PDA

View Full Version : Hz tuning, okay whats the deal...

Demi
12-20-2006, 07:54 PM
Alrighty so ive been reading, and trying to educate myself of proper box construction. Been reading the Car Stereo Cookbook. To calculate port tuning frequency it states Fb = 0.39Fob, where Fb is tuning frequency and Fob = Fs/Qts, suggesting that tuning frequency is not a flexible number. Alot of people recommend 32hz for 12" type Rs. Im wondering where are these numbers coming from? What are the advantages of tuning lower or higher? By the formula 26hz is ideal. How do you guys get your numbers from the T/S?

Volenti
12-21-2006, 02:54 AM
Think of that formula as a starting point, there's lots of old "rules of thumb" like that that can keep you out of trouble if you are otherwise unsure, but when you understand how everything works together you can stray from that path and forge your own.

LinxuS
12-21-2006, 02:59 AM
It's something to do with your cars Resonance Frequency? Not sure if that's the right word.

Demi
12-21-2006, 05:48 AM
Think of that formula as a starting point, there's lots of old "rules of thumb" like that that can keep you out of trouble if you are otherwise unsure, but when you understand how everything works together you can stray from that path and forge your own.

I see, but what is the advantage from going higher or lower?

Volenti
12-21-2006, 09:19 AM
In very general terms tuning higher gains you more spl over a given range at the expense of low frequency extension, and tuning lower gains you more low frequency extension at the cost of peak spl.

When you combine different tuning points with different enclosure sizes you end up with many different options that you can utilize to get the in-car response you want (or at least as close to it as you can)

This is where enclosure modeling comes in, with experience, you can combine all these factors so the response curve you end up with is something that you know will sound right in the car.

Unfortunatly it can be difficult for a novice to know what curve will sound good and what won't, this is compounded by the "ideal" curve changing depending on what car you're in and where the enclosure is placed in the car. (and your specific performance requirements)

Demi
12-21-2006, 01:06 PM
In very general terms tuning higher gains you more spl over a given range at the expense of low frequency extension, and tuning lower gains you more low frequency extension at the cost of peak spl.

When you combine different tuning points with different enclosure sizes you end up with many different options that you can utilize to get the in-car response you want (or at least as close to it as you can)

This is where enclosure modeling comes in, with experience, you can combine all these factors so the response curve you end up with is something that you know will sound right in the car.

Unfortunatly it can be difficult for a novice to know what curve will sound good and what won't, this is compounded by the "ideal" curve changing depending on what car you're in and where the enclosure is placed in the car. (and your specific performance requirements)
Okay im learning that with playing with WinISD. Ive found the the design im using right now for my 12" Type-x really has a high slp peak for around 45hz. As in like +5.5 dbs, but the downward slope is really steep. It explains alot why i can listen to a song and the bass will be hitting good and then suddenly there is a bowel destorying note out of nowhere. I love how loud it gets but i dont like the unevenness of it, it makes a lot of songs sound strange, like my sub has no range. I can handle a -5db drop for a more flat response. Guess ill just have to add another sub....

Oh for you SPL guys with type-Xs seems that 6 cubes @ 38hz almost a 11Db gain at 45hz. Which is madness.

Guess it really depends on what you listen to, rap in deafening on this setup, but rock is all over the place.

96civ
12-22-2006, 12:39 AM
WinISD is an approximation -- don't take it as your car audio software bible, but it does give you a good idea of the output without any information about cabin gain, which is hard to account for in your box.

Demi
12-22-2006, 09:22 AM
Is there anyway to have an idea?