The Tactile Transducer FAQ v1.7

• It is an electro-mechanical device that shakes. It is very similar to a loudspeaker woofer driver minus the cone. It is your basic physics damped mass on a spring model driven by an oscillating force (the voice coil). You hook tactile transducers up to an audio amplifier and mount them to a solid object. They can operate at higher frequencies but people typically cross them over at subwoofer frequencies and use them to reproduce bass. The buzz (; is that they vibrate and some people like that.

1. Basically anything you want. It is a free country.
2. Most people mount them to the floor, couch, chair, or the floorboard under the car seat.
3. You could mount them to a vest that you wear like some failed product that a company tried to sell years ago. It was called the "AURA INTERACTOR" and it was advertised as "Virtual Reality Game Wear."
4. If you mount it to a video game controller you would infringe on Nintendo's Rumble Pack patent and most likely get sued like Sony did. The story is that Nintendo purchased this patent from Atari.
5. Or for the kinky, you could mount it to your bed.
6. And for the truly insane you could mount it to a crash helmet you wear on your head.
7. One company even recommends hot tubs and boats for "ultra sonic hull lubrication!"
8. Another company suggests mounting it to a drum seat? Now why a drummer would want to feel his chair shake is unknown to me. Mixing the other musicians to headphones during a live performance makes sense, but being able to feel the vocalist sing with your butt is just plain bizarre.

1. It gives you that big bass feeling at low SPL levels.
2. Even at high SPL levels it adds that certain tactile sensation. It is a little something extra. You hear it and you feel it. You know, it reaches out and touches you.
3. Play Telarc's 1812 and you will swear that the earth just moved. Now try that with your 2000W 18" servo sub by itself!

• Yes, and no. With tactile transducers you feel things shake similar to what mega high SPL's from conventional subwoofers will do but at low volume levels. So you get the touchy feely parts of bass but at lower SPL levels. This makes the bass seem heavier and a little more pounding, but it is not ultra low in frequency. Tactile transducers have little output below 25 - 30Hz. A single 10" subwoofer in the proper enclosure in a car will give lower and louder deep bass, but the 10" just won't shake you as much.

1. Line level signal
   • Tactile transducers work best with their own separate amplifier. Now the question is where to "tee" the line level signal from?
   • You could use the tape outs of your receiver/preamp, but I would recommend a variable level output. It is nice having one volume control adjust both the speaker SPL levels and the transducer volume levels. Having two different gain knobs that require constant adjustment is a pain.
   • They need to have a sharp LPF (low pass filter) / crossover setting of about -12 to -24dB/octave at around 80 to 100Hz. Otherwise you will hear the higher frequencies emanating from them. It is not cool to here voices coming from your couch. So you either need a separate crossover or just use a Y connector and send the transducers a line level tap off of the subwoofer output from your receiver/preamp. Using the subwoofer line level output has the additional benefit with AC3/DTS systems in that you will also be feeding the LFE (Low Frequency Effects) channel to the tactile transducers.
   • Using the subwoofer line level out of an AC3 receiver/preamp is ideal.
2. Amplification
   • Attach the crossed over (LPF'd) line level output to a dedicated transducer amplifier. You can buy a 100 or 200W mono amplifier or you can use a spare receiver that you have sitting around gathering dust. I recommend that the amplifier that you choose to use can driver low impedance loads. Safely being able to drive 4 ohm loads is good, 2ohms is better. You want a hearty amplifier that has excellent heat sink cooling capability, the reason for this is that your transducer amplifier will most likely be the hard working and hottest amplifier in your system.
   • If you have just one transducer then simply hook it up to amplifier. Polarity is important and I recommend playing a sine wave source (around 40Hz) simultaneously through both your tactile transducers and your subs. Flip the polarity of the transducers such that the maximum SPL is measurement from the combined sub/transducer playback. The idea is you want maximum reinforcement and you want to avoid any unnecessary cancellation.
   • If you have more than one transducer, then you will need to figure out a wiring scheme that works out to an 8 or 4ohm load. Two 4ohm transducers in series will give a 8ohms, and two 4ohm transducers in parallel will give 2ohms. So if you have four 4ohm transducers and one amplifier channel then I would recommend a series - parallel combination that would result in a 4 ohm load. Avoid 2ohm configurations if possible because your amplifier will already be running hot enough with an 8ohm load.
3. Physical
   • Now mount and bolt them to a solid object such as you floor of couch. Loose unmounted transducers will do a poor job at transferring energy and it is likely that they will buzz or rattle unless securely fastened.
   • Ideally having a digital delay to compensate for the difference of distance between you subwoofer and tactile transducers would be ideal. Remember that sound travels at about 1 foot per millisecond so if the tactile transducers are mounted in your couch and your subwoofers are 20 feet away then the transducers will be firing about 20ms to early, this interaction could do strange things to the room modes and the flatness of the overall bass frequency response could suffer. But then on the other hand because of the high Q-ness of some transducer, they tend to ring (oscillate after the driving force is removed), so firing a little early will actually help things by having them damp down (stop ringing) a little earlier. Remember installing transducers is both art and science.

