Tubes are more or less "mass produced cheaply" to meet the meager demand for them. The only real demand is in the musical instrument amplification world. What a guitar player wants out of a tube, you as an audiophile may well abhor. Tooling is very expensive, and the last major production lines in the West were either sold into China or were scrapped. The GE 6650 line in Kentucky was scrapped. The M.O. Valve plant was torn down to put up a shopping center, and its Gold Lion KT-88 and KT-77 production equipment went to China. The KT-66 line which had lay dormant for decades was scrapped as unfit for rehabilitation.
The last consistent quality tubes came from the East block and Yugoslavia. With the fall of the Iron Curtain, the production of vacuum tubes became almost exclusively the province of Eastern Europe and China. With the Kosovo war the E.I. plant in Belgrade absorbed substantial bomb damage, and the Company went down. It was bought by its British distributor after the conflict and reopened with direct orders from New Sensor to cheapen up the product. Solvtek stopped manufacturing 5AR4's for a while because they could not produce them and make a profit. So, you want cheap tubes??? They are already made in low wage environments, and extremely few businessmen are not going to invest in exceedingly expensive tooling that must be meticulously maintained to satisfy minuscule demand. There is no profit to be made by in large. That being said, there are some very decent tubes being made today in Eastern Europe and China.
The tubes prior to the mid sixties were made to meet mass demand where quality was expected. Once tubes became "obsolete," what incentive did these companies have to reinvest and maintain quality control? If you wish to live with tube audio equipment, I suggest you decide on exactly what tubes you want to deal with, and then, buy a life time supply whether N.O.S. or current production. N.O.S. Tung Sol 6550's from the "golden age" will blow away any similar tube made today. That being said, if one does not have unlimited money, they might consider the current Solvtek 6550's.
In my opinion all vacuum tubes become low pass filters starting at about two thousand hours. I remove tubes stage by stage every 500 hours starting at 2000 hours and back check them against new tubes. It is a rare day I do not hear significant signal degradation by 3000 hours. When one drops $300.00 or more for a pair of small signal tubes, one has an enormous incentive to not hear such sonic degradations. And, I am an old guy. I have a life time supply of "red label" pre-war E.I. KT-90's. I really prefer 6SN7's, and while I have an adequate N.O.S. supply, there are a few current production tubes that I like. Alas, my supply of N.O.S. GZ34 Telefunken's and GZ37 Mullard's is used up or sold. Thank God for rectifier diodes.
The last consistent quality tubes came from the East block and Yugoslavia. With the fall of the Iron Curtain, the production of vacuum tubes became almost exclusively the province of Eastern Europe and China. With the Kosovo war the E.I. plant in Belgrade absorbed substantial bomb damage, and the Company went down. It was bought by its British distributor after the conflict and reopened with direct orders from New Sensor to cheapen up the product. Solvtek stopped manufacturing 5AR4's for a while because they could not produce them and make a profit. So, you want cheap tubes??? They are already made in low wage environments, and extremely few businessmen are not going to invest in exceedingly expensive tooling that must be meticulously maintained to satisfy minuscule demand. There is no profit to be made by in large. That being said, there are some very decent tubes being made today in Eastern Europe and China.
The tubes prior to the mid sixties were made to meet mass demand where quality was expected. Once tubes became "obsolete," what incentive did these companies have to reinvest and maintain quality control? If you wish to live with tube audio equipment, I suggest you decide on exactly what tubes you want to deal with, and then, buy a life time supply whether N.O.S. or current production. N.O.S. Tung Sol 6550's from the "golden age" will blow away any similar tube made today. That being said, if one does not have unlimited money, they might consider the current Solvtek 6550's.
In my opinion all vacuum tubes become low pass filters starting at about two thousand hours. I remove tubes stage by stage every 500 hours starting at 2000 hours and back check them against new tubes. It is a rare day I do not hear significant signal degradation by 3000 hours. When one drops $300.00 or more for a pair of small signal tubes, one has an enormous incentive to not hear such sonic degradations. And, I am an old guy. I have a life time supply of "red label" pre-war E.I. KT-90's. I really prefer 6SN7's, and while I have an adequate N.O.S. supply, there are a few current production tubes that I like. Alas, my supply of N.O.S. GZ34 Telefunken's and GZ37 Mullard's is used up or sold. Thank God for rectifier diodes.
