{Collins} 32S3 audio problem

Something in my 32S3 seems to be very fussy as to B+ voltage.  I've  
aligned it and everything seems right, with full power on all bands.  
Yet the original problem of distorted audio is still present, using 
either of two known good and unmodified 516F-2 power supplies.

My nominal line voltage is 118 VAC and the 516F-2 was designed for 115 
VAC so my line input is 2.5% high, which makes my low B+ run high as 
well (350 VDC unloaded and around 290 VDC under full power), as would be 
expected.    If I reduce my line voltage to 112 VAC, the B+ drops to 275 
VDC under load and the audio sounds fine.  This is a 5% reduction from 
my normal line voltage, or 2.5% under the design spec of the 516F-2 - 
and should be within the range the transmitter is designed to tolerate. 

The audio distortion is hard to describe - it sounds "burbly",  maybe a 
bit of FM?   I can't believe the AC line being 3 volts high should  make 
a difference in audio quality.   Any thoughts would be appreciated.

Thanks and 73,

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