A Free Tube Guide
| Posted in Guitar
By the addition of a third electron to the simple diode valve the current could be modulated between cathode and anode for a given voltage between the cathode and anode. The relationship between plate and grid voltage and current flow can be seen as a characteristic curve. Voltage gain is the achieved using the modulated current flow. If you’re still reading, thanks. And no, I don’t understand it either.
Up to the late forties when the transistor was invented, every radio, gramophone, TV set and lot of military hardware relied on the valve or tube but the lower wastage and manufacturing cost of the transistor has enabled it to dominate in the production of almost all electronic goods since. The result was that the traditional valve suppliers like RCA and GEC simply stopped making the glass vacuum tube.
As far as guitar amps were concerned, this was very bad news indeed, but somehow, a few dedicated companies like Mesa Boogie and Groove Tubes persuaded Chinese and Russian factories to take over production. We now take valve amps for granted and the solid state variety are usually at the lower end of the spectrum as far as quality and price is concerned.
For what to expect from a certain valve as far as sounds are concerned, here’s a basic guide.
1. The EL84. Best known for its use in the Vox AC15 and AC30 and in lower powered Class A amps like the Hiwatt hand wired models. Model to try: Vox Night Train.
2. The 6L6. Used in many Fender amps. Hi power, glassy clean, can be pushed into creamy distortion. Model to try: Fender Hot Rod Deluxe.
3. The EL34. Used mainly in Marshalls. Has a hard, aggressive edge. Loud! Model to try: Marshall JCM800.
4. The 6V6. Used in smaller Fender combos. Breaks up at lower volume levels. Refined. Model to try: Fender 65 Deluxe Reverb.
Personally, I’d rather talk about what valves sound like than what they do, it’s a tad more interesting and much easier to understand. Of course, talking about it doesn’t really do it either and when you get a chance to compare say, a 6L6 gainst an EL34, the different characteristics become clear, unlike my opening sentence.
