PDA

View Full Version : What makes an automotive woofer different....



HipoFutura
05-02-2006, 12:17 PM
I'm using a pair (two cabinets) of Infinity 12.1D subwoofs to compliment L100s. The Infinity subs are marketed as an "Automotive Subwoofer". What makes it so? How is it any different than one designed for home audio use?

I love to listen to "Long Time Gone" by CSN. You can feel the bass in your gut. Not to mentions the floors, walls, etc!

SUPERBEE
05-02-2006, 12:40 PM
I'm using a pair (two cabinets) of Infinity 12.1D subwoofs to compliment L100s. The Infinity subs are marketed as an "Automotive Subwoofer". What makes it so? How is it any different than one designed for home audio use?

I love to listen to "Long Time Gone" by CSN. You can feel the bass in your gut. Not to mentions the floors, walls, etc!

An "Automotive Subwoofer" just makes your car sound like its farting?

I thought car audio was 4 Ohm and home audio was 8

Titanium Dome
05-02-2006, 02:08 PM
I know more about JBL than Infinity, so I'll speak to that. JBL's car subs have different wiring options that can produce 1, 2, 3, 4, 12, and 13 Ohms depending on how they're installed. These are very robust drivers, made to withstand horrible conditions and keep working.

They're also specialty drivers in the sense that they're intended to be used in specific enclosures or mounting locations and to put a large volume of sound into a relatively small, acoustically challenging, noisy environment. Of course, virtually all autosound speakers could be used in the home if one wanted to, though impedances would need to be watched closely when matching up to amplifiers.

If the walls in your house are made of steel covered in vinyl, if the top half of your room is glass all the way around, and if you have listening chairs that are within a few inches of the front and side, or rear and side walls, then auto speakers might work well in that environment.

As for the subs, they're probably going to work OK in the home, but they won't have the kinds of response curves you'd hope to see in a home product, because they're made for the wacky world of automotive engineering. You could build a network to help it out or try to use EQ to smooth it out.

However, if you like what you're hearing, that's always point #1. Keep it that way until you hear something you like better (that you can afford).

hapy._.face
05-02-2006, 02:26 PM
also...


...Auto speakers tend have a much higher moving mass when compared to home speakers. The mass is part of the extra protection the cones need to endure the hardships of temp and humidity extremes found in cars. Some auto speakers use materials for the cone that a home speaker designer wouldn't dream of using. As a result- most (but certainly not all) auto speakers tend to be less efficient (as a general rule). This is more evident when comparing the larger woofers which are even more prone to damage in a car and thus have even greater moving mass and require even more power to get them moving. As a result, some claim auto speakers are less critical and less musical. It's a rather unscientific thing to say but- I would assume a "high quality" auto speaker could outperform a "lesser quality" home speaker. Ti's got the right idea- if it sounds good to you and you aren't damaging your amp- enjoy it. Despite the heavy handed opinions- there really is no right or wrong when it comes to this stuff.

HipoFutura
05-02-2006, 02:50 PM
The Infinity 12.1D is a dual voicecoil driver. I've wired them for an 8 ohm load.

You are absolutely right about the cone material. It looks like ridgid plastic with a rubber surround. Very durable, kinda pretty. It's remarkable how much air they move.

As to requiring an EQ or some sort of tone correction; the thing only handles 50 hz. The x-over is set for 80hz, leaving the 30 - 80 range for the sub. Not much that can be adjusted there.

I suspect they are not as efficient as home audio subs. However, the subs have their own dedicated Phase Linear 400 amp. A twist of the knob and the windows vibrate. The PL 400 Series Two amps have input sensitivity controls, so I can tweek the volume balance between the JBLs and the Infinitys.

toddalin
05-02-2006, 05:41 PM
While many on this forum poo poo the idea, I've been using a W15GTI for one of my two subs (the other is a Sunfire Signiture) with outstanding results! And, (I better don my Teflon flame suit here), it produces far more bass and extended low frequency response than my 2235 mounted in the same cabinet.

Each woofer is in 4 cu ft of space and there is a 2 cu ft central cabinet between them. Each woofer is ported to the baffle board and the central space, that is also ported to the baffle board. All ports are 4" diameter x 9" long.

http://www.largescaleonline.com/eimages/lsolpics/Team_Member_Pics/toddalin/center-2235-w15gti.jpg

4313B
05-02-2006, 06:06 PM
While many on this forum poo poo the idea, I've been using a W15GTI for one of my two subs (the other is a Sunfire Signiture) with outstanding results! And, (I better don my Teflon flame suit here), it produces far more bass and extended low frequency response than my 2235 mounted in the same cabinet.

