Fellows
Somewhat related to this earlier post regarding markings on the vintage Mullard EL34 tubes with acid-etched markings "XF2" B (numeric).
https://www.avforums.co.za/index.php/topic,57970.msg721799.html#msg721799
Theres an interesting article that I read (it evades me now, wanted to link it in here) regarding the Mullard EL34 vintage tubes made at the Blackburn plant in England, with code XF2 etched at the bottom side of the glass envelope where it meets the base.
Would like some opinion on the XF2 which is a somewhat sought-after tube and was produced in two varieties and periods : single halo getter and double halo getter types.
These were apparently quite a nice sounding tube, preferred in guitar amps (instead of the XF1 tube...which I understand has its own desireable characteristics) and known for an excellent lifespan with many of these tubes still running strong today.
The XF2 double-getter tubes were also supplied in the Dynaco ST70 (period specific about 1966 - 1969).
I have three of these tubes, and missing one. Still need to find another tube to complete this set and have them measured.
I have noticed that when the tubes are shaken gently there is a slight rattling sound inside, nothing looks loose and no debris in the envelope. Its hard to see what could be rattling in the tube as the tube is shaking at the time...somewhat of a challenge looking for something shaking within something thats already shaking.....but I suspect it may be the halo getters which I noticed with some movement.
In your experience :
Is it normal for such mechanical noise to exist in these tubes and could/ does this cause microphonic performance ?..one tube has slightly more rattle than the other two. (note that these three have welded plates and are double halo types)
What is your experience with such tubes and could these three that I have still be good ?
Can one mix single and double halo getter types to make up a pair and are there any sonic or performance differences between them ?
Any other advice welcome.
Thank You.
Somewhat related to this earlier post regarding markings on the vintage Mullard EL34 tubes with acid-etched markings "XF2" B (numeric).
https://www.avforums.co.za/index.php/topic,57970.msg721799.html#msg721799
Theres an interesting article that I read (it evades me now, wanted to link it in here) regarding the Mullard EL34 vintage tubes made at the Blackburn plant in England, with code XF2 etched at the bottom side of the glass envelope where it meets the base.
Would like some opinion on the XF2 which is a somewhat sought-after tube and was produced in two varieties and periods : single halo getter and double halo getter types.
These were apparently quite a nice sounding tube, preferred in guitar amps (instead of the XF1 tube...which I understand has its own desireable characteristics) and known for an excellent lifespan with many of these tubes still running strong today.
The XF2 double-getter tubes were also supplied in the Dynaco ST70 (period specific about 1966 - 1969).
I have three of these tubes, and missing one. Still need to find another tube to complete this set and have them measured.
I have noticed that when the tubes are shaken gently there is a slight rattling sound inside, nothing looks loose and no debris in the envelope. Its hard to see what could be rattling in the tube as the tube is shaking at the time...somewhat of a challenge looking for something shaking within something thats already shaking.....but I suspect it may be the halo getters which I noticed with some movement.
In your experience :
Is it normal for such mechanical noise to exist in these tubes and could/ does this cause microphonic performance ?..one tube has slightly more rattle than the other two. (note that these three have welded plates and are double halo types)
What is your experience with such tubes and could these three that I have still be good ?
Can one mix single and double halo getter types to make up a pair and are there any sonic or performance differences between them ?
Any other advice welcome.
Thank You.
