DR Fuller Sound

Tubes, tubes, tubes! Recall back to the "Edison Effect" where a heated wire in a vacuum gives off electrons. The first practical use of this effect as in about 1904, when it was found that if you put two wires in a vacuum and heated one, an electrical current would flow from the heated wire to the non-heated wire. Thus the "diode" was born. It proved useful for changing alternating current (AC) to direct current (DC). Today, most of this is done with semiconductor diodes. Its other use was in detecting and demodulating radio signals. It was far more robust than the crystals which had been previously used. And AC/DC still didn't have its tube amps yet. Using tubes for amplification was still a couple of years away... To be continued.

Well, all you guitar players. Did you know there is a scientific reason why you prefer those tube amps? Transistors, when you overdrive them, reach the power supply voltage, and then make a straight line at the power supply voltage until the signal drops below the supply voltage. Due to the physics of the vacuum tube, when you overdrive it, the voltage reaches the supply voltage, and then actually drops slightly, producing a "sag" until the signal approaches the supply volt...age again, then rises to the supply voltage and then follows the signal again. A mathematical analysis of this phenomenon using calculus shows the transistor signal has mostly odd harmonics, but due to the sag, the tube signal contains mostly even harmonics. The human ear finds the even harmonics much more pleasant and "warm". Hence the major preference for tube amplification for guitars. Yes, there really is a difference. To be continued...

Hey all you guitar players! You all know your tube amps are old school, but likely more than you thought! The first glass envelope "vacuum" using electricity were actually made in the late 1700's, but didn't really do anything practical. The first discovery to make practical "thermionic valves" was Thomas Edison in the 1883, who discovered the "Edison Effect", that when you heat up a wire in a vacuum, it gives off electrons, not to mention heat and light. That old incandescent light bulb does more than you thought it did! To be continued...

I'm expanding my services. Not just repairs to guitar amps, but rebuilding of the electronic portion of transistor and tube amps, PA equipment and guitar effects.

Guitar amp repairs. Please call for rates.