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car subs question....


pinipig523

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my first guess would be that they have low sensitivity.

this is a total guess, not too versed in car audio, when i was into it, looks made more difference than performance, but i was only a teenager also.

i think if you put a high sensitivity speaker in a car, you would pick up all kinds of noise from the primary coil, alternator/generator, and other "not so clean" power sources in your car.

so you put in a less sensitive speak, and ram a bunch more watts into it to get the same result.

makes sense in my head...but again, it is a guess.

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Well, with any sub design you always have tradeoffs. Usually the trio that is most often balanced is... bass extension, box size, and efficiency. Trying to improve the performance in one area will usually decrease the performance in the others. Best a designer can do is optimize two to the great loss of the third.

In car audio, SIZE is the most critical followed by bass extension. Some will point out that car subs rarely extend very much below 30hz... but even this is VERY low when you are looking at a 1cuft sealed box. Efficiency is pretty much last on the designers considerations as power is almost considered limitless.

This gives birth to the 1000W run of the mill car sub which will pump some SPL in the 35 to 80hz range... in a 1cuft box.

One other important factor that we shouldn't forget is marketing. Many consumers are under the impression that power is the "defining" factor when it comes to volume (SPL) when in reality it isn't. I don't think I have to explain efficiency and mechanical linearity here.... But it is true that the maximum power rating only tells someone how much power will melt the voice coil, even though the sub may have reached it's mechanical limits a long time before it's power rating.

Home subs simply have larger enclosure and more discreet marketing... 2.gif

Rob

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Not an expert here but my son has a 1100 watt amp on a 10 inch sub. It does about 147db's at the dash and the box is at the other end of an Xterra. The abuse these subs go through requires that the cones be rigid and heavy and the surrounds thicker and less flexible than most car tire sidewalls or something is gonna tear. Takes a lot of power to get all that moving. Just my guess.

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Its very easy to climb to extreme SPL in a car,the volume is very small compared to a house/room.

Car interior flexes less than walls inside a house,less loss.

The proximity of the woofer(even at the...other side of the car...still very close)combined with the acoustics inside a car(a natural BIG,FAT and generous bass boost)make even small woofers(8") sound BIG.

Any cheapo 12" woofer can hit over 120dB in a car powered by even a crappo $99 amp.

Plus as was said before,most car woofers need plenty of wattage to reach their max linear travel,when mounted in very small sealed boxes.This is why uou often have these 1KW amps powering 10 and 12" woofers.

Take a Tumult or two,mount it in a sealed box,power them by 3000W (into the woofers load of course)and ...you would hit hellacious SPL so high you would RUIN your hearing for LIFE(life in this world anyway).

Take the same dual Tumults still mounted in the same sealed box and powered by an amp of the same capabilities,this time used in a large room...and you hit dozens upon dozens of dB's.

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I have two 15 inch aluminum Eclipse subs powered by a 1000 watt Xtant 1001dx amp bridged to deliver 500 watts per, helped out by 2 Scoche stiffening capacitators, and running off a yellow top deep cycle Optima battery. While I can hit about 154.2dB, I'd say the frequency response only extends to about 28hz. I listen to alot of music in my car, as well as at home and I can say that after extensive listening to the same cd's, the subs in the car SUCK. Certain passages are overly boomy, and the upper LFE frequencies sound terrible. It is nowhere near as smooth or deep as my SVS PB2+. The only good thing about my subs are to drown out other would-be blokes on the street trying to bump their sounds.

Oh, and most subs for autos are 4ohms.

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With my experience I don't think you need a lot of power to extend low? With cabin gain you get a huge boost in the lowest octave.

I got a 15" Kove Armageddon M-Series DVC-4ohm coils running on about 1/4 gain off a Crossfire BMF1000d so essentially it's getting around ~150-200W. Box is 3.25CF net tuned to 35Hz and the whole system seems to peak at around 50Hz. I've set off my neighbours car alarm from two houses down when playing a sine sweep.

I also ran a Shiva in a 3CF box tuned to ~28Hz, I only had about 150W on there and the low end extension on that sub was incredible. When you have the response of the box coupled with cabin gain you have a really nice extension down to 20Hz.

