folks,
tapping and sound pressure have extra large differences in values so ain't no need to compare or giving such examples.
microphony of tubes is realy brand and quality depended. it's caused by loose electrodes as a result of tube's aging or becomming unfunctional in vast majority of cases.
folks at upscale audio despite being respected and honest dealers try to create illusion as many of audiophiles do that microphony is good. it does however help the tube business. well, it was never good and it was a big issue upto mid- 40-s.
not precicely sure but probably different vacuum technology and electrode mounting was introduced ever since and surely tubes produced in 50's are not microphonic. i was never shopping for NOS tubes and don't know if any of the tubes are sold manufactured before mid- 40's but i guess they're too few... therefore if the tube is microphonic you can bet 1000 against 1 that it's already bad.
i'll repeat myself about tapping being not a good example and it can blow the speakers. but you can realy tap on component chassis or mounting board next to the tube to check the microphony.
tapping and sound pressure have extra large differences in values so ain't no need to compare or giving such examples.
microphony of tubes is realy brand and quality depended. it's caused by loose electrodes as a result of tube's aging or becomming unfunctional in vast majority of cases.
folks at upscale audio despite being respected and honest dealers try to create illusion as many of audiophiles do that microphony is good. it does however help the tube business. well, it was never good and it was a big issue upto mid- 40-s.
not precicely sure but probably different vacuum technology and electrode mounting was introduced ever since and surely tubes produced in 50's are not microphonic. i was never shopping for NOS tubes and don't know if any of the tubes are sold manufactured before mid- 40's but i guess they're too few... therefore if the tube is microphonic you can bet 1000 against 1 that it's already bad.
i'll repeat myself about tapping being not a good example and it can blow the speakers. but you can realy tap on component chassis or mounting board next to the tube to check the microphony.