Re: Tube Questions
This is from Justin Holton's Unofficial Fender Hot Rod Deluxe Owner's Guide:
How are tubes named?
In the United States vacuum tubes are identified by a naming system that is fairly standard.
1. The first part of a tube designation is a number (or numbers) which tells us the approximate voltage required for the filament of the tube. For example, the filament of a 6J5 requires 6.3 volts, the filament of a 5U4 requires 5 volts, and the filament of a 50L6 requires 50 volts. 12AX7s require 12.6 volts when wired in series, but when wired in parallel, as in almost all musicial instrument amplifiers, they require 6.3 volts. It's no coincidence that the 6L6-GC requires 6.3 volts, this allows us to hook them to the same voltage source.
2. The second part of a tube designation is a code letter (or group of letters) for identifying the tube types and functions.
3. The third part of a tube designation is a number which sometimes indicates the number of useful elements brought out to the base terminals. For example, a 12AX7 has seven elements if we consider the filaments (pins 4, 5, and 9) as one element.
4. The fourth part of a tube designation, if included, will consist of a letter or letters describing some particular characteristic of the tube. For example, a 5Y3-G has a glass (G) envelope. A 5Y3-GT is the same as the 5Y3-G except it's glass envelope is smaller (GT) than that of the G.
It must be emphasized that the following descriptions are generalized, and that there are many exceptions to what's listed here. Also note that Europeans use a different naming system. The only method of retrieving accurate information about a tube is to refer to its spec sheets.
Power tubes you should NOT use:
The 6L6 and 6L6GC are not the same tube!
Any power tube advertised as a 6L6, 6L6G, 6L6GA, or 6L6GB. Generically, 6L6GCs are usually referred to as "6L6s." Technically, these are NOT the same tubes! In fact, they are very different from each other! If you direct your attention directly to the right you'll see blatant proof of this: a comparison of a RCA 6L6 with a RCA 6L6GC. Take note that the differences are far more than just superficial, as I'll soon show. So why do techs and tube dealers refer to 6L6GCs as 6L6s on message boards? Laziness. I guess it's just much easier on the fingers to not include that extra "GC." I, on the other hand, will be very specific on this website and on the internet forums that I frequent. You should be too, as being ambiguous only adds to the confusion that plagues most discussion boards.
The Hot Rod amps have a plate voltage of around 430V (Deluxe) or 475V (Deville). They were designed to be used with 6L6GC tubes, which can handle 500 volts/30 watts on the plates, and 450 volts/5 watts on the screen. Lets take a look at the other 6L6 variations and see exactly how they differ.
