Tube matching?

Edword

Edword

Jun 23, 2005
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#1
I'm once again on the hunt for 6KG6As for my Traynor YBA-3A, and as usual can't find a matched set of four.

Could I get away with getting 2 matched pairs and installing one pair V1 - V4 and the other V2 - V3?

TIA
 
#2
#4
Edword said:
I'm once again on the hunt for 6KG6As for my Traynor YBA-3A, and as usual can't find a matched set of four.

Could I get away with getting 2 matched pairs and installing one pair V1 - V4 and the other V2 - V3?

TIA
Click to expand...

With separate bias for each pair of tubes it should work, but the more dissimilar the tube's operating characteristics are, the worse the results will be.

Two tube are connected to one side of the output transformer (OT), and two tubes are connected to the other side of the OT. Pairing a weak tube and a strong tube together typically results in the weak tube conducting less and the strong tube conducting more, so you want a reasonably matched pair on each side of the transformer. 15% variance is reasonable; 20% will work. As the mismatch gets worse you loose output power because the tubes are operating further from the ideal bias point.

Separate bias is required to balance current passing through each side of the output transformer. In others words, the total current passing through each pair of tubes should be equal.
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At some point you may want to convert over to JJ EL509S. These are current production tubes. You'll need different tubes sockets and a bit of rewiring. Here's a thread you may find interesting. Traynor YBA-3A 6KG6 to EL509S
 
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