Okay so i'm designing my box for the 2nd Gcon 15'' and i'm thinking about going with 10^3ft box and i wanna know what a recommended tuning for it would be and how i would measure the port hole.

Recommended was between 28-33hz and the recommended optimal ported was 4.00-6.00ft cubed per sub. let me know

Tuning is preference based, generally based on misconceptions as to what is best for daily, so I won't suggest much there.

10ft^3 is pretty big, so be sure you don't need the space.

Volume = width * height * depth. Take into consideration the wood thickness. IE: using 0.75" MDF, and making a 12"x12"x12" box would be 12 - 0.75 - 0.75 = 10.5" 10.5"^3 = 1157.625 in^3

Divide 1157.625 by 1728 to get cubic feet. You end up with 0.669921875 ft^3

Don't forget about the displacement of an additional panel for "double baffle" if that's done, driver displacement, bracing displacement, and port displacement.

Port area for a slot port is width * height, or 3.14*radius^2 if using an aero port. Port length will dictate the tuning, but it's also dependent on the enclosure volume, so if your off on the volume, then your tuning will be off as well.

I would choose the amount of port area based on the port speed when modeled in a program such as WinISD. Too small port = port noise & possible reduction in output.

Hopefully this gets you started, and others can chime in on other specifics such as how much port speed is acceptable, or how to calculate for port displacement.

Don't be afraid to use the search function.

Well yes i mean at 10.5^3ft it will work out well since the minimum for optimal ported is 8.00^3ft so that gives me the space for that extra .75in that the Board will take away

also the box isn't gonna be 12x12x12 its gonna be different dimesnsions to make it more convenient for the space its fitting into.

also the box isn't gonna be 12x12x12 its gonna be different dimesnsions to make it more convenient for the space its fitting into.

I said "IE," in example. I'm not going to do everything for you.

Haha i figured you were using it for example bro. haha but here this is what im thinking of.

Dimensions of H= 2' | L= 3' 3.5'' | w= 1' 3.5"|

Edited June 28, 201213 yr by Austin863

Dimensions of H= 2' | L= 3' 3.5'' | w= 1' 3.5"|

39.5" width, 24" height, 15.5" depth

After subtracting 0.75" from depth of the enclosure for accounting for double baffle, you'd get: 6.55599ft^3

Then port displacement, and you'll be well under 5ft^3

yeah i mean i can go more width or height or length. i mean what do you suggest more width would be my guess right?

yeah i mean i can go more width or height or length. i mean what do you suggest more width would be my guess right?

Whichever makes better use of the space in the vehicle.

yeah i mean i can go more width or height or length. i mean what do you suggest more width would be my guess right?

Whichever makes better use of the space in the vehicle.

well its going in my van so probably width. Can you explain to me more what port speed is and all that stuff i'm learning yet and i am not sure what that means

yeah i mean i can go more width or height or length. i mean what do you suggest more width would be my guess right?

Whichever makes better use of the space in the vehicle.

well its going in my van so probably width. Can you explain to me more what port speed is and all that stuff i'm learning yet and i am not sure what that means

Vent mach / Port speed is the speed at which air is being excited in the port(s). An increase in port area causes this speed to go down. If you don't have enough port area, the speed will be too high, and the port can cause audible noise (ie: chuffing sound), and it can also limit potential output (loudness) due to port compression.

As to what an acceptable port speed thus port area is, it's going to vary from one person or program to another. Generally in car audio you can get away with a higher port speed because the enclosure is in the cargo area or trunk, so the port noise may not be heard, and a smaller port is often times easier to fit for those who want to tune "low."

You can copy all the T/S specs of the ssa gcon into WinISD (google it), input your box specs, and it'll show the vent mach / port speed. Depending on the version of WinISD you have, it may show the results as a decimal, and in that case, it suggests staying under 0.15 Which is 15% of the speed of sound, so in meters per second, 340.29*0.15 = 51 m/s or in feet per second 1126*0.15 = 169 ft/s

I've read on forums where others thought one should stay under even less, and I've read a few papers that suggested under 10 m/s, but they were also geared toward Home Theater then car audio.

If you use flared aero ports then you may be able to get away with less port area then you would require with a traditional slotted port, but they are also relatively pricey compared to a sheet of mdf.

Okay i see what you mean cool thanks man ill take that knowledge im gonna jump over there to that WinISD

how do you work this WinISD?

I believe it has a help section. If not, search the forum / Google.

Somewhere around 55 sq in will be fine...depending on power. With less than RMS you can go lower and vice versa.

It will be at exactly what the RMS is required 1500 @ 750 a piece @ 1 ohm on the amp.

My port may be conservative, you should hear port noise and if you do it shouldn't be bothersome. Mid 30's for Mach at full gain. If you really run out of space you could make it smaller, but I wouldn't make it all that much.

Please just remember that the driver RMS isn't a requirement, in fact it has nothing to do whatsover in how much power you may need...

Yes, but my amp is going to run both the drivers at 750w a piece its a AP15001D so it will be at 1 ohm running both of the drivers at 1500w. thats just how we are gonna have it set up

Yes, but my amp is going to run both the drivers at 750w a piece its a AP15001D so it will be at 1 ohm running both of the drivers at 1500w. thats just how we are gonna have it set up

You may have your drivers and amp wired that way, but your drivers will rarely, if ever, see 750watts each.