• Not much. Despite manufacturers specs on the order of a hundred or more watts per transducer, this much is actually dangerous. It is the same problem with speaker drivers at low frequencies but worse since transducers don't have the air spring to fight against. The situation is not a RMS limited problem but instead a displacement (excursion) based problem. Manufacturers claim high wattage numbers in order to sound impressive. If you equalize your transducers then even more of a burden is placed on the low frequencies (20-35Hz). I recommend 20W per transducer as a good number. A transducer bottoming out sounds worse than amplifier clipping. You can use more wattage per transducer but more attention to clipping will be required. This might be a good application for a tube amp or a soft/smooth clipping amplifier. 100W per transducer is just plain overkill.

Coupling is having a good transfer of vibrational energy to the environment. Just like a raw speaker out of a cabinet and floating in free space does a poor job of re-creating bass. A tactile transducer needs to be solidly bolted to something for the transfer of energy to take place. An unmounted tactile transducer is rather worthless. Bolt it to a floor, chair, or couch and now you have coupling.

• Some journalists claim that tactile transducers just buzz. This is incorrect. Yes, you can hear distinct notes, they are NOT "one note hum buzzers!" The key to discernible and distinct notes is a fairly flat frequency response. Tactile transducers do have their rolloffs and resonances and are by no means perfect, more on this later, but they are far from being just one note bass tone generators.

1. Tactile Transducers are not very efficient. They crave power. 1W into a sub driver will create a lot more output than it will into a transducer. My tactile transducer amplifier is, without a doubt, the hardest working and hottest running amplifier in my system. It is very easy to overpower my 4 RBH transducers with a 150W amplifier.
2. They require their own amplifier. Because of the serious mismatch in sensitivities, don't try to run them in parallel or in series with your subwoofer.
3. The RBH and Aura/Alpines have very strong resonant peaks around 45Hz. Their frequency response is far from flat and I would NOT call this quality bass. Actually such peaky high Q bass has a certain slowness or delay effect with some music. This is unnerving. Serious EQ helps here (like a -24dB cut). This problem is at its worst with rhythmic music with heavy bass, movie special effects fare better. Parametric or graphic EQ is recommended.
4. Transducers don't have the dynamic range of sub woofers. If max SPL is your game then transducers are not for you unless you're willing to mount 64 transducers under your seat and power them with around 3kW of juice. Yes, a little silly, and you still wouldn't get anything under 20Hz or near 150dB. This serious mismatch of dynamic range also causes problems with transients like explosions or punches. The subwoofers have no problem re-creating the impact, but the transducers will be hopelessly under powered and bottom-out creating an unpleasant sound. Solution? Turn down the volume.
5. Low bass really isn't practical with todays tactile transducers despite manufacturers claims of a frequency response down to 5 - 15Hz. Just like subwoofers, this is a displacement limited problem and not a RMS wattage limited one.
   • shake output ~= moving_mass * Xmax * frequency^2;
   This is physics and there is no way around it. As the frequency gets lower you need to dramatically increase the Xmax excursion and/or the moving mass of the system. Think about it, all a transducer does is shake a mass. Either a bigger transducer or an array of a large number of smaller ones is needed if you want significant output at low sub sonic frequencies.
6. I haven't done any accurate measurements of this but it seems that the RBH and Aura transducer ring a bit after a transient occurs. I believe the transducers are not critically damped or even highly damped oscillators on a spring. This most likely (by definition) is due to their high Q resonant nature. Since you feel and don't really hear the transducers this is not as serious of a problem as it would be with conventional drivers. EQ-ing, which effectively lowers the Q, helps this.
7. I am concerned that I have noticed a spreading of energy in the frequency domain when a transducer reproduces a transient. On my spectrum analyzer it looks like a smearing of frequency. The same transient reproduced on a subwoofer looks sharper. This could be due to the springiness of the transducer and my couch are acting like a plate style reverb unit, think RT60 times, different modal resonances being excited, etc. This is one complicated set of equations. How much of a problem is this? Not much since the effect for the critical listener is impressive and pleasing. Tactile Transducers work, all I'm saying is that they might not hold up to the scrutiny of the audiophile crowd.

