subsonic filter
09-30-2005, 06:49 PM
#41
1000 Watt CAFz'r
Join Date: Aug 2001
Posts: 1,770
Originally posted by Car Trek:
As the input signal drops below the tuned frequency two factors occur.
First: the excursion of a driver is inversely proportional to the frequency....the lower it goes, the more it must move to achieve the same output.
As the input signal drops below the tuned frequency two factors occur.
First: the excursion of a driver is inversely proportional to the frequency....the lower it goes, the more it must move to achieve the same output.
09-30-2005, 09:17 PM
#42
500 Watt CAFz'r
Join Date: Oct 2004
Posts: 870
that also happens when you go up in frequency as well
Excursion may increase as you rise in tone from the tuned freq, but only as a function of the removal of the port effect.
The higher the tone, less excursion is required to achieve the same output.
You are getting a double whammy below the port, causing excursion to rise beyond what should be there in the original signal.
Anyway....it is just a theory....if anyone can mix a subsonic tone with an audible tone, and play them through a ported sub, a difference will either be heard and measureable or not, when switching the filter in and out.
If it can't be detected at all, then I guess I'll owe ya all a brewski [img]tongue.gif[/img]
In the meantime, I'll keep selling the F-Mods.
[ September 30, 2005, 10:27 PM: Message edited by: Starterwiz ]
09-30-2005, 10:13 PM
#43
500 Watt CAFz'r
Join Date: Oct 2004
Posts: 870
Originally posted by DWVW
I'd agree with that.
Harmonic distortion is fairly easily tolerated, as it is essentially the same note....just octaves apart.
That fact lets you pull an extra 3-6dB from a sub amp, by driving it into clipping (the square waves from a clipped fundamental are composed of all the harmonics of the fundamental note) without noticing the distotion.
Intermodulation distortion is far more noxious to the ear, (try playing two adjacent piano notes together...very "sour") and can be heard at much lower percentages.
Funny, but I haven't seen IMD mentioned for years...at least not in car audio specs.
Most people start hearing distortion at about 10% with a full range music signal.
Harmonic distortion is fairly easily tolerated, as it is essentially the same note....just octaves apart.
That fact lets you pull an extra 3-6dB from a sub amp, by driving it into clipping (the square waves from a clipped fundamental are composed of all the harmonics of the fundamental note) without noticing the distotion.
Intermodulation distortion is far more noxious to the ear, (try playing two adjacent piano notes together...very "sour") and can be heard at much lower percentages.
Funny, but I haven't seen IMD mentioned for years...at least not in car audio specs.
10-01-2005, 09:46 AM
#44
500 Watt CAFz'r
Join Date: Mar 2005
Posts: 884
I personally do not like to use subsonic filters..... I could see maybe for like in the old days when turntable rumble gets recorded onto cassette tapes, and needs to be filter out to be played at high level.
With CD...... It has limited bandwidth at 20 hz and in a car. As soon as the windows are up. preasure in front of the cone or port limits the lowest octave anyways. Unless you have a ported box.... tuned to 45 hz then anything below that would not load the driver and will needs to filter out. Ultimately is to use a sub system thats plays low and has good trancient response...... which are the sealed or AP type enclosures.
[ October 01, 2005, 10:48 AM: Message edited by: SweetnLow91SC ]
With CD...... It has limited bandwidth at 20 hz and in a car. As soon as the windows are up. preasure in front of the cone or port limits the lowest octave anyways. Unless you have a ported box.... tuned to 45 hz then anything below that would not load the driver and will needs to filter out. Ultimately is to use a sub system thats plays low and has good trancient response...... which are the sealed or AP type enclosures.
[ October 01, 2005, 10:48 AM: Message edited by: SweetnLow91SC ]
10-01-2005, 10:03 AM
#45
1000 Watt CAFz'r
Join Date: Aug 2001
Posts: 1,770
Originally posted by Starterwiz:
</font><blockquote>quote:</font><hr />that also happens when you go up in frequency as well
</font><blockquote>quote:</font><hr />that also happens when you go up in frequency as well
Excursion may increase as you rise in tone from the tuned freq, but only as a function of the removal of the port effect.
The higher the tone, less excursion is required to achieve the same output.
</font>[/QUOTE]ya and and the port is also the reason for the rise below the freq
what box program do you use?
10-01-2005, 11:51 AM
#46
500 Watt CAFz'r
Join Date: Oct 2004
Posts: 870
I use Boxplot2 currently, though I used to have Leap, and found it to be the best.
When I first started out, I did all the math with a pen paper, and a calcualtor, but I doubt if I'd even know how any more. Talk about workin with a rock and a piece of flint LOL.
Used to take a good hour or so to get a place to start....and then redo it all 3 or 4 times to adjust volumes and port sizes.
When I first started out, I did all the math with a pen paper, and a calcualtor, but I doubt if I'd even know how any more. Talk about workin with a rock and a piece of flint LOL.
Used to take a good hour or so to get a place to start....and then redo it all 3 or 4 times to adjust volumes and port sizes.
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