Turntable hum (yet again)

[denti alligator]

So I got a new Rega in part to upgrade my tt, in part to get away from the hum that my P1 was causing.

At first I had issues with a buzzing that was solved by grounding the Seduction to the Power supply unit that is separate from the Rega.

But there was still hum. I understand that this is in some respect inevitable, especially when you turn the volume way up.

But last night I reinstalled the C4S boards (thanks, Eileen, for the replacements), and now the hum is much louder.

I'm starting to get impatient and really disappointed. I'm assuming this is a problem with the Rega, since my old Technics doesn't display the problem. I guess it could be the cartridge, but I doubt it, since the hum was present with the stock cart, too.

The hum is audible with phones at about 30 on the volume, getting louder as I turn it up. I have a ground loop isolator that I will add between the table and the Seduction once I get a coupler in the mail (the ground loop is male/male). Other than that I can't think of what else to do, except maybe return the table for a different brand. From what I can tell, this isn't a Rega problem, but with two in a row like this I'm skeptical.

I might try mounting the cart to my Technics to see if it's the cart...

[Grainger49]

Sam,

Hum comes from anywhere and everywhere when you turn the volume up.  Some things will increase the hum, some will lower the hum. 

Have you used a pair of shorting plugs with the Seduction?  Short the inputs and see what hum is heard.  This breaks your system at the Seduction and sees if it is still there or is from the Rega.

If it goes away you have isolated it to the Rega, but most likely there will be some hum still there indicating there is hum elsewhere as well as in the Rega.  If there is no change in the hum level the Rega is acquitted! 

I'm always big on grounding the TT chassis (sub frame, or some metal like the motor case) to the Seduction.  This is easy to try with a "random" length of wire.  Also, try with the Rega motor on and off, any change?  Try moving the arm from the outer part of the platter to the inner part, does the hum increase?  How about moving the Rega away from any other transformers like the SEX and Seduction? 

This is a seek and destroy mission.  Sadly hum creeps into a system in many places.  Old folks like me don't hear the hum in my system unless it is pointed out, younger folks hear it immediately.  Growing old is a good thing!

Have you tried the Technics recently?  Remember that the Seduction right and left negative leads are on the signal ground in the Seduction.  That grounds the cartridge.  Often cartridges have a "grounding strap" that grounds the cartridge body to one of the channel common leads.  A jumper from the green lead and touching the cartridge body will show you if there is some hum being picked up by the cartridge.

Just a few things to try on New Year's Day.

[denti alligator]

Looks like the Ortofon is most likely the culprit. In removing it from my Rega to mount to my Technics one of the pins at the back of the cartridge came out with the clip! And another one got loose. I doubt this is supposed to happen, and that just pushing the pin back in (as I did) will not do. Indeed, when I mounted the Ortofon on the Technics (after simply pushing the pin back in) it hummed!

Guess I'll need a new cartridge. Don't tell the wife!