97 GTP box

[moparerrnocar 10+ year member]

Edit;

actually w/ my box vol. at 3.11 I get 42hz. The calculator is a backwards, I had to guess my hz to match my length of 12.25

Port width 3" Port height 11.5" Box vol 3.11 Tuning freq 42hz Port length 12.09"

 

[Joseph7195 10+ year member]

I think you have the right idea, but are you calculating a box for one or two subs. If it's for two subs then you have to adjust for a middle divider and 2 ports (one on each chamber). I think i may have missed a post or two. I am gonna take a look again, no need in me messing you all up when you worked so hard for your calculations

 

[moparerrnocar 10+ year member]

The box I'm currently figuring out is the second box in the pix w/ the sony's. The box I'll be building will be shared chamber w/ a single shared slot port for two 12" type R's.

 

[Moble Enclosurs 10+ year member]

First thing first. What it should be tuned to is 41.35Hz. So your 40-42Hz is ok. Next, as far as box and port, That I have figured as 4.85 cubic ft and port of 14x7, at 19.25". Now, as for what you have, it is tuned to 40hz with those drivers installed. But my recommendations will give you 2-3dB increase from 36hz up mainly around 37-42hz and a decibel or two for the rest of the response. Phase response is also smoother than your current box. my recommendations are 0 degree at tuning, while yours is around -45degree but since your port is on the same baffle as the drivers, this causes phase issues-very minor, but you can hear the difference. Its the exact difference that makes a custom box sound "better" than a prefab. Also, the custom design give less of a load on the amp, for better amplifier cooling and likely less distortion in the process over time. Efficiency also rises. So, you see, this is why custom designs can be better overall. Its sometimes not something you hear, but other parameters, such as loading, efficiency, and distortion are better as well. Hope that helps.

 

[moparerrnocar 10+ year member]

So your recommending a 4.85 Ft^3 @ 41.35hz w/ a 7x14x 19.25 port? I can only go as tall as 11" if I use 1" MDF. You said subs back(towards trunk)/port passenger? I dont think a side port would do so good. There's .25" gap between my box and shock tower side to side. Box=36" Towers= 36.5". Id like to keep it at 36" so it stays securely snug when driving like a jackass. Basically 36wide and 13tall is what i have to work with. Why do you recomend such a high tune freq?

 

[Moble Enclosurs 10+ year member]

Ok, so 11x8.9" port. And I didn't mention driver/port placement yet. I also said nothing about a side port. And third, do not drive like a jackass....4th, recommended tuning is not high. It's just not stereotypical tuning (i.e. 33-34hz). last, I recommend it because that is what the driver likes, not me.

 

[moparerrnocar 10+ year member]

My bad I thought you did, I miss understood the phasing issue because of my port being on driver side baffle. The rest of what you said in that reply was all over my head and hard to read. So how long should the port be? What type/placement/orientation do you suggest. Btw, you dont buy a GTP to drive diligently lol. I just dont want a 100lb box shifting back and forth effecting the handling or balance of the car on an aggressive corner like an on ramp or twisty road for example.

 

[moparerrnocar 10+ year member]

Also, I thought a box design is based on the type of music, power, application. Not solely on what the driver likes. The driver might like techno, that doesn't mean I like techno lol. My subs like screwed and chopped, quaking bass, as do I //content.invisioncic.com/y282845/emoticons/redface.gif.62fdbfe1a101588a808c4cff71bcb942.gif. Just saying.... Not to mention, I dont think I have the room for that big of a box @ that high of a freq. Call it sterotypical, but 4-4.5 @ 30-33 hz seams to be the norm for 12's. Let me know what the box dimensions would be for a 4.85 @ 41hz. I just dont think its going to fit unless I build the box in the trunk ha.

 

[Moble Enclosurs 10+ year member]

Thats kewl. all of those factors would depend on too much for me to give a general answer and be comfortable with it yet. Are you looking at doing another box and getting rid of what you have? If so, you can purchase a design, and I can figure all of that out for you. And about the car....thats kewl, as long as you dont live by me, lol. I have kids to keep safe. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif But yea, mounting the box is always a good idea anyhow, so I understand what you mean. So, just let me know if you are interested!

