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10-30-2026, 12:30 AM
Hi Martin
With microphonic tubes, some can be saved by doing a simple test. Place a rubber band around the glass envelope and line the band with the mica supports inside the tube. The band tightens the glass a little - it is a very slow moving liquid, not a solid - and also damps the glass from vibrating. if this works, then replace the rubber band with a high-temperature O-ring.
preamp tubes are getting expensive and some older amps have odd types. best to keep the originals in place whenever possible.
An extreme fix is to install a shock-mounted tube socket. These usually have silicone grommets and require flexible wiring to them.
Also, as TUTs state, never use plastic standoffs for PCBs as these make excellent vibration conduits. Metal of any kind is preferred.
With microphonic tubes, some can be saved by doing a simple test. Place a rubber band around the glass envelope and line the band with the mica supports inside the tube. The band tightens the glass a little - it is a very slow moving liquid, not a solid - and also damps the glass from vibrating. if this works, then replace the rubber band with a high-temperature O-ring.
preamp tubes are getting expensive and some older amps have odd types. best to keep the originals in place whenever possible.
An extreme fix is to install a shock-mounted tube socket. These usually have silicone grommets and require flexible wiring to them.
Also, as TUTs state, never use plastic standoffs for PCBs as these make excellent vibration conduits. Metal of any kind is preferred.