1. "That tactile transducers make no sound they just shake."
   This is not true. They make noise by shaking whatever they are attached to just like it was a speaker cone. You can measure the sound tactile transducers make with the Radio Shack SPL meter. This sounds like sound to me!
2. "That tactile transducers can not replace a subwoofer."
   This is a common myth. Trust me, my transducers can shake the walls, the floors, the venetian blinds, pictures, even the dishes in the kitchen just like my subs can at high volumes. They might not make a great subwoofer, but properly equalized and at low volumes the effect is quite convincing. Experiments have been conducted and the conclusion of the A/B tests was listeners can be led to believe that a transducer is actually a subwoofer. One problem is once you leave the "sweet spot", I mean the couch, the effect quickly diminishes. So if pushed by space/spousal requirements, transducers can take the place of a subwoofer. But I highly recommend having both a sub and transducers.
3. "Tactile transducers are great if you have thin walls or thin floors and you live right above your landlord."
   This again is not true. Unless you put the transducers in your couch and completely isolate it on a floating platform (like an optical table or concrete slab) then transducers are going to bother your neighbors more than subwoofers will. Why? Tactile Transducers have a direct coupling to the building's structure unlike subs which first transmit their energy to the air and then to the walls.

• Chances are you have a subwoofer. The goal is to blend the bass output of the transducers to the subs. You don't want the transducers to be blatantly overpowering, and you want the subs to fill in the frequency gaps that the transducers will have. Set the subwoofer with the standard 75dB C pink noise and Radio Shack SPL meter procedure. Once you have the sub calibrated to the front speakers with the pink noise built into your receiver/pre-amp or from a test disc, now it is time to calibrate the tactile transducers to your subwoofer. Turn off the subwoofer since we have already calibrated it, play the pink noise, and adjust the volume knob on the transducer amplifier such that the meter that you are holding at ear height reads 72 dB C. This is -3dB down from the 75dB level subs, the reason for this is that we want our ears to hear the sub and not the transducers, also being 3dB down gives the transducers a little more dynamic range which they desperately need. Studies show that -6dB is a better choice for isolating the brain/bass/butt/ear localization functions, but I feel -3dB is a better compromise. Another way which is very similar to the -3dB method is to place the Radio Shack SPL meter on the seat of the couch in the middle of the listening position. Now adjust the transducer gain so that the meter reads 75dB C with pink noise. Think of this as the bass level your butt feels. Actually these two methods give similar gain settings and are somewhat equivalent. I prefer the 75dB SPL on the "sitting position" method.
• If you don't have a subwoofer then I would treat them as a subwoofer and use the same procedure. 75dB C SPL pink noise matched to the front speakers. Use the pink noise in your receiver/pre-amp or use a test disc.
• An alternate method is to set your receiver to the 0dB reference level, or if that is too loud just set it to the loudest or the normal volume level you listen to music/movies. Now turn off the front speakers and the subwoofers and put on something with real heavy bass like the Jurassic Park LD or the AC3 Topgun, or the Professional DVD which has this 26Hz transient which almost pegs the LFE meter. Go to a really loud dino stomping or jet flying scene and adjust the transducer amplifier gain such that the transducers aren't clipping, bottoming out, or making any other horrible noises. Now check the transducer gain with the above pink noise procedure. Chances are your transducers will now be set way below the 75dB C level. The only way you'll be above 75dB is if you have more transducers and amplifier power than you have brains or you listen to movies at relatively low levels. So, if by some chance the transducer gain is above 75dB C then adjust their gain down to that level.

