In my opinion no. You need that tube rectifier to get that sag the JTM is known for. Also kt66 in JTM just sound so much better IMO.
There’s the official opinion folks.A true JTM45 will not have KT66s but 6L6s or after that EL34s, originality is key
A true JTM45 will not have KT66s but 6L6s or after that EL34s, originality is key
Wow, I was under the impression that many were produced by Marshall with KT66's. So much information shared here that dispells inaccurate beliefs.
The KT66s were fitted ex-factory after Ken left the company. I believe that Dudley and Ken’s used 5881s as they were ex-military versions of 6L6. KT66 were used once the military (probably cheaper) valves got used up and GEC/Marconi being a U.K. company had the nearest spec.
Marshall first used EL34s with the output transformer changes in early 1967 (Drake 784-128 in the 50w and 1202-119 in 100W) as these had lower primary of 3.4K and 1.75k respectively compared with the earlier 8k and 4k OTs in 65 and 66 supplied by Drake.
That's a 1987 with JTM45 Badge![]()
My first one had 5881's The latest RI I've had for the past 10-15 years is set up with 6L6's.
Never seen a JTM45 with EL34's and they all have GZ34/5AR4 tube rectifiers.
Sounds more like a 1987x to me too.
Played a 1987x once. Didn't fit the bill for me.
There’s more to it than just output tubes and a rectifier. There are many other differences between it and a 1987, notably the topology and voicing at the first valve as well as the tone stack. These directly affect the tone every bit as much as the rectifier and output valves, arguably more so. Then there are differences in transformers, plate voltages, a slew of other component values and whatever else I’ve failed to mention. The JTM45 is basically a Fender Bassman, just made with parts that were available in the UK.That's a 1987 with JTM45 Badge![]()
The first PTs were the self lead RS with hammerite paint and selector on top. You also see the open frame lug type but AFAIK same specs. The Drake successor 1202-55 is also broadly the same. All approx 450vdc post rectification. The only high voltage 50w PTs I know of are the Drake -133 on the late JTM Black Flags for 470vdc or thereabouts.Neil, was there a PT or circuit change during the change from 5881's to KT66's? Seems like 450-475v on the plate is more than is normally used with the 5881 variant of the 6L6.
Agreed.There’s more to it than just output tubes and a rectifier. There are many other differences between it and a 1987, notably the topology and voicing at the first valve as well as the tone stack. These directly affect the tone every bit as much as the rectifier and output valves, arguably more so. Then there are differences in transformers, plate voltages, a slew of other component values and whatever else I’ve failed to mention. The JTM45 is basically a Fender Bassman, just made with parts that were available in the UK.
I know most of you already know this, but it bears repeating whenever someone implies that the difference between a super lead and a jtm is the rectifier and output valves.