Previous installments in this series appeared in Issues 209, 210, 211, 212 and 213.
After having gotten the perfect idea of how to build my own power generating station from engineer and audiophile, Doug Goldberg – connect a sine wave oscillator to an audio power amplifier—the next challenge would be a bit of a ball buster.
Audio power amplifiers aren't that hard to design and build. While at PS Audio and Genesis Technologies, I had designed and built any number of them. These power amplifiers were designed to drive loudspeakers: 8-ohm and 4-ohm loads at wattages that ranged from several watts to hundreds of watts.
To do that, a power amplifier has to produce a certain amount of voltage at its output. That voltage is what drives the loudspeaker, powering the coil of wire that moves the speaker's woofers and tweeters back and forth. To maintain that voltage that is driving the speaker, we need current (motive force), which we express in watts. Volts times amps equals watts, and it’s the combination of voltage and current that determines how many watts an amplifier will deliver.
The typical voltage out of a power amplifier, even a decent sized power amplifier of, say, 200 watts, is about 40 volts. So, if you have a power amplifier that outputs 40 volts and you place that voltage into an 8-ohm speaker, you can confidently say you'll get 200 watts. Cut the speaker's impedance in half, to 4 ohms, and that same output voltage would now give you 400 watts.
Simple, right?
Well, yes, unless you, like me, needed to build a power amplifier that could produce upwards of 230 volts. Yikes! Even the US line voltage out of our home's wall socket at half that, at 120 volts, represents a huge demand. And, it would be from a power amplifier I did not have.
Let's do the math. A power amplifier producing 120 volts RMS into an 8-ohm load is the same as an 1,800-watt amplifier. If that wasn't bad enough, try this on for size. In 1997, the only reasonable power transistors available to me with enough power to build an amplifier were voltage-limited to around 80 volts. Try running them at a higher voltage and poof, they die.
Yikes.
More thinking. More late night walks. Think. Calculate. Stress.
The biggest amplifier I could imagine building with any practicality was around 500 watts into an 8-ohm load. That was pretty much the limit of what I could do. Unfortunately, that only produced a little over 60 volts – half of what I needed.
Half. Think about it. Half.... 2 x 60 equals....120, just what I needed. How could I get double the voltage?
Years earlier, PS Audio had produced a little power amplifier called the 2C. It was a cute little 60-watt-per-channel stereo amplifier housed in a breadbox sized chassis. We sold tons of them. Great sounding, reliable, and easy to build. The 2C had a rather novel (at the time) feature: a switch on the rear of the unit that converted the little stereo amplifier into a much more powerful mono amplifier.
How did it do that?
By flipping the phase of the input signal. It's the same idea we find in a balanced XLR cable. Two conductors inside a balanced cable – one out of phase with the other. And between the two conductors, what do you get? Double the voltage.*
*This is because as one signal is going positive, the second signal is going negative. Think of two cars each traveling at 60 mph. If they move in opposite directions, then the speed between them is doubled to 120 mph.
Bingo! Build a 500watt stereo power amplifier and place one channel out of phase with the other, thus doubling the voltage. Now, we have a power amplifier that can produce 120 volts RMS.
Just what we need.
******
Finally, after months of work, and lots of thinking, tinkering, designing, and building, I was ready to see if this crazy idea of turning an 1,800watt (capable) power amplifier into an AC power generator would work. And, if it did work, what would the results be?
If you'll recall from previous installments, the knowledge that passive power conditioners only make matters worse, followed by the realization that the core of the problem was actually the wires in the home themselves – coupled with the sharing of the AC power by everyone connected to the same power grid, and that the only solution was either my impractical electro-mechanical generator or its electronic equivalent – the fate of our new company rested solely on the outcome of this next experiment.
There were no other choices down this long and winding road. If this did not work, a total reset and change of direction would be needed.
My great and bold idea to build an electronic version of a power generating station that was living room -friendly, solved all the problems inherent in our home's electrical grid, dramatically improved the measured and audible performance levels of a high-end audio system, and was worth investing time and money in, was the right thing to be doing at the time, but would only matter to our world if it worked.*
*The list of great and bold ideas where people have invested their lives in futile attempts at solving problems is long: perpetual motion, 100 miles per gallon carburetors, space fountains, the Chronovisor, cold fusion, and on. Still, without these efforts at what seems crazy or impossible we would never stretch our imagination far enough to make strides into the unknown. Sometimes, these kinds of ideas work – mostly, they do not. Regardless of the outcome of this experiment, I would not have changed a thing regarding this perilous gamble I was undertaking.
I got it all working. On the test bench, at least. The real test would have to take place on an actual high-end audio system.
With PS Audio, four teenage boys and a crazy howling beagle named Snoopy filling our home, there was no room for a stereo system.*
*At the time, there was no PS Audio physical presence anywhere except our home in Vail, Colorado. I had converted part of our garage into my lab (challenging in that "sort of" heated environment when mountain temperatures dropped below zero) and Terri had turned a corner of our living room into her accounting office, though the only thing to account for was a growing stack of debt.
