SAVING PUSH/PULL FROM ITSELF
WHY DO MEN ARGUE ABOUT ART?
The first reason is that sex, sports and television can get very boring. The second reason is that men love to argue because apes love to argue. And the third reason is that men are vain men who are artistic enjoy self glorifying arguments like push/pull versus single-ended circuits. If this vanity weren't forceful there would be nothing in museums.
Fashions change for a good reasons boredom and expanded awareness. After almost twenty years of expansion of push/pull tube amplifiers they have finally reached a level of wretched excess and crudity that is completely antithetical to their inherent thermionic nature. Push/pull created a rebellion, its artistic antithesis, which is called single-ended circuits about eight years ago..in America. This return to ultra-simple circuits occurred because a tribe of men care about more about beauty than the size of their toys.
Each topology has its limitation, and even with the shortcomings of SETs they were preferable to the grossness of the dominant Williamson type pentode amplifiers.
The purpose of this the first article in a series is to accelerate the process of saving push/pull from itself and stimulate a new fashion in push/pull design
THE PUSH/PULL PARADOX
It is the most popular tube amplifier topology in America, and yet hardly anyone knows what it sounds like. Just because you have eaten a Mc Donald's Whopper you assume you know what a hamburger tastes like, and you don't if the subtle beauty of the burger is your quest. The cry heard that explains why so many flocked to ultra-simple low powered single-ended circuits is "Something is wrong with the way push/pull pentodes sound they lack the magic and finesse of SET DHTs". This statement is inaccurate because it should focus on the fact that the way American companies design push/pull amplifiers is out of fashion, tends to concentrate on maximum crude horsepower, and therefore suffers from a high degree of aural discombobularity. The reason we are going to see, very shortly, a new fashion of push/pull amplifiers, is because fashions change, and this is good news, because many of you need more than 20 watts of highly refined horsepower, and when done right, push/pull has its own sublime musical magic, that is unknown in America.
THE GOOD OLD DAYS
Twenty five years ago the Mc Intosh 275 and Marantz 9 defined the high power rung of the thermionic ladder. How could anyone need more than 90 watts?
When solid state designers realized that men would buy into the idea that more power was more macho the era of the mega-transistor amp began. In the mid 1970s the Phase Linear 700 was the shot that was heard around the world with its 350 watts per channel, and when you weren't using it for music, you could use it to cut glass, that is how bad it sounded. Japanese receivers were boasting 150 watts per channel, and the horsepower race was on, and soon speaker manufacturers were in the running. Speaker companies boasted that their speakers were between 2 and 1 ohm, which were perfect for solid state amplifiers, who could dump tons of crude horsepower. An amplifier that was putting out 300 watts into 8 ohms could boast 1,000 watts into 2 ohms in the hope of giving the ultimate audio erection. American men were getting horsepower and watts confused.
In the early 1980s Audio Research and Conrad Johnson recognized that there was a market for an analog of these big transistor amps and started to build high horsepower pentode push/pull amps. In a perverse way this made sense, because these amps definitely sounded better on these low impedance speakers than comparable transistor amps. If you could afford to buy these tube mega-muthas, you could afford to replace the tubes every six months, even if that was often at a cost $1,000 because this was a bad speaker/amplifier interface. I wish I had a dollar for every phone call and email I got that asked "Why are my output tubes blowing up?". My answer is.."What do expect when you are using a 16 wheel truck on a Formula One race track?".
Because this is a sport of comparison big push/pull pentode amps do sound better than big transistor amps, which is as obvious as saying a rose smells better than a turd, but really misses the point. These big push/pull amps compared to a "proper" push pull amp are musically mediocre for a number of reasons:
You may not have a choice. If you need more than 20 watts and YOU probably represent 95% of music maniacs who love their "made for transistor" speakers you need a push/pull amplifier.
On the other hand when push/pull is done right it is a very ecstatic form of musical beauty that has its own unique aural matrix that is completely different than SET. It is wider, more uniform in its wave front top to bottom, and it is definitely more bombastic bass. What you give up is the 3D holographic wholosity of single-ended circuits and their harmonic purity.
AND NOW THE GOOD NEWS
THE GEORGE WASHING OF THE PUSH/PULL REVOLUTION
Every revolution needs its George Washington and Lynn is it. Most of you don't know who he is, yet among the savy he is considered a heavy duty savant. In the coming years he will be identified as the starting point, the leader of the new American push/pull revolution. In the same way, in 1992, they all laughed at single-ended circuits, we are about to see the beginning of a push/pull revolution, and you wont recognize it because it looks like nothing you have ever seen before in push/pull amplifiers, and Lynn has a beautiful vision of it to inspire you.
Now that the pendulum has properly swung towards single-ended circuits, , it is time to re-explore push/pull circuits from a completely new point of view. and Lynn is the first American to do it.
Lynn and I started to discuss this "push/pull abyss" about two years ago, when I raved to him about my experience with the Sun Audio 300B amps with transformer phase splitters. He sent me a schematic of his own very impressive design, which was a radical update of a very old, pre-Williamson concept..and looked way cool. Two years later his design has reached maturity.
Because Lynn is a Zen Buddhist thermionic techno shaman, aesthetic principals precedes and guides engineering. Judging by knowing them both, Lynn is the American closest to the spirit of Nobu Shishido which is probably explained by the fact Lynn lived in Japan for many years. I can think of no higher compliment. Now go to his web site and experience the place where the revolution is beginning. Because of the fertility of Lynn's mind I have asked him to create a compilation of his writing and articles, let's call it The Encyclopedia Olsenica, which you can download from his web site. Consider it "The Push/Pull Declaration of Independence", and it is an historic document. (address of web site). www.aloha-audio.com
CLOSE OF PART I
America is the land of powerful push/pull tube amps out of necessity because this is the land of the dysfunctional "transistor" speaker, but the fashion revolution, which is your ascending sensitivity to music is climbing up the thermionic ladder. A new generation of push/pull amps will be appears because YOU know more and demand more you are The Declaration of Independence from Push/Pull aural discombobularity. Fortunately Lynn Olsen is here to guide the march. Spend time investigation this subject. Check out a bunch of Japanese web sites and stay tuned to the next articles in this series.
e-mail Dr. Harvey "Gizmo" Rosenberg: firstname.lastname@example.org
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