Mullard 12AX7 Old Stock Gurus needed

[Guiary]

Just wanting to know if there is really any difference in sound between an I61 and an I63 tube?

I know that the I61 was the original and the I63 was the revision, and for that matter, any difference with the hard to find I62?

 

Thanks,

 

Gary

[charveldan]

Just wanting to know if there is really any difference in sound between an I61 and an I63 tube? I know that the I61 was the original and the I63 was the revision, and for that matter, any difference with the hard to find I62? Thanks, Gary

Any NOS Mullard with the Blackburn codes are excellent, you'll have to try it and see how it sounds.

[Guiary]

I'm just trying to stock pile them since they're used in my V2 slot. The ones I've been searching for are I63 that have IEC written on the tube, then of course I begun to realize that any I63 Blackburn code would/should be the same as the IEC.

 

Now reading around I've come to discover that 'apparently' the I61 Mullards have more of a 'woody' sound () and sound a little more open than the I63. Has anyone on here noticed such differences?

 

Also how rare are siemens 12AX7 triple mica 6681. I'd like to find another but with no luck yet.