Air free sub

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Here IB or free air is always IB install far as I know. If you want cheap, I mean cheap, try the pyramid originals in the blue paper cone. They don't take much to get going and wont take anymore once they bottom. I like
this place. I'm going to try them, had good luck a long time ago with them and they look close to the same build but not 100% sure. Otherwise many will work but it is still a bit of a guessing game. Plan on using as many as will fit if you want more output, I have 4 infinity 12s that work well. Actually they overpower the rest of the system but is a heavy rig. Most subs will take about half of their RMS rating running IB. I only have 420rms on these 4 but can't max them out either; they are rated 300rms- so 150rms IB running at 100 each.

I used to run the pyramid 10s one or two pair on a 2x75rms amp. That could max them out and they went pretty loud for music. They could hit 30hz but hard to get under that, but sounded good. May have to experiment with crossover slopes.
 
luka said:
Hi

What do you mean? They all can be free air, but won't produce any sond... Unless I don't understand what freee air sub is...:xeye:


Free air is simply Infinite Baffle which is exactly the same as a sealed box only much larger (if done properly).

I have used lots of different drivers in Free Air setups as they generally have a better (flatter) frequency response, though less output, and generally will play lower than a normal small sealed box.
I have used a pair of Kicker f10a's which were designed for free air installs and more recently a pair of Orion 2nt10dvc's which worked very well.
I have also used Orion Xtr15's and these also worked well.

Most subs will work well if they are not meant for extremely small sealed boxes, you just need to seal the front from the back for best performance.
 
Like mentioned before, alot of the real cheap (like $20) subs from Pyramid, Pyle etc have ridiculously high Qts (like .8+) and would probably work OK in an OB/free-air type application.... But these are still $20 subs, so I wouldn't expect any miracles... Thier Qts are usually very high due to the fact that they don't have enough motor strength for thier given size.... Not because they were intended to be a high Q driver... They just really ended up that way...
 
It is a trade off; you get a higher Q driver real cheap and they tend to be more efficient (but maybe not at the lowest frequency, and can be harder to crossover due to more roll off on bottom), but are cheaper and need less amp to run. You said cheap;) My subs peak at 30-35Hz and blend at about 60 then I can't hear them anymore with test tones. I ended up with them because Infinity actually says IB use is ok in the manual, and got a good deal on them

Also depends on the car a lot, some cars IB rules and others it takes work to get it going good. In the rear deck of a large car they usually shine. Mine are into the rear seat that is why I went with 4 to make up for any loss but it sounds 98% the same with the seat out in testing. If I put some stuff in my trunk I lose 20Hz. I think I have 14cf so 3.5cf per 12" sub, if you model that you will see 20Hz dropping off when you go much smaller than that.

In my experience a large amp can hurt performance of them though not as much with a higher wattage driver w/more xmax. Reason is because a large amp with more headroom can more easily bottom the sub on a loud hit, while the smaller amp will tend to play louder without doing that. However some amps appear to have more control over the subs, I have researched and not found a good explanation for that but could be how the amp clips. I swap amps a lot with IB. I'm not so sure about the more HD lower Q subs I have now, they take more power and don't seem to go a lot louder than other setups with small amp/light driver. These dig deeper without as much effort. A parametric EQ can help a lot with tuning them in, even a good EQ and/or variable crossover slopes also help if they are not right. That is more of an issue the higher Q you go.

You can model IB with a huge sealed box to get an idea of response, but you still have cabin gain to add to it. The more roll off they have the less db you get at lowest frequency, I like them low so that is why I try to run 4 subs to get db back. It is still much smaller than a box w/equal output, of course you can hardly run one driver in that size box and get the same low end extension. On the other hand I don't really want heavy subs and big amps if I don't need them. Requires more power and the stuff gets big and heavy in there. If you want super high output then IB is not what you are looking for but it can be impressive for music and some of mine would carry for a mile. No kidding, and that with only 4 cheap 10s.

Used to be you had to run high Q so the cone could stay in control of itself without a box. But now if you take a low Q driver good for 800rms+ and run much less into it IB it will work fine because it is so heavy duty (the suspension). They are doing that in HT. They tend to be expensive though. Some run one 15 or 18" and it is working well. Dayton also has an IB sub I have not seen before, but it does roll off pretty good on its chart.
 
Not exactly low $$$, but very good quality.

http://www.partsexpress.com/pe/psho...nfinite baffle&CFID=30766080&CFTOKEN=21173700

Fi also makes a 15" and an 18" specifically for IB installations. Again, not low $$$.

http://www.audiojunkies.com/blog/866/fi-infinite-baffle-subwoofers

And another.

http://www.aespeakers.com/drivers.php?driver_id=8

I'm of the opinion that using anything other than a driver specifically designed for IB is a mistake, IF optimum performance is desired. If that is not the directive, then the choices are many.

Also, "inexpensive" has a different meaning to all of us.

For myself, the initial cost is only part of how "expensive" something is in the long run. Some things are not a bargain at any price.
 
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