Hey...
the stock tubes for marshall amps nowadays are EL34, but in the early days of the amp the overseas models were usually equipped with 6550 due to a shortage of el34 tubes in America (AFAIK)....
many of the "heavier" guitarist prefer their 2203s with 6550 instead of el34 (Zakk Wylde (obviously), Kerry King, Wino (the god of doom))...
so I decided to put some 6550 in my '78 JMP 2203 and make a blind test.
it's not 100% fair though, cause the EL34 were new and fresh while the 6550 (sovtek) were rather old and would need replacement soon I guess....but they're not ancient or anything.
modifications done to adjust the circuit to the 6550:
replaced the 2 220k bias splitters with 150k Rs and piggy backed a 47k on the bias resistor to get the bias into the right range.
You'll notice that the differences between these 2 different types of tubes are far from big, but if you listen closely to the mids you'll probably hear a difference
A
B
of course there's no post processing going one.
Settings one the Amp: 5,6,4,5,4,max
the amp was hit with a tubescreamer, settings: drive: 9:00, tone: 12:00 level: 12:00
the stock tubes for marshall amps nowadays are EL34, but in the early days of the amp the overseas models were usually equipped with 6550 due to a shortage of el34 tubes in America (AFAIK)....
many of the "heavier" guitarist prefer their 2203s with 6550 instead of el34 (Zakk Wylde (obviously), Kerry King, Wino (the god of doom))...
so I decided to put some 6550 in my '78 JMP 2203 and make a blind test.
it's not 100% fair though, cause the EL34 were new and fresh while the 6550 (sovtek) were rather old and would need replacement soon I guess....but they're not ancient or anything.
modifications done to adjust the circuit to the 6550:
replaced the 2 220k bias splitters with 150k Rs and piggy backed a 47k on the bias resistor to get the bias into the right range.
You'll notice that the differences between these 2 different types of tubes are far from big, but if you listen closely to the mids you'll probably hear a difference
A
B
of course there's no post processing going one.
Settings one the Amp: 5,6,4,5,4,max
the amp was hit with a tubescreamer, settings: drive: 9:00, tone: 12:00 level: 12:00