Our dear friend and attorney (and eventually the first president of the new PS Audio), Peter Rudy, had a stereo system. And a really sweet one at that. A beautiful pair of Genesis II loudspeakers (a smaller four-piece system mirroring the configuration of the Infinity IRS) sat in his Vail living room, along with a collection of Sonic Frontiers, conrad-johnson, and Audio Research electronics. Peter, ever the tinkerer and adventurer, was ready, willing, and eager to give this newfangled contraption a try.*
*An unusual combination of attributes for an audiophile, because most people I know with this much invested in a system would run away screaming at the thought of connecting an untried contraption like this to their equipment. The likelihood of this 1,800-watt power amplifier going DC or oscillating or simply producing a cloud of acrid blue smoke rising up to the ceiling in was high. And likely.
The experiment would be built like this: my cobbled-together power amplifier/regenerator that, at its output, could produce a whopping 120 volts RMS, and had enough grunt available to power on equipment (good to remember that on turn-on, our equipment quickly sucked down enormous amounts of current to get up and running – known in engineering circles as inrush current). The amplifier was fed at its input by my big Hewlett-Packard vacuum-tube bench oscillator.
Peter agreed to go for the gusto. Throw caution to the wind and power on the entire system, from preamp to power amp and source. All of it. Let's just fricking go for it!
Came the big moment and I winced before flipping the switch that would power on (or blow up) the system.
******
I don't believe I was breathing at the moment I flipped the switch to power up my friend's 50K stereo system. No, I am pretty certain I was holding my breath at the moment my cobbled-together power amplifier, fed at its input by a vintage HP signal generator, came to life.
Set the controls for the heart of the fun: a vintage Hewlett-Packard 200A audio oscillator. Courtesy of Wikimedia Commons/Colin.
It worked. Dang! No telltale whiffs of blue smoke, just everything in his system powered on and happy.
That was the first good news, which slowed my heart beat to something less than a speeding locomotive. The next step would either slow it to a normal rhythm or stop it altogether.
How would it sound?
Well, it’s probably not a spoiler alert to suggest it sounded beyond our wildest expectations. We had our collective fingers crossed, hoping to hear an overall improvement, but we certainly weren't expecting the magnitude of change we heard. In fact, so big was the improvement that we turned the system off, removed the power amp/regenerator, plugged everything back into the wall socket and tried again.
Sanity check.
Plugged back into the wall sockets, the experience we had become accustomed to without the power amp in the system instantly returned.
With the new power generating station feeding Peter's system, we had both exclaimed that it sounded like someone pulled a blanket off the speakers. With the system plugged directly into the wall socket again, the muddled and thick sound was back. Gone was the enormous front-to-back depth from that had seemed to extend outside the windows of his home with the regenerator in place. Gone too was the extraordinary new-found space between instruments and vocalists. In its place, the performers now felt scrunched and crowded.
We reconnected the regenerator and bingo! Back again. Wow!
The HP sine wave generator connected to the power amplifier's input had on its face a huge dial that determined the frequency of the sine wave. Because our homes in the United States run on 60 Hz, while homes in Europe and much of Asia run at 50 Hz, I figured it would be fun to see what differences we might hear when I changed the frequency. Easy to do. Just turn the big dial and voila! New frequency.
Interestingly, moving the dial from 60 Hz to 50 Hz had a noticeable sonic difference: bass was strengthened but the higher frequencies thickened. OK, weird enough, but confirmed. Changing the frequency of the sine wave powering our equipment changed the way it sounded. As Mr. Spock was fond of saying, "fascinating."
Peter, ever the tinkerer, asked, "what happens if we go the other way?"
Great question, easy to try. With every increase in frequency the top end and midrange opened up while the bass frequencies thinned out. On that day, we took the frequency to as high as 400 Hz and were just stunned at the difference in sound quality.*
"This revelation about frequency affecting sound quality would lead us to invent yet another innovation, one our good friend and Northrop Grumman engineer Doug Goldberg would spearhead called MultiWave, that is still in the PowerPlants of today.
It worked. It worked so well that then and there I decided this would become the fundamental foundation of the new PS Audio. The first product would launch the next year, 1998, with the world's first high-end audio regenerator featuring fully-adjustable frequency and voltage. It was called the P300 and was capable of producing up to 300 watts of pure, low impedance AC power. This device was limited to 120 volts output (for reasons now clear to you). To produce 230 volts, export models had an added step-up power transformer at their output. We sold thousands of these units and today, most are still in use, helping stereo systems around the world perform at their best.*
PS Audio's first product, the P300 PowerPlant. Images courtesy of TONEAudio.
*Unbeknownst to us at the time, Japanese manufacturer Accuphase had been working on the same idea and launched a 500watt version of the AC regenerator though it did not have adjustable anything. Still, a fine unit.
From that glorious moment at Peter's home, we built a company that today, 50 years after its inception, remains based on our original dream of building performance based high -value products, starting from the AC wall socket and covering everything in between all the way to your ears.
The PowerPlants were the start of it all and, still to this day, remain the core of any great system, because the AC power problems in our homes, the ones that will never be solved by passive power conditioners or any technology that does not measurably address the real problems of the power feeding our equipment, remain.
Hope you enjoyed this look into our history.
Header image courtesy of Pexels.com/lil artsy.
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