Smash Microphonics

[Doc B]

You didn't mention whether you have tried the isolation techniques mentioned in this thread. If not, you might try isolating the preamp from the vibrations from the passing traffic. Something as simple as a few layers of bubble wrap between preamp base and the item it sits on can be tried to see if this kind of isolation will help. If it does you can switch it up to some sorbothane pucks or similar isolation devices.

 

[dpwoos]

We have tried to isolate the preamp case (on a wall-mounted shelf inside what had been a closet), but without much benefit. We have also wrapped the tubes with teflon tape, which maybe helps a bit. What seems to stop the microphonics is to push down hard on the top of the tube with a finger, and we have been thinking about how best to accomplish that. Maybe we need to look harder at the tube sockets, and use rubber washers to separate them from the top plate? Also, we haven't secured the top plate to the base so that is something we can try.

Bottom line - we will work on this more over the next few weeks. We have been hugely distracted and captivated by our first moving coil cartridge (DL-103 + Cinemag CMQEE-3440A transformers) and it is hard not to play another record, and another ...

 

[Doc B]

Your ideas are definitely on the right track. In my experience the most effective approaches have been isolating the wood base from the shelf and putting mass on the tube (like when you press on the tube). Silicone o-rings under the tube can help too, but they are usually not as effective. Mass on the chassis can create a small improvement, but not as effective as mass right on the tube. You might try something like bendable lead fishing weight wire coiled to sit on top of the tube. Maybe like this -

https://www.walmart.com/ip/Bullet-Weights-Solid-Core-Lead-Wire-1-lb/16928066?wmlspartner=wlpa&selectedSellerId=0&wl13=2317&adid=22222222227000000000&wl0=&wl1=g&wl2=c&wl3=42423897272&wl4=pla-51320962143&wl5=9033458&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=local&wl12=16928066&veh=sem&gclid=Cj0KCQiAjfvwBRCkARIsAIqSWlMbAZKigLU2whcUaOHOPdPRUCEIIqj6I-7nMwO4YAaPEJyqk8H6zOYaAq6FEALw_wcB