The 6SJ7 is a pentode and is strapped as a triode I believe in this design, the 6SN7 is a dual triode so potentially could also be strapped to a single triode and used in the driver position via an adapter. Not sure how it would sound though, as the operating point would likely be different...

Unfortunately no further answer to the date codes! Would also like to know if anyone else has further insights :)

Send me a PM- might be able to help you out with that :D

Been a bit quite here recently! Here is a really interesting find today on this pair of Mullard 6J5G. The construction looks identical to the MOV L63/6J5G we know and love, with the grey glass and the distinctive top mica construction as viewed from the top. But I've never seen them with brown...

Seconded for the RCA6AS7G. One of my favourite pairings with my HD800, the warmth balanced out very nicely with the HD800, I dont feel you lose much detail if at all. Another option to try if you have it is the GEC 6080, will give even more liquid mids. EF86 would be a good choice for inputs...

Another important thing to note- British AVO tester manuals also quote new values with precise parameters for heater, anode, grid voltages instead of bias points. These parameters set up the test at a singular point chosen from/corresponding to a specific point of tube operating curves on...

Anyone know of a place to get 90 degree octal socket savers/adapters? Have a friend wanting to use 6J5s in place of 6SN7 but their amp doesn't fit the adapter in the current configuration!

6CG7 is electrically equivalent to the 6SN7 in a 9 pin envelope, so should be fine as long as the adapter is the correct pinout. I used an ECC88 --> 12AU7 adapter as they have the same pinout 6CG7 and ECC88.

That certainly looks like a good option too! When applying heat with the iron, do you just do it to the top, or from underneath on the 'male' pins of the socket saver?

That looks like what I had in mind/looking for, but 'flying lead adapter' wasn't coming up with anything on ebay. Thanks!

So I've just grabbed some flying lead CV4038 (normal version is the CV4079/A2293). Anyone have any experience soldering 9 pin flying leads into bases? Not sure what parts I should use for the base+ any tricks to getting it done. I've got maybe 2.5cm on the leads to work with.

Those are definitely not 421A, and as said above they are TS 7236 tubes. They sound great, but perhaps not for that price!

I'll go backup on some tubes if you need to split for sale as well :)

Hi LordGwyn, yes after some experimentation it seems outputs are being taken off the output capacitors, as there is no sound without power tubes- good to know and thanks for the explanation! :( I had a 6C4 tube testing better than ever on my tester and the filament burnt out as soon as I...

A few quick question about the preamp out function on the GOTL I've always wondered about- does the signal go through only the 6SN7 slot/driver tube, or does it go through the power tubes as well? I.e. would changing the power tubes when just using preamp out change anything? And would that be a...

I am curious about experimenting with the 7/7.6 volt 6DJ8/6922 equivalents, does operating the heaters at 6.3V change their electrical characteristics in the circuit? I know that testing a tube below its nominal filament voltage results in lower emissions, plate current and gm.

The GEC 6080s are a really nice sounding tube, very different from the GEC 6AS7. Much warmer and rolled off treble. Really nice midrange though- I like to think of it as a more balanced Mullard 6080 :)

CV4079 is equivalent to half a 6AS7, so a pair with adapter is a suitable replacement

It would be for the L63 driver version of the amp different from the 6SJ7 :) The HD6XX would definitely enjoy a slightly more forward tube combination- some power tubes to consider are Tung Sol 6080, 6AS7, 5998 or 7236. Drivers try the EF86 or EF80 with adapter :) Unfortunately some of the...

Are you able to see what the right hand column says? A little hard to read from the pictures :) The internals look very similar to the Siemens 'triple mica' ECC82/12AU7 with the grey plates and 3 mica big halo construction- wouldn't be surprised if it is Siemens made!

I believe the only black glass Ken-Rads were the military ones from the 40s. Ken Rad was considered a 'second tier' tube maker before the war, and made quite a few during it. KR was acquired by GE in 1945 and the branding continued a little into the early 50s before all becoming GE. There are...

I have experimented with 2x 6SN7 to 6J5 adapters (using just 1 triode of each 6SN7) then a dual 6J5 back into 6SN7 socket. It has always been noisier and I think the 6J5 equivalents are cheaper and sound the same/better :)

Thanks mordy, gibosi and leftside for your replies, they have encouraged me to take a deep dive and further investigate these Aussie made tubes! Here is a discussion of my discoveries/thoughts so far in a mini-exhibit :) Here's a photo of all the 'Australian' 12AU7s I have come across. They all...

I've come across an interesting 12AU7/ECC82 that I am unable to decipher. It's branded as an Australian Mullard with long 17mm plates and top foil getter similar to those of the 1950s Amperex long plate. Looking at the codes at the bottom 8G k6, factory code 8 confirms it is Philips Herleen...

Been a bit quiet here lately! Received a big lot of metal cans recently and found some pretty rebranded tubes- I believe they're all RCA made, the Cossor is branded Ken Rad on the other side. And this little guy made it all the way to the Düsseldorf cinema :)