Autoformer

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A stereo pair of Autoformers used to increase the impedance of a pair of speakers so they look like an easier load to the amplifier.




The ZEROs are the simplest type of transformer called an auto-transformer or autoformer. They are used to multiply the impedance of any speaker so that it "feels" like the optimum load for the amplifier being used. They are very helpful in matching speakers to amplifiers. By adjusting the speaker's impedance, both the damping factor and the maximum power transfer of the amp/speaker can be tailored for best sound. Almost all amplifiers sound better when driving a higher impedance speaker, because amplifiers produce less distortion when driving less current.

The ZEROs are a great way to get better amplifier performance when driving low impedance speakers.



The ZERO-Boxes are simply the "naked" ZERO-Autoformers installed in a beautiful hand crafted lacquer finished solid Cherry or Birdseye Maple wooden box with African Ebony wood accents on the four corners. The connections are available on Cardas solid Copper binding posts allowing you to use your favorite speaker cables. The single pair of binding posts are the connections that go to the speaker. The quad set of binding posts allow you to choose the multiplication factor (depending on which two of the four are connect back to the amplifier). Polarity passes through the box: Left in-Left out, Right in-Right out.



Highlights:

60 day Trial Period
Multiply any speaker's impedance by 1.4x, 2x, 3x, or 4x
Example: a 4 ohm speaker becomes 6, 8, 12, or 16 ohms
Includes a set of Jumpers to connect from the boxes to the speakers
Typical Reported Sound Improvements:

Lower distortion "sounds cleaner" (due to an easier load on the amplifier)
Firmer bass (due to an increased damping factor)
Higher resolution (due to an easier load on the amplifier)
More extended and better focused high frequency.
Uses:

Use with any low impedance speaker
A problem solving device for when there is an Amplifier/Speaker mismatch
Popular when driving Magnepan speakers with Tube Amplifiers
Enables using a tube amplifier's better sounding 8 ohm output tap when driving 4 ohm speakers (popular with Audio Research Corp. tube amp owners)
Greatly Increases Smaller OTL (output transformer less) Amplifiers' Output Power:

Get 50 watts/ch out of the 30 watt Atma-Sphere S-30 amp
Get 80 watts out of the 60 watt Atma-Sphere M-60 amp


The scope picture show frequency along the horizontal axis (log scale from 20 to 40KHz), and impedance along the vertical axis ( 2 ohms/ major line). Zero ohms is the bottom line, moving up there is 2 ohms on the next line, 4 ohms on the next line, etc. The lower trace is of an actual 4 ohm speaker. Notice that it exactly crosses 4 ohms at the center line (1KHz). The above line shows the impedance of the same speaker after its impedance has been multiplied by two (2x) with the ZERO-Autoformer. Notice that it now crosses 8 ohms at 1KHz.

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