PDA

View Full Version : Ported enclosure questions



pimpnyou204
06-25-2011, 06:37 PM
I love car audio so I constantly read into things and I have a few questions on some things of what I read and I know some may be repetitive so a simple yes no or true false would suffice and anything else you'd like to add would be very beneficial.

Sub/port on same side of box would a L slot port that goes behind 1 of the motors hinder the sound in the port?

If slot area is generally 12-16 is aero really slightly less with 8-12 per cube?

If tuning high 40+ u go with 16 per cube 30-40hz about 14 and 12 per cube if below 30?

For spl burps you can go in the upwards of 18-20 per cube?

How exactly does tuning above/below and building a box above recommended ts specs affect the overal sound?

Kind of a broad question but.. How is box size relevant to tuning? Big box for tuning low and small box for high tuning..

Buck
06-25-2011, 06:46 PM
Sub/port on same side of box would a L slot port that goes behind 1 of the motors hinder the sound in the port? Not really ***edit, I usually like to not have this happen though.

If slot area is generally 12-16 is aero really slightly less with 8-12 per cube? Yes, but both of these rules of thumb aren't always accurate.

If tuning high 40+ u go with 16 per cube 30-40hz about 14 and 12 per cube if below 30? No.

For spl burps you can go in the upwards of 18-20 per cube? Yes, but testing > theory for SPL.

How exactly does tuning above/below and building a box above recommended ts specs affect the overal sound? What?

Kind of a broad question but.. How is box size relevant to tuning? Big box for tuning low and small box for high tuning.. You can tune a box to any frequency, no matter what size. Large box tuned low tends to have a flatter response. Smaller boxes tuned higher tend to have a peakier response. I like tuning low for daily.

Kangaroux
06-25-2011, 06:58 PM
to elaborate on port area vs. tuning...the lower a frequency the more air it will move. therefore, it would make sense to have more port area to let the air flow freely on a low tuned setup rather than a high tuned setup. not to say you can't have a large amount of port area if youre tuned mid 40's, but it just makes more sense to use that in a lower tuned box

RAM_Designs
06-25-2011, 07:10 PM
to elaborate on port area vs. tuning...the lower a frequency the more air it will move. therefore, it would make sense to have more port area to let the air flow freely on a low tuned setup rather than a high tuned setup. not to say you can't have a large amount of port area if youre tuned mid 40's, but it just makes more sense to use that in a lower tuned box

Actually, for a given excursion you're going to have air moving more rapidly in and out of the port with a higher tuning(makes sense, more cycles per second vs a lower frequency). So theoretically, given the same excursion you'd need less port with a lower tuning in order to avoid port noise. The issue is that with a lower tuning, like 28-30hz, it's easier to hear port noise or vehicle vibrations since that upper 20's to low 30's range(which is where the port will be working the hardest) is where sound starts to go from being audible towards more of a feeling experience.

I do understand your point with a sub moving easier at a lower frequency, but around the tuning frequency the sub won't be moving that much anyways.

pimpnyou204
06-25-2011, 07:11 PM
I mean like if said sub suggested a box be 2-4 cubes and I decided I wanted to get deep lows I'd go with a 4.5 cube box. Would that just be stupid bcuz the box would be too large for the subs to be able to move that much air in the box?

If they suggest a 30-34 hz tuning and u like 36 how is u tunin to that frequency going to change that sound? I guess what I'm saying is tuning far from the speakers fs going go effect the SQ or roll off of the sub

Buck
06-25-2011, 07:13 PM
I mean like if said sub suggested a box be 2-4 cubes and I decided I wanted to get deep lows I'd go with a 4.5 cube box. Would that just be stupid bcuz the box would be too large for the subs to be able to move that much air in the box?

If they suggest a 30-34 hz tuning and u like 36 how is u tunin to that frequency going to change that sound? I guess what I'm saying is tuning far from the speakers fs going go effect the SQ or roll off of the sub


It really depends. Give us specifics.

