Mad Science... yes please

I love failing at making speakers from scratch. I was playing with some unmoumted speakers recently. I had 3 identical speakers. Hooked speaker 1 up to an amp. Rested speaker 2 face to face with speaker 1. Hooked wires to speaker 2 and ran 20 feet away and hooked it up to speaker 3. The end result was speaker 1 played and drove speaker 2 like a passive radiator. It in turn generated enough power and was able to drive speaker 3 across the room. Could this be a first? Or a new way of creating a quasi passive active radiator powering other speakers. ? Smarter people let me know. Thanks. Please post crazy things here.


I don’t even understand this (just an IEM guy) but I fully approve of the enthusiasm and the crazy.

Me too. But speakers can basically a power generator being that they have a magnet and the copper voice coil winding. The basic components of a traditional power generator much like the power company delivering electric to your home. A microphone is a basicaly a speaker but inverted. Vibrating a diaphram and voice coil and now generating a signal to be amplified. You can take head phones and plug them into mic jack. If you speak into the headpphne speaker it will perform as a microphone. This is kinda what is taking place in my experiment.


Basically what you’ve done is couple a low-gain microphone to the first active speaker. A speaker driver and a microphone are essentially the same thing, they just operate in opposite directions: a microphone converts the mechanical energy of a vibrating membrane (which is caused by the alternating high and low pressures of a sound wave) and converting it to electrical energy; a speaker driver converts the electrical energy from the amplifier to the mechanical energy of a vibrating membrane. So any speaker can be used as a microphone and any microphone “driver” can be used as a speaker…but they are optimized for different roles. A microphone driver has to be even lower mass than a speaker driver because it needs to pick up very sublte mechanical vibrations. A speaker driver usually has power behind it, so while being lighter is better, it is not necessary for it to be as light as a microphone membrane. Hence most speaker drivers are “low gain microphones” in reverse becaue their extra mass makes them harder to move (Newton’s first law!). If you use an actively powered speaker to drive a microphone like this, the ‘mic’ signal will be 180 degrees out-of phase with the active signal. The reason is simple, as the active speaker moves out, it pushes the ‘mic’ driver in, and so forth. Speaker makers that use passive radiators (Def Tech, GoldenEar, Legacy…there are others), have to do some high-level cajiggering so make sure that motion of the passive radiator works with the active driver rather than cancelling it out.

Also not a speaker guy, but I absolutely can appreciate the enthusiasm to tinker and experiment.

Super reply. Chock full of knowledge. Share any thoughts on electric guitar pickups. There a low power signal being generated by the ferrous string vibrating and exciting the magnet and copper coil of the pickup. More indepth info would be cool. Thanks