 

[Moble Enclosurs 10+ year member]

Also, I thought a box design is based on the type of music, power, application. Not solely on what the driver likes. The driver might like techno, that doesn't mean I like techno lol. My subs like screwed and chopped, quaking bass, as do I //content.invisioncic.com/y282845/emoticons/redface.gif.62fdbfe1a101588a808c4cff71bcb942.gif. Just saying.... Not to mention, I dont think I have the room for that big of a box @ that high of a freq. Call it sterotypical, but 4-4.5 @ 30-33 hz seams to be the norm for 12's. Let me know what the box dimensions would be for a 4.85 @ 41hz. I just dont think its going to fit unless I build the box in the trunk ha.

Both. The recommendations are just that......recommended for optimal performance. The listener creates a less than optimal configuration everytime, because everyone is different. But yes, it is taken into consideration. The recommendations, just as any, are for a basis, and will likely always be altered for a specific listening preference, BUT a basis is always best to use as it allows the driver to be controlled the way it was meant to. You dont want to put a 10" sub in an 8 cubic ft ported box just because you want to play below 20Hz.it will unload at high power, no question. So, given the driver recommendations (my own calculations), we can keep tuning controlled as well as all other factors by basing the changes from basis parameters.

As far as "norm", I do not base anything on "norms", but individual preferences and off of correct acoustics for safe operation of the driver and proper loading and acoustical performance. You would be surprised how many people come to enjoy the sound of a properly designed subwoofer box above 40Hz tuning.....even some at 50. The designs at the clubs, and concerts are not even designed to perform with efficiency below 50hz, even though it feels like it. It just happens that a lot of people like 30-33hz for low end sound, but this is not always recommended. And in some cases, tuning as low as 30 can ruin the efficiency of the design, depending on the preferences, variables, and limitations of course.

By the way, where do you plan on building the box, if not in the trunk? And again, I cannot give anymore information about a design without a purchase of a design.

 

[moparerrnocar 10+ year member]

I cant reply w/o a deposit to my paypal.//content.invisioncic.com/y282845/emoticons/santa.gif.e1ec9cf2e0a0dd232ad35aa594a126d0.gif

 

[Moble Enclosurs 10+ year member]

I run a business. If i give everyone all my information for free, what use would I be over time and what would I gain from my hard work? The information I have, and use, is not something taught from a google search bar. I am a college and military educated acoustical engineer. Do you expect me to work for free all the time? Im not on here to joke around, I am on here to help people, but my time and effort is worth a price as it should be. Everyone should be glad it is so inexpensive. For the work I do, I can charge much more based on average labor and material costs and markup values for a profitable business. I do not use generic calculators. I do not use anything from anyone but what I have came up with and what physics allow me to utilize, along with specific formulas that have been proven effective in audio reproduction that cannot be altered in its purpose. I wrote two programs for my calculations and use them for deciding enclosure specifications ALL based on pre-handwritten calculations. It's not as simple as, "make it 4 cubes and tune it to 33 hz and put a lot of power to it and you will be fine". I am not that type of designer, or I would not be accurate. If you are looking for free and simple, then we have nothing else to discuss, I'm sorry. I have given out free designs before, but that is my option and right to do that at will. And it is not without gaining recorded information for improving my calculations either, if need be....or testing them out if they are new. By doing free designs every now and then, I improve efficiency as I am testing at the time I offer them, and it helps others later in the future and my business with speed and accuracy. Nothing i do is technically free, nor should it be. I'm sorry if you assumed I was anything else but a business on here. I am compassionate, but still professional. So, if you want my help further, yes, "I can't reply w/o a deposit to my paypal". I was send here from a good friend to help you and I have as much as I can with information unless you ahve more questions, but for getting specifications from me any further will come as a purchase of my time and skills.