Hi there.I have read with interest the subject of the EF86 being inherently microphonic,http://www.googleadservices.com/pag...ttp://www.canford.co.uk/Products/79-7203&nm=1well some are.But you must tailor the gain to try and prevent this.Pay attention to the plate (anode) load resistor and cathode resistor values.Also suspending the valve base with small rubber grommets does help a lot.