[LobalWarming]

Yeah I tried both sockets with both tubes, equally stiff. There's no way I can get the other tube out without breaking it without tools. It's super stiff. The pins on both tubes were in perfect condition too, so something is up with the sockets I think.

Sorry about the troubles... CV4079s are delightful tubes. Can get stiff sockets to 'relax' their death grip with years of rolling.

Or... if you're in a rush... can use a small flat blade screwdriver to open up each socket a little. On close examination may notice a too closed or offset socket pin.

Or if you have a spare B9A noval adapter can use that to wear-in the 4079 adapter, by inserting/removing a few hundred times.

As you discovered, it's called tube rolling for a reason. Rolling (side-to-side) the tube into the socket is better than attempting to push straight into the socket.

Could also contact @Deyan about a custom CV4079 adapter.

 

[JackarlTwo]

Sorry about the troubles... CV4079s are delightful tubes. Can get stiff sockets to 'relax' their death grip with years of rolling.

Or... if you're in a rush... can use a small flat blade screwdriver to open up each socket a little. On close examination may notice a too closed or offset socket pin.

Or if you have a spare B9A noval adapter can use that to wear-in the 4079 adapter, by inserting/removing a few hundred times.

As you discovered, it's called tube rolling for a reason. Rolling (side-to-side) the tube into the socket is better than attempting to push straight into the socket.

Could also contact @Deyan about a custom CV4079 adapter.

I was just about to post an update. I used a super flat phillips screw driver to gently pry up the tubes (had I done it normally I'd break the other tube too). After inserting and removing them a couple of times the sockets feel relatively normal, and no way as stiff as the first time. In any case I ordered a couple of more so I'm looking forward to giving it another shot!

 

[CAJames]

I was just about to post an update. I used a super flat phillips screw driver to gently pry up the tubes (had I done it normally I'd break the other tube too). After inserting and removing them a couple of times the sockets feel relatively normal, and no way as stiff as the first time. In any case I ordered a couple of more so I'm looking forward to giving it another shot!

That's good to hear. I was going to post that if a socket feels extra tight I'll work it with a socket saver rather than risk breaking a tube.

 

[mvneufeld]

I have a couple of the same CV4079 adapters from Xuling and agree that they are scary tight. I was so afraid a tube would shatter that I wore gloves the first time. As LobalWarming said, they will loosen somewhat over time. He's right that you want to rock the tube (slightly) from side to side when you put it in or take it out of the adapter.

 

[raindownthunda]

Comparing GEC variations

 

[JamieMcC]

Comparing GEC variations

You definitely need a round base one

 

[leftside]

Comparing GEC variations

There's a few more than two

 

[raindownthunda]

You definitely need a round base one

There's a few more than two

Those curved brown bases seem to be a real crowd pleaser...

Here's a curved base A1834 as a driver (via 6SN7 adapter) paired with curved base A1834 power tubes. No, the A1834 does not pair well with itself... at least it makes for fun pictures:

Back in the *J5 family with these Raytheon 12J5WGT. Very nice sound. These have a slight rounded corner at the base - not nearly as pronounced as the A1834 but noticeable up close.

More brown base drivers - now paired with these Cossor OM5C (EF37A/6J7). I also tried the brown base Mullard 6J5G which caused my amp to overdose on warmth.

Are there any curved brown base driver tubes?

 

[triod750]

Curved glass isn't bad either....

 

[leftside]

Curved glass isn't bad either....

Oh you said "glass" not....

 

[Melting735]

Can anyone tell me what the date code 722 mean? My guess is week 22 of 1967

 

[gibosi]

Can anyone tell me what the date code 722 mean? My guess is week 22 of 1967

More likely, 1957, week 22. In the 1960's, most manufacturers used 4-digits. for example, 6722 for 1967, week 22.

 

[Melting735]

More likely, 1957, week 22. In the 1960's, most manufacturers used 4-digits. for example, 6722 for 1967, week 22.

Got it. Thanks!

 

[JackarlTwo]

Round two with the GEC A2293/CV4079. These are dated 1981, but sound really sweet. Had a few listening sessions and no problems so far.

 

[triod750]

Round two with the GEC A2293/CV4038. These are dated 1981, but sound really sweet. Had a few listening sessions and no problems so far.

Do you mean CV4079? I have CV4079 from 1981 bought from Langrex and also a quad of them from July 1961 bought from this seller https://www.ebay.co.uk/itm/265348682503 They seem to be old stock from Bundeswehr and they were cheaper and I like them better. This could be just in my head but if so, it is in good company.
I also have square getter A2293 (taller bottle). They sound different with more clarity. They all sound good.