"Earl Kiosterud" <someone@[EMAIL PROTECTED]
> wrote in message
news:yRLSj.1193$sp.393@[EMAIL PROTECTED]
>
> "Phil" <phil_lee@[EMAIL PROTECTED]
> wrote in message
> news:481a81c7$0$4093$4c368faf@[EMAIL PROTECTED]
>>
>> "Arny Krueger" <arnyk@[EMAIL PROTECTED]
> wrote in message
>> news:QI2dnWsKt7JXPYTVnZ2dnUVZ_gWdnZ2d@[EMAIL PROTECTED]
>>> "Phil" <phil_lee@[EMAIL PROTECTED]
> wrote in message
>>> news:481912a7$0$7052$4c368faf@[EMAIL PROTECTED]
>>>
>>>> Would I be able to get low 40-90Hz sounds from a 6.5"
>>>> sealed sub in a car?
>>>
>>> Shouldn't be a problem, with the right 6.5 inch driver. Efficiency
>>> won't be wonderful, and you may have to search around for a 6.5 inch
>>> woofer with enough Xmax. I think there are some in the Peerless
catalog.
>>>
>>> Doing low bass in a car is far easier than in rooms, because a car is
in
>>> essence a small room. Even a large SUV does not have a lot of cubes
>>> compared to a typical listening room.
>>>
>>>> I'm looking to use my factory sub
>>>> with a different amp with an adjustable crossover to turn
>>>> the resonating frequency down from the 160-250Hz range to
>>>> the 50-90 range.
>>>
>>> What car?
>>
>> 2008 Scion TC. Small cabin and very small trunk.
>>
>>>> I'm looking for decent-quality sound
>>>> without being "boomy."
>>>
>>> Doable. If the problem is boominess, it might be that your car audio
>>> system has the basics for low bass, but suffers from a poor factory
>>> tuning. The audio system in my Milan sounds like boomy, tizzly crap
>>> until you work over the bass and treble controls. Max cut for the
bass,
>>> lots of cut on the treble.
>>
>> That's what I'm thinking. I ran a test track outputting a sine wave
from
>> 350 Hz to 20Hz and it definitely started becoming boomy starting at
250Hz
>> and sharply cut response at 160Hz. It was the first time I had run
such
>> an audio signal through the system and I was surprised to see that the
>> car's engineers had seemed to band-pass that range to get the maximum
>> amount of boom for the small wattage factory sub amp. Quite annoying
>> because some of the songs that I listen to will be resonate-y at some
>> points and then lose the low end, especially on sweepy types of tracks.
>>
>>>> Has anyone seen this done easily,
>>>> or am I looking for too much out of a 6.5" sub? Would I
>>>> need to go to 8, 10, 12 inches?
>>>
>>> Low bass is all about displacing air. The ability to move air goes up
>>> with the approximate cube of the diameter. Squared because of simple
>>> geometry of areas, and cubed because there is a fair correlation
between
>>> diameter and Xmax.
>>
>> Makes sense... probably akin to the volume formula of a cylinder, huh?
>>
>>>> I'm not really willing
>>>> to sacrifice trunk space for this project; I'd only
>>>> retrofit an existing setup to the current spot where the
>>>> stock speaker is.
>>>
>>> Try equalization, then try a large Xmax driver, more power and keep on
>>> working with equalization.
>>
>> I ended up getting a cheap amp with a on eBay last night... I'm
>> beginning to think I'm about to embark on an expensive endeavor ;)
>>
>> Would any old equalizer like something here do the trick?
>>
>> http://www.pyramidcaraudio.com/itempage.asp?model=714EX
>>
>> Phil
>
>
> Phil,
>
> A lot of output broadly around 200 Hz. in a regular passenger car, with
> the speakers in the rear deck, is universal, even if the speakers are
> usable down to the bass range. It's an acoustic thing. A Scion is
shaped
> quite differently, though. But if you're hearing nothing below 160 Hz,
> then something else is amiss. A couple things could be going on.
I wouldn't say that there's nothing below 160Hz, but it's definitely a low
level after 160Hz. I'll try to see if my crappy sound meter can read out
a
dB reading at those frequencies.
> There could be a lot of leakage from the rear of the speaker to the
cabin.
> Is this speaker mounted so the trunk is its cabinet? I suspect so. Or
is
> there a sealed enclosure for the speaker in the trunk? And if so, is
> there a ****t in the cabinet?
It is a sealed enclosure with a 2"x2" ****t, but I was so sick of the
boominess when I first got the car that I stuffed foam into the ****t to
seal
it up and the sound became tolerable. Apparently though, I just read that
the frequency in a sealed enclosure is higher so maybe I ended up moving
the
response higher inadvertently and didn't notice.
> I suspect not. Look or feel for cone movement when it's doing bass
stuff.
> Cone movement, except in a ****ted box, goes up 4 times when the
frequency
> is half -- it has to, to keep the same sound pressure. I suspect it'll
be
> doing squat.
Hmm... so cone movement = 1/(frequency^2)? Correspondingly, the voltage
has
to go up by that same amount... and I'm guessing power has to also.
> It's most likely that the cone resonance of the speaker is up around 200
> Hz. where you're getting so much output. That's a cheap trick used in a
> lot of small systems to fool the ear into believing that the overall
> response is balanced -- instead of providing response down into the bass
> region, they let the speaker provide a lot of output via a peak up
around
> 150 or 200 Hz where it's easy to do, but nothing below that. They do
that
> by designing the speaker with a resonance somewhere around 150 or 200
Hz.
> and a high Q (big peak in output). The response below that settles to a
12
> dB/octave downward slope , as freq goes down. Costs way less. Some
small
> home systems do it, and most boom boxes do it. If that's the case, the
> speaker is totally unusable for real bass, most of which is generally in
> the 50-100 Hz octave.
That stinks. I was beginning to think that the speaker may have been a
big
part of the equation.
> I have some 6 1/2" 4 Ohm woofers that have a free-air resonance around
70
> Hz that wouldn't get you to 40 Hz much, but would likely do a goodly bit
> better than we think your speaker is doing. Contact me via my web site,
> and I'll send one to you. You can have it. www.smokeylake.com/excel.
My
> email is at the bottom of the page.
Really??? That is just too generous of an offer! Let me take care of the
****pping costs at least. Thanks!
Phil
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