Dbox - Linear Actuator - Need input / suggestions

First off I hope I am posting in the right section of the forum, if not moderators please feel free to move the post as you see fit.
Secondly - thank you for allowing me to join.

I am intending to make a poor mans DBOX and am hoping for some member input regarding linear actuators.

The premise is that I have audio out of my amp.
This is fed through a low bass filter (basic speaker cross over).
The output of this is fed into a light box circuit that turns on/off a SCR to switch on / off a high current relay at the presence of sound.
The input of this circuit is adjustable to compensate for volume from various media content.

If your not familiar typically a light box (also called a light organ) consists of 3 different colors (low, mid, high) and flashes lights based on the frequency range of the music. In this application its simplified down to simply the bass.

What I intend to do is to control a linear actuator with a stroke between 2" and 3" - when the presence of bass is there. It will turn on the relay and apply +12v to the actuator causing it to extend, and when there is no bass I will use a DPDT relay to apply -12v and retract the actuator.

The intent is to mount a pair of actuators under a theater chair and as bass is present (such as the sound of a plane flying overhead) the bass will start on one channel and pass through to the second causing the chair to sway from left to right (or vice versa) or alternatively just bounce in unison when there are explosions and such.

What I am looking for is input on what actuator would be appropriate to use.

  • I need some thing fast.
  • I am looking for a stroke between 2 & 3 inches.
    I figure about 200lb of force - between the chair and a heavy human you would only be lifting one side of the chair with the other part of the chair remaining on the ground (assuming sound from one channel) or since there are two actuators then a full lift it would have the combined capacity of the two actuators ~400lb. (i am 175 lb). This is for home use not commercial so I don’t have to overspec it.

When I look at the various actuators I see some pretty short duty cycles and not too sure how to interpret that in relation to the project.
If you think about the sound of an explosion the bass sound would be on/off/on/off at high resolution but it is not continuous.

Any suggestions…