept up with technology and would like some suggestions for a driver to use for reproduction of a single octave - 25hz to 50hz - in the trunk of my sedan. I have a new Audio Control LC1-800 to interface with my stock speaker level outputs for the OEM subs which begin to roll off at 47hz. Was planning on using the 'bass restoration' feature in the amplifier to restore the lowest octave, driving a sub. While a tapped horn would be awesome in order to go as low as I need I would have to sacrifice excessive trunk volume. I'm hoping someone can suggest a new driver that I can use with either a 4th or 6th order bandpass or a vented enclosure to achieve my goals.

Any help would be appreciated.

(I have a pair of Alpine SWR10D4 that refuse to go much lower than 30hz without enormously long port tubes so I want to find better drivers than the Alpines.)
 

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You could go IB, or sealed, ported, or bandpass.
Basically transient response gets traded for gain.


(I have a pair of Alpine SWR10D4 that refuse to go much lower than 30hz without enormously long port tubes so I want to find better drivers than the Alpines.)
Passive radiators can save on port tube volume/length.
 

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Discussion Starter · #6 · (Edited)
I agree that a trunk IB is a good idea. Saves all the trunk space, and is especially good for getting the deep lows.

Not all subs work well in IB, but some “non-IB” subs will work really well (I’ve had success with 12w3, 12w7, IDQ12). View attachment 314602
View attachment 314603
I like this idea, I remember back in the day we had a device called the Iron-Lung by Speakerlab that would attach to the front of a 12" woofer (presumably mounted on standoffs on the trunk floor) and was essentially an accordion style tube that one would route up to the rear deck and vent it there. Never seemed to work too well.

This may work well since there are no speakers mounted in the rear deck. Matter of fact, just as a test I put the pair of Alpine SWR10's in the trunk in a nasty ported enclosure that's boomy as hell, and I closed the trunk lid on the speaker-wire, powering the sub with a pro amplifier in my garage. I would say there's easily at least -30db of attenuation when in the car - the trunk is sealed that well. I do have a similar middle arm seat fold away cushion like you have - so now all I would need to do build a baffle to mate the driver with the rectangular hole as you've done.

Do I see correctly, do you have the board with the driver bolted to the back seat framework?

I may as well go with a B&C 15" driver or an 18 Sound 18" driver if I'm going IB. I don't think I like the idea of modifying the back of my car, however and my car will need a ton of mods to create an air-tight mate at the driver and the opening.
 

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Discussion Starter · #7 ·
^True^, and few people like using All-pass or the FIR based GD-EQ,
Regarding passive radiators, I'm a huge fan but never used them in a vehicle situation. I have a pair of subs in my home theatre that each have two 15's and two 18" PR's in them. The boxes are designed by Tom Danley back when he was at Intersonics - and have a usable response to 16 hz.
 
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Do I see correctly, do you have the board with the driver bolted to the back seat framework?
Yes, in my case bolted to the back of the seat itself since it doesn’t fold down, and the seat itself is decently insulated. In many cars it would still be advisable to have the baffle the full length of the back seat, to avoid any leaks through the seat itself.
If you do a full size baffle, you can still bolt to back of the seats, or attach it to the trunk itself just behind the seats.

You could also look into the “5-sided box” method, essentially a sealed box with no back, and then just seal the edges for any gaps behind the seat.
 

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Discussion Starter · #9 ·
I'm going to use extruded aluminum channel to frame the opening behind the seat up to the deck and to each tire well. I'll attach my baffle material to the channel - if I'm careful enough I think the baffle can be cut pretty close then wrapped with carpet it will be super tight.

What's your suggestion for infinite baffle driver to use given the single octave desired response and the Audio Control LC1-800 amplifier (2 ohm)
 

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There are a number that will work well, but I’d put these near the top from the feedback I’ve received:
SI SQL
ID IDMAX
FI IB

On a budget, I’ve heard the Dayton ultimax will also do very well.
Add AE IB to that list.