• The same reason calibration of subwoofers is important. Transducers make audible sound. You want the bass units to blend with the front speakers.
• Now I for one believe in high fidelity through overkill, but moderation is key. Turning the transducers volume down leaves more headroom so that they don't bottom out on the really loud peaks.
• "Riding the gain." One hand on the transducer amplifier gain control and the other in the popcorn is cool, but it gets old real quick. You want to be able to set them and forget them, so you can enjoy the movie or not get into any accidents while you are driving.

• The Aura units have a resonant frequency around 45Hz. The old Clarks had a 550Hz resonant frequency and operated below resonance just like the BagEnd subs. The new Clark transducers have a 65Hz resonance peak. With the Aura transducers and their kin, this resonance is manifested as a very peaky frequency response centered at 45Hz. If fidelity is important to you, then the Aura units need serious equalization. The Clarks are more expensive and have a much flatter frequency response. Clark Synthesis claims that the bandwidth of their product is flat (-7 dB) from 10Hz to 100kHz and drops about 12dB from 10Hz to 1Hz. I have a hard time believing this claim, if the mass on the spring physics model still holds then this should be a displacement (Xmax) limited problem at the low frequencies. Drop an octave and now the Xmax excursion limited output should drop by -12dB! So if through clever engineering the Clarks are really flat down to 10Hz, then it is only at extremely low and basically unusable output levels. That is just the physics of the situation.

• Yes you can, but the results won't be that great, and I would recommend extreme caution. Tactile transducers don't have enough dynamic headroom to begin with. Dropping the bass an octave and mixing it back in will put extreme excursion requirements on an already displacement limited problem. Over powering is a concern but I would be much more worried about over excursion. Bottoming out doesn't sound good and it most likely is harmful to the longevity of the transducer. For example: An RBH transducer at 20Hz bottoms out with only 10W of input!

• Now that is an interesting idea. The founder of Clark Synthesis recommends running his tactile transducers without a crossover so that you "can feel the instrument". While many disagree with this philosophy since hearing voices coming out of your couch is strange, the surrounds idea is intriguing. Dipole surround speakers make the surround field more diffuse and many swear by them. Turning the couch into a surround speaker actually will maintain the directional surround effect of Dolby Pro Logic, on the other hand, AC3 with its stereo surround does pose an imaging problem. The problem with feeding the tactile transducers the surround channel signal is that the transducers really work best for low bass and the surround channels have all the low bass filtered out. A mixer could be incorporated and some of the surround channel's signal could be mixed into the subwoofer signal that drives the tactile transducers. This could be a very interesting effect. Some experimentation is needed. Required hardware: A summing amp with individual gains or an outboard mixer.

• No, tactile transducers work by shaking what they are attached to. A concrete slab floor is a very heavy solid object. Either you will need on the order of several tons of force or you won't feel a thing. With concrete slab floors I recommend mounting the tactile transducers in a piece of furniture like a couch or chair. This way the couch will shake and make a direct coupling to you. The solidness of the concrete floor will inhibit the transducer response a bit. I would recommend placing hard foam rubber pads as insulators under the couch's feet. This will isolate the couch from the solid floor a bit and increase the vibrations that you feel. Using rubber pads under the feet of furniture is probably a good idea for everyone who mounts transducers in their furniture, not just those people with concrete slab floors. See the question below for more info.

