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Gear Closet / Re: Marshall DSL15H project
« on: October 13, 2015, 11:16:39 AM »
The main problem with using lower gain pre-amp tubes, is that I don't want to lower gain on the Green CH at all. In fact I would like to increase it so it behaves more like the Green Crunch mode on the big DSLs.
Just to clarify the signal chain of the DSL: The guitar signal goes to one side of V1. After that the Green CH signal goes on through both V2 triodes and into V3A and then into V3B. The signal is taken from the cathode of V3B to the tone stack (EQ). The amplitude of the Green signal from V1 to V2 will determine how clean and how much gain the Green Ch will be/have.
The Red CH signal is split from the Green CH signal right after V1 and re routed so that that it cascades into the other V1 triode at a clipped level. It then cascades through both sides of V2 and V3, making it five cascaded gain stages at overdriven levels. But I really need to find a Schematic of the 15 watt version. The JCM2000 schem of the DSL preamp design is almost unreadable, it so convoluted and complex. The DSL15 only has Green and Red modes, without crunch, and lead 1 modes.
I have seen some internet postings that 12AU7 side of a 12DW7 actually pins out to the Green CH when used for V1. That would be exactly opposite of what I want. JJ makes a 12DW7 with the triodes reversed, but I don't know how easy it is to obtain that tube in the USA. It might be just as well to mod resistors and capacitors on the board......
The nuclear option is to just gut the amp and use the chassis and transformers to support a 6V6 Vintage /Modern type build.
Just to clarify the signal chain of the DSL: The guitar signal goes to one side of V1. After that the Green CH signal goes on through both V2 triodes and into V3A and then into V3B. The signal is taken from the cathode of V3B to the tone stack (EQ). The amplitude of the Green signal from V1 to V2 will determine how clean and how much gain the Green Ch will be/have.
The Red CH signal is split from the Green CH signal right after V1 and re routed so that that it cascades into the other V1 triode at a clipped level. It then cascades through both sides of V2 and V3, making it five cascaded gain stages at overdriven levels. But I really need to find a Schematic of the 15 watt version. The JCM2000 schem of the DSL preamp design is almost unreadable, it so convoluted and complex. The DSL15 only has Green and Red modes, without crunch, and lead 1 modes.
I have seen some internet postings that 12AU7 side of a 12DW7 actually pins out to the Green CH when used for V1. That would be exactly opposite of what I want. JJ makes a 12DW7 with the triodes reversed, but I don't know how easy it is to obtain that tube in the USA. It might be just as well to mod resistors and capacitors on the board......
The nuclear option is to just gut the amp and use the chassis and transformers to support a 6V6 Vintage /Modern type build.