FWIW - you won't need 800W with Trunk Baffle (versus true IB - slightly different and if you have used Danley then you'll appreciate the difference) as your efficiency is raised tremendously in this configuration.

What car are you using?

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Add AE IB to that list.

FWIW - you won't need 800W with Trunk Baffle (versus true IB - slightly different and if you have used Danley then you'll appreciate the difference) as your efficiency is raised tremendously in this configuration.

What car are you using?
It's a 2007 BMW E90 3-series sedan... with a sealed trunk (no folding seats or ski pass). Cut my own hole behind the rear armrest to accommodate the trunk IB.

I started with a JL 12w3v3-4, on a JL JX 500/1 (which outputs 300w @ 4ohm)... was already happy, but who doesn't like to keep tinkering, right?
Sold the JL, got a stupid deal on a IDQ12v2, which I used for a while (and is currently back in on a temp basis). I replaced the amp with a JL HD 1200/1, which is way more than I can use on that sub in IB, but the amp is turned down accordingly...
I've got a JL 12w7 which will be my next sub going in, but had to add reinforcements to how my baffles mounts to the car to accommodate the extra weight and force.

I've also got an Arc xdi 1200.6 on the mids/highs (semi-active), and both amps are fed by a Dayton DSP.
 

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Sorry - I meant for the OP's car...

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Add AE IB to that list.

FWIW - you won't need 800W with Trunk Baffle (versus true IB - slightly different and if you have used Danley then you'll appreciate the difference) as your efficiency is raised tremendously in this configuration.

What car are you using?

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My Stereo integrity like a couple others on here is custom made IB18. Nick doesn’t list them on his page but he will build one to order if you call him. For IB the custom IB18 out performs the SI SQL
If I was to list the order of best I would say
SI IB
SI SQL
FI ib3
AE / ID max

theSI IB and Fi bi the have almost double the Xmax of AE and IDmax

 

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Discussion Starter · #16 · (Edited)
Add AE IB to that list.

FWIW - you won't need 800W with Trunk Baffle (versus true IB - slightly different and if you have used Danley then you'll appreciate the difference) as your efficiency is raised tremendously in this configuration.

What car are you using?

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Wheel Tire Car Vehicle Building




Merc S550 with Burmeister OEM with footwell subs that use the chassis frame as an enclosure. Seems to work alright except lower than about 45hz.

Thank you all for your excellent advice. I think at this point I'm most interested in the IB15AU or the IB18AU. I have removed all of the internals in the trunk space and it looks like it won't be too much trouble to install a baffle there at an angle, and I can use some factory threaded holes for fastening. I want to use some aluminum extrusions fastened to the deck and trunk floor area and then attach my baffle material to that. Since the only hole into the cabin is behind where the middle arm rest recesses and where the factory refer is mounted (I don't have that option), and given this pocket is simple to remove, I hope to use that area alone for sound to enter the passenger compartment. It is almost as if I am doing a 6th order box (I hope not) as this passthrough area is not enormous. I intend to passband the IB from 18hz to 40hz - just a little bit over one octave.

Auto part Automotive exterior Personal luxury car Gas Automotive design


But plans are reality are two different things, aren't they. We'll have to see how it sounds before I can definitively say the crossover points.

Any advice on the best place to acquire extruded aluminum, or black cloth to cover the baffle, I'm all ears. Wheel Tire Car Vehicle Building
 

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My Stereo integrity like a couple others on here is custom made IB18. Nick doesn’t list them on his page but he will build one to order if you call him. For IB the custom IB18 out performs the SI SQL
If I was to list the order of best I would say
SI IB
SI SQL
FI ib3
AE / ID max

theSI IB and Fi bi the have almost double the Xmax of AE and IDmax

@Selkec can you give me the T/S from your SI IB driver so I can do a model comp for OP?
 

