tube replacement on Vincent SV236 amplifiers : beware there are two versions of SV236 MKI model

The new version of the Vincent SV236 is called SV236 MKII. Before that they produced SV236 MKI. But there's a trick. The SV236 MKI comes in two versions…

Version 1 is easily recognizable because it does not have a preamp output.
In that version you have two 6DJ8 tubes inside the amp and a single 12AX7 tube in front of the amp (for arrange the NF-Signal to the left and rigth channel tubes).

Version 2 does have the preamp outpout.
In that version you have two 12AX7 tubes inside the amp and another 12AX7 tube in front of the amp (for arrange the NF-Signal to the left and rigth channel tubes).

So, putting 3 12AX7 tubes inside a SV236 MKI version 1 does lead to obvious sound problems !

Prices ?

2 MATCHED NOS MULLARD GOLDPIN E88CC 6922 6DJ8 7308 tubes cost about 180 USD

2 Electro Harmonix GOLDPIN 6922 cost about 25 USD