Why so many tubes?

The number of tubes increased as speaker efficiency decreased.  Paralleling tubes or going push pull can increase power but also can muddy the sound.  As a builder of SET amps I focus on using as few tubes as possible.  Each tube has its own sound due to its harmonic signature.  To many harmonic signatures can lead to a softer or muddy sound.  A well set up SET can be as detailed solid state amp.  With the addition of a level of harmonics that keep it from becoming sterile.  But you are back to using efficient tubes.

As to using a giant 50 or more watt transmitting tube.  They are hard to power their heaters.

Paralleling tubes or going push pull can increase power but also can muddy the sound.

The word 'can' in the statement above prevents it from being false. Going PP can also **decrease** muddiness by decreasing distortion. The trick is to not combine PP circuits with single-ended. Otherwise you get some emphasis of the 5th harmonic (this is old news; Norman Crowhurst was writing about this 60 years ago...).


A fully differential amp (with no dedicated phase splitter) will have dramatically less distortion than a single-ended amp. The harmonics generated will fall off at a faster rate as the order of the harmonic is increased as well. But it still falls off with an exponential decay, which is what you're looking for if you want the amp to sound right. The difference in overall distortion can be dramatic- as much as 3 orders of magnitude lower for a given power output; about 1 magnitude lower for a relative output (IOW if both amps are driven to clipping). That translates directly to increased detail and smoother presentation.

More tubes more power....Tubes sell...

Are you kidding? Have you not heard? Tubes, sound better!

In 1979 I put together my first assault putting together a high end system by taking out my first loan for $5,000 (that is $18,871 in today’s dollars) for. Threshold s500 amp, my system was all solid state. Over the years of continuously investing and learning, and trading up… one by one each of my components were swapped out for tube equipment. Now, by far the best system I have ever had… all of my components are tubed. (Click on my user ID to see my systems).