Hello all, I bought a stash of 6021 pencil tubes a long while back. These are low plate voltage, medium mu (35?) dual triodes. I have been reading up on them and many generally like them a lot...they are designed for really abusive military environments.... I get empty 9 pin bases and solder them into the bases as 6922 pinouts (9AJ base pinout) and then fill the base with hot wax....So I jumped on them when I found a bunch of them NOS cheap....I have used them in the pole position in my Aikido pre (230v B+) with 6922 or 6H30 in rear seat...
Anyway I have a Knight 600 tester and looking for the 6021 settings...nothing...I can use the 6922 settings, but resulting numbers are somewhat all over the place (understandable as these curves are exponential)... does anyone have the settings or can offer up another tubes setting that is closer to the 6021 that I can use to try to better match these tubes? Datasheet attached...
I have another Aikido (Aikido LV) with 24 Volts B+ intended for certain tubes that work great at very low plate voltages (6GM8/6N27P/ECC86)….while waiting for these tubes, I put in a quad of somewhat matched 6021 (in 9AJ basing)....works / sounds fine, but temporary...or maybe this tube is perfectly fine in this low plate voltage application....
Anyway I have a Knight 600 tester and looking for the 6021 settings...nothing...I can use the 6922 settings, but resulting numbers are somewhat all over the place (understandable as these curves are exponential)... does anyone have the settings or can offer up another tubes setting that is closer to the 6021 that I can use to try to better match these tubes? Datasheet attached...
I have another Aikido (Aikido LV) with 24 Volts B+ intended for certain tubes that work great at very low plate voltages (6GM8/6N27P/ECC86)….while waiting for these tubes, I put in a quad of somewhat matched 6021 (in 9AJ basing)....works / sounds fine, but temporary...or maybe this tube is perfectly fine in this low plate voltage application....
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My apologies dear, but I don't understand the core of the issue. These tubes resembles 12AU7 except for higher tranconductance (5.3mS vs 3mS rougly speaking).
So I should use setting for 12AU7 and just keep heaters at 6.3v? This is closer than the 6922 settings? Thanks....
I'm a big fan of the 6021 and many other subminiature tubes. I use them in line/phono stage. Excellent sound, compact enclosures and bargain pricing. I think some of the Soviet versions can sound even better than US versions, but limited access to those.
I have used sockets, but they eventually get noisy. The wax fill is a good idea. Best is to just solder the leads.
It sounds like you have a bunch of NOS, so measure a few with settings for a medium mu triode, and record the readings you get on your Knight tester.
I have used sockets, but they eventually get noisy. The wax fill is a good idea. Best is to just solder the leads.
It sounds like you have a bunch of NOS, so measure a few with settings for a medium mu triode, and record the readings you get on your Knight tester.
Hifiamps - thanks - I like these tubes sub min tubes too....
Do you think using the 6021 at 24v B+ in an Aikido is doable with its capabilities?
Do you think using the 6021 at 24v B+ in an Aikido is doable with its capabilities?
Here is an article by John Atwood in VTV on subminiature tubes "Tube Dumpster: Subminiature Types" page 28. I'm not sure about the 6021 at 24V B+. I think the 12SX7 (not subminiature) would work, since they were used with 28 volt supplies, but they are hard to find. I'm sure there are other subminiatures that could do it. Some were used in hearing aids.
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