FI SSD12 frequency response

[goldmax99 10+ year member]

I've been testing this sub powered by a Soundstream Rubicon 702 and have noticed that the frequency response is not as flat as I would like it to be. I have it in a 1.5 cubic foot sealed enclosure. I did my frequency response test with my ears and a cd with test tones and sweeps. From 0 to 20hz it's barely audible. Then from 20 to 40 it slowly begins to increase. It then peaks real hard at 40-50hz. And starts to decrease from 50 and higher. I would really like a flat response from 20 to 60hz.

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[azimuth 5,000+ posts]

you won't be able to hear anything under 20hz no matter what sub it is.

 

[Immacomputer 10+ year member]

you won't be able to hear anything under 20hz no matter what sub it is.

********. 20hz and below is completely audible in my car and 20hz is not attenuated at all. I'm also just running a single 12" sub getting 100w from an old Profile amp. Bass I love you sounds very flat and nice on my setup. The 7hz quick note is definitely audible and it's not some flapping sound from the driver. The 17hz note is very powerful and really gets my shirt shaking.

If you want to get down to 20hz and still use a sealed box, I suggest going to about 2.5 cubes and implementing a Linkwitz transform circuit into your system if you have plenty of power at your disposal (or if you're not too terribly concerned with output).

Another option would be to go to about 2.5 cubes and tune between 22-25hz. That would definitely bring out the low end extension and your top end should not change much at all from how they are now. That will have roughly the same output from about 40-60hz that you get now but it should also bring the 20-40hz range into a more audible level and no, that does not mean that it will be peaky. Being peaky in the low 20hz range isn't a bad thing at all since your hearing starts to roll off around there. My hearing begins to degrade around 25hz and below and I have a 4dB peak at 22hz. To my ear, it's not a noticeable peak and it actually sounds flat when compared to frequencies in the 30+ range.

A transmission line may also suit your needs. Something with about 45in^2 of line area at about 110" long with a small compression chamber of about .5 cubes or so. I would probably steer clear of this option if you have a trunk vehicle though.

 

[azimuth 5,000+ posts]

********. 20hz and below is completely audible in my car and 20hz is not attenuated at all. I'm also just running a single 12" sub getting 100w from an old Profile amp.
If you want to get down to 20hz and still use a sealed box, I suggest going to about 2.5 cubes and implementing a Linkwitz transform circuit into your system if you have plenty of power at your disposal (or if you're not too terribly concerned with output).

Another option would be to go to about 2.5 cubes and tune between 22-25hz. That would definitely bring out the low end extension and your top end should not change much at all from how they are now. That will have roughly the same output from about 40-60hz that you get now but it should also bring the 20-40hz range into a more audible level and no, that does not mean that it will be peaky. Being peaky in the low 20hz range isn't a bad thing at all since your hearing starts to roll off around there. My hearing begins to degrade around 25hz and below and I have a 4dB peak at 22hz. To my ear, it's not a noticeable peak and it actually sounds flat when compared to frequencies in the 30+ range.

A transmission line may also suit your needs. Something with about 45in^2 of line area at about 110" long with a small compression chamber of about .5 cubes or so. I would probably steer clear of this option if you have a trunk vehicle though.

i've never been able to hear anything below 20hz. i just see the sub moving.

 

[Immacomputer 10+ year member]

The absence of evidence is not the evidence of absence; just because you have not been able to experience it with any equipment/designs you are familiar with does not mean that it is impossible for any sub. Besides, the driver is a VERY small part of your actual frequency response in a vehicle.

 

[mlstrass 5,000+ posts]

You do NOT hear 7hz, you hear/feel the effects of that note on your car's interior...

 

[azimuth 5,000+ posts]

The absence of evidence is not the evidence of absence; just because you have not been able to experience it with any equipment/designs you are familiar with does not mean that it is impossible for any sub. Besides, the driver is a VERY small part of your actual frequency response in a vehicle.

when i play a tone below 20hz, it rattles the crap out of the vehicle, but not really any sound. i've probably played subsonic tones on around 10 subs total in my life. never been able to hear them on any sub. i suppose some amps have a built in ssf?

 

[NDMstang65 10+ year member]

The absence of evidence is not the evidence of absence; just because you have not been able to experience it with any equipment/designs you are familiar with does not mean that it is impossible for any sub. Besides, the driver is a VERY small part of your actual frequency response in a vehicle.

The human ear cannot audibly process anything below 20Hz, some people can process things as low as 17Hz..but the vast majority simply can't hear it. You may 'think' you can hear it, but you can't.

What you are hearing is mechanical noise either coming from the woofer itself or the environment in which you are in that is resonating...and relating that to being able to hear such frequencies.

Now you can lay down an elephant dead in its tracks with a 10-12Hz tone...you can also crack foundations of buildings with ultra low subsonic frequencies..

But you can't hear it. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

To the OP: Your not going to find a woofer in a car that will do that with no equalization, you are simply hearing the peaks and valley's of the resonant frequency response of your car...which you will either have to counter with box tuning, changing volume etc. That box is on the big side of things anyhow, 1.1 cubic feet is optimal for an SSD 12.

Thanks!

-Nick

 

[Immacomputer 10+ year member]

You do NOT hear 7hz, you hear/feel the effects of that note on your car's interior...

