Eros Microphonics?

[adeep42]

I love my Eros. I believe that's the proper reaction to a pre-amp so named. It is really terrific. The only issue I have at times is very loud microphonic "rumble". This tends to happen mostly during warm up and I can stop it by pressing on the top plate with my finger. I believe that is absorbing the mysterious vibration. I have checked and rechecked every solder joint and made sure every screw is tight. I've swapped tubes, yet It still happens occasionally. IS this a tube problem? Is one of the eros tubes particularly prone to an issue like this? Any thoughts are most welcome.

Alan

[Paul Birkeland]

If pressing on the plate stops the noise, I would be most focused on the power transformer hardware and/or the ground post nuts. 

If this is just a little noise while the preamp warms up, I wouldn't be too concerned about it.

Both the EF86s and 6922 can be microphonic depending on the tube itself.  I have found that sometimes the springs in the tube shields help reduce microphony, and sometimes pull them out and using just the shield can help too.

[adeep42]

Thank you Paul. Double checked all the transformer hardware. All super tight. I guess I'll have to live with the occasional annoyance since the Eros sounds just great in my system. BTW, hope you noticed in my tread about the switch for two turntables, The new second This set up and the switch works perfectly. Both turntables are about as quiet as one could expect. No additional noise or hum with the switch in the circuit. Thanks for all the help.