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On 11/14/2003 11:52:07 PM nicholtl wrote:

I have two 15 inch aluminum Eclipse subs powered by a 1000 watt Xtant 1001dx amp bridged to deliver 500 watts per, helped out by 2 Scoche stiffening capacitators, and running off a yellow top deep cycle Optima battery. While I can hit about 154.2dB, I'd say the frequency response only extends to about 28hz. I listen to alot of music in my car, as well as at home and I can say that after extensive listening to the same cd's, the subs in the car SUCK. Certain passages are overly boomy, and the upper LFE frequencies sound terrible.

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There goes the entire trunk! ...

You have some nice components in you car... I don't know if you've got one, but if your willing to sacrifice SPLs (you can't listen to 150+db without earplugs anyways) you can parametrically eq your subs flat same as for a home... it'll definitely balance most of the boom out. Given what you've already gotten invested in the system, it'll make those long drives more pleasant...

Later...

Rob

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Hmm, that might be an idea to consider. The subs are party controlled by the Alpine IVA-C800 LCD head unit I have, which is kinda acting like a HT receiver as it electronically cuts off my LFE frequencies above 100hz (as high as it will allow). I also have the Audiocontrol Three.1 EQ, which only has a gain control and frequency sweep. I have the sweep set to it's max - 120hz, which I guess is the same as what people do to their HT subs if there is no bypass feature.

It's not that the Eclipses' sound terrible...it's just that compared to my gear at home, they are not nearly as pleasant to listen to.

What's pretty amazing too, is that I also have 4 Boston Acoustics Pro Series 6.5 components in my SUV which run off the Xtant 604dx (75 watts x 4) and they seem to have no problem keeping up with the subs, even at earthshaking levels. They definately distort though...to bad we can't throw some FAT A$$ HT amps in our cars huh? ... but then, we'd be cooking like a microwave in there.

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On 11/14/2003 11:52:07 PM nicholtl wrote:

I have two 15 inch aluminum Eclipse subs powered by a 1000 watt Xtant 1001dx amp bridged to deliver 500 watts per, helped out by 2 Scoche stiffening capacitators, and running off a yellow top deep cycle Optima battery. While I can hit about 154.2dB, I'd say the frequency response only extends to about 28hz. I listen to alot of music in my car, as well as at home and I can say that after extensive listening to the same cd's, the subs in the car SUCK. Certain passages are overly boomy, and the upper LFE frequencies sound terrible. It is nowhere near as smooth or deep as my SVS PB2+. The only good thing about my subs are to drown out other would-be blokes on the street trying to bump their sounds.

Oh, and most subs for autos are 4ohms.

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A flat in car reponse is usually achieved with a sealed enclosure. What kind of enclosure are those Eclipse subs in?

You can see I have fairly flat response and good extension with 3 MTX Blue Thunder 10's in a 2.8ft^3 sealed enclousure with good extension in the trunk of my sedan. My front speakers start to drop off ~70hz.

post-7551-13819250093252_thumb.gif

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On 11/15/2003 2:47:20 PM fabulousfrankie wrote:

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On 11/14/2003 11:52:07 PM nicholtl wrote:

I have two 15 inch aluminum Eclipse subs powered by a 1000 watt Xtant 1001dx amp bridged to deliver 500 watts per, helped out by 2 Scoche stiffening capacitators, and running off a yellow top deep cycle Optima battery. While I can hit about 154.2dB, I'd say the frequency response only extends to about 28hz. I listen to alot of music in my car, as well as at home and I can say that after extensive listening to the same cd's, the subs in the car SUCK. Certain passages are overly boomy, and the upper LFE frequencies sound terrible. It is nowhere near as smooth or deep as my SVS PB2+. The only good thing about my subs are to drown out other would-be blokes on the street trying to bump their sounds.

Oh, and most subs for autos are 4ohms.

----------------

A flat in car reponse is usually achieved with a sealed enclosure. What kind of enclosure are those Eclipse subs in?

You can see I have fairly flat response and good extension with 3 MTX Blue Thunder 10's in a 2.8ft^3 sealed enclousure with good extension in the trunk of my sedan. My front speakers start to drop off ~70hz.

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Yes, my dual 15's are in a sealed box...unfortunately I have no pics of the inside of my truck, just the outside but since it's irrelevant to this thread I didn't post it.

All my point was, was that it's pretty safe to say that most (not all) of our auto systems cannot compare to our home systems. I, for one, spent about 6 times more on the HT system that I did for the car.

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