Each woofer is in 4 cu ft of space and there is a 2 cu ft central cabinet between them. Each woofer is ported to the baffle board and the central space, that is also ported to the baffle board. All ports are 4" diameter x 9" long.

Let's take a quick look at the W15GTi (red) in one of the enclosures JBL recommends - a 4.0 cu ft vented box tuned to ~ 28 Hz and then lets look at a 2235H (green) in that same box. That way everyone has a graphical.

4313B
05-02-2006, 06:07 PM
.

4313B
05-02-2006, 06:10 PM
The W15GTi has a bit more Q than I personally like in a home hi-fi transducer but to each their own.
I notice the Kappa Perfect 12.1D has a lower Q.

Enclosures Sound Quality (http://manuals.harman.com/JBL/CAR/Boxes%20and%20Parameters/W15GTi_rev_f.pdf)
Enclosures Competition (http://manuals.harman.com/JBL/CAR/Boxes%20and%20Parameters/W15spl_f.pdf)
W15GTi Owner's Manual (http://manuals.harman.com/JBL/CAR/Owner%27s%20Manual/W101215%20OM%20FINAL%20(revised%2092000).pdf)
W15GTi Tech Sheet (http://manuals.harman.com/JBL/CAR/Technical%20Sheet/W15GTifn.pdf)
Kappa Perfect 12.1D Boxes and Parameters (http://manuals.harman.com/INF/CAR/Boxes%20and%20Parameters/P12.1d_f.pdf)
Kappa Perfect 12.1D Owner's Manual (http://manuals.harman.com/INF/CAR/Owner%27s%20Manual/KAPPA%20PERFECT%2012%20om.pdf)

KenWH
05-03-2006, 07:57 AM
In my youth I was big into caraudio. In general car audio speakers/drivers are designed to work in conditions dictated by the enviroment of cars. ie small box designs for subs and ib type installs for door speakers and it all needs to stand up to heat and moisture.

My first decent diy sub I built for home use used a pair MTX 15" subs in 3ft sealed boxes. This was many years ago before the net made getting good drivers as simple as point and click.

KenWH
05-03-2006, 08:08 AM
One more thing to add, imo the line between good caraudio drivers and home drivers is almost gone. Many oe speaker manufactures like TC Sounds make basically the same drivers and it gets sold to several different labels.

For instance my original SVS ULTRA's use 12" woofers made by TC SOUNDS for SVS. It's the exact same woofer, other than a few t/s specs, as the AudioMobile sold as their famous "MASS" car audio sub. I know cause the last car sub I bought was a MASS and it's sitting in a box in my basement.

Now that small subs with big amps have caught on in the home there is little difference these days between mobile sound drivers and home drivers.

4313B
05-03-2006, 08:10 AM
At some point I should scan and post JBL's old brochure on Car Audio. Maybe I already have and it just hasn't shown up in the Library yet.

Basically they took a bunch of the components from the LCS and made them available to Car Audio installers. LE10H, LE8T-H, LE5H, etc. That sure didn't last long. :p They've come a very long way. :)

Titanium Dome
05-03-2006, 08:43 AM
Paul Galvin's Motorola (Motor-ola: moving sound, or sound in motion) was the first mass produced car audio unit, around 1930. Even given the bad timing (Great Depression) it survived. There we some small advances after that, but usually only DIYers or custom shops (West Coast for the most part) went much beyond the original Galvin concept: head unit, single speaker

A Jim that I admire a lot (Jim Fosgate) really made the move with his PR-7000 car amp in the early 70s. Speakers, EQs, giant caps, big subs all followed in time, with an entire industry getting into purpose-driven design for automotive applications. When we go back and look at the POS radios being offered even in the finest cars in the 70s, it's easy to see why custom car audio got so big so fast.

But then, what could one expect of a kid who put a tube radio on his bike when he was 12?

http://www.stereophile.com/interviews/1204fosgate/


(Side note: this success helped bankroll Fosgate's research into multichannel audio, which is the second great wave of his legacy.)

GordonW
05-05-2006, 08:16 AM
I think I still have a Fosgate PR200 (the little amp, 22w/ch). Used it in my computer, believe it or not! Put a 12V power supply, and tapped off the voltage rails for +-15V phantom power, and used it with an Orion PEQ200, to amplify the output of my sound card. Had the whole mess mounted INSIDE the computer...

Regards,
Gordon.

duaneage
05-09-2006, 10:17 PM
Car audio has gotten ridiculously expensive and overblown anymore. Many manufacturers are building cars with non-standard radio openings, making it hard to replace the OEM head unit. The tradeoff is the heads are much better today than they were 10 years ago.

I did systems in my cars for years but I have not done my XG350 yet. The wife wants more bass but we use the trunk too much. I am working on an innovative design of bandpass that might be just the ticket