Always on the quest to pack more power into a single tube, the 6550 was launched in the 1950s by Tung-Sol. Tung-Sol is an American company who specialise in vacuum tubes. They still sell their reissue of this famous valve. The 1950’s version was rapidly improved in the 1960s to produce the MKIII version. Since then the valve has been further developed by other manufacturers so now a great valve is even better.
The 6550 tube or 6550 valve has a plate dissipation of 42 Watts. This means it can handle a LOT of power. Compare this with, for example, the 6L6GC which can handle 30W or the EL34 which can handle 25W. The 6550 valve allows for amplifier designs up to 100W (peak) using just a pair of valves. This would normally require four EL34s.
Ampeg started using 6550 valves in their SVT range of amps, typically 6 per amp yielding an awesome 150 watts of raw power. A side advantage is you can also do your toasted teacakes on the heat chucked out by 6 of these 6550 beasts.
6550 valves in hi-fi applications
The 6550 tube was also used in many Hi-Fi amps from the 1960s.
Hi-Fi users love the warmth, the tone and just the “feel” of these valves.
It’s fascinating to note the harmonic distortion for these valves is about 10%. TEN PERCENT!! Compare that with the 0.005% for a good transistor Hi-Fi amp! This doesn’t matter if you’re using the 6550 tube in a guitar amplifier of course since a guitar amp is effectively a fuzz pedal in a big box!
The JJ 6550 Valve
We have been in the guitar valve business for decades and have chosen the JJ 6550 as our favourite. The JJ version of the 6550 is a ‘straight bottle’ version of the original Tung-Sol (which came in a pear-shaped bottle). These JJ 6550 valves produce a really excellent sound in both bass and guitar amplifiers. They are also sensibly priced. Often a JJ 6550 will be half the price of a Tung-Sol 6550 reissue.
Technically, the 6550 valve is a high power beam pentode. That means it has five electrodes. A cathode, an anode and three grids. It has a standard octal base with a keyway for lining it up with the socket.
If you are looking to buy JJ 6550 valves or JJ 6550 tubes, click on the links below.