27 August 2008|
|Rockford Fosgate IBeam|
My first real car – 1971 Dodge Monaco with a 383 and a 4bbl carb., 16MPG highway and possibly (?) the first car in Canada to have subwoofers in it, circa July,1978.
Back then, there were very few real car amplifiers or subwoofers, so I cannibalized a set of Altec Model 9 home speakers to build a very rudimentary low pass crossover, mounted the woofers infinite baffle style in the Monaco’s huge trunk, and tried to drive them with an under-dash Muntz “power booster”. This attempt was met with little success, so after some searching, I found a blown up 100 watt (I think) Audiomobile amplifier, and after I made some repairs, that drove the woofers with far greater authority.
Of course within a few years, amps and woofers were becoming more widely available, and my understanding of subwoofer enclosure design and woofer selection began to take shape, and led to all sorts of crazy bass systems in various cars.
Fast forward 30 years (wow) and things are much different. Amps and subwoofers are available from all sorts of sources, and it’s possible to build bass reproduction systems in your car that would rival the kind of output I was so awed by in 1975. But, what if you don’t have room for a large woofer system, or maybe even none at all? How can you experience real bass without big woofers, bigger enclosures, and gobs of power?
The fanatics over at Rockford Fosgate have come up with a solution in their new IB-200 IBeam Tactile Transducer. If you recall, bass information can be perceived and enjoyed without you actually having to “hear” it, via the generation of tactile sound. When used in a vehicle, tactile transducers are designed to attach directly to the seat frame, or alternatively the floorpan of the vehicle. If the floorpan is used, it’s best to pick a strong area with some shape to it, such as the transmission tunnel. This will prevent large flat sections of the cars floor from vibrating too much, and causing unwanted resonances by “oil canning”. And the IBeam applications aren’t limited to car audio, you can also use these transducers in your home system by attaching them securely to the frame of your seating.
Now I know most of us have experienced tactile sound in one way or another, the concept is commonly found in simulators and thrill rides, and at some movie theatres. While providing an exciting effect for explosions or car crashes, in many cases the “shakers” used in these venues leave a lot to be desired, and don’t result in a realistic experience. In fact, very few of them are decent enough to even be considered for musical use. This is because they have a relatively narrow bandwidth and generally operate between 20 and 80Hz. For realistic tactile sensory input, the upper frequency limit needs to be increased significantly, and the output needs to be maintained at those higher frequencies.
Thankfully, the product folks at Rockford understood this, and the IBeam is a very high quality tactile transducer, ideally suited for musical reproduction. Measuring only 6.875 x 4.25 x 2-inches, the Rockford Fosgate IBeam will fit any vehicle. And with very modest power requirements of only 100 watts at 4 ohms, it doesn’t need a big power sucking amp to drive it.
The product connects exactly like a subwoofer, with a simple pair of spring loaded speaker terminals. It weighs about 2.5 lbs., which also makes it a lot lighter than a subwoofer for those of you who are vehicularly weight conscious. Capable of delivering about 2.5 pounds of force per watt, the IBeam is quite a bit more efficient than many of the “shaker” type products which required 500+ watts.
Nominal impedance is 4 ohms, so it is compatible with virtually any amplifier. Additionally, when I measured the impedance curve, I noted it was pretty flat well past 1kHz, so the IBeam will indeed be fast enough for great musical reproduction. Recommended maximum peak power limit is 250 watts, and a Polymer Positive Temperature Coefficient (PPTC) self-resetting fuse (commonly known as a poly-switch) is included in case you get overly enthusiastic.
The IBeam transducer works on the same electromagnetic principles as a subwoofer, but instead of a stationary magnet moving a voice coil and cone assembly, in the IBeam there are a pair of stationary coils on each side of a carefully suspended and powerful moving magnet. As the polarity and amplitude of the AC signal through the stationary coils changes, it generates a magnetic field which in turn, forces the magnet to move or vibrate on its suspension, creating inertia and force inside the transducer, which gets transmitted to the housing via the specifically tuned suspension. It’s this vibrating mass (the magnet structure) that creates the tactile sensations. Then when you bolt the IBeam to your seat, the vibration is transmitted through the frame of the seat and you experience the “feel” of the bass.
