Thin sounding JFET based pedals with Ernie Ball volume pedal

[paulrm]

I made a Catalinbread Sabbra Cabbra clone and it sound great into little Roland Cube test amp but into my Blackheart BH5 with an Ernie Ball volume pedals sounds really thin like an old transtor radio even when the amp is on full. There is no bass at all. Same problem with an ROG Britannia, both pedals use FETS, I think the Sabbra is based on the BSIAB stacked JFET mu-amp configuration. Do I need a buffer or booster after the pedal, is it impedance mismatching or something. Thanks.

[MrStab]

i can't find a schematic for the Sabbra (do you have one?), but upon looking at a vero layout, there seems to be a 250k pot right before the output. without knowing much about the circuit, that's my first instinct as to where the consistency problems could arise.

[MrStab]

if it's a passive Ernie Ball pedal, 250k to ground from the Sabbra pot and 250k from the volume pedal parallel to create 125k, could be that?