• Volume, max SPL, decreased by about -10dB. Quality, improved by a lot. As mentioned above the use of foam and rubber isolations pads does help. As an experiment a couch with 24 tactile transducers was moved from a suspended floor to a solid concrete slab (meaning I moved). Before any re-EQ'ing it was noted that the tactile SPL at the butt had decreased by 10dB. By using the +3dB gain for doubling amplifier wattage rule mentioned in the dB laws, etc. list of physical laws, constants, and formula it is calculated that a +10dB increase in gain required approximately a 10X increase in amplifier power. So what was once satisfied with a 200W amp now requires a 2kW amp for the same gain, that is assuming of course the transducers are still linear with that kind of wattage and they don't melt. But this -10dB loss of gain is not all lost to nothing. After EQ'ing this 24 tactile array on a concrete slab setup it was noticed that bass had become much tighter and less laggy or sloppy. It was actually a dramatic improvement. This is what happened: vibrational energy was built up in the previous suspended floor like how audio standing waves (room modes) work and this energy that was imparted to the floor continued to vibrate until the energy was slowly damped from the system, this took a small fraction of a second and it was a main contributor to the lagginess and sloppiness of the bass quality. Now since the solid concrete slab weighs several tons, it is rigid, and it does not vibrate. So you don't have any built up energy that needs to damped from the system. This is yet another variation of the efficiency vs. quality tradeoff. So as counter intuitive as it seems, if you have the tactile headroom to burn (2kW into 32 shakers), then having your transducers on rubber isolation pads on a concrete slab will improve the tactile quality.

• Yes, if you run a sine wave at high volume for an extended amount of time the transducers will get hot. Music at high volumes can make them slightly warm, and for movies the temperature increase is negligible. The reason for this is in the source material. A sine wave is constant power. Music with a heavy beat has a lot of bass energy. While movies do have their bass energy peaks (explosions, gun shots, punches, music, etc.) but most of the time a movie is fairly low energy, so the transducers have plenty of time to cool down. Does this mean you need less transducers for movies? By all means no, movie transient sounds require a lot of transducer excursion and the AC3 LFE channel just made the problem +10dB worse.
• This is nothing to get alarmed about since all speakers get hotter the harder you drive them. Amplifiers also get hotter the harder you drive them. Ample ventilation is a good idea.
• Many auto sound people have complained about the Bass Shakers getting too hot. This is most likely due to the fact that tactile transducers are not as efficient as traditional speaker drivers. Also car people typically play music at louder volumes than HT people do. Tactile transducers just can't compete SPL-wise, if you want max SPL don't get tactile transducers.
• What's important here is that you shouldn't mount tactile transducers near gas tanks, and when mounting them in a couch, caution should be practiced in installation and/or in playing of program material. You don't want to start a fire. While this is highly unlikely, one should always be concerned about such things. Flammable fabrics and glues deserve special attention.

• Yes, damage to furniture or electronics from long term exposure to high amplitude vibrations is a possibility. Foam rubber padded feet are recommended for vibrational isolation. Any padding material will work. Either the commercial rubber ball halve like products. Or go to your local hardware store and purchase a one foot square piece of foam rubber or solid rubber and cut it yourself. Also vibrational isolation of the furniture with tactile transducers can slightly enhance the vibrational output.
• The psychological effects of tactile transducers is unknown. But some subjects have felt continued shaking and vibration hours after the transducers have been turned off. The long term effects of tactile transducers could lead to nervous disorders or paranoia. Just like video games have the epileptic seizure warnings, caution should be practiced with tactile transducers.

• Yes, with floors of a very flexible structure, the resonant frequency of the floor can be found and energized. Caution should be exercised because irreversible structural damage could result. Remember, in Physics class, the Tacoma Narrows suspension bridge that was destroyed by a mild wind that energized one of its major vibrational modes (natural frequencies)? Mounting tactile transducers in this fashion will also turn the floor into a giant speaker membrane. Even with an Xmax of 1mm, this still is an incredible amount of displacement. To simulate this try plugging 1 mm of excursion, 144" diameter for the oscillating floor, and a 40 Hz signal source into the Piston Excursion Calculator and solve for dB SPL. Be nice to your neighbors or they will kill you, it is amazing how bass brings out the anger in people. So be careful.