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2018 MB S550
The 2018 S550 has 16.3 cubic feet of trunk space according to MB so this comparison will use that as a sealed (we all know it's a leaky aperiodic enclosure but WinISD won't model those so sealed is the best free tool we have for now) and how sealed is entirely up to the install, enclosure to see what the difference is between the driver's discussed above...

Contenders:
SI HT18v3-D4 = $200
Fi IB3v2-18S2 = $294
AE IB18AU-S4 = $449
SI SQL15-D4 = $390

Both SI Subs will handle 800W without exceeding Xmax IF you use an 8Hz Infrasonic Filter as applied to this modeling.

AE Sub will only handle 400W before hitting Xmax...

Fi IB18 is at 28/34 of Xmax so it will actually handle more than 800W.

This screenshot shows all four subs in sealed 16.3 cubic foot enclosure with 800W (400W on the AE - excursion limited) with cabin gain (which is conservative for Trunk Baffle.)

The Fi models the best in this comparison but the HT18 from SI is well within the margin of error for this comparison given the parameters mentioned above and for the Price is probably the best bang for the buck in your situation. The Custom SI IB Sub will obviously be even better and probably handle more power (like the Fi) but getting either the Fi or the SI custom sub will be lengthy wait whereas the HT18 is in stock the last I checked.

The SQL15 is also out of stock and suffers from not enough cone area vs the 18s.

Regardless all are within +/- 5dB at peak (130-135dB) at or below 20Hz and that's stout in the confines of a well sealed and quiet car like the S550.

Rectangle Slope Font Parallel Pattern
 
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Discussion Starter · #19 ·
It's a 2007 BMW E90 3-series sedan... with a sealed trunk (no folding seats or ski pass). Cut my own hole behind the rear armrest to accommodate the trunk IB.
.....
I've also got an Arc xdi 1200.6 on the mids/highs (semi-active), and both amps are fed by a Dayton DSP.
I have an Arc xdi 800.5 in my wifes car. You probably know that the Arc amplifiers are designed by Robert Zeff - and so are the Audio Control amplifiers. His company, Nikola Engineering, is in Sequim, WA. Here's the guts of the Audio Control LC1-800.
Light Circuit component Dishware Wood Tableware
Art Font Gas Audio equipment Technology
 
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Discussion Starter · #20 ·
The 2018 S550 has 16.3 cubic feet of trunk space according to MB so this comparison will use that as a sealed (we all know it's a leaky aperiodic enclosure but WinISD won't model those so sealed is the best free tool we have for now) and how sealed is entirely up to the install, enclosure to see what the difference is between the driver's discussed above...

Contenders:
SI HT18v3-D4 = $200
Fi IB3v2-18S2 = $294
AE IB18AU-S4 = $449
SI SQL15-D4 = $390

Both SI Subs will handle 800W without exceeding Xmax IF you use an 8Hz Infrasonic Filter as applied to this modeling.

AE Sub will only handle 400W before hitting Xmax...

Fi IB18 is at 28/34 of Xmax so it will actually handle more than 800W.

This screenshot shows all four subs in sealed 16.3 cubic foot enclosure with 800W (400W on the AE - excursion limited) with cabin gain (which is conservative for Trunk Baffle.)

The Fi models the best in this comparison but the HT18 from SI is well within the margin of error for this comparison given the parameters mentioned above and for the Price is probably the best bang for the buck in your situation. The Custom SI IB Sub will obviously be even better and probably handle more power (like the Fi) but getting either the Fi or the SI custom sub will be lengthy wait whereas the HT18 is in stock the last I checked.

The SQL15 is also out of stock and suffers from not enough cone area vs the 18s.

Regardless all are within +/- 5dB at peak (130-135dB) at or below 20Hz and that's stout in the confines of a well sealed and quiet car like the S550.

View attachment 315874
Thank you for going to all this effort on my behalf. I'm quite grateful. PM sent.
One thing to keep in mind is that after the baffle is installed a large volume of air will be subtracted from the trunk space. I had planned to install the driver (if possible) between the rear seat back and the baffle, the cone facing the rear of the car.
 
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