Guide to the EL34 / 6CA7 (7.th Edition)

Seven years have passed since the last edition. New curious details, unexpected and interesting reader’s reports, further investigations and random discoveries forced me to consider a new edition.

I am not young anymore and the trouble of drafting a new version scared me a little. I am used (for my job and hobbies) to synthetize topics and simplifying them until they are understandable to myself. I made it especially for scientific arguments, because I have had predominantly humanistic education, and only when a topic became easy for me did I start writing about. 

Writing in English was for me another problem. I am Italian and all that I know about English comes from my distant school studies, various readings, e-mails, internet browsing, some foreign trips and short live conversations. At my age, learning and overall memorizing new notions isn’t very easy. 

The tubes or valves, as you like to call them, are gaining increasing interest in audiophiles and musicians. Therefore, the demand of these wonderful and timeless devices become more and more pressing. Thus, it is essential to acquire sufficient knowledge to navigate into an increasingly global market. Tube’s new old stocks are getting more difficult to find and more expensive to buy, hence the need to turn our attention to other ones who are misunderstood and often better than others more popular and much used. A striking example is the long series of EL34’s forerunners, pentodes which dominated for decades the mondial market. 

Therefore, thanks also to the advices of some tube collectors and experts, I decided to rewrite completely the chapter about these famous ancestors, starting with the forerunners, the AL1 and EL1, carrying on throughout the AL- EL- series, until metal based and tubular shaped 46- series tubes. Only this new chapter amounts to about one hundred pages and one hundred and fifty new color pictures.

Furthermore, for a better comparison between them, I have included summary tables. Many and important information have been added about European made EL34s, such as those produced by Philips, Telefunken, RFT, Tesla and so on. I tried to clarify some significant aspects about Philips codes, making easier their decoding. I revisited also the chapter about Telefunken EL34s made in West Germany, adding new information about tube and getters shape (e.g. the controversial issue about dimple top tubes made in West Germany by Telefunken). 

Moreover, I added further notes about the other European tube makers, such as Tungsram date codes. I revisited too the chapter about Russian EL34s, making easier understanding the differences between St. Petersburg and Saratov production. 

Many other details and information were added which would be too long to list now. Finally, some old pictures, because ugly or unclear, have been changed or modified. To the readers, who – I hope – will want to read this new work of mine, my apologies for my grammar mistakes and my bad English.

April 2021                                  Pasquale Russo