Box hz tuning

[argenis69 10+ year member]

Hi, I want to know what's the best clean bass and loudest tuning frequency recommended for a Fi SP4 15" on a 3.5 cu feet flare ported box? Or which flare port is best also? I listen mostly to carribean hispanic music and some hip hop, r&b, etc... Thanks.

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[mazdakid 5,000+ posts]

Loudest and cleanest dont always go together.

What kind of music do you listen to?

 

[argenis69 10+ year member]

Thread updated

 

[Ronny 10+ year member]

Just use either two 4" aeroports or a single 6" aerport and length for 33Hz tuning.

This is 3.5 cubes NET correct? How much power BTW? Or the amplifier and the impedance you plan to wire to?

 

[argenis69 10+ year member]

I have a crescendo bc3500d wired @ 1ohm

 

[Ronny 10+ year member]

Two 4" aeroports would need to be 15.84" with flares.

Single 6" aeroport would need to be 16.6" with flares.

For future reference, this makes round port length related inquiries SO incredibly easy //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif :

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[argenis69 10+ year member]

I doesn't matter what sub it is, its the size of the box that determines the port?

 

[Ronny 10+ year member]

I doesn't matter what sub it is, its the size of the box that determines the port?

Well, for the most part yes. The volume of the enclosure, and desired tuning and response that you would like out of it determines what you would utilize for the specifications of the port.

Now, the driver being used, as well as power being used, play a role as well.

Take your SP4 for example. SP4s are quite capable drivers, they have the ability to move lots of air, and do so with authority because of the power they can handle as well as the "motor force" of the motor of the drivers. Because the SP4 has a lot of excursion capability and handle tons of power and play very low frequencies (and well, heck, meaning for the most part most people will actually give them this power as to get what they are capable out of them - I paid for 540 horses for my car, and you are darn right that I will use the race fuel needed to obtain the power I paid for, so 110 octane it is). So, anyhow, say this driver is going to have LOTS of power going to it, say it is going to be seeing and playing 28Hz in the music quite often, and say you give the driver the proper amount of volume it needs. Now, say that you use a port that is tuned just fine for the music you want to play, so you go an make an enclosure 3.5 cubes net, with a port of say 3" diameter, and the proper length to obtain proper frequency tuning. Just dandy right? Nope. That enclosure might be fine for a 15" HT driver with only 5mm of excursion. It won't be moving too much air, but it will properly reproduce the frequencies needed. But, an SP4 with... Err, iirc almost 40mm of excursion, on 3.5kW, well, that is going to cause lots of PORT COMPRESSION. Uber turbulence and chuffing and horrible performance will be had there. SO, utilizing proper amounts of port area is a big deal. In our hobby, where so many drivers' TSPs are somewhat close between certain types of drivers, we have plenty of starting points essentially. You then go and fine tune you enclosure. Like above, a starting point that I recommended was in regards to port area, for many of us and in our experiences, in any enclosure with capable driver(s) a pair of 4" round with must be flared ports, or single 6" round flared ports work well. But again, it is a starting point. You are always welcome to mess with internal enclosure volume and/or port length. 33Hz for many folks, gives a fantastic balance of being able to pick up the lows many are after, as well as being able to play up to higher notes in order to cross or mesh decently with the mid drivers' frequency response. But the vehicle also changes TONS of characteristics of how a loaded enclosure will react as well. Like in my car, I can tune to 35Hz, and still dig down to 26Hz JUST fine with no (un)loading issues, and play up easily to 65Hz with ease. So, as stated, starting points and/or proven specifications that work just fine, which puts you in a great spot to start messing with the parameters to get the response exactly as you'd like it. I think I may be becoming quite redundant now. There were an incredible amount of points I wanted to make but I'm not too sure I have covered them all lol. Unfortunately I slept 3 hours yesterday, and have been running on fumes now since probably 5pm or 6pm :s Eek!

If you have any more questions, or if I started talking about something and left it open-ended and whatnot et cetera... Please ask or let me know

'Night,

Ron

 

[argenis69 10+ year member]

Ronny, I will pm you later on today.