[chrisdrop]

To me it is a fact that tubes change during burn-in. Sometimes subtly, sometimes radically, sometimes after a few hours and reaching full burn-in after 20-30 hours; sometimes considerably more - well over 100 hours at times.
Another mysterious aspect of our hobby...
I am also chartering the 6C5/6J5 waters, getting a kick out of trying dozens of tubes for just a few dollars each. The GEC L63 ST type is too expensive for me. I have been enjoying the Sylvania 6J5GT/T for a couple of weeks - great sounding tubes.
Today I tried a pair of these:

Tung Sol 6C5GT - a predecessor to the 6J5 . The screen is not a mesh but stamped metal and the purpose is to be a RF shield (Faraday cage).
There was some hum using these, but by connecting pins 1&8 with a tiny piece of stranded wire the hum disappeared, and these tubes are very silent now.
First impression: In comparison to the Sylvania 6J5GT which are airy and open and have a wide sound stage, these are a little laid back and have a less wide sound stage and more emphasis on the lower mid range and mid bass; more nasal but still very enjoyable - have to let them run longer to finalize my impressions.
So far I have not found a bad sounding 6C5/6J5 tube. It is remarkable that these bargain tubes are such (overlooked) performers. Perhaps one reason is that most tube amps would need four of them with two adapters whereas we lucky GOTL owners only need two triodes and one adapter.

Yet-another tube-healing device from doctor @mordy's medical bag. What makes this approach "connecting pins 1&8 with a tiny piece of stranded wire" the right thing to do to help (or by contrast, where should this device not be applied)? This article http://vinylsavor.blogspot.com/2013/03/tube-of-month-6j5.html says "pin 1 is either connected to the metal shell or unused" and the pinouts here https://frank.pocnet.net/sheets/049/6/6J5.pdf (pick any 6J5) show 8 as the cathode (and 1 to shell). Was the 1 pin unused in the above tube or was it to the shell/ base? What made you aim to connect it to the cathode? Sorry if these are dumb questions - just trying to understand.

Thanks again for sharing your tools for tube healing

I broke the top-cap off of an EL32 this weekend. Whilst ordering new (very inexpensive) ones to experiment with, I just had to order a few more pairs of inexpensive 6J5s, thanks to @L0rdGwyn -some 6C5s and a pair 12J5 too. They really have been fun and not expensive (except for the 1 GEC pair aforementioned). All of these were single-digit price per tube! Since I have 2 weeks at home starting Friday, I intend to have a LOT of listening time!

 

[UsoppNoKami]

GOTL tube roll for the week:



WE422A + GEC 6J5G ST drivers + Bendix 6080 slotted plates and GEC 6AS7G

Power tube combo appears to have enough current to run my HE1000SE planars, good listening times ahead

 

[GDuss]

I tried the solid black all-metal RCAs @mordy had mentioned too for a week or so (still probably not at critical tube break-in time?). I will have to cycle back to them. While the RCAs were pretty solid, I prefer the Sylvanias.

These are the RCAs you posted a photo of last week? On your recent purchase of additional 6J5s did you buy any more RCAs, possibly older versions (e.g. with the meatball logo)? I'm curious whether the sound of these metal RCAs is different depending on when the tube was made. There is a discussion on the 6SN7 thread about the RCA 6SN7 VT-231 grey glass tubes being different depending on manufacture date (older being better). Obviously this doesn't have to be true for other RCA tubes, but it's something I've been wondering. I need to get some later manufacture date RCA metal 6J5s to test this question.

 

[GDuss]

GOTL tube roll for the week:



WE422A + GEC 6J5G ST drivers + Bendix 6080 slotted plates and GEC 6AS7G

Power tube combo appears to have enough current to run my HE1000SE planars, good listening times ahead

I'd say this is not just a GOTL tube roll, but a TOTL tube roll .

 

[UsoppNoKami]

I'd say this is not just a GOTL tube roll, but a TOTL tube roll .