Which makes that frequency audible as long as there is significant pressure to break the threshold of detection or not. I can detect a 7hz note played in my car with this enclosure much easier than I can with the same sub in a sealed enclosure with more power in the same car and position.

When I say audible, I mean that there is significant pressure to cause my brain to detect a very low frequency. It doesn't matter what part of my body is reporting the frequency, just that it is detected. It does not matter if my hearing starts to roll off around 25hz (which I already mentioned) because I can still detect the signals much lower than that and detection is what it's all about.

This also applies to NDMstang65's post as well. And yes, my system has a -3dB points at 15hz and 70hz with NO EQ whatsoever. This was measured response too, not just numbers pulled out of my ass. From 24-65, I am flat within .1dB. At 22hz I have a 4dB peak and it slowly rolls off down to 15hz and I didn't measure any lower than that due to not having the test tones at the time.

 

[NDMstang65 10+ year member]

It's known as psycho-acoustics...

You can't hear it, but the vibrations make you 'think' that you can. It is not audible, however your brain is picking up the vibrations of the displacement of air making you think that you are 'hearing' the frequency...when in all reality you are feeling the frequency...not hearing it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif.

 

[azimuth 5,000+ posts]

Which makes that frequency audible as long as there is significant pressure to break the threshold of detection or not. I can detect a 7hz note played in my car with this enclosure much easier than I can with the same sub in a sealed enclosure with more power in the same car and position.
When I say audible, I mean that there is significant pressure to cause my brain to detect a very low frequency. It doesn't matter what part of my body is reporting the frequency, just that it is detected. It does not matter if my hearing starts to roll off around 25hz (which I already mentioned) because I can still detect the signals much lower than that and detection is what it's all about.

This also applies to NDMstang65's post as well.

so you can't technically hear below 20hz. feeling is not hearing. you are detecting the presence of sound, as you said.

 

[Immacomputer 10+ year member]

so you can't technically hear below 20hz. feeling is not hearing. you are detecting the presence of sound, as you said.

Go ahead and build a system that plays flat down to at least 20hz and then tell me the difference between detecting a 30hz signal and a 20hz signal. There is no difference.

when i play a tone below 20hz, it rattles the crap out of the vehicle, but not really any sound. i've probably played subsonic tones on around 10 subs total in my life. never been able to hear them on any sub. i suppose some amps have a built in ssf?

Just because you have not experienced it does not mean it's not possible. Again, the specific sub used is a VERY small part of the equation. Having experience with 100 subs wouldn't make you any more right/wrong. With one specific sub, I have had completely different types of sound and frequency response. I have had cases with this sub where playing 20hz just kind of caused a lot of a excursion and distortion but no surrounding bass presence that the 30-40hz range caused. This is NOT a problem now as 20hz has that tight all around your ears sound as if it's coming from everywhere. It makes you feel like your ears need to pop and be "unpopped" almost constantly.

 

[azimuth 5,000+ posts]

Go ahead and build a system that plays flat down to at least 20hz and then tell me the difference between detecting a 30hz signal and a 20hz signal. There is no difference.


Just because you have not experienced it does not mean it's not possible. Again, the specific sub used is a VERY small part of the equation. Having experience with 100 subs wouldn't make you any more right/wrong. With one specific sub, I have had completely different types of sound and frequency response. I have had cases with this sub where playing 20hz just kind of caused a lot of a excursion and distortion but no surrounding bass presence that the 30-40hz range caused. This is NOT a problem now as 20hz has that tight all around your ears sound as if it's coming from everywhere. It makes you feel like your ears need to pop and be "unpopped" almost constantly.

this has been my experience. would building a system that way be feasable for a daily music system?

 

[Immacomputer 10+ year member]

It's known as psycho-acoustics...
You can't hear it, but the vibrations make you 'think' that you can. It is not audible, however your brain is picking up the vibrations of the displacement of air making you think that you are 'hearing' the frequency...when in all reality you are feeling the frequency...not hearing it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif.

I never said it wasn't psycho acoustics; I know how human hearing works so you're not telling me anything I don't already know. What I don't think you know is that your brain is like a CPU as it works on a digital based logic system. The rest of your body is the analog portions used to transfer electrical signals to your brain. Your brain processes these signals and then it is able to be in touch with its surroundings. Your ears work very well as an analog portion for pressure detection. All your ears do is take a pressure wave and turn it into an electrical signal for your brain to process. Note that your ears do no processing at all as they are strictly analog. Your body can send these same pressure detection signals to your brain if they are of a large enough amplitude. When your brain gets the signals from your nervous system, it can process them them same way it processes the signals from the ear. Basically, your ears do NOT do the hearing, they just convert a pressure signal into an electrical signal. Your BRAIN does all the "hearing".

Bottom line, it comes down to this:

There is a difference between a system that is 20dB down at 20hz from a reference point of 50hz and a system that is 3dB down at 15hz from a reference of 50hz. I have had both setups in the same vehicle changing only the enclosure and difference is HUGE.

 

[Immacomputer 10+ year member]

this has been my experience. would building a system that way be feasable for a daily music system?

Which way? Having the 20hz range be distorted and attenuated? That's not something I want to listen to in music.