Home audio drivers vs. car audio drivers
Slappy, Car audio isn't designed for anything that resembles flat frequency response. All listening is nearfield. The amps used in car audio are, for the most part, junk compared to home audio amps. There is perhaps 50 cubic foot of volume in the automobile environment versus a couple of thousand cubic feet in a modest home audio room. Engineering challenges for car audio include road vibration, temperature and humidity extremes and the ability to survive clipping to name a few. And, talk about terrible electrical supply. Air conditioning, turn signals, fuel injection, headlights and countless other electrical stuff is going on all the time. This electrical environment makes a homes circuits look incredibly stable in comparrison. |
Car audio actually has way more hype and BS, if you can believe it (!) than home audio. More of it is crap than the equivalent home audio stuff. I've built stuff using car audio 2-way separates before - they were ok, but really nothing outstanding for the $ and effort involved. Like high-end home audio, most of the truly good/exotic/well done car stuff is about custom one-off type of things, including installation and modification. Not many truly good sounding cars just use off-the-shelf stuff that you can buy at Tweeter. In fact some of the high-end car stuff I have seen/heard used high-end home drivers (e.g. Focal, horn drivers, etc.) instead of the car stuff. most of it is designed around marketing and BS and ruggedness. (tons of it gets returned so making it stand up to abuse is one of the high priorities, esp. for woofers... e.g. able to handle being plugged into a wall socket (AC) with that connected to speaker driver, and nonsense like that.) I think a lot of (young guys?) folks go through a car-audio phase. Many outgrow it. Or at least settle to something good but sane. -Ed |
Ignorance is bliss,I'm told. But I know from personal experience, back around '96-'97 Soundstream made an amp that was designed by Krell and to their standards. I took the amp apart once to see if it was up to high standards of home audio and beleive me, it was built to a pretty darn high standard, Looked to beat out the mid-fi equiptment we have on hand today. It would run all day on a one ohm load. I ran two channels of it bridged into a 2 ohm load for almost 2 years and never had a problem or any over heating. It was one a thousand made. But still, your statement is way off. Their were other companies that built some high quality car audio, also. Of course $1800 for a car audio amp, or any amp is a bunch of money. But to make the statement that 12 volt amps are junk, is not a smart statement. But, if you buy from Tweeter or other appliance stores you most likely will get junk car audio equiptment. I can't imagine 'car audio' has all gone to the dogs since I messed with it. Btw, in the late 80's Bob Carver and one of the hi-end mags did some comparisons of amps (12v vs. 110v) with a pr. of Maggie's and the 12 volt amps didn't do too badly. Held their own in some respects. I remember back in the mid-late 90's Wes Philips had a 'car audio' column in Stereophile every 3 months . I doubt they would have given 'car audio' an editotial spot if it wasn't worth a darn or if it wwas junk. |
Fs, Qts, and impedance. When you put a bass speaker in a rigid enclosed area you experience 12dB of gain per octave you drop below where the longest dimension equals half a wave length. So to get flat bass inside a car you need the sub woofer to roll-off at a high frequency. Power = V^2/Z. In a car you're starting with 12VDC vs. 100-240VAC in a house; so it's easier to make power when you're driving a lower impedance load. |
Drew: To those that understand what Fs, Qts and impedane mean, they will understand exactly what you're getting at. For those that are reading this, it probably went right over their heads : ) Speakers are designed very differently as they have very different atmosphere's ( acoustically and environmentally ) to deal with. Amplifiers are designed very differently as they have a very different power source to deal with. Having said that, you can get "pretty decent" car audio gear for not that much money. Just like in home audio, you have "pretenders to the throne" who rely on hype, cosmetics and fictitious spec's and then you have "the real deal" type of components that are built and designed around real world operating conditions and environments. Guess which type of product is most likely to be found in the majority of "boom boom" vehicles heading down the road. If you're not sure, just think about how much Pioneer / Sony / Kenwood type stuff you see in home audio as compared to even