• Yes. Just like room modes, standing waves occur in solid objects such as wood and concrete. The size of an object, its density, its Young's modulus, ... all play a role in the vibrational modes of an object. The speed of sound in a solid object will also be much higher that it is in air. This increased velocity should have the effect of stretching the nodal frequency response as compared to the room's modes in air, so that the low frequency response isn't much affected, but instead the opposite has been witnessed. Frequency response of transducers in a couch will have far more severe peaks and nulls than is typically measured of subwoofers in normal walled rooms. Peaks and nulls in a couch will be multiples of octaves just like they are in room modes. Two nulls with extreme "suck out" separated an octave apart with a resonant peak directly in the middle is common. Combating this with layers of materials of different springiness and absorption coefficients is most likely possible and practical.

• Cancellation. Imagine mounting 12 tactile transducers in a row on a 7 foot long piece of wood. The idea is to get all of the transducers to work together and transfer their vibrational energy to you. Unfortunately what the transducers are also doing is exciting vibrational modes along the piece of wood, some constructively and some destructively. Think of the piece of wood as a sine wave on a stretched piece of string and you get the idea, Actually the middle point of the wood is more like a fixed endpoint but it is much more complicated than that.
• Getting the best impedance load so as to maximize the amplifier wattage is a little tricky with large numbers of transducers. Remember the series summing and the parallel dividing rules. Factors of 2 are nice such as 4,8,16,32,64 and so are nice multiples like 3x5, 3x3, 4x7, and so on. Your chosen ohm-age can also be used to limit amplifier over powering that will result in transducer bottoming out.
• With that many transducers wired up series-parallel the possibility of a wiring mistake/bad connection or a transducer failure is more likely and more difficult to detect. I recommend building a wiring bus that would facilitate quick and easy disconnect and section testing for simplified debugging.

• Good question. Most likely "in phase" is the best general solution. Think of sonograms or phased array antennas/radar, an array of tactile transducers could be steerable. A more practical solution would be to have a computer control the individual phase and filtering of each tactile transducer so as to improve the net summed output and avoid some cancellation. Possible but not a practical real world solution since each transducer would require its own DAC and power amplifier. This could be a real cool thesis project for someone as the math, theory, and solution are far from trivial. If anyone does this please let the author of this FAQ know.

• Bad. Tactile Transducers ring like all high Q systems. Serious EQ'ing helps the response in the frequency domain but time domain problems remain. With tactile transducers, this problem is in a completely different realm than even the worst subwoofer. Remember a tactile transducer is basically a mass on a spring with not much damping. Shaking a couch is, literally, a lot of work. Even if tactile transducers were critically damped, the problem would still remain because you can't critically damp a 250 pound couch. Think of a tactile transducer pumping energy into a heavy couch, it will take many cycles, maybe a third of a second, for the transducer/couch system to achieve equilibrium / max SPL. Then the input force is turned off, the high Q tactile transducer will continue to oscillate for several cycles, but this is a minor problem, the big problem is trying to get the couch to stop vibrating. And the lower in frequency you go the worse this problem gets.
• Consider this series of events / phases of the system:
  1. Pump energy into a harmonic system at rest.
  2. total energy storage / equilibrium state.
  3. then termination of input energy.
  4. slow release of energy until the system decays back to the rest state.
• With a large tactile array, high output at 20Hz can be achieved but it could take a quarter second or more before appreciable energy is felt. Decaying is also slow as the RT60 time of a couch is high, a quarter to half second for the couch energy to decay by 12dB is a good guess.
• Transducer design/selection can help damping, but only the transducer damping which is considered a magnitude of order less important than total system (couch) damping. Improving RISE time can be accomplished with larger tactile arrays (more moving mass), lighter couches, stiffer couches, and playing with the damping material under the couch like rubber feet. Improving DECAY time can be accomplished by lighter couches, more softer stuffing (damping material), playing with rubber/foam/felt foot pads (like a tuned Helmholtz resonator bass trap concept), or building a servo feedback system that will play a signal out of phase in order to use the transducers moving mass in a manner to help "brake" the system. Another simple solution to both the rise and decay problem is to calibrate the tactile system to a lower -6dB level which will make the sub woofers output more dominant, thus masking the tactile transducers deficiencies.
• EQ'ing to fix the frequency response of the tactile system will improve the rhythm and pace of the system. The effect will be to improve a timing or a lagging slow bass problem. This is good, but the transient/time domain problem will still remain. Some think the time domain problem can be fixed with a digital delay, this is incorrect. Both the frequency and the time domain problem create a sort of "muddiness", but they are different problems. Listen to walking bass notes or bass sweeps found on some techno music to hear the frequency domain problem. Listen to some transient bass drum beats to hear the time domain problem. There is a difference.

