:shock:
Hot tube requires more plate current to provide the same distortion as a cold tube that has early onset.
Hot tube = late distortion, cold tube = early distortion. Cold tubes will make clean channel dirty at moderate volume where as the hot tube will have plenty of headroom before clipping. In other words, the hot tube has less gain than the cold tube as it requires more current or high volume settings to clip.
I honestly thought the EH EL34 were hot tubes since I really had to open up the amp to get any power tube clipping. Now they saturate at much lower volume settings. I was at a point where I was not going to buy any more Reflektor made tubes, Not any more. The TS7581 were great out of box but with burn in time, they suddenly had a tone shift and were easily over heated in the Mark V. Only the SED 6L6GC and the TAD6L6GC-str have not overheated the plates. The SED will glow at the seams under use with moderate to high volume but is barely noticeable. TAD never changed color (plates looked cold). 7581, Mesa STR440, Svetlana 6L6GC under the same conditions would generate a nice orange glow on the plate surface. This is all related to current flow heating the plate metal. The EH EL34 under operation will create a slight hue at the seam. JJ6CA7 also generated the hot spot similar to the 7581, but there was another phenomenon, incandescence of the grids which was seen on the mica spacer. Almost as bright as a small night light. Those were the only tubes that exhibited white light. JJ tubes would probably provide better service in an adjustable bias amp. This is all speculative since I have no empirical data to support my statements.
Considering how much I am enjoying the EH EL34, I will have to try the 6CA7 version. As for the combo Mark IV, I have grown to like the Svetlana 6L6GC. They sound close to the SED 6L6GC (hard to tell the difference with the single speaker combo). The Mark IV thought the 412, SED sounded the best, almost evil and sinister when distorted (in other words, holy-S). As for the Mark V, I may not go back to 6L6 tubes.
Hot tube requires more plate current to provide the same distortion as a cold tube that has early onset.
Hot tube = late distortion, cold tube = early distortion. Cold tubes will make clean channel dirty at moderate volume where as the hot tube will have plenty of headroom before clipping. In other words, the hot tube has less gain than the cold tube as it requires more current or high volume settings to clip.
I honestly thought the EH EL34 were hot tubes since I really had to open up the amp to get any power tube clipping. Now they saturate at much lower volume settings. I was at a point where I was not going to buy any more Reflektor made tubes, Not any more. The TS7581 were great out of box but with burn in time, they suddenly had a tone shift and were easily over heated in the Mark V. Only the SED 6L6GC and the TAD6L6GC-str have not overheated the plates. The SED will glow at the seams under use with moderate to high volume but is barely noticeable. TAD never changed color (plates looked cold). 7581, Mesa STR440, Svetlana 6L6GC under the same conditions would generate a nice orange glow on the plate surface. This is all related to current flow heating the plate metal. The EH EL34 under operation will create a slight hue at the seam. JJ6CA7 also generated the hot spot similar to the 7581, but there was another phenomenon, incandescence of the grids which was seen on the mica spacer. Almost as bright as a small night light. Those were the only tubes that exhibited white light. JJ tubes would probably provide better service in an adjustable bias amp. This is all speculative since I have no empirical data to support my statements.
Considering how much I am enjoying the EH EL34, I will have to try the 6CA7 version. As for the combo Mark IV, I have grown to like the Svetlana 6L6GC. They sound close to the SED 6L6GC (hard to tell the difference with the single speaker combo). The Mark IV thought the 412, SED sounded the best, almost evil and sinister when distorted (in other words, holy-S). As for the Mark V, I may not go back to 6L6 tubes.