Parasound, Adcom, NAD, etc.. type gear. This is not to mention the likes of "audio standards" such as ARC, Krell, Pass, etc... Cheaper junk that promises you the best for the least amount of money is what keeps the economy alive. People buy cheap junk, find out exactly how junky it is and then sell it to buy the next higher level of junk. Without all of the low grade junk and the learning experiences involved, we wouldn't have a "High End" in either home or car audio. It's just too bad we can't to how "junky" the low grade "junk" really is : ) Sean > PS... Most car audio subwoofers are designed for maximum output at higher frequencies with little concern for extension and / or linearity. This results in more apparent bass, which is why you hear "boom, boom boom" or "thud, thud, thud" rather than musical notes. Then again, most of the recordings that have that "boom, chukka, splash" on them isn't very "musical" to begin with : ) |
LOL @ Slappy correcting himself. In the early '80s I used a lot of home speaker components in my car. One of my favorites was a home ribbon tweeter I got at a local electronics shop. It was extended, but not bright, but it was a bit on the dry side. I also enjoyed ADS and Boston Acoustics separate speakers from that era. I remember when Nakamichi and KEF came out with car audio components my friends and I got excited because we thought some of the home audio tech, and quality would migrate to the car scene. But in general, I wasn't too impressed with their initial offerings. My faovrite speaker combo was one I Frankensteined together along with a homemade three-way crossover. and all 8ohm drivers. It sounded much more musical than anything I bought off-the-shelf from car audio manufacturers. This was especially true when it came to bass. I thought all the Rockford Fosgate and Pyle woofers I used 4 ohm or 8ohm were too punchy, and one-notey. That home woofer on the other hand was more natural. I think car speakers would be tougher for an amp to control because of their 4ohm rating. They would draw more current from the amps and their damping factors would be half that of an 8ohm dirver. But in small space like a car, that may not matter as much. |
Most mobile speakers target specific size and envirmental issues as in size,depth,flush fit,nominal 4ohm impeadence. when you go to seperates the tweeters are ussually permanently grilled,neodymium magnets,and ferrofluid are most common.And to top it off most all designs expect use in free-air application.Also many off the better car tweeters tend to be focus dispersion so as not to splash highs off many unfriendly vehicle interiors as well as an increase in on axis sensitivity.Material choice is a comprimise for in car sunlight and moistures relentless assualts.Pl++++++us!Most of the time thiele/small parameters from mobile manufacturers if available,can't be trusted.So what size cabinet vented/reflex or sealed acoustic suspension would you set out to build. I have heard few rigs made for home from mobile sound gear which yeilded loud and clean,yet always missed 3 dimensional accurate sonic picture.IMHO |
Gunbei: Most car stereo woofers have a high Qms, which results in a big impedance peak at resonance. This is what causes the bloated, indistinct bass that you hear from the "boom / tizz" vehicles. Lower impedances aren't a problem for a good amp, but as you mentioned, damping factor is reduced. As a side note, damping factor is NOT the ability of the amplifier to control or load into the driver so much as it is the ratio of how much potential there is for the reflected EMF from the driver to modulate / distort the output of the amplifier. This is a very commonly misunderstood spec with even EE's, designers and manufacturers not knowing how to interpret it or what it really means. The higher the damping factor, the less susceptable the amp is to being affected by the reactance of the speaker. The ability of the amp to efficiently transfer power into the driver / speaker system ( including cabling ) is what will determine how much "control" the amp has. Unfortunately, there is no spec for this that i'm aware of. Take a look at this link pertaining to impedances, reactance, loading characteristics and power transfer in the AA Speaker Asylum archives. Pay special attention to the exchanges between myself and that of Dan Wiggins of Adire Audio and to a lesser extent the few responses between myself and Bobby Palkovic of Merlin. One of these two guys is a LOT smarter / more experienced than the other, but i'll leave that up to you to figure out which one it is after reading the exchanges there. While punching in T/S parameters into a computer program and then interpreting the data can provide a lot of useful information, it does not make one a knowledgable speaker designer. Sean > |
