The U.S. Patent on our power supply, which we call GreenForce, is Patent No. US 8,411,475 B1, date of patent April 2, 2013.
Introduction
The power supply that runs most audio equipment today is called a “linear” supply. It was designed in the 1920s and hasn’t changed much. In more recent years, some audio devices have begun using a second kind of power supply – the “switching” supply, developed in the 1950s.
At Backert Labs, all of our preamplifiers use the new GreenForce™ power supply. Because GreenForce is totally unlike previous power supplies, Bob Backert was granted a patent on GreenForce in 2013.
For those who are familiar with electronics, an example of the surprising quality of GreenForce is that the capacitors used to power our Rhumba preamp total less than 1 uF (one microfarad). Most power supplies for a similar preamp would use hundreds, or 1000’s of microfarads.
Because so little capacitance is needed, GreenForce is the only power supply in the world that can run a stereo component entirely on PTFE capacitors such as V-Cap™ capacitors, which we feel are the finest type of capacitor for a power supply available today. More about that here. In contrast, the power supplies employed by almost all other manufacturers rely on electrolytic capacitors, which no longer perform at their best after a period of years and which we feel are some of the worst-sounding capacitors on the market. Other manufacturers use them, but not necessarily because they want to. They have no other choice. With GreenForce, that changes.
Green…
Bob Backert wanted to eliminate electrolytic capacitors from the power supply because electrolytic capacitors are famous for their disappointing sound quality. If that’s true, why do other manufacturers use electrolytic capacitors? Because their power supplies require very large capacitor values (like, the difference between a AAA battery and a D battery) that only electrolytics can provide. Because GreenForce uses such small capacitor values, we are able to use much higher quality capacitors to power our preamps.
Eliminating electrolytic capacitors is also helpful to our planet, because every part used in a preamp will eventually find its way to a landfill someday, and electrolytic capacitors contain chemical sludge that is essentially hazardous waste. The power supply is where you’ll find the largest electrolytic capacitors in any piece of audio gear. So eliminating electrolytic capacitors from the power supply has a happy side-effect for our environment.
…Force
Unlike traditional power supplies, in which a capacitor passively bleeds power out when the amplifier needs it, GreenForce provides power to the amplifier at all times with a kind of pressure, or force, that makes GreenForce proactive rather than passive.
The Benefit: This makes GreenForce more nimble and accurate than conventional supplies when the preamp needs to respond to changing current demands, for example, when more power is called for to reproduce the sound of a loud bass drum or the pluck of a double bass string.
Example: Capacitors in a power supply act like batteries that constantly get charged up and then discharge their power to run the preamp, or whatever device they are powering. Think about a typical linear power supply that powers a preamp. Imagine that the capacitor (the energy source) in this power supply is a barrel full of water. The water is the capacitor’s power, its energy. Picture this barrel of water hooked up to your preamp, powering it with the energy (water) that comes out of it. Your music constantly demands power, and the capacitor doesn’t have very much of it. So the barrel will constantly get low on water and need to be re-filled. In fact, it will need to be re-filled multiple times each second. The barrel sends its water to your preamp through a hose that is hooked up to the bottom of the barrel. In a typical power supply used by other manufacturers, the water just drains out of the barrel into the preamp, when the preamp needs it. But here’s the problem: imagine that right now, the barrel is low on water. And right now, a powerful bass drum hit happens in your music. Because the water in the barrel is low at this moment, the pressure of the water coming out of the hose is weak. Therefore the barrel’s ability to immediately provide all of the required power for that bass drum hit will be impaired. Full power will only be possible an instant later, after the barrel has been re-filled with water.
GreenForce changes that. GreenForce is like placing a lid on the water in the barrel, and steadily pushing the lid down as the water comes out of the hose at the bottom of the barrel — gently forcing the water out at all times. Now, the pressure of the water coming from the barrel remains steady, even when the barrel is getting low on water. This is similar to the power produced by the capacitors in GreenForce. No matter how much power your music calls for, and no matter when, it’s right there. The music will never get more power than it needs, because the regulator continuously soaks up the difference.
The Sound
The GreenForce™ power supply gives sound equipment improved dynamics — the lightning-fast changes in volume that all instruments and singers on a recording are constantly employing to give music its drive and emotion. GreenForce also improves soundstage, with a more accurate and spacious physical presentation. And GreenForce improves the sense of rhythm in Backert Labs preamps. Your favorite music will propel you, move you, like never before.
Why Power Supplies Matter
The power supply is surprisingly critical to the accurate reproduction of music. Read why here.
Tech Talk
GreenForce uses smaller capacitor values. To put that in context, the values in a GreenForce power supply are usually on the order of 0.5% of the value required by a normal power supply. The amount of energy or power in a capacitor is measured in uF (microfarads). A typical tube preamp might use 200 uF in the power supply, or 500uF, or even many thousands of uF. Our Rhumba line stage uses a fraction of one uF.
GreenForce has nothing in common with a switched mode power supply, and shares only a few similarities with linear power supplies. It achieves isolation from the AC line the same way a linear power supply does, by starting with a typical transformer.
Typical linear power supplies rely on energy stored in a capacitor. These storage caps are constantly delivering energy to the device being powered (in our case, a stereo preamp), so these storage caps need to be constantly “topped up” with more power from the transformer. These top-ups give the storage cap a surge of voltage, a “jolt” of power, many times each second. Bob Backert believes these jolts reduce linearity – i.e., reduce the capacitor’s ability to deliver the exact amounts of power being requested by the music signal at exactly the correct times, reducing the accuracy of dynamics in music.
Bob Backert wanted to rely more on “real-time” energy, similar to what you would get if you could directly hook up his preamps to the AC line. His response was to develop a power supply that greatly reduces the role of storage capacitors, while also greatly reducing the size of those capacitors. As a result GreenForce provides better current linearity, feeding the regulator with current more nimbly than other power supplies, thereby improving the accuracy of dynamics and other audio cues in your music.