Which mfrs?

I have found that that the half a dozen or so Dyn drivers that I have modelled in WinISD end up with box volumes (@Qtc~0.7) that are considerably smaller than what the mfr recommendeds.

 

Ah...then my question changes...why not same as WinISI?

I was speaking of two different subwoofers I'd modeled (10" MB Quart PWE-254 & Alpine SWX-1243D). WinISI modeled both as >3ft^3 enclosures...event the 10". When I called MB Quart, they said 1.25...then I called Rockford, since that model came out when they owned Quart. They said the same thing.

I was thinking it might be because of the cabin gain...that is, you need a bump to even out the low end. ...but perhaps I was giving them too much credit.

 

My thoughts:

Most manufacturers are concerned with the brand image of longetivity, and quite frankly, "bump". You get both in a smaller enclosure, and you get to boast that it fits in a smaller enclosure.

Note that quality subs like AE, Dayton, etc., ... they actually FIT in small enclosures normally.

 

People want the best bass with taking up as little space as possible. If the manufacture recommends a smaller enclosure the sub will be able to handle more power. If you are comparing subs A and B then the sub with the smaller box requirement and higher power handling will probably win.

 

As a friend to another on another forum page that worked at RF ^ is the reason right there. The average Joe that comes in doesn't have a clue to these sort of things so it comes down to the smallest size wins.

 

maybe its because of cabin gain, manuracturers know youll get great perfomance all the way down to 35 hz in a box that has an fs of 45hz

 

It has more to do with the response curve in a vehicle as well as powerhandling. With the transfer function of most cars the low octaves have so much boost that a typical .707qtc enclosure will end up being "overly" strong on the low end. a .8-.9 Q with most drivers does much better in a vehicle.

But in reality you have to consider the vehicle in question. A Civic is going to have a completely different transfer function than an Escalade. The bigger the vehicle, the bigger (or more) subs, and the more you need to bias the box toward low end output, be it running closer to a .707 or lower Q or tuning lower in the case of ported.

 

Durability. A box with too big of a port will unload near tuning, and eventually cook a normal sub, but more port area makes ****ty subs louder. Therefore most SPL or fart boxes have too big of a port, and too small of a box, to counter unloading issues.

I always find it amazing that most sub manufactures simply reccomend box size and tuning, but never port area... My Fi Q for example would unload like crazy with more than 14 sq in of port (per cube), while some of the SPL subs I've had would have port noise in the same box. IMO port area and port construction are hands down more crucial than box size.

 

Preach on brother

It's kinda amazing how little thought is put into ports. They're really quite complex, and one might argue that the engineering behind the port may be more important than your choice of driver!

In other words, a $50 subwoofer from Best Buy with a well-engineered port will outperform a $200 subwoofer from Crutchfield with a mistuned port. IE, one of the main reasons that a lot of people don't like ported designs is that they screwed up the port.

OTOH, I don't agree that a port can be "too big." It all depends on what your design goals are. In most cases, you want a VERY large port, to increase efficiency. There are some cases where you might want to use an under-sized port because the air in the port will become resistive at high SPLs.

But generally I'd use a beefy driver with lots of XMAX and a huge port.

The pic above is a big tapped horn. For the most part, that dude is STANDING inside of the port. I am building one of these with a couple of Diyma 12s for my house, and it's big enough for me to stand inside too

 

has nothing to do with cabin gain, Qtc, transient response ...

Acoustic response is irrelevant. Smaller enclosure means higher power handling. The more "watts" you can print on the subwoofer carton, the higher the sales numbers will be, period.

Welcome to car audio

 

has nothing to do with cabin gain, Qtc, transient response ...

Acoustic response is irrelevant. Smaller enclosure means higher power handling. The more "watts" you can print on the subwoofer carton, the higher the sales numbers will be, period.

Welcome to car audio

Exactly !!!
This is all it has ever been about >>> $$$$$$$$$$$$$$$$

 

Try modeling the box and including a crossover and cabin gain. The "bump" in the response doesn't look like a bump with those two considerations added.

 

I tried a bunch of average mass produced subs in small sealed and ported, forget it. Spend some money or use a bigger box. The only one that came close was a MTX 4510. Yeah, so I bought some pyle 15s...

My car must have no cabin gain, because they sounded far worse than the factory plots for in-car. I could not EQ far enough. I don't have that problem with IB 15s now, and the IB 12s were workable. However the sealed 12s did do spl pretty good I just could not stand the poor response, it was certainly anti-essque.

 

LOL the matterhorn.