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Hum from Grado on LP12.. Better carts to consider?

I've had a problem with hum on my LP12 for as long as I can remember. The table (bought used) came with a Grado Signature 8MZ and I've since tried a Grado Z+ that I had from another table. Both have the same amount of hum. I have a lot of RF and noisy AC in my house. The hum is noticeable when I switch to phono and gets louder as I move the cart over the rim of the platter. From there it decreases as I move the arm towards the spindle. (The table is 80's vintage with Ittok and Circus/Lingo upgrades).

A (non-Linn) dealer said 'oh Grados do that on LP12s - lack of shielding'. My Linn dealer didn't nave a strong opinion. He suggested a Benz Ace H given my under- $700 budget. From reading the Agon forums, some think an AT150 M series has better sound for less $. I've also heard good things about the Dynavector DV-20X. Does MM/MI vs. HOMC matter in terms of hum or is the degree of 'shielding' a variable from cartridge to cartridge no matter which type? Does a good review on a MC necessarily extend to the HO version, as opposed to the LO/MO versions?

My system: ARC PH1 (48 dB gain, variable loading via soldering iron)
ARC LS2BII
PSE Studio IV/V's
Audio Physic Tempo III's
FWIW: Meridian 508 CD player is dead quiet in this system.

Music: from Joni Mitchell to Ian Dury and the Blockheads, Monk to Mozart.

Thanks for any knowledge you can impart!
geor
bob_bundus
1,834 posts
 
a phono step up transformer is another option if you chose a low output design.
coxhaus
231 posts
 
I have a Grado "The Statement" on an old Linn LP12 which I bought new in 73 or 74 can't remember. I now have an Itok arm which was not original. I have absolutely no hum. My dealer was a Linn dealer for many years and sold Grados with Linn tables. Do you have cable connected to a device in your system? It is easy to create a ground loop which will cause hum.
metralla
945 posts
 
I have a Grado Signature 8MR on a Sondek using a Linn Basik LVX arm from 1984 - this unit is in storage back in Australia. This has no hum at all into a very high gain preamp (the preamp could handle a moving coil cartridge without a transformer).

Something must be wrong.

Regards,
geor OP
37 posts
 
I don't have cable, but I do have noisey AC power. I can hear my Braun coffee maker's thermostat cycle on and off! I also have an FM transmission tower about a mile away.
geor OP
37 posts
 
Thanks Coxhaus and Metralla. I did some research on hum problems and tried one suggestion with some success. That was to move the LP12 away from other components, especially their transformers. I realized the turntable motor was about 6-8" away from the preamp (ARC LS2BII) transformer on the shelf below. I lifted the turntable as much as I could - about 18"- with no change. Then I tried rotating it and the hum was almost gone.

The ARC transformer seemed to have a 2-dimensional planar beam (?) running vertically. (The transformer is mounted on the side wall of the preamp).
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