Crowson Technology Shadow-8 Dual Motion Actuator Review

Posted on 13th July, 2021

Crowson Technology Shadow-8 Dual Motion Actuator Review

Tony O'Brien gets to grips with this novel Tactile Motion Actuator and matching Tactile Motion Amplifier combination…

Crowson Technology

T108SS Shadow-8 Dual Motion Actuator (AUD $2,099)
D-501 Tactile Motion Amplifier (AUD $1,799)

The stomp of the T-Rex in Jurassic Park or the afterburners of an F-14A in Top Gun are all part of the excitement of a good home cinema system. If you've ever grappled with getting good bass in your home theatre, you know that it's not as simple as sticking a subwoofer in the corner of the room. Reproducing low frequencies correctly requires not only serious subs but also careful attention to room acoustics. Even if you're lucky enough to achieve this, the largest designs can't quite reproduce the last few octaves that are more felt than heard.

Enter Crowson's Tactile Motion Actuators, the brainchild of Californian engineer Randolph Crowson. He worked on magnetically levitated pump parts for left ventricular assist devices for heart failure patients until the late nineties. A home theatre aficionado, he felt haptics and vibration were key to immersive movies and video games. Working from his garage in Santa Barbara, Randolph created his patented Linear Drive Technology. In 2001 Crowson Technology was launched to manufacture and commercialise his actuators, and the rest, shall we say, is history.

Asked about the difference between his and other products, Randolph explains: 

Many such devices have a natural resonant frequency in the middle of their operating range. This is good for maximising output but it results in a “rumble” like effect because they favour a narrow frequency range. Also, it takes a bit of time to ramp up the output and a bit more time to settle down.

Crowson's T108SS Shadow-8 Tactile Motion Actuators differ in that each contains a powerful voice coil and magnet assembly. In other words, you're quite literally sitting on a speaker. 

They are capable of reproducing 5 to 500Hz with a very flat frequency and near-perfect response time, allowing beautiful alignment with the action of the subwoofer. The actuators expand and contract beneath the chair's feet, moving and vibrating the chair in a uniform way, resulting in more natural vibration, as opposed to a localised vibration within the chair.

He continues: 

Many home theatre enthusiasts feel that large, powerful subwoofers are all that is necessary to get good tactile feel and vibration. The “feeling” that you get from high bass SPL is very different from the feeling you get from Crowson Actuators. No subwoofer(s) can cause your chair to move up and down .25” at 5Hz. The efficiency of putting the LFE energy directly into the chair allows for a very special experience.

The 122x279x145mm actuators are made to be placed directly under the leg of a chair, each having a maximum weight load of 133kg. The top of the actuators, which come in contact with the chair legs, features a non-slip scuff plate and sturdy loudspeaker binding posts situated on the side of the actuators. The Motion Isolators are polypropylene feet, with holes for screws to attach directly to the chair feet.

Equally well built is Crowson's D-501 Tactile Motion Amplifier. At 432x43x284mm and 9kg, it's an easy fit for all but the most burgeoning equipment racks. Rated at 500 watts (700W peak) and with a rated frequency response of 5 to 160Hz, the D-501 can power up to four actuators. While another amplifier can be used, it needs to be fit for the purpose, meaning that it should work properly down to 5Hz and have ample power.

Despite its simplistic elegance, the D-501 is built like a battleship. The front panel is finished in brushed black metal, proudly adorned by a large silver Crowson badge. It's here you'll find Intensity Control, which functions like a volume control, Mode selector (music or movie), power switch and IR sensor. Moving to the back reveals dual speaker binding posts and analogue audio inputs, a dial for crossover (selectable low pass filter 40 to 60Hz), phase switch 0/180°, power mode selector (on, auto or trigger), mini-jack input, voltage selector and the main power switch.

The D-501 also ships with a power cord and credit-card style remote. Much as I'm not a fan of this style of remote, most will be using it with a control system. All the controls you'll need are present, including power, volume, mute and movie/music mode selector. Buttons are on the smaller side, and there's no backlighting for dark theatre rooms, but after the system's been tuned, it's likely to live out the remainder of its days in a cupboard or draw. The products are built in California, and the attention to detail and build quality is unmistakable. Both amplifier and actuators come in cloth bags, each carefully packaged to reduce the chances of damage in transit.


