Its the only game in town for us Valco/Supro Magnatone guys. I personally prefer the long bottle RCA, or GE black plates or gray. These are edgier and more harsh out of the box, but seem to smooth out some with 100 hours of use. They test a tad weak on Gmohs and hot on Ip/Ik. I still seem to prefer these to the short bottle Sylvania 6973. Those are almost sterile and devoid of the RCA tone I so dearly love. These cost about $110 less per pair and deliver an acceptable tone that seems to get better as the tube does its "aging thing". To prefer these over an expensive USA NOS tube says something anyway. The RCA still has the best sound, but the price is 5x higher! Tubes age in an odd sharp curve(0-200 hours), then a long less than new (around 85%)life span plateau, and then curve downward into uselessness again. In that plateau area the Electroharmonix settles down and is less gritty and edgy sounding. They test consitently well for Gmohs, and emissions. I am not going to go into microphonics, noise floor and all that other stuff. Its used in a guitar amp's output stage 90% of the time. A reverb driver may present problems, and then you may have to swap things around. These can be microphonic. These are actually preferred by some people over USA 6973s. (Usually after they see what USA 6973s cost.)JK LOL A second version of the 6973 would be great, and the 6EU7 while I am wishing. XPo`Pul's factory makes some nice stuff, and various designs for some tubes. Kudos on this one guys! A Tungsol version of the 6973 and 6EU7 would be just cool as hell. Then I would have something to compare this one to that is not USA NOS NLA. NOS= New Old Stock NLA= No Longer Available (as if these are made from unobtainium) Stay away from 6973 substitutes!! The Supro 1624T 6424 and other models puts 400 volts on the plates, and over 450 during warm up. This will fry many other substitute 6973 tubes and some used USA 6973s. The Electroharmonix has not presented this problem so far.
Product Reviews
Its the only game in town for us Valco/Supro Magnatone guys. I personally prefer the long bottle RCA, or GE black plates or gray. These are edgier and more harsh out of the box, but seem to smooth out some with 100 hours of use. They test a tad weak on Gmohs and hot on Ip/Ik. I still seem to prefer these to the short bottle Sylvania 6973. Those are almost sterile and devoid of the RCA tone I so dearly love. These cost about $110 less per pair and deliver an acceptable tone that seems to get better as the tube does its "aging thing". To prefer these over an expensive USA NOS tube says something anyway. The RCA still has the best sound, but the price is 5x higher! Tubes age in an odd sharp curve(0-200 hours), then a long less than new (around 85%)life span plateau, and then curve downward into uselessness again. In that plateau area the Electroharmonix settles down and is less gritty and edgy sounding. They test consitently well for Gmohs, and emissions. I am not going to go into microphonics, noise floor and all that other stuff. Its used in a guitar amp's output stage 90% of the time. A reverb driver may present problems, and then you may have to swap things around. These can be microphonic. These are actually preferred by some people over USA 6973s. (Usually after they see what USA 6973s cost.)JK LOL A second version of the 6973 would be great, and the 6EU7 while I am wishing. XPo`Pul's factory makes some nice stuff, and various designs for some tubes. Kudos on this one guys! A Tungsol version of the 6973 and 6EU7 would be just cool as hell. Then I would have something to compare this one to that is not USA NOS NLA. NOS= New Old Stock NLA= No Longer Available (as if these are made from unobtainium) Stay away from 6973 substitutes!! The Supro 1624T 6424 and other models puts 400 volts on the plates, and over 450 during warm up. This will fry many other substitute 6973 tubes and some used USA 6973s. The Electroharmonix has not presented this problem so far.