one of my 121b's is rolling off the high end starting at 6k at 6bd per octave. any ideas what i should be looking for?
thanx,
thanx,
yes sir.
when using my other 121b on the same panels, the panels don't start rolling off till 14k.
when using my other 121b on the same panels, the panels don't start rolling off till 14k.
Clearly you have something wrong in the HF circuit, which is pretty simple. I would look at contact integrity on the HF balance control (i.e. loose or corroded connections). You might also check the (2) large, .01-uF capacitors on the PCB board. Those capacitors (along with the 50K-ohm resistors) blend the outputs of the LF and HF audio transformers. Perhaps one of those capacitors has gone open circuit. You may also have a bad HF transformer, which is best checked by swapping with a known good HF transformer.
![20230913_113856[1].jpg](/community/data/attachments/1120/1120714-c0394623f15762d9a1e2893238952852.jpg?hash=wDlGI_FXYt)