Crowson recommends placing an actuator under each of the back chair legs and an isolator under the front feet. If you're using a sofa with more feet, you'll need to add extra isolators. Somewhat of an anomaly, my primary listening position contains a two-and-a-half seat recliner with four feet. As such, I placed actuators under each of the back feet and isolators under the front feet. They can simply be placed beneath the feet of the chair. 

When it comes to the isolators, Crowson recommends removing the plastic supporting feet and screwing the isolators directly into the bottom of the chair legs. For the review period, I rested the front chair legs directly on the isolators without issue. Connecting the actuators to the D-501 Tactile Motion Amplifier is simply a matter of running speaker wire between the two; the isolators don't need to be connected.

The amplifier can be hooked up directly to the subwoofer pre-out of a receiver/processor, or by using a 'Y' adaptor between the subwoofer and processor. As you're effectively sitting on a speaker, the room is removed from the equation, and it's for this reason I believe Crowson recommend room EQ is defeated for that input. This may yield the best response but is simply not possible in many systems with one or more subwoofers. For this reason, I used a Y adaptor off the Dirac Corrected sub output to one of my dual VAF custom 10” subwoofers.

My review system consisted of VAF signature i91 front and centre speakers and i90 rear and overhead speakers for a 5.2.2 Atmos configuration, powered by a JBL Synthesis SDR-35. Visuals consisted of a Sony VPL-VW270ES 4K projector, Lumagen Radiance Pro 4242Panasonic UB-9000 4K Blu-ray player, Apple TV and a Severtson Cinegray 100” 16.9 projector screen.


Any misconceptions I might had about Crowson Motion Actuators were quickly dispelled. They're just at home reproducing the tactile effects of a T-Rex stomping its way around through the listening room, as they are lending weight to subtler fare, or even music. Bolstering the stomp of the T-Rex or the shrill cry of a Velociraptor in Jurassic Park is where the Actuators excel, elevating the DTS-X soundtrack to a new level. Here the visceral impact is well and truly felt at the listening position. The same was true with the excellent Dolby Atmos soundtrack on the 4K Ultra disc of Top Gun. The actuators blended beautifully with my subs, making them feel bigger than they are and imparting a heightened sense of engagement and excitement.

Good as it is considering its age, the Dolby Atmos Soundtrack of Star Wars: A New Hope can't hold a candle to today's blockbusters, at least in terms of sound. Here the 108SS faithfully produced the bass in the soundtrack without over-inflating it. I wasn't sure how I'd feel with more subtle programme material such as the DTS-HD Blu-ray soundtrack of The Little Things. Where I expected the 108SS to overwhelm proceedings, I found myself preferring the 108SS turned on, albeit at a slightly reduced level. 

While you can reduce the level of effect as wanted, the ability to recall different presets would have been a welcome one. The music and movie modes mitigate this somewhat, but without the ability to store differing volume levels I still found myself making changes on the fly. Handed the likes of a modern soundtrack, such as the Dolby Atmos soundtrack of Terminator Dark Fate, and the Crowsons excel. The level of visceral impact they provide is pure, unalloyed home theatre bliss. What impressed most was the 108SS's ability to reproduce soundtracks faithfully. Rather than try to thrill with artificial bass that isn't part of the soundtrack, they seemingly extended the range of my subwoofers.


Crowson's Motion Actuators raise some exciting possibilities. Granted, they're no substitute for inadequate in-room bass response, yet they sure are capable of restoring lost visceral impact. Likewise, it can make a sub feel much more impactful without waking the house up. And Crowson's Motion Actuators are one of the most exciting products I've reviewed to date, so I highly recommend you arrange a listen – I mean feel!

For more information visit Crowson


    Tony O'Brien's avatar

    Tony O'Brien

    As the owner of Adelaide based ‘Clarity Audio & Video Calibration’, Tony is a certified ISF Calibrator. Tony is an accomplished Audio-Visual reviewer specialising in theatre and visual products.

    Posted in:Home Theatre Amplifiers Power Amplifiers Loudspeakers Subwoofers
    Tags: crowson  oceanic 

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