Haha, only in cost. Good sound on GOTL comes in so many flavours, we all know TOTL tone and sound quality can be had with modest 6BX7/6BL7s

 

[leftside]

These are the RCAs you posted a photo of last week? On your recent purchase of additional 6J5s did you buy any more RCAs, possibly older versions (e.g. with the meatball logo)? I'm curious whether the sound of these metal RCAs is different depending on when the tube was made. There is a discussion on the 6SN7 thread about the RCA 6SN7 VT-231 grey glass tubes being different depending on manufacture date (older being better). Obviously this doesn't have to be true for other RCA tubes, but it's something I've been wondering. I need to get some later manufacture date RCA metal 6J5s to test this question.

My experience with RCA tubes is older the better. I have 12ax7, 5751, 6SN7, red base, 6J5, 6C5, and a few others. But, I guess "older the better" is true of most tube manufacturers (as long as the tube is still performing of course).

 

[chrisdrop]

These are the RCAs you posted a photo of last week? On your recent purchase of additional 6J5s did you buy any more RCAs, possibly older versions (e.g. with the meatball logo)? I'm curious whether the sound of these metal RCAs is different depending on when the tube was made. There is a discussion on the 6SN7 thread about the RCA 6SN7 VT-231 grey glass tubes being different depending on manufacture date (older being better). Obviously this doesn't have to be true for other RCA tubes, but it's something I've been wondering. I need to get some later manufacture date RCA metal 6J5s to test this question.

Hey @GDuss - yes they are. Below are a few more up-close shots. I was hoping the #s might be meaningful, but all the #s are standard on these tubes. This page has this tube, with the same #s on it https://valvetubes.com/products/manufacture/rca/6j5-cv1932-rca-usa.html. Every marking is identical as far as I can tell. This doc https://frank.pocnet.net/sheets/049/6/6J5.pdf has some dates on it (1943, 1950), but nothing clearly dates these valves.... except...

The meatball logo is older. These valves use a logo from 1968 https://1000logos.net/rca-logo/

I do like these RCAs, which are very inexpensive. They may need more hours of use to get to their sweet-spot. I will seek out older RCAs. Langrex has some glass ones.

On the next batch of valves the relevant tubes I have en route just: 12J5GT KENRAD VT135, 6C5GT USA of some make (they had Fivre's but gone).

FWIW - while browsing, I came across some more expensive 6J5s, for example here: https://valvetubes.com/catalogsearch/result/?q=6j5 and here https://www.langrex.co.uk/?s=6j5&post_type=product

Fun adventures.

 

[GDuss]

My experience with RCA tubes is older the better. I have 12ax7, 5751, 6SN7, red base, 6J5, 6C5, and a few others. But, I guess "older the better" is true of most tube manufacturers (as long as the tube is still performing of course).

I haven't tried enough later production RCAs to be able to say for myself that older is better, but this is the rationale I've been using for purchasing earlier production RCA 6J5/6C5/12J5. I know the "older the better" phrase has also been used for Ken Rad tubes, especially given that they didn't remain an independent company past 1945. I'm sure there are plenty of other examples of manufacturing changes, company acquisitions etc that play a role in shifts in the design/quality of tubes over time.

 

[GDuss]

Hey @GDuss - yes they are. Below are a few more up-close shots. I was hoping the #s might be meaningful, but all the #s are standard on these tubes. This page has this tube, with the same #s on it https://valvetubes.com/products/manufacture/rca/6j5-cv1932-rca-usa.html. Every marking is identical as far as I can tell. This doc https://frank.pocnet.net/sheets/049/6/6J5.pdf has some dates on it (1943, 1950), but nothing clearly dates these valves.... except...

The meatball logo is older. These valves use a logo from 1968 https://1000logos.net/rca-logo/

I do like these RCAs, which are very inexpensive. They may need more hours of use to get to their sweet-spot. I will seek out older RCAs. Langrex has some glass ones.

On the next batch of valves the relevant tubes I have en route just: 12J5GT KENRAD VT135, 6C5GT USA of some make (they had Fivre's but gone).