RAM_Designs
06-25-2011, 07:14 PM
I mean like if said sub suggested a box be 2-4 cubes and I decided I wanted to get deep lows I'd go with a 4.5 cube box. Would that just be stupid bcuz the box would be too large for the subs to be able to move that much air in the box?

If they suggest a 30-34 hz tuning and u like 36 how is u tunin to that frequency going to change that sound? I guess what I'm saying is tuning far from the speakers fs going go effect the SQ or roll off of the sub

Box volume and tuning is going to affect your frequency response. Up the tuning and you get more output, but lose some of your low-end output that you'd have with a lower tuning. Tune low and it's the opposite, you sacrifice loudness in the upper frequency range to be able to reproduce the lower frequencies well.

pimpnyou204
06-25-2011, 07:17 PM
Actually, for a given excursion you're going to have air moving more rapidly in and out of the port with a higher tuning(makes sense, more cycles per second vs a lower frequency). So theoretically, given the same excursion you'd need less port with a lower tuning in order to avoid port noise. The issue is that with a lower tuning, like 28-30hz, it's easier to hear port noise or vehicle vibrations since that upper 20's to low 30's range(which is where the port will be working the hardest) is where sound starts to go from being audible towards more of a feeling experience.


I do understand your point with a sub moving easier at a lower frequency, but around the tuning frequency the sub won't be moving that much anyways.

Makes sense but only thing I'm not understanding about thatis why do u tune low for a hair trick (more air movement) if a higher tune will displace more air at a fast rate?

RAM_Designs
06-25-2011, 07:22 PM
edit

pimpnyou204
06-25-2011, 07:22 PM
It really depends. Give us specifics.

Example:

AQ says to tune 37-40 I'm assuming that's bcuz the natural fs is 41 right? Bcuz they say to tune it at that spot does it mean it will have it's highest peak at that spot if u were to build a box to each frequency? (assuming there was no resonant frequency being involved in a car)

Buck
06-25-2011, 07:27 PM
It would be loudest at if you tuned the enclosure to the subs Fs, I believe. But that's all it is. There are so many other factors.

Slo_Ride
06-25-2011, 07:27 PM
I try not to have the port to close to the sub. I've had problems with the sub unloading if it is to close to the port resulting in mechanical failure.

pimpnyou204
06-25-2011, 07:29 PM
Box volume and tuning is going to affect your frequency response. Up the tuning and you get more output, but lose some of your low-end output that you'd have with a lower tuning. Tune low and it's the opposite, you sacrifice loudness in the upper frequency range to be able to reproduce the lower frequencies well.

Well we know the higher the frequency the more loud to our ears it gets (playable by subs.) for the ppl who tuned real lowish (27ish) , to our ears would that give a more flat response bcuz it would peak low and flatline around 33 and even out the low notes we hear faintly and bring them to the same level a 45hz note plays?

Buck
06-25-2011, 07:29 PM
I try not to have the port to close to the sub. I've had problems with the sub unloading if it is to close to the port resulting in mechanical failure.

This is true.

pimpnyou204
06-25-2011, 07:35 PM
edit

Lol wow I asked aquestion ram doesn't know I'm kinda shocked! But in all serious though aren't most spl comps won at higher frequencies is that bcuz their resonant frequency in the car is that high? If not my thought would be if low tuning is related to more air disruption then that would give u more pressure (spl.) much like a hurricane or tornado when they come by the pressure is much higher. I dont know maybe over analyzing at this point...

pimpnyou204
06-25-2011, 07:39 PM
It would be loudest at if you tuned the enclosure to the subs Fs, I believe. But that's all it is. There are so many other factors.

That was my thought also otherwise their suggested tuning would be solely based on opinion.. It has to be done with real design, tests, and actual advantages no?

Buck
06-25-2011, 07:40 PM
Lol wow I asked aquestion ram doesn't know I'm kinda shocked! But in all serious though aren't most spl comps won at higher frequencies is that bcuz their resonant frequency in the car is that high? If not my thought would be if low tuning is related to more air disruption then that would give u more pressure (spl.) much like a hurricane or tornado when they come by the pressure is much higher. I dont know maybe over analyzing at this point...

