E
ecc83
Well-known member
Ok, re "no whistle with no input" AFAIK all guitar amp input jacks short the input until a plug is inserted. The lack of whistle shorted shows at least the noise is getting in via the input and NOT via power line nor speaker cable.
Now, with a guitar plugged in does turning the VOLUME pot down on the guitar kill the whistle? If so it suggests that the RF is NOT getting in via the cable screen and since "zero VC" is equivalent to shorting the input this suggests less than 100% internal screening in the guitar. The tone pot "shorts" the input same way but only at 3kHz or so and up.
Have you checked that the strings are bonded to jack earth?
On that "Mkll" filter B.D. I am pretty sure the input is also shorted sans plug. Try a lead from tin to amp but with no plug in input. The fact that the filter made little difference tells me that the RF field must be very strong. The filter is in fact just a gash one I had that is fitted to the front end of all S1 amps and, as I said before, I never had a report of RFI trouble with the amps before, in any case, all products have to pass EU EM testing.
Dave.
Now, with a guitar plugged in does turning the VOLUME pot down on the guitar kill the whistle? If so it suggests that the RF is NOT getting in via the cable screen and since "zero VC" is equivalent to shorting the input this suggests less than 100% internal screening in the guitar. The tone pot "shorts" the input same way but only at 3kHz or so and up.
Have you checked that the strings are bonded to jack earth?
On that "Mkll" filter B.D. I am pretty sure the input is also shorted sans plug. Try a lead from tin to amp but with no plug in input. The fact that the filter made little difference tells me that the RF field must be very strong. The filter is in fact just a gash one I had that is fitted to the front end of all S1 amps and, as I said before, I never had a report of RFI trouble with the amps before, in any case, all products have to pass EU EM testing.
Dave.