• I don't know. Probably the same person who invented the first solenoid or speaker driver, Mr. Edison. Since then, many companies have made or sold devices like the vibrating back massage chair or a hydraulically enhanced flight simulator. But these devices are not the focus of this FAQ. In 1994 AuraSound (a former defense contractor) introduced the Bass Shaker and marketed it to the automotive mobile audio industry. A lot of people bought Bass Shakers for their cars. The reactions were mixed. Some thought it was cool, others criticized the Shakers problems for lack of performance. The Bass Shaker was not a huge commercial success. So it is fair to say, in regards to this FAQ, that Aura created and commercialized the first tactile transducer. Having a less than stellar success in the mobile audio market, it looks like tactile transducers are attempting to make a comeback in the home theatre market.

• Aura Systems (also sold by Alpine)
• Clark Synthesis (the flying saucer)
• Crowson Tech TES 100
• Guitammer Company ButtKicker
• RBH (basically OEM'd from Aura)
• Invisible Stereo (Rolen Star)
• you can, (read the DIY article)

It all depends. What is more important to you, ultimate loudness, flat frequency response, or the lowest bass, or high damping? How much wattage do you have? Do you want to invest in electronic correction devices? Do you want a packaged deal? Are you an adventurous do it yourself'er (DIY)? Also what is your budget? What are you going to mount them to? These are all important questions and there is no "best choice" for everyone. Personally I believe having several transducers is better than having just one. The more moving mass your tactile system has, the louder and lower it will play. That is just simple physics.

• A shaking steam roller is a really cool experience.
• So are the couple of California earthquakes I've been through, they've been more of 1/2 Hz queezy type of lose your stomach bass.
• Jacking into the central nervous system and providing the precise electrical impulses ala Cyberpunk. When this happens we won't have home theatre anymore, so this really isn't a factor.
• Now it would be cool for your couch to do the Days of Thunder ride at Great America, but then you'd have to add seat belts!
• But the ultimate tactile transducer has to be the ~150 pound transducer that is designed to be bolted to the frame of a skyscraper. It's purpose is for testing out the skyscraper for vibrational modes that could get excited in earthquakes or high winds. A 1000W amplifier and a frequency response of .5 to 500 Hz mean serious bass. Chances are that this transducer is not damped at all, and also likely that it's very resonant. Most likely it would be slow in responding to transients and that it rings like all high Q systems do. This is a resonant mass transducer like the Aura, RBH, Clark, and Buttkicker shakers.
  • Update The skyscraper shaker has been out powered by the Unholtz-Dickie high force shaker Model T5500. It is an actuator style transducer like the Crowson Tech model but much larger and designed for industrial stress testing applications. The T5500 is rated at 55,000 lbs (244 kN) Force Sine / Random and 3 inch (76 mm) Stroke. It can shake with full rated performance up to 2000 Hz and it can support payloads up to 3000 pounds in weight. It is powered by a 480 KVA class D power amplifier. I will write up a detailed and complete review when UD sends me an evaluation unit. (:

• Particular product specifications do not belong in a generic FAQ such as this. For a comparative survey of popular tactile transducer specifications check out the Tactile Report.
• If you are curious what equalizers and signal processors are available for use with tactile transducers, then check out the list of Electronic Bass Augmentation Devices.

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