It becomes physics at some point. Lower frequencies make vehicles, well, resonate more. Think about how much a vehicle flexes on 30 hz vs. 50 hz. Flex= lost sound. Woofers also have a harder time reproducing lower frequencies than higher frequencies (generally, in my experience).

Basically, hitting higher scores at higher frequencies is easier, that's why I like lows.

Buck
06-25-2011, 07:43 PM
That was my thought also otherwise their suggested tuning would be solely based on opinion.. It has to be done with real design, tests, and actual advantages no?

Yes. Tuning a box to a frequency changes the phase of the frequency that it's tuned to the most. In free air, that frequency would be loudest. The farther away from the tuning frequency you go, the more the phase changes (farther away from 180 degress different than rear wave), which means basically the less sound is produced. That's what a ported box does, if I understand and explain everything correctly. Basically switches the phase of the rear waves of the woofer 180 degrees so that they compliment the front waves of the woofer, thus having more output.

pimpnyou204
06-25-2011, 07:53 PM
Yes. Tuning a box to a frequency changes the phase of the frequency that it's tuned to the most. In free air, that frequency would be loudest. The farther away from the tuning frequency you go, the more the phase changes (farther away from 180 degress different than rear wave), which means basically the less sound is produced. That's what a ported box does, if I understand and explain everything correctly. Basically switches the phase of the rear waves of the woofer 180 degrees so that they compliment the front waves of the woofer, thus having more output.

So in theory minus a vehicles resonant frequency the further from fs u go the less out put u may possibly have? But a speakers sound is created by friction and frequencies are made by the friction why would a lower note cause a sub to heat up more?

Also is it just me but do amps start to clip more at lower notes than higher ones? Or maybe it's just my test tones..

Slo_Ride
06-25-2011, 07:55 PM
Also is it just me but do amps start to clip more at lower notes than higher ones? Or maybe it's just my test tones..

Probably your electrical, may need mo powa!

Buck
06-25-2011, 07:55 PM
So in theory minus a vehicles resonant frequency the further from fs u go the less out put u may possibly have? But a speakers sound is created by friction and frequencies are made by the friction why would a lower note cause a sub to heat up more?

Also is it just me but do amps start to clip more at lower notes than higher ones? Or maybe it's just my test tones..

I don't see what you are saying with friction.

pimpnyou204
06-25-2011, 07:58 PM
It becomes physics at some point. Lower frequencies make vehicles, well, resonate more. Think about how much a vehicle flexes on 30 hz vs. 50 hz. Flex= lost sound. Woofers also have a harder time reproducing lower frequencies than higher frequencies (generally, in my experience).

Basically, hitting higher scores at higher frequencies is easier, that's why I like lows.

Hmm that actually makes a lot of sense bcuz fart boxes tend to never flex just vibrate everything like a *****. But if u deaden your entire car like 8 layers thick and super caulked all your doors and windows you probably would get a much higher score at a lower frequency.

The roll off on a sub playing lower than the tuning would cause the sub to bottom out faster correct?

Buck
06-25-2011, 08:00 PM
Hmm that actually makes a lot of sense bcuz fart boxes tend to never flex just vibrate everything like a *****. But if u deaden your entire car like 8 layers thick and super caulked all your doors and windows you probably would get a much higher score at a lower frequency.

The roll off on a sub playing lower than the tuning would cause the sub to bottom out faster correct?

Yes. The port tends to "unload" under tuning frequencies. Don't know why that is, I just know that it is. So that's why we have the F3 lower, and F3 upper.

pimpnyou204
06-25-2011, 08:01 PM
I don't see what you are saying with friction.

Sounds are made by the motor moving back and forth, this motion causes friction and friction obviously causing more heat. But frequencies (hertz) are measured in the amount of times they move back in forth right? If that's true why would a low note with less motion in the motor cause more heating?