Listening As with any product, I read all the claims and then hook it up and judge it for myself. In the case of the IBeam, I actually did 3 separate evaluations of it, one in my listening room, one in my truck, and the last one saw the IBeam get mounted in a rather rudimentary yet effective way to my drummers throne.
Once activated, the IBeam will cause the supporting surface structure to vibrate over the tactile range. The result helps the listener “feel” rather than “hear” the low-end frequencies found in music. The IBeam is carefully calibrated to produce an accurate tactile sense, which can be totally missing without a large and powerful subwoofer system. Consequently, you are able to feel the natural percussive impact of sounds when listening to music, or watching a movie in your home. But unlike a subwoofer and normal speakers, tactile transducers do not add any SPL to the experience. The greater perceived loudness of a tactile sound transducer equipped system allows you to experience the full effect of the music, even while listening at lower volumes. With the IBeam securely fastened to the frame of my favorite listening chair, I connected the wires to a moderately sized amplifier and began my “listening” session. I was able to switch the device on and off during the session, and I have to say the difference was remarkable. With my “front speakers” set at 80Hz and up, I ran a full range signal to the IBeam. Instantly I was able to perceive the bass guitar lines, and feel every beat of the kick drum. While it seems a bit unsettling at first to “hear” the low frequency stuff without a woofer system playing, I soon became accustomed to the sensation, and in some cases found that the IBeam actually provided superior definition to a subwoofer system. I experimented with crossover points and seemed to enjoy it most at about 200Hz. I admit when I first read about the IBeam, I was skeptical having several unpleasant encounters with less well thought out products in the past. But after an hour or so, I liked it enough to mount it in my daily driver to see what it would be like in a vehicle and accompanied by a 10” woofer. I was equally impressed! The IBeam allowed the bass to be much more defined and apparent without having to crank up the system. I could pick out kick drum and bass guitar licks while driving at freeway speeds with the windows down. This makes an interesting point, while the IBeam will provide you with the tactile sensations of realistic bass without a subwoofer, it’s also excellent as a complimentary device for a system that has a good subwoofer.
Have you ever experienced real serious bass? I mean the kind that you actually feel, more than hear? When we “hear” sound, the means of transmitting the sound to our auditory system has several possible paths. The most common of course, is via our ears and eardrums. In this case, vibrations in the air (fluctuations of pressure) cause our eardrums to vibrate, and our auditory system translates those vibrations to sound. But our eardrums can only vibrate within a certain range of frequencies, and this is what determines the upper and lower frequency limits of our hearing. However, the body is an amazing instrument, and we can also use our skin, deep tissue, and bones to “hear” low frequency information. This allows us to “feel” frequencies as low as 10Hz, even though we don’t actually hear them, we know they are there. This method of sound perception is known as “tactile sound”, and is quite effective as high as 800Hz.
Measuring only 6.875 x 4.25 x 2-inches, the Rockford Fosgate IBeam will fit any vehicle. And with very modest power requirements of only 100 watts at 4 ohms, it doesn’t need a big power sucking amp to drive it... With my “front speakers” set at 80Hz and up, I ran a full range signal to the IBeam. Instantly I was able to perceive the bass guitar lines, and feel every beat of the kick drum. While it seems a bit unsettling at first to “hear” the low frequency stuff without a woofer system playing, I soon became accustomed to the sensation, and in some cases found that the IBeam actually provided superior definition to a subwoofer system.
Once activated, the IBeam will cause the supporting surface structure to vibrate over the tactile range. The result helps the listener “feel” rather than “hear” the low-end frequencies found in music. The IBeam is carefully calibrated to produce an accurate tactile sense, which can be totally missing without a large and powerful subwoofer system.