@goofy you are highly unlikely to exceed the current capacity of a 5Y3 rectifier with a preamp utilising 2 6H30 tubes and two shunt regs. OTOH the suggestion of substituting 12A*7/ECC81,82, 83’s/5751’s, 7025’s, 6DJ8/6922/ECC88’s is ludicrous as they are totally different types of tubes with MUCH higher gains and plate resistances and totally unsuited to your preamp (6DJ8 family are less bad but still unsuitable). God only knows how they would bias. Behause they draw far less current than the 6H30 they may also overload the shunt regulator in the pre which is supplied by a constant current source. 6CG7/6FQ7 have a similar gain, but their plate resistance is about 10 x that of the 6H30 and they run at about a third of the current so you would lose a lot of drive capability. The only sub I would suggest trying is the 6N6P, 60‘s Reflektor are very nice.
Rectifier Tube Rolling in a Modwight LS 36.5DM
I was hoping to get advice, I have been rolling Rectifier tubes in my two box preamp I am blown away how different tubes change the sound ,I own two sets of Mullard GZ37/CV378 a set of GE 5U4GB both vintage early 1960's and a set of stock Sovtek 5AR4 also have a NOS set of 6H30 DR I am trying in the clean box , both the Mullard's and Dr tubes only have about five hours of run in time but the sound seems defused on the top end ok on the bass the GE Tubes are good in the mids but soft on the highs and bass so far the stock Sovtek seems to sound best ,Dan says try 5R4-GY Tubes, any one tell me about the Mullard's in this preamp I am getting frustrated, thanks
Showing 3 responses by pesky_wabbit
@goofy you may find this article by Lucas Ficas of Lampizator fame of interest: http://www.lampizator.eu/UPGRADE/upgrade%20noval%20tubes%20to%206H6P.html |
the 5R4GY draws an additional 0.1A filament current, and will drop more voltage at any given operating point. Their stated maximum current capabilities are identical. The 5R4GY is directly heated, 5AR4 indirectly: fast voltage ramp up vs slow. Purported sonic benefits of directly heated tubes. draw your own conclusions |