The Reference Pentode and Beam Tetrode Thread EL34, KT66, KT77, KT88, EL11, EL12, EL3N, EL35, EL37, 6550, 6L6, EL51, EL39, 4654, 4699, KT63, KT61, 6V6, etc
Sep 4, 2021 at 7:38 PM Thread Starter Post #1 of 638

leftside

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There have been a few discussions of these tubes and related on here, so @UntilThen suggested I create this thread. I also know @Monsterzero and @whirlwind have some nice variations of these tubes.

I have spent quite a few years learning and collecting these tubes, and I'd like to share that knowledge. There are also others on here who have a lot more knowledge than me, and it would be great to learn from them.

Most of these tubes are quite well known, but some not so much.

Here are the IMO best sources of information, and I have learnt a lot from these two books by my friend Pasquale Russo:
https://musica-parole.it/manuali/guide-to-6l6-6550-kt66-kt88-by-pasquale-russo/
https://digilander.libero.it/pasqua49/GUIDE TO EL34/guide to EL34 6CA7.htm

Other good sources of information can be found here:
http://www.jogis-roehrenbude.de/EL34-Story/EL34-Story.htm (If German is not your native language, then open in Chrome and use the Google translate plugin)
https://jacmusic.com/nos/EL50/index.htm
https://mullard.org/blogs/news/83886851-cv-numbers-and-uk-military-date-and-factory-codes
https://tubemaze.info/deciphering-european-tube-date-codes/
http://files.mxv.be/blog/Lampes-code-usinesphillipes-philipstubecodes.pdf
https://tubes4hifiaudio.nl/tube-testing-quality-control/philips-etceteras-date-codes/
http://www.tubebbs.com/tubedata/sheets/046/suppinfo/02/06_power-output-valves.pdf (good info on the 4654, 4689, 4699 and EL51 tubes)
 
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Sep 4, 2021 at 7:45 PM Post #2 of 638

leftside

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Let's start with some tube porn. So, what do we have here then?
KT66 earliest version (1939- 1945). Shoulder type, clear glass, black base. There are multiple variations of these tubes - grey glass, etc
KT66 second version. These are from 1952. Grey glass, black base. Lot's of variations.
KT88 the last and most well known version with 3 getters (one on top, two on the sides). These are from 1972.
KT61 first version? Grey glass, black base. 1951
KT77 from 1969

IMG_7013.jpg
 
Sep 4, 2021 at 8:46 PM Post #5 of 638

UntilThen

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Tung Sol 6550. There were a few versions of the Tung-Sol 6550 tube over the years. These are from 1960's. This tube has grey flat plates, and triple 'O' getters. They were made in the USA at Tung-Sol's Newark, NJ factory. Smooth highs and powerful bass. I love these tubes in my amp.

IMG_3085.jpg

IMG_3084.jpg
 
Sep 4, 2021 at 8:48 PM Post #6 of 638

UntilThen

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No mention of the 6V6 family of tubes. Also a beam-power tetrode.

I've subscribed. I'll work on assembling my 6V6 collection over the next bit and see if I can shoot a few pictures to share. Fun!

For sure, let's have them in here. Lovingly remembering my time with Studio Six.
 
Sep 4, 2021 at 9:13 PM Post #8 of 638

RobertSM

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The Visseaux 6V6gt metal base.

I'm currently running a pair of these in my Studio Six that I bought that were used but measured nearly NOS. This pair, in the pictures is true NOS, matched pair, with matching date codes and fully tested, with documentation, by a well respected lab in Germany.
 

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Sep 4, 2021 at 9:23 PM Post #9 of 638

leftside

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No mention of the 6V6 family of tubes. Also a beam-power tetrode.

I've subscribed. I'll work on assembling my 6V6 collection over the next bit and see if I can shoot a few pictures to share. Fun!
Yes definitely include those! Great pics.
 
Sep 4, 2021 at 9:26 PM Post #10 of 638

leftside

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Sep 4, 2021 at 9:39 PM Post #11 of 638

UntilThen

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I don't have much information on EL39 but everyone knows by now that I love them in Odyssey. Some info from Audio Asylum by Jean Luc / France. https://www.audioasylum.com/cgi/t.mpl?f=tubes&m=128712 under the title of 'EL39 is a very good audio valve'. Bass on this tube is special as is the body tone.

IMG_3086.jpg
 
Sep 4, 2021 at 10:03 PM Post #12 of 638

UntilThen

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