FWIW - while browsing, I came across some more expensive 6J5s, for example here: https://valvetubes.com/catalogsearch/result/?q=6j5 and here https://www.langrex.co.uk/?s=6j5&post_type=product

Fun adventures.

Interesting link on the dating of RCA logos. The RCA metal tubes I have look like the one on the right in this link (with the meatball logo)

https://www.ebay.com/itm/Strong-Pai...2100gm-Metal-Serious-Tubes-K284/174105022026?

But the one on the left uses a logo that is not listed on the webpage you linked. I'm guessing that logo is later than the meatball but earlier than the 1968 logo.

As you point out, the great thing about these tubes is that they can often be found for single-digit prices. I've had a few instances of paying more for shipping than for a pair of tubes. The thing that stands in the way of me buying more of them is having enough time to actually listen to them. I suppose there are worse problems to have.

 

[mordy]

Hi Chrisdrop,
You say that nothing dates these tubes...well, you may be able to date them by looking at the metal base where it is stamped 6J5. Next to it there should be another letter and number stamped into the base, The sequence of these two symbols matters.
Once we know these designations the dates can be decoded.

Re the jumper between pin 1 and 8 to eliminate hum in some 6C5 family tubes I think I got the tip from Glenn. It is easy to know which pins to connect - the two on each side of the notch for the guide pin. In my experience not all tubes of this kind need it, but it does not do any harm if not needed. How it works I don't know, but it works very well for the 6C5 tubes I have that hummed.

Re the anode cap coming off one of the EL32 tubes - this is a common thing with old tubes, especially European ones in my experience. The glue deteriorates over time, and I routinely crazyglue the anode caps and bases on these old tubes. I found a little bottle of crazy glue with a built in small brush in the cap that easily reaches into the space between the base and the glass and also brushes on small amounts of glue easily on the area where the anode cap meets the glass. I only have good experiences with this, and nothing came apart again. Sometimes you can get a better buy on a tube if an honest seller lists the tube as having a lose base - can be fixed in a few seconds. But best to let it dry for 24 hours before using.
This is what I use:

IMHO a must for tube rollers and very inexpensive - less than $3.

Finally, about comparing EL8 to EL32 as additional drivers, I did compare them today. While the EL8 tubes are quite nice (in triple driver configuration), the EL32 sound better with more drive (pun intended). Next is a comparison between the EL32 and the TFK tubular EL11....

 

[mordy]

Forgot to mention that DL had a repair done to an anode cap that came off an expensive tube. If there is a little piece of wire left above the glass it is doable. However, given the low price of the EL32 it may not be worth the trouble unless you can do it yourself.

 

[whirlwind]

Rolled in the GEC KT66 last night , listened to Gary Clark Jr's live acoustic version of "When My Train Pulls In"
Hearing Gary's fingers pluck those guitar strings is quite epic!

 

[leftside]

Rolled in the GEC KT66 last night , listened to Gary Clark Jr's live acoustic version of "When My Train Pulls In"
Hearing Gary's fingers pluck those guitar strings is quite epic!

Very nice! Amp also looks great with those tubes.

 

[Zachik]

Rolled in the GEC KT66 last night , listened to Gary Clark Jr's live acoustic version of "When My Train Pulls In"
Hearing Gary's fingers pluck those guitar strings is quite epic!

Joe - you're making the wait for my amp even harder.......

 

[mordy]

There is a young women composer Alma Deutscher, that is an expert violin and piano player in addition to being a composer. Here is an unusual composition of hers that was recorded a couple of days ago by a full harmonic orchestra at Carnegie Hall. It starts with the chaotic sounds of the inner city with cars, trucks and police cars and gradually evolves into a beautiful waltz. Her music has an otherworldly beauty with hauntingly wonderful melodies.
On this recording she does not play, but at the end of the performance she comes on stage and thanks the audience - all of 14 years old.......
Amazing and astounding genius.
Good quality recording.