Re: JTM45 RI & Bassman RI , How much alike
Many bassman RI come with a plug in solid state rectifier. That's one major difference. You can replace the plug in SS recitifier with a 5AR4 (GZ34), and that brings back the sag and lowers the power. The re-issue bassman is louder than the reissue 45 in stock trim. The original Bassman used a 12AY7 in V1 instead of a 12AX7. The Marshall always used the 12AX7 or eqivilant in all positions.The re-issue Bassman uses all 12AX7's too.
Both are PCB amps, and the Fender has recieved critism for using cheaper componants on the board. I'm not sure of the bias circut in the re-issue bassmans, but someone told me that mods must be made to adjust the bias, properly.
The Marshall re-issue has recieved critism for not faithfully adhering to the original design, as far as some cap and resistor values in the pre-amp. Additionally, the filter caps of the re-issue are plexi/ JMP50 value, differeing from the original JTM45. This makes the amp sound much stiffer, but also prevents bad humming and ghost notes. Both reissues are not original in the filter cap values. Furthermore, the reissue Marshall has recieved critism of the output transformer (always different from the Fender Bassman and another major diffrence in the designs) compared to the original JTM45. The Sovtec 5881's are okay in a Bassman but not a JTM45, IMO. The 45's need KT66's or even the EL34 for the more Marshall type sound.
