Published on Dec 27, 2019
Hi all you bass heads!
We all love our bass in one way or another.
It could be the ability of your sub woofer system to faithfully and accurately reproduce the lower octaves of a church organ or the thundering sound of the huge timpani drums being played by an orchestra. That hard forceful punchy knock your head off with a sledgehammer type pounding bass. Or the type of bass that has the ground quaking and trembling beneath your feet as the bass proceeds to vibrate and disrupt everything within its path.
Hang on that is very much like the lower octaves of the church organ. Of course you can probably tell that I`m a lover of the lower side of the bass frequency spectrum. If you are still reading this then nice one! You are obviously interested in Bass or are very bored.
My name is Marcos Barnes and I`m the Founder and creator of the (((pd))) propper droppers SPL format.
What is bass?
Well in the Car Audio world and as far as I can remember it has been regarded as anything below 80Hz. “Hz” in case you don`t know, is the amount of times something vibrates per second. This 80Hz standard I guess was originally set by “Wayne Harris” who is the Founder and Creator of one of the worlds largest SPL formats – dB drag. Most popular or dance music bass lines are centered at around 40Hz to 45Hz which is fine. These bass frequencies are quite low and hit hard, as the frequency increase the bass gets more punchy and hits harder. But there are loads of bassheads who love low or Ultra Low Bass, so much so that they strive to be able to have a system that can play these types of frequencies down to the lowest octaves and at the loudest volumes possible.
We are now talking 40Hz and below.
We`ve all heard bass that seems to come from far away then after what seems like a very long time it intensifies as the vehicle playing it gets nearer. The vehicle drives past and you can certainly hear the bass but you can also feel the bass as the air around you is moved so violently. The ground trembles, shop windows are vibrating, your loose clothes are moving, some people are covering their ears – “oopse, better turn it down!”
This is one of many effects of low bass and it`s great fun. If you have ever been to a cruise or car show you will have probably experienced some of these types of vehicles with lovely ladies doing what we call “hair tricks”, cans of drink and other items being suspended in the gaps of air between the open windows of the vehicle whilst the bass is playing.
It`s even more crazy inside the car that is creating those lows. Grab a demo and sit inside one of these insane bass vehicles and you will probably bail out because it is too intense or you`ll be captured by the undulating low frequency bass that has somehow caught you like a fly in a spiders web. Smiling like that Cheshire cat in Alice in wonderland, you`ll enjoy the feeling of your whole body being buffeted by the bass and as the owner cranks up the volume, your smile may well turn into laughter, something we call the “bass giggles” – It`s fun and it`s addictive.
How do you create low frequency bass?
Going to get a bit technical now and explain about enclosure relationship to create low bass, don`t worry I`ll keep it very simple and just scratch the surface of this subject. Playing low bass that we can hear at loudest volume levels possible with our systems requires a lot of air movement.
When using a “sealed box” the limits are quickly reached because you are reliant on the sub woofers cone area and its maximum ability to move in and out (overall excursion). This is called it`s X-max. When playing low frequencies at a loud volume with a sealed sub the X-max Limit is typically often reached at 33Hz or so, unless the cone is mass loaded (weighted to make cone heavier) then the lower frequencies will destroy the sub, making it over-excurt (bottom out).
So a “ported box” (hole in box) is deployed to enable us to control the cone movement for the lows. Tuning the box lower allows the cone to be controlled so that it moves less when playing the low frequencies whilst still creating a louder low bass wave as the port now adds more volume to reinforce the front wave and more than makes up for the loss of cone movement (It`s like having double the cone area). This works incredibly well but the tuning will have to be at something like 24Hz or possibly lower depending on how low you really need to go.
So if you use the combination of a ported box with a sub that has a very good thermal power handling and a hell of a lot of excursion. You will be able to give it loads of power to make it move even more, without the coil burning up and if tuned low enough, no bottoming out either. Sub Woofers require a certain amount of air within the box to make them work properly.
A normal off the shelf ported box is usually tuned to between 45Hz and 50Hz. And a good box has a nice largish port area of usually 10″ Sq Inches per Cu.Ft. BTW Larger port area= Lower port noise and shorter port length – better “transient response” (ability of sub woofer to follow a tunes bass line accurately). To play low we need to tune very low and this always results in loss of port area and increase in port length. Where a 45Hz tuned box may have 10″ of port area and is 10″ long, a low tuned box with the same port area will need to have a port that is maybe 4x longer, 40″ inches!
You can probably guess that the port will take up all the available box space that a subwoofer can work in. So to be able to tune low, we have to shrink the port area or increase the box size to allow port length to be shorter. It`s an often tricky balancing act as too small a port area results in lots of huffing and puffing (port noise) as well as limited output. Flaring or rounding off the port edges internally and externally help greatly. Increasing the box size again helps but make it too big and you`ll have problems with bottoming out.
There are many other box designs that can be used to create ultra low bass, we have just very briefly looked at two of the most practical and popular choices for car audio systems. Most of the other options like 4th order / 6th order Bandpass require much larger enclosures. Horn loaded and Transmission Line even larger so it`s rare to see these types of enclosures used in car Audio, unless you have a van.
So hopefully you can now see that it is a very different kettle of fish to play those lows. Our systems can literally make the earth move.
Having a bass line that can last forever and drop to the lowest frequencies, shaking and vibrating all around, is immensely satisfying and for lot of us it`s an incredibly cool thing to be able to do. There are even competitions for Ultra Low Bass. Testing SPL levels at 4x set frequencies of 40Hz – 33Hz – 25Hz – 20Hz and a optional 10Hz.
Please check out the link below.
Yes this has become a shameless plug for My SPL format. It is run by Bassheads, for Bassheads who love Ultra Low Frequencies and can be found in the following countries.
Australia – England – Finland – Germany – Italy – Netherlands – New Zealand – Poland – Romania – South Africa and soon to be in South America…
Thank You if you`ve got this far.
Enjoy your sound system, whichever type of music or bass you like.