Modeling for vent mach using 750watts will put you on the safer side of this, because in reality you'll have less power, less air displacement, and thus less vent mach. As suggested above.

If you would like to know why your speakers won't be seeing 750watts very often then I, or others can explain, otherwise I'll save myself the typing.

I would like to know haha curious.

According to Ohm's law I = V / R where I is current (amperes), V is volts, and R is resistance (ohm), we can derive Power (watts) = voltage * current.

As impedance (ohm) increases, current (amperage) lowers, so you end up with less power (watts).

Now you should be thinking: "But hey, my speakers are wired to 1ohm, so impedance isn't changing."

The voicecoil(s) in speakers are coils, and they have a nominal resistance measured in DC (this will be the Re value in the T/S specs of the driver), but this resistance changes when it's in an AC circuit. The reason it's not referred to resistance in an AC circuit is because it does change as it's actually a function or ratio in relation to the voltage and current.

As the voice coil heats up, impedance increases, and less current can "flow." So you could play a constant sine wave, and in the first two seconds measure 100watts, but in ten seconds, only 70watts.

Also, as frequency changes, impedance changes, and sound is composed of tons of different overlapping frequencies.

The speaker enclosure will also effect impedance in conjunction with frequency.

You may have seen graphs or models of impedance vs frequency for a specific speaker or enclosure design, they are never flat lines, nor are they exactly linear either.

So unless your playing constant sine waves all day, the impedance in the circuit for the amp's output is constantly changing, and thus the power output is constantly changing.

Don't fret about matching amp power ratings to speakers' RMS values. Just another thought to consider: You need to double power in order to increase loudness by 3dB, and that would be with an 100% efficient speaker, and depending on the frequency, 3dB isn't much of a change to the ear--if any.

----

I'm sure someone else can better explain, or correct any flaws above, but hopefully you get the jist of it.

According to Ohm's law I = V / R where I is current (amperes), V is volts, and R is resistance (ohm), we can derive Power (watts) = voltage * current.

As impedance (ohm) increases, current (amperage) lowers, so you end up with less power (watts).

Now you should be thinking: "But hey, my speakers are wired to 1ohm, so impedance isn't changing."

The voicecoil(s) in speakers are coils, and they have a nominal resistance measured in DC (this will be the Re value in the T/S specs of the driver), but this resistance changes when it's in an AC circuit. The reason it's not referred to resistance in an AC circuit is because it does change as it's actually a function or ratio in relation to the voltage and current.

As the voice coil heats up, impedance increases, and less current can "flow." So you could play a constant sine wave, and in the first two seconds measure 100watts, but in ten seconds, only 70watts.

Also, as frequency changes, impedance changes, and sound is composed of tons of different overlapping frequencies.

The speaker enclosure will also effect impedance in conjunction with frequency.

You may have seen graphs or models of impedance vs frequency for a specific speaker or enclosure design, they are never flat lines, nor are they exactly linear either.

So unless your playing constant sine waves all day, the impedance in the circuit for the amp's output is constantly changing, and thus the power output is constantly changing.

Don't fret about matching amp power ratings to speakers' RMS values. Just another thought to consider: You need to double power in order to increase loudness by 3dB, and that would be with an 100% efficient speaker, and depending on the frequency, 3dB isn't much of a change to the ear--if any.

----

I'm sure someone else can better explain, or correct any flaws above, but hopefully you get the jist of it.

okay i understand so basically you're sub is going to see a range of different amounts of watts. i gotcha. not just a constant 1500w alright

According to Ohm's law I = V / R where I is current (amperes), V is volts, and R is resistance (ohm), we can derive Power (watts) = voltage * current.

As impedance (ohm) increases, current (amperage) lowers, so you end up with less power (watts).

Now you should be thinking: "But hey, my speakers are wired to 1ohm, so impedance isn't changing."

The voicecoil(s) in speakers are coils, and they have a nominal resistance measured in DC (this will be the Re value in the T/S specs of the driver), but this resistance changes when it's in an AC circuit. The reason it's not referred to resistance in an AC circuit is because it does change as it's actually a function or ratio in relation to the voltage and current.

As the voice coil heats up, impedance increases, and less current can "flow." So you could play a constant sine wave, and in the first two seconds measure 100watts, but in ten seconds, only 70watts.

Also, as frequency changes, impedance changes, and sound is composed of tons of different overlapping frequencies.

The speaker enclosure will also effect impedance in conjunction with frequency.

You may have seen graphs or models of impedance vs frequency for a specific speaker or enclosure design, they are never flat lines, nor are they exactly linear either.

So unless your playing constant sine waves all day, the impedance in the circuit for the amp's output is constantly changing, and thus the power output is constantly changing.

Don't fret about matching amp power ratings to speakers' RMS values. Just another thought to consider: You need to double power in order to increase loudness by 3dB, and that would be with an 100% efficient speaker, and depending on the frequency, 3dB isn't much of a change to the ear--if any.

----

I'm sure someone else can better explain, or correct any flaws above, but hopefully you get the jist of it.

okay i understand so basically you're sub is going to see a range of different amounts of watts. i gotcha. not just a constant 1500w alright

Yes, the maximum output of the amp will be lower then it's rated 1500w because the impedance will be higher then 1ohm, and of course, music is dynamic.