Hum Issues - Rega P-25 w/ Grado Reference Platnum

Hey Tom- Where is ya? :~)
Hum? Nah!

Hello,

Your problem is normal with your grado cartridge because it is not protected against the magnetic and electric fields from the motor. You have two solutions. First, put a metal cover under the turntable between the motor and the plinth. Finnally, change your cartridge and choose one which is well protected against the magnetic and electric fields. An example, the rega Elys or the old Linn K9.

Here's a link for their site:

Mu Shield

Here's more info on one solution that was recommended above:

Well, here is one from the archive : (for Rega 2/3, from an article in Audio 1998 by Cory Greenberg)

The material used comes from Magnetic Shield Corporation and is called Mu-Metal. There is a lab kit that contains several sheets for $80, CO-NETIC AA for low intensity fields and NETIC for high intensity fields.

Shielding the motor with the NETIC didn't work so he tried placing the CO-NETIC sheets on the base under the platter, and this did it.

He recommends is to remove the cart from the arm and the glass outer platter and plastic inner spindle from the turntable. Be careful when cutting the hole for the bearing, because the sheets can bend and may scrape the underside of the plastic inner spindle. Fix it with double-sided tape. If you don't like the color, you an paint it without changing it's shielding properties.

One can buy directly from the company 630/766-7800; ask for product LK-110.

This was pulled from an AA archive.

I'm surprised that TAS didn't title the following article "Two great tastes that *don't* taste great together."

Affordable Gear from Two Veteran Companies

From what is implied in this article, and if I didn't know better, a Rega / Grado combo would be a *huge* bang for the buck. Note that they don't talk about the synergy of the two together.

I'll back Jim up on the sound of his combo (especially with the RB-1000 arm)...it sounds great and is getting better over time (his cartridge is out-of-the-box brand spankin' new). But if this problem is well known, someone *has* to have a tweak / mod to address this issue.

Jim, maybe you should fire off an e-mail to Rega.

Any other thoughts out there? the table in question is mine :-) The problem is not unbearable, but the more I talk about it, the more it annoys me. The sound so far, not evven broken in is great, except for the hum torwards the end of the disc. Getting a new cart. or a new table is NOt an option so any help or mild fixes would be great.

Grado cartridges all hum on Rega turntables as they move toward the center of the record. LP12s do the same, but not quite as much. The Grado cartridges are particularly susceptible to the motor’s magnetic field. The only solution is to change the table or the cartridge. They are incompatible.

There was a Stereophile from way back when that contained an article about covering (part) of the plinth with adhesive mu-metal. It worked, but I don't know whether there was any stubborn residue left by the adhesive. Maybe a Stereophile, Agon, AA or google search could give you more details.

While the P-25 already has speed problems, I'm don't think adding material to the platter would be a good idea. Who knows though, maybe it'll slow it down to what the speed should be. Good luck

if you search the archives, you'll find many people who have had similar experiences. it appears that the rega/grado combination is notorious for the exact hum of which you speak. i'm not sure if anybody's come up with a solution yet, but you should have a look and check.

Dont know if Grado cartridge is not suit for Rega RB arm. The VTA angle may not be right.

Also clean your cartridge as well. Sometimes thats the reason.