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September 18, 2020, 04:12:06 AM

Author Topic: Eros Microphonics?  (Read 455 times)

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Offline adeep42

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Eros Microphonics?
« on: September 03, 2018, 08:24:06 AM »
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
Crack with Speedball
Eros
VPI Prime
Ortofon Cadenza Bronze
Bob's Devices VPI SUT
Phoenix Eagle PSU & Tach
Cambridge 752BD
Apple Airport Express
PrimaLuna Prologue Pre-amp
PrimaLuna Prologue Amps(as mono-blocks)
Martin Logan Summit X's

Offline Paul Birkeland

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Re: Eros Microphonics?
« Reply #1 on: September 03, 2018, 08:58:57 AM »
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.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline adeep42

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Re: Eros Microphonics?
« Reply #2 on: September 03, 2018, 10:41:32 AM »
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.
Crack with Speedball
Eros
VPI Prime
Ortofon Cadenza Bronze
Bob's Devices VPI SUT
Phoenix Eagle PSU & Tach
Cambridge 752BD
Apple Airport Express
PrimaLuna Prologue Pre-amp
PrimaLuna Prologue Amps(as mono-blocks)
Martin Logan Summit X's