The Reference 6J5 Thread (L63, 6C5, 12J5, 6P5, etc.)
Jun 11, 2020 at 12:50 PM Thread Starter Post #1 of 1,667

chrisdrop

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[Thanks to @tintinsnowydog here is a consolidated list of tubes in this family]

Inspired by The Reference 6SN7 Thread, I thought I'd start one for the 6J5 "family of tubes".

Several people that I know have taken to using these as their drivers often, across a few different amps. The Glenn thread has been using them quite heavily ((2x) anywhere 6SN7 were formerly used). They have become my main input valve and I have a small collection of them now. As a quick reminder/summary, each 6J5 is 1/2 an 6SN7 (triode vs dual-triode). "Same as one triode unit of 6SN7GT"

What do I mean by the 6J5 "family of tubes"? I think all of these should be "in play" for the thread as they are equivalent or thereabouts the same: 6J5, 6C5, 6P5, L63, VT94, CV1932, (12J5 - 12v heater if your amp can support). There are many metal, glass tubular, shoulder-types and even metal-glass tube types out there. That means you will find 6J5 (metal), 6J5G, (shoulder-types), 6J5GT (glass-tubular), and 6J5MT (metal-tubular). The same mostly for 6C5. I haven't seen any metal 6P5s, L63s. Here is a 6J5 "tube of the month" post from 2013 that has some info.

What amps are these currently being used in (around here, that I am aware of)? Glenn OTLs (mostly via 6SN7 adapter), there is at least one Glenn OTL that was modified to have 2x 6J5 sockets.@Zachik's new Glenn (GEL3N?) amp has sockets for these. Some amps that @A2029 has built (and is building) have sockets for these. For example @leftside's amp (Thunder?) has sockets for these. I believe @L0rdGwyn has made at least one amp with these sockets. I am quite certain there are more. Of course other amps that use 6SN7 tubes will likely have users that have tried the 2x6J5 adapter route.

Many amps have 6SN7 sockets. 6SN7 tubes have become over-bid. I'd love for that *not* to happen to the 6J5 family. I also think it is also worth sharing impressions with this forum. If you have a single 6SN7 socket, you can call @Deyan and get a very nice 2x 6J5 > 6SN7 adapter (or search on eBay). If you have 6J5 sockets in your amp, well done! Disclaimer: your amp, your tubes, your responsibility. Make sure this will work in your amp before taking my suggestion.

Some users here on head-fi have very nice collections of these tubes. I look forwards to seeing them. I'll make a few posts with pics/ comments on some.

** Of exceptionally minor note (but amusement to me), I was going to call this "The Reference ^(6|12){1}(J|C|P){1}5(G|GT|MG){0,1}$ Thread", but I thought the tube matching regular expression was a bit too arcane except a small group of people!
 
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Jun 11, 2020 at 1:48 PM Post #2 of 1,667

chrisdrop

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And now, a first post. Mullard 6J5G

I heard from another head-fier that these "brown base" Mullards are an uncommon variety. I did a bit of googling and it seems the same is true of other Mullard tubes too, brown base seems rarer. That is, a happy accident for me, not any of my tube-smarts. These came via Billington here in the UK. I highly recommend them. Always top quality and excellent service.

I have used this pair for around 50h so far. They have taken some time to burn in and have changing characteristics. The sounded pretty "taught" in the beginning. They have slowly relaxed linearly from 10h to now - opening up. I have sometimes had a long burn in on other tubes (I think a pair of GEC tubes took ~80h to change, maybe even more). These are very solid and enjoyable tubes. They are pretty neutral in their representation, not bassy/trebly, etc. I have other tubes that I'd say are more coloured (posts on them eventually).

At the 50h mark, they still sound a touch congested in the mids to me. They have very good tight representation of the whole spectrum. I like their clarity. They don't have the biggest headstage IMO, but they are presented very nicely nonetheless.

Of note, I can't find a date code on these things. The only markings I can find are these "5"s on the bottom of each tube, visible in the picture below.

They are pretty tubes.

20200611_175140.jpg
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20200611_175244.jpg
 
Jun 12, 2020 at 6:15 AM Post #3 of 1,667

chrisdrop

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"New logo" RCA CV1932

Radio Museum seems to denote CV1932 as = 6J5G but clearly this one is not a shoulder-type glass tube.

I didn't particularly fancy this pair. IMO it is hard to 6J5s wrong, especially the "ugly duckling" metal can ones, which are usually good sounding. Now, in all fairness - they are almost free, at ~$5 each, but still - usually the metal 6J5s are pretty good.

RCA changed their logo in what looks like 1968 according to this link. That makes these newer build tubes than the older "beach ball logo" versions.

