I bought a FX loop kit from Metro and want to install it on my Blackstar Artisan-100, Plexi super lead based, point to point.
On Step 1 from the instructions:
15: Now last step is to swap out the 8.2K circled below (in series with the 10K) with the 4.7K metal oxide
resistor provided. This is necessary to compensate for the extra bit of current the loop draws through these
resistors, and keep the amp operating as it was. This is not always absolutely necessary, as voltages will only
be lower in the PI and preamp as a result, but the intent is not to effect the original tone, so swap that 8.2K
resistor for the 4.7K.
- If your amp has a two 2 watt 10K’s in series here, swap out one 10K with a 5.6K 2 watt metal oxide
resistor instead.
- If your amp had only a single 10K here, there will not be as much voltage change, so can leave as is, or can
swap the 10K for an 8.2K resistor to get about right back to where you started concerning voltages
throughout the amp.
- If your amp has a single 8.2K 2 watt resistor here, swap with 7.5K 2 watt resistor if desired though nothing
really need be done.
my amp has a single 22K resistor (R28) and then 1K5 going to all el34s from it… so Im a bit confused on what value I need to replace this resistor to avoid changing the sound and dropping to much voltage when the FX is ON.
Here is part of the schema that shows the resistor: