moving coil pre-preamp hum


Hi all,

I am having a bit of a problem with a moving coil head amp. I am using an Ortofon MCA 76 and getting the horrid low level 40-60hz vibrating hmmmmm. at moderate-to-loud listening levels it is extremely faint, but at high listening levels it is apparent.

My old man is using the same headamp with a maplenoll turntable in a high end system and he swears by it and has never had any issues. Did I get a lemon?

Here is a little background: Tried a Madrigal carnegie one and a Supex Super 901 Low output. They sound incredible to say the least and are in very god condition, however the hum is driving me nuts. Using a VPI HW 19, Jelco arm. Bryston 4B amp. Dual Mono Tube phono section that no one has ever heard of but is amazing -Soundtech Preamp one. Have used a number of moving magnet carts with great results and NO NOISE, Grace f9 Ruby, Ortofon 2M Red (booo)...Totem sttaf speakers. Kinber 4tc speaker cables.

Okay so you have the background, lets hear the diagnosis and recommended course of action that will place me in moving coil heaven.

Does the headamp need a recap, is it mismatched in terms of load, does it need a flu-shot? I am dying to hear it, so please guys help me out.



dfelkai
My suggestion is simple. Try experimenting with, very carefully, moving the head amp around. It may simply be picking the hum up from another nearby component or cable.

Not unusual with phono preamps or head amps. Many have issues like this.


Ortofon MCA 76 is fixed... wow that was easy :) There was nothing wrong with it in the first place, it was the tubes in my pre . Swapped out a pair of RCA tubes and replaced with some Magnavox tubes noise is gone!!!!

BTW this headamp is awesome, and dead quiet, I am in love with it again.