Dynastar Speaker Knife Speaker Protector

Okay, I give up, what's a Speaker Knife? I've been in the audio industry for thirty years, and I've never heard of a speaker knife.
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Product PointsApplications: Studio Recording

Key Features: Dual-channel vacuum tube compressor/microphone preamplifier; auxiliary input tube section; XLR microphone and line inputs, XLR line outputs; individually switchable phantom power.

Price: $2,949

Contact: Drawmer/TransAmerica Group at 805-375-1425, Drawmer 1969 Dual Vaccuum Tube Compressor/Microphone Preamplifier

Plus: Authentic and effective tube compression, Versatile, Excellent tube aux input section, Clean mic preamps

Minus: Limited attack and release settings, Poor front panel labeling (being addressed by Drawmer)

The Score: The Drawmer 1969 is a high quality tube compressor with smooth and "musical" results. The clean mic preamps and tube aux input are a bonus!Okay, I give up, what's a Speaker Knife? I've been in the audio industry for thirty years, and I've never heard of a speaker knife.

A Speaker Knife is actually a rather cool idea. It's a device that is like a high-speed, passive-spike/transient speaker and driver protector that will self-reset once the over-powering situation is solved.

The Dynastar Speaker Knife ($89.99) is ideal in those situations where rental companies seek to idiot-proof or blowup-proof their equipment. About the size of a power supply for a portable CD player, the Speaker Knife is designed to mount internally in a speaker cabinet. It is waterproof and can mount externally as well.

Simply put, it's a little black box with three wires protruding from it. One wire is a common ground, one is the input hot and the third is the output hot. A screw-driven adjustment lets you set the transient response range appropriate for your speaker load.

This adjustment functions like a threshold sensitivity adjustment. First calculate the impedance of the entire speaker load and then use the trimmer adjustment to find the threshold at which you want the Speaker Knife to react. Dynastar designed the device to work in the following ranges: 100 W to 5,600 W at 2 ohms; 50 W to 2,800 W at 4 ohms; 25 W to 1,400 W at 8 ohms; and 12.5 W to 700 W at 16 ohms.

The manufacturer includes comprehensive instructions for using the Speaker Knife, as well as mounting hardware and wire nuts to complete the installation.

I wired the Speaker Knife to a JBL 2482 phenolic driver (an indestructible driver, just in case I did something idiotic), and powered it with a Yorkville AP 6040 power amp, which delivers something in the neighborhood of 750 W at 16 ohms. I ran a CD program through the network and began adding volume at small increments.

I reached the point where the driver began to bristle at the amount of volume and began adjusting the threshold of the Speaker Knife. The threshold was attained, and instantly the transients above that threshold literally disappeared. As soon as the volume was reduced, the signal reappeared. There was no apparent loss of frequency response or compression of the signal as the Dynastar Speaker Knife truly reacted quickly and cleanly.

I repeated the process with other components and frequency ranges, and the result was about the same. The Speaker Knife worked well protecting the various speakers. I recommend using a more solid connection than wire nuts when installing this device, as they will probably vibrate loose in time.

The Dynastar Speaker Knife is an interesting idea and is viable for rental speaker systems that might be controlled by untrained or novice personnel. I recommend giving it a try - it just may save your speakers!

Contact: Dynastar at 559-433-9700.