Question about my Advents

I have a pair of the re-issued (about 1990) Original Advent speakers in the walnut cabinets. They are being powered by a circa 1990 Scott RS 250 receiver. This combination usually sounds great.


I have noticed that there is a vibration noise eminating from my right tweeter whenever an instrument plays a Bb below middle C. This includes any fundamental frequencies that may contain this Bb prominently in their harmonic series.


This is not static. It is a definite vibration on specific frequencies around Bb. There is nothing vibrating around the cabinet, which is sitting on a carpeted floor away from the wall. It seems definitely to be coming from the tweeter, but usually when a low requency is playing. All of the screws on the tweeter seem to be very tight.


Can anyone give me advice on how to eliminate this vibrating sound. It disrupts the music, especially in softer passages.


Stan