someone finally explaines corner loading

The RC posts are by Richard Clark


But there are some ways of getting a good deal more output from a car sub. Down fireing and corner fireing are two ways to do this. With this driver I would leave at least 3 inches between the baffle and the floor of the car because of the greater than 1 inch of excursion. Personally I would mount it in the back of the trunk firing into a well damped rear fender or down with a slight upward and forward angle. You can slot load it by covering 1 or more of the sides. But I think the rule of thumb is that the area of the vent should be at least 1/3 the cones Sd. I have my wife's brahma 10 in my trunk fireing into the rear fender now. It's significantly more powerful in this position than 180 degrees the other way, and likewise fireing upward. And even seems a little better than angling slightly to the rear of the trunk. Probably because my fender is damped better than the trunk lid. ... jmaxima


jm----the effect is simple-----the reflecting surface causes a pressure buildup because the pressure front from the speaker has no where to go---when energy is thus concentrated into a smaller space than it naturally wants to be there is a pressure increase-------this happens when the wavelenghts are large relative to the reflecting surfaces----it is simply a ratio thing-----------------but the real fact about aiming speakers in a car into a corner or fender is totally misunderstood but the truth will never be accepted-----its one of those beliefs that will never be cleared up but i am going to run it by you anyway-------firing a speaker into a fender or against a surface in a car is not what causes an increase on output-----while facing a speaker close to a surface will cause a pressure increase BETWEEN THE CONE AND THE SURFACE, UNLESS YOU CAN SQUEEZE YOUR EARS INTO THAT SPACE IT WILL DO YOU NO GOOD----as soon as the sound leaves the confined space the pressure will drop to normal in the actual listening space------you cannot get something for nothing and since the waves of interest are already confined by the dimensions of the car there is nothing to be gained by "down firing" "corner loading" or fender trapping or whatever it is called------IF an output increase actually happens it is due to the actual location of the moving speaker diaphragm---------in any sealed space there are locations of high and low pressure due to the nodes and antinodes within that space----if the location of the speaker happens to be in one of the high pressure areas the speaker will see more radiation resistance and exhibit an increase in efficiency------if this happens the speaker can be turned in any direction and the output will be the same------NOTICE THAT I SAID SPEAKER and not box------if the effective high pressure area happens to be close to a surface it is not possible to turn the box around because the box will space the speaker cone away from the surface---------corner loading is right up there with amp soundquality, power wire routing, distortion hurting speakers and numerous other "installer voodoo beliefs" that will always be with us------but if we are intelligent and study the science that determines how things really work we don't have to believe such nonsense..............RC


From experimenting, it seems that for most cars with a trunk, facing subs in the truck rearweard (and several inches from to the rear wall) must very often place the sub in one of these high pressure nodes. I think that the location of these nodes is frequency dependent. Assuming sub frequecies, is there a rule of thumb we could use to show that facing a sub rearward, in the trunk of a car, will generally place the diaphram in a high pressure node?? So, in theory, tuning an enclosure based on the cabin gain of a given vehicle and placing the diaphram in a high pressure node should maximize the output of a given subwoofer system.

It looks like the real challenge may be to find the locations of these high pressure nodes in any one vehicle. . . xman


xman------you have it figured out exaclty-----including the part about maxing spl by finding the high pressure zones and making sure the speaker is placed exactly in it------BUT it must be remembered that the loaction of the nodes/antinodes is frequency dependent------figuring out their location is EXTREMELY comples due to the odd shape of a car----its easy to do in a square or rectangular shaped room-----there are lots of shareware "room mode" programs on the internet---------also note that if the space is a perfect sphere there will be no nodes/antinodes since standing waves will not be generated in such a space-------meaning the more circular or the more the car shape is broken up the less this will matter------a VW would probably be a good example of this where a rectangular van would probably exhibit the most variation due to nodes/antinodes.........RC

Paul, "corner loading" has always been something alot of people at least KNOW about, but how to explain it to others is pretty hard. I mean take a look at some threads from people asking "Which way do I point my subs" and alot of people will say face them to the back of the trunk - but wont be able to say WHY this works. And they are right - it is totally subwoofer and frequency dependant. If you have a little 100 watt max Legacy 8" subwoofer - its not going to matter WHERE you put it, it wont nearly sound loud enough.

Pretty good read but alot of people probably wont read it or not care. Alot of times as well, people will not want to put subs there because it sorta makes the rest of your trunk area useless, since the box will be taking up all the area to place OTHER items into your trunk. When doing an install one important question that should always be asked by an installer is how functional do you want the trunk, and how easily do you want it removed (should the sub box be covering say the spare tire well etc) - something that is often overlooked.

well, I certainly agree with everything on your post ........ certainly, most people are just as interested in looks as they are sound. And thinking of what you want to go where is a VERY important part of selecting and installing equipment that is often overlooked. I was very impressed that someone finally answered the question using science instead of voodoo or wishful thinking though.

hey i gotta question. i want to reproduce the sound from slot/corner or just aiming it against the trunk, i dont care about the looks, but i want trunk space. having it pushed to the back, as it is now, takes away all storage. heres a very fancy sketch of what i wanted to do, lemme know if the idea woud work.
http://shane@shane.qubilent.com/images/31321321.jpg
basically, i would extend all walls from the box, leaving the outside edge slanted to hopefully help aim upwards. i wanted to then place the box against the rearseats, and the opening on the subbox would push the air up though the openings in the reardeck... since i have no rear speakers. is that idea plausable, or am i just thinkin crazy?


or would this work?
http://shane@shane.qubilent.com/images/sdgsdfgfdg.jpg
that way it would force all the pressure through the top, and then of course, up through the reardeck. if neither of those would work, what can i do to keep the cornering affect yet have it pulled back to the seats?

if the sub (or box outlet) end up in a high pressure zone, then the output will be maximised. It looks pretty cool though .......