The Reference 6J5 Thread (L63, 6C5, 12J5, 6P5, etc.)

[pravous]

My black base pair of the Fivre 6c5g. I keep telling myself I will roll a different pair of inputs tomorrow and then another month goes by.

 

[raindownthunda]

I have a soft spot for Cossor re-brands. These Brimar-made 6J5G have great clarity running by themselves in BH mode. By adding the GE (Ken Rad) 5814 black plates as a triplet, the bass because thick and intoxicating (the 5998's are standing by idle in the last pic).

 

[leftside]

I have a soft spot for Cossor re-brands. These Brimar-made 6J5G have great clarity running by themselves in BH mode. By adding the GE (Ken Rad) 5814 black plates as a triplet, the bass because thick and intoxicating (the 5998's are standing by idle in the last pic).

British tube porn. Amazing how the print is so well preserved on those tubes.

 

[mordy]

If “plate size”matters the Visseaux have no envy problems. I have one quad with a nice pair and a noisy pair. Think I need to suck it up and finally resolder the pins on the noisy pair and see if that helps.

If re-soldering the pins doesn't help for the noise, TLO suggested running the tube for a minute on 12V. Haven't tried it myself yet but seems to me to be worth a try if the solder trick doesn't help.

 

[pravous]

If re-soldering the pins doesn't help for the noise, TLO suggested running the tube for a minute on 12V. Haven't tried it myself yet but seems to me to be worth a try if the solder trick doesn't help.

I will start with the pins and then see where it goes. I am guessing the 12v to the heaters might burn off any little bits on the heater windings?
I have a capacitor leakage tester I built with variable voltage and current limiting that might do the trick.

 

[Isaacc7]

I have GEC/Marconi ST and Brimar/STC ST bottles, and my MOV/Marconi straight bottle L63 is still a fav. Haven't sold off the rest... because hoarding collecting reasons.

The 6SN7W is pretty special in that aspect. Uncertain even a metal base GEC can offer that same sparkle. Franken 7N7 can get very close at a tenth the cost - racetrack micas, flat(ish) top version. Could summon @bcowen for the full frankenphile info. Have one pair of Sylvi 6J5s that gets close(ish)... but not quite.

I have mentioned here before, I think the clear glass 14n7 is probably the same tube as the metal based Sylvania 6sn7w. It’s 12v so not a direct replacement but they are cheap. Not as easy to find these days though.

Need to look up the details about the “Frankie” 7n7. I have a decent number of them and I’m bound to have at least of few of them. Just need to know what to look for.

 

[bcowen]

I have mentioned here before, I think the clear glass 14n7 is probably the same tube as the metal based Sylvania 6sn7w. It’s 12v so not a direct replacement but they are cheap. Not as easy to find these days though.

Need to look up the details about the “Frankie” 7n7. I have a decent number of them and I’m bound to have at least of few of them. Just need to know what to look for.

1. Tall bottle
2. Top getter with the flash covering a third (or more) of the top of the bottle
3. Opposing T-plates
4. Racetrack top and bottom micas (full unbroken oval, not a rectangle with rounded ends)

Plate colors can vary from shiny black to dull gray, but if the other parameters are met I have not been to hear any difference between the plate colors.

 

[mordy]

1. Tall bottle
2. Top getter with the flash covering a third (or more) of the top of the bottle
3. Opposing T-plates
4. Racetrack top and bottom micas (full unbroken oval, not a rectangle with rounded ends)

Plate colors can vary from shiny black to dull gray, but if the other parameters are met I have not been to hear any difference between the plate colors.

Is an almost flat glass top (as opposed to a rounded glass top) also one of the identifiers?

 

[bcowen]

Is an almost flat glass top (as opposed to a rounded glass top) also one of the identifiers?

Yes, but doesn’t have to be flat to have the other features. The first one I got had that flat top (thus the Franken moniker), but I picked up others later that were more traditionally rounded and they sounded just as good. One of the main requirements is the shape of the micas. That fully oval one seems to be key, and probably indicative of a specific manufacturing period.

 

[mordy]

Yes, but doesn’t have to be flat to have the other features. The first one I got had that flat top (thus the Franken moniker), but I picked up others later that were more traditionally rounded and they sounded just as good. One of the main requirements is the shape of the micas. That fully oval one seems to be key, and probably indicative of a specific manufacturing period.

The pair I have is labeled GE and on the glass in faint print it says Lansdale. Is it possible that these were made by National Union?

 

[LobalWarming]

The pair I have is labeled GE and on the glass in faint print it says Lansdale. Is it possible that these were made by National Union?

Yes it does... Unless some GE engineers snuck into the Lansdale plant late and built a batch of 7N7s using GE materials just for a laugh - for a practical joke that took 75 years to discover.

 

[mordy]

I could get another pair to try in the Envy. But Felix Audio said no.

I don’t have experience with 6L5 tubes, but 6J5 tubes can be used in the Euforia from Feliks Audio.
You need the same adapters as used for 6N7 tubes.
The only drawback was that the volume had to be set higher compared to using 6SN7 tubes.

 

[bcowen]

The pair I have is labeled GE and on the glass in faint print it says Lansdale. Is it possible that these were made by National Union?

It’s possible. I think they are Sylvanias, but I haven’t been able to determine that conclusively. The first one I got was also Lansdale labeled, saw it on EBay for $5 and bought it on a whim. What a nice surprise. I’ve also been unable to determine (conclusively) what role Lansdale had in this. I know they manufactured some tubes, but don’t believe they made receiving tubes — CRT’s and such and maybe some transmitting type tubes, but not audio tubes. I think when it came to the receiving tubes they just tested and sorted, as all the Lansdales of any type that I’ve seen carry the military designation (CBRZ). Could be wrong on that too though…so much conflicting info out there.

 

[mordy]

It’s possible. I think they are Sylvanias, but I haven’t been able to determine that conclusively. The first one I got was also Lansdale labeled, saw it on EBay for $5 and bought it on a whim. What a nice surprise. I’ve also been unable to determine (conclusively) what role Lansdale had in this. I know they manufactured some tubes, but don’t believe they made receiving tubes — CRT’s and such and maybe some transmitting type tubes, but not audio tubes. I think when it came to the receiving tubes they just tested and sorted, as all the Lansdales of any type that I’ve seen carry the military designation (CBRZ). Could be wrong on that too though…so much conflicting info out there.

According to the below write-up, NU started the Lansdale factory in 1942 in order to produce WWII tubes for the military. After the war the Lansdale factory was used for commercial tubes (?) and in 1954 it was sold to Sylvania.
The tubes I have are dated January 1952.

 

[mordy]

According to the below write-up, NU started the Lansdale factory in 1942 in order to produce WWII tubes for the military. After the war the Lansdale factory was used for commercial tubes (?) and in 1954 it was sold to Sylvania.
The tubes I have are dated January 1952.

I removed the link because all kinds of ads were attached to it. Just google Radiomuseum National Union and you will find it.