TAD TONE BONES ,PAIR , TRIODE VERSION 

plug these into the sockets of your amp that has 2 x el34/5881/6l6gc  and put el84s in the other side .

 they tame the volume of your amp
 ( roughly 50 watt down to roughly 15 watt ) 

. they can also be used in 4 x valve  power  amps in one push pull pair only to go from  roughly 100watt to 65 watts  leaving the other pair functioning normally .
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. i dont know if my adaptors will be of some use to someone who already has spare valves  in their collection.