[R-390] 5814A/ 6C4 tube placement

[Scott Bauer]

I wonder if there is any particular circuit in the 390 or 390-A
that would benefit from using a triple mica / dual support rod
version of the 5814A? 
I have read that 6C4's can be very micro-phonic and a triple
mica type would be very helpful in the R390 and 390-A.
Also, has anybody noticed any difference using 6189's rather
than 5814a's or 12AU7's?

 Scott W3CV