Buck
06-25-2011, 08:03 PM
Sounds are made by the motor moving back and forth, this motion causes friction and friction obviously causing more heat. But frequencies (hertz) are measured in the amount of times they move back in forth right? If that's true why would a low note with less motion in the motor cause more heating?

There isn't any friction in the woofer. The coils slides in and out of the gap (:naughty:).

I'm not sure with your question, but maybe it has to do with the fact that air is being cycled less, thus having less air around the coil. Just a guess and just a thought. Take it with a grain of salt.

pimpnyou204
06-25-2011, 08:04 PM
Yes. The port tends to "unload" under tuning frequencies. Don't know why that is, I just know that it is. So that's why we have the F3 lower, and F3 upper.

How much below tuning can u go before needing to filter is that dependent on variables? F3 upper/lower? new subject to discuss lol

Buck
06-25-2011, 08:06 PM
How much below tuning can u go before needing to filter is that dependent on variables? F3 upper/lower? new subject to discuss lol

That can be calculated, but, according to my experience with winisd, you can usually play 3 or 4 hz below tuning frequency. But it all depends on what you are tuned at. The lower you tune, the waves get exponentially longer, making the difference from 50 to 49 much less than 30 to 29.

pimpnyou204
06-25-2011, 08:13 PM
So it's better to tune lower if u want to cover more frequencies bcuz u can always cover the higher ones but the lower u go with a higher tuning u risk bottoming out?

Buck
06-25-2011, 08:15 PM
Yes. Tuning lower will allow you to play lower. That's why I'm tuned at 27 hz (was supposed to be 28hz, but port was a lil smaller, etc).

Generally a larger box with lower tuning with have a flatter frequency response.

pimpnyou204
06-25-2011, 08:24 PM
But all with a loss of some spl correct?

Last thing.. Is it true that the fewer amount of ports will creat less turbulence than one larger one of equal area?

RAM_Designs
06-25-2011, 08:36 PM
Last thing.. Is it true that the fewer amount of ports will creat less turbulence than one larger one of equal area?

More often than not one port is more ideal than multiple smaller ports that equal the same port area as the larger one.

Buck
06-25-2011, 08:44 PM
I like one big port usually. Once again, not going of technicalities, but with people that have more knowledge than me- multiple ports can cause some minor cancellations.

pro-rabbit
06-25-2011, 09:15 PM
I like one big port usually. Once again, not going of technicalities, but with people that have more knowledge than me- multiple ports can cause some minor cancellations.
Smaller ports will change your tuning do to the flow of air(forcing out of a smaller area). This is generally speaking of course.

pimpnyou204
06-25-2011, 09:30 PM
So it is true larger is generally better thanks a lot for the info guys especially buck

Buck
06-25-2011, 09:32 PM
Yes, I usually use 1 port for my designs, give that it's a slot port.

pimpnyou204
06-25-2011, 09:42 PM
Have any of u mounted a aero by it's tubing and not the mounting flare?

Like if u are short of mounting a port by like a half inch on a side so u mount it by the tubing part of it and the mounting flare is sticking out about an inch away from the box mdf? Or would u assume the outside flare would block the subs air dispacement?

Buck
06-25-2011, 09:49 PM
Have any of u mounted a aero by it's tubing and not the mounting flare?

Like if u are short of mounting a port by like a half inch on a side so u mount it by the tubing part of it and the mounting flare is sticking out about an inch away from the box mdf? Or would u assume the outside flare would block the subs air dispacement?

I would try to avoid a situation like that.

elancohen92
06-25-2011, 10:02 PM
I mean like if said sub suggested a box be 2-4 cubes and I decided I wanted to get deep lows I'd go with a 4.5 cube box. Would that just be stupid bcuz the box would be too large for the subs to be able to move that much air in the box?

If they suggest a 30-34 hz tuning and u like 36 how is u tunin to that frequency going to change that sound? I guess what I'm saying is tuning far from the speakers fs going go effect the SQ or roll off of the sub

just because you like a 36hz tuned box on a specific sub doesnt mean you like a 36hz box. you liked that sub at 36hz. the same box with a sub that has completely different TS specs will sound much different.