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   Home » Audio For Dummies ™ » Get, or made up a tube tester, it’s necessary (45 posts, 3 pages)
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  »  New  Hickok Tube Testers: Quick Reference..  Hickok Tube Testers: Quick Reference...  Audio Discussions  Forum     0  20861  08-09-2005
  »  New  How to test 6C33C?..  You might not need it....  Melquiades Amplifier  Forum     7  106212  04-02-2006
  »  New  The 6E5P tube data...  Bartola Valves: 6e5p beam tetrode SPICE model...  Melquiades Amplifier  Forum     44  490868  07-23-2007
01-26-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,155
Joined on 05-28-2004
Post #: 41
Post ID: 3557
Reply to: 3556
RE: the sound of one trace looping

Actually I am not preoccupied with the discovery of how the anomaly might sound. My primary interest is to discover if this “mystesises” is avoidable sign of the tube ageing. If so then it would be very good.  I will send you more used tubes…..

Also, if the tracer could do two tubes at once then it make sense to have one selected reference tube and test all candidates against its reference traces, am I right? An alternative would be to have a contemporary digital scope with ability to run one channels from memory and another from input….

The CaT

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-27-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006
Post #: 42
Post ID: 3569
Reply to: 3557
just keep spending more money on equipment
do two tubes at once then it make sense to have one selected reference tube


I see.  Yes, the digital scope option would work.  I have one, might try it out.  With a 6c33, the VacuTrace has only enough power to trace one tube at a time.  For its built-in dual sweep function to work, the tubes must be completely cutoff at -70V, as their plates and cathodes are tied together.  Otherwise, the currents start to combine at higher plate voltages. 

Hmmm, that gives me an idea.  You can straighten out the curves of a 6c33 by combining the two sections at different bias.  That is, bias the grid of one side 50V lower than the other.  Then ac couple audio signal to both.  Basically, you get the power of one section, but use the other side to improve linearity!  At higher plate voltages the secondary section adds output, thus preventing the rp slope of the curves from changing.  Same for mu spacing.  Might be able to create an uber-tube.

jh
01-27-2007 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,656
Joined on 10-12-2006
Post #: 43
Post ID: 3570
Reply to: 3569
Leapin' Lizards, Hagman!
Is this one of those shining moments?  And could the same general principal be applied to any other dual-ies?  Shades of the "split" cathode follower!  Onward and upward to A2!

Congrats!

Now get the copyright...

Best regards,
Paul S
01-27-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006
Post #: 44
Post ID: 3573
Reply to: 3570
galloping geckos
Is this one of those shining moments?


It could have been.  The theory seems pretty reasonable to me at the moment.  Time will tell.  I'll make up a new adapter card that runs both sections and add a pot to negatively bias the grid on one of them.  I wonder if I need to maintain dc (for the tester)?  Should act as a distortion control, I think. 

The concept should apply to any tube, dual or not.  I think a 6080 type would be a good candidate.  Or even a 6sn7.  I don't believe the tubes need to be of the same type, either.  One could make a composite tube out of just about anything.

Not sure how patents or copyrights work if the idea had been published in a public forum.  Probably too late already.  Besides, maybe we're just ressurecting something that was done 80 years ago.  On the plus side, it's not something I have ever heard about or seen used in the past ten years.  If anything, it could make a nice article for audioXpress.  If it works out nice on the VacuTrace, I might have to patch together an amplifier to prove it out with actual distortion measurements.

jh
01-30-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006
Post #: 45
Post ID: 3599
Reply to: 3573
doh!
Started building a test board for the "composite" 6c33.  Then I realize I could not hook up the grids separately.  They be connected internally.  So no way to do this test.  Not with this tube anyway.

jh
Page 3 of 3 (45 items) Select Pages:  « 1 2 3
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Hickok Tube Testers: Quick Reference..  Hickok Tube Testers: Quick Reference...  Audio Discussions  Forum     0  20861  08-09-2005
  »  New  How to test 6C33C?..  You might not need it....  Melquiades Amplifier  Forum     7  106212  04-02-2006
  »  New  The 6E5P tube data...  Bartola Valves: 6e5p beam tetrode SPICE model...  Melquiades Amplifier  Forum     44  490868  07-23-2007
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