The History of Synergistic Research Active Shielding
To understand Active Shielding, it is necessary to first understand the principles of Synergistic Research cable design. Our first step in designing a cable to complement a target system is to develop a geometry that complements that system at an engineering level by precisely controlling capacitance, inductance, and resistance in the cable geometry. Next, we 'voice' every cable in its target system by building each design out of literally dozens of different material combinations, seeking specific materials to yield natural sound.
For seven years, we worked with hundreds of passive cable geometries and over one thousand different material variations. During this process we realized passive differences in geometry and material selection could only take us so far and that ultimately we were limited by reactive capacitance (signal and cable interaction) and shield performance (RFI - Radio Frequency Interference and EMI - Electro-Magnetic Interference). During this process, we had an idea to actively suppress reactive capacitance and RFI and EMI to dramatically improve cable performance. So began our Active Shielding cable program.
Our first experiments with Active Shielding began early in 1996 and involved the placement of batteries in a static circuit, with the positive annode of the battery tied to a conductor running the length of a cable and the negative annode of the battery tied to the shield. These initial prototypes subjectively improved performance in the high frequencies. However, they also increased the noise floor (especially on long-runs), with its positive conductor running the length of the cable and not being terminated to signal or ground, thus acting like an antenna picking up RFI and EMI.
We then experimented with closed circuits where the shield carried a DC current with a buffer circuit between shield and ground with seperate conductors carrying the ground signal. This closed circuit design not only improved subjective performance, but also made our cables measureably quieter thus improving detail with greater frequency extension from top to bottom. Since a closed circuit draws current, we could no longer use batteries as this would drain a battery in a matter of hours.
Mini Power Coupler (MPC)
A more powerful solution was needed so we developed an AC to DC power supply (Mini Power Coupler or MPC). With the advent of our new TESLA series cables, we are in our third generation of Active cable technology.
Each Synergistic Research Active cable comes with an MPC to provide power for the active shielding.
Quattro (Full System) Active Power Supply
The Quattro Full System Power Supply was developed for 2 reasons:
1. Performance - Synergistic Research has opened a door into a whole new world of cable performance with Active Shielding technologies. Mini Power Couplers are the first step into that world, but it does not end there. Through research we have discovered that using our A/C Power Cable technology applied to our Active Shielding technology multiplies the effect so that the level of cable performance dramatically improves. This is done by using a Quattro Full System Power Supply in conjunction with a Synergistic A/C power cable. As you move up from an entry level A/C Master Coupler all the way to an Absolute Reference A/C Master Coupler the effect of Active Shielding increases.
2. Convenience - Using more than two or three Active cables in any given audio or audio/video system will improve overall performance, but can lead to a dilemma in where to plug in multiple MPCs. The Quattro Full System Power Supply has been designed to power up to 12 Active cables. Multiple Quattros can be daisy-chained together to accommodate any number of Active cables.
