[BDM]

Yes I'll check it. I'm not sure it was ever used. I actually received that coupler in it's original box which itself is in mint condition. Where ever that piece sat, it was a dry area for many years and really appeared unused. But, I do note a fairly big difference in the BCB when switching it on or off, that's the strange thing. Trouble is in that vid you cannot tell because I suffer such terrible noise from a neighbor. That neighbor isn't very cooperative I might add. Maybe I'll explain that out some other time. Anyhow I'll take it apart and check it out along with the values of the components. I have the little diagram you drew up. Saved it to my files