Sean, I can't figure it out. You say Dan Wiggins can't use a vented box that can outperform a sealed box but he shows how he can. Bobby is lowering bass below tuned freq. which you say increases distortion and he says he found a way around that. Sounds like you don't think either one knows what they are doing / following the laws out physics. To my ears Dunlavy's sounded much less dynamic than Virgo III's or B&W. And B&W publishes distortion under 1% with their vented boxes. Bass is very tight and picks up on the beat (toe tapping). |
Cdc: "You say Dan Wiggins can't use a vented box that can outperform a sealed box but he shows how he can." Beat it in what manner? Given optimally tuned designs, a vented box may have greater extension and output, but it will never have the same amount of definition and transient response that a sealed box can achieve. Like i said, quantity vs quality. "Bobby is lowering bass below tuned freq. which you say increases distortion and he says he found a way around that." That is what Bobby says. As i mentioned in that thread, NOWHERE in the Stereophile review is distortion measured or quoted. "Sounds like you don't think either one knows what they are doing / following the laws out physics." I think that Bobby has a much better idea of what he's doing than Dan. Dan is all about computer designing a product for maximum quantity, not maximum quality. If you doubt this, look at the Adire website and you'll see the "monster" sized woofer with mega-excursion that they are working on. Given that Dan doesn't understand the difference between an amp being able to load into a speaker and what damping factor means, it is pretty obvious that he's letting the computer do his thinking and work for him. On the other hand, Bobby is about hands-on experience and tweaking for optimized results with minimal trade-offs. He understands what the words "control", "loading" and "damping" mean. Dan will get you a lot of sound. Bobby will get you good sound. "To my ears Dunlavy's sounded much less dynamic than Virgo III's or B&W. And B&W publishes distortion under 1% with their vented boxes. Bass is very tight and picks up on the beat (toe tapping)." Dunlavy's had their own problems, just like any other mass-produced speaker. On top of that, most people aren't used to listening to "tight" bass with minimal ringing. Facts is facts, personal preferences are something all-together different. Try taking a look at this >website. Click on "tech notes" and then "bass loading" and read that. He basically repeats the same things that i said in that and a few other threads. For sake of clarity, i'm not taking credit or saying anything that hasn't been said and proven to be fact long ago. If you doubt these facts or just want to delve deeper into the subject and learn for yourself, pick up a copy of Vance Dickason's Loudspeaker design cookbook. As i've mentioned before, I would always encourage one to learn for themselves, both through reading and hands on experience. The more that you know, the less bullshit you'll be forced to unknowingly swallow. Believe me, i learned the hard way. I used to think that sealed speakers were for idiots when i was younger. Why would anyone want a speaker that didn't play as loud, go as low or took more power to operate? The answer is obvious once you learn how and what to listen for. Like i said before, quality vs quantity. Sean > |
I read and reread the 'Speaker Design Cookbook 10 years ago and reread it 'til I understood it. For anyone that believe's you can't get great tuneful bass out of subs design toward cars, then you don't or won't understand the Cookbook. I've forgottern more on the subject of subs in a vehecle than most people will ever know. Lets not forget, the driver is only part of the equation. The cabinet and the interior of the auto also have to be taken into consideration, if you really want topnotch bass in a 4 wheeler. But the bs you find in car audio can be found from manufacturers of home audio. Example that pops in my mind every time I see it, is the Sunfire subs that claim 2400 watts of amp output. Not happening in that product. Very simple reason. A 15 amp breaker will blow long before you achieve 2400 watts. I have forgotten the formula, as I mentioned earlier I've forgotten a lot of this stuff, but if I recall correctly, about 1500-1800 watts is the max draw on a 15 amp circuit. There's as much deceptive advertising in home audio as car audio. CDC, you can't change the laws of physics. A vented box can NOT give the same Q, QTS, of a sealed designed. Read the book. Please. |