20191126_192239.jpg
20191126_192313.jpg
 
Jun 12, 2020 at 12:26 PM Post #5 of 1,667

chrisdrop

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GEC 6J5G Grey Glass

These are my favourite drivers. I like others, but I always love coming back to these.

These are pre-1945 tubes according to the knowledgable folks over on the Glenn thread. They were expensive-ish but most excellent.

These too a loooong time to get to peak performance. I wasn't even sure I liked them until > 50h perhaps, then they kept getting better and better.

In short, they have all of the right characteristics; clarity, excellent representation across the frequency spectrum, thump, speed, and so on.

I'd love to get more of the M-OV family of tubes from this era, but I believe they will be similar.

These pictures were shared in Nov on the Glenn thread, but it is worth posting them again here:
20191118_183001.jpg
20191118_183015.jpg
 
Jun 13, 2020 at 1:31 PM Post #6 of 1,667

chrisdrop

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Fivre 6J5GT

These are interesting tubes. They have some of the "air", pleasant mid and treble representation, and a feeling of "delicate sounds". They are quite spacious sounding. They lack a bit in the heft and lower end, but it is compensated nicely by the rest. They do sort of remind me of C3G tubes, which are very clear and can sometimes (to me) become fatiguing.

I can't tell when exactly they are from. The date on them is a tax date from the ministry of finance (in 1959), not a manufacture date. Also the "MM" faintly visible on them denotes that they are military tubes (I think like JAN in the US).

These tubes make me want to hear more Fivre tubes...

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Jun 13, 2020 at 2:35 PM Post #7 of 1,667

CAJames

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I decided to start at the bottom and ordered a pair of 6J5 -> 6SN7 adapters and some (cheap, metal) KenRad 6J5s. I'm also interested in 6P5s because I'm looking for a way to turn down the gain a little on my amp. The tubes you're posting are beautiful, but seem like they cost as much or more than a lot of 6SN7s, esp. if you need 4 of them like me.
 
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Jun 13, 2020 at 2:53 PM Post #8 of 1,667

chrisdrop

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I decided to start at the bottom and ordered a pair of 6J5 -> 6SN7 adapters and some (cheap, metal) KenRad 6J5s. I'm also interested in 6P5s because I'm looking for a way to turn down the gain a little on my amp. The tubes you're posting are beautiful, but seem like they cost as much or more than a lot of 6SN7s, esp. if you need 4 of them like me.
You are right. So far, I have posted 2 more expensive pairs. The GECs are expensive (170 GBP for the pair if I recall correctly). The Fivres I got for ~40 EUR, which is very good.

I also want to get some 6P5 tubes (successor of the 76 tube, which I also plan on getting - with yet-another-adapter!).

Several users on the Glenn thread prefer the metal tubes. I love my 5$ GE 6C5 tubes. They are great. I really like the metal KenRads, which are inexpensive and have great thump. I will post more inexpensive ones too.

There are some overpriced 6SN7 tubes that are good; (not so expensive) KenRad VT231, Tung Sol Black Glass Round Plates, Sylvania Bad Boys, (expensive) ECC32, ECC33 etc - all are expensive relatively IMO. While I like those tubes, I still think the 6J5s have been generally cheaper and better.
 
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Jun 13, 2020 at 3:46 PM Post #9 of 1,667

leftside

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As nice as the coke bottle glass GEC tubes are, I find the best bang for the buck 6J5 are the early metal base tubes from KenRad, Sylvania, TungSol, etc with foil getters.
 
Jun 13, 2020 at 4:02 PM Post #11 of 1,667

chrisdrop

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I was told to go with a 6j5 socket over 6sn7 for the type of music I listen to. I planning to get a glenn amp made. Is this the way to go?
I would do that.
In my Glenn amp I usually use 6J5 and related tubes in the 6sn7 slot.
 
Jun 13, 2020 at 4:11 PM Post #12 of 1,667

Bonddam

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I would do that.
In my Glenn amp I usually use 6J5 and related tubes in the 6sn7 slot.
Ok
Stupid question
Is there particular tubes that are best with electronic music? There’s so many to get I’d like simplicity and get the best right away. I figure bass fast detailed great highs.
This amp will be for listening to my Verite open.
 
Jun 13, 2020 at 5:03 PM Post #13 of 1,667

CAJames

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I was told to go with a 6j5 socket over 6sn7 for the type of music I listen to. I planning to get a glenn amp made. Is this the way to go?

JMO but if you get a 6SN7 socket that gives you a lot more options. Fairly straightforward to go from 6SN7 -> 6J5 and also gives you the option of using e.g. 7N7 or 6CG7s with adapaters. Seems like if you get a 6J5 socket you are committed to the single triodes, unless you want to buy dual triodes and only use half of them.
 
Jun 13, 2020 at 6:04 PM Post #14 of 1,667

leftside

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