Garrard 401/rb250 buzzing

[33.3rpm]

I picked up a mint Garrard 401 with SME 3009 improved a couple of weeks ago. It was in a boxy/hollow plinth that caused a fair bit of rumble so have knocked up a 25mmx4 layered ply plinth and have fitted a rewired rb250. The arm has separate ground wire which is clipped to amp earth but am still getting a lot of buzz, esp at higher volumes. If I remove the ground wire from amp it is really noisy with rf hum so re-earthing def does something. If I touch the 401 and the metal arm board that the 250 is attached to then the buzz is pretty much gone.

Any ideas how I can get rid of the buzz without standing there touching the player for the whole time?

 

[33.3rpm]

Oh, and I have tried 2 different cartridges, an old vms20e and a Nagaoka mp-110, same result.

 

[33.3rpm]

Think I might be answering my own question here but the 3009, which was buzz-free was grounded to boththe amp and the 401 chassis. Might I just need a thin earth wire back from amp earth back to 401 chassis?

 

[Darren L]

Sounds like your 401 needs an earth/ground.

 

[Mr Pig]

The RB250 rewire is to blame. The arm's not designed to have a separate earth wire and if you wire it that way you can have no end of trouble. There is nothing wrong with the stock Rega grounding. Return the arm to that grounding pattern and it should be fine.

 

[33.3rpm]

Thanks for the reply. I seem to have fixed it - I have run an earth back from amp to 401 chassis and is pretty quiet. In fact not even a rumble. ‘Solid Air’ is sounding very nice indeed. Cheers.

 

[Craig B]

@33.3rpm,

Depending upon the amp in question, you may wish to consider revising your new ground scheme, as you may well have just provided a path to mains earth for the turntable via the amp, not just a means to common tonearm earth with deck. Should there be a fault with the decks electrics, for example, this may go unnoticed until such time as someone innocently disconnects the ground between deck and amp. What most 301/401 restorers do (or should do) is upgrade the mains cable to a modern 3-wire with appropriate plug from the antiquated (hopefully double insulated) 2-wire convention. The third ground wire can either be connected to turntable chassis at the motor to chassis ground stud, or to the motor itself where the motor to chassis ground connection originates, i.e. nearer to the voltage changeover block (see 'View from below base Plate. Diagram 10' on pg. 16 in the manual).

Post mains ground scheme modernization of the deck, if your RB250 has been modified in the way that I suspect it has, you may get away with connecting its dedicated ground wire to amp chassis only, without any ground strap to deck chassis, as, with 401, there typically isn't any direct tonearm to chassis contact. I base this upon your description 'The arm has separate ground wire which is clipped to amp earth'.

There are numerous posts on this subject on here, however, the only ones that readily come to mind are within @Tony L's TD124 restoration thread. The same mains safety rules apply.

 

[33.3rpm]

That makes sense. I have a 301 that is as quiet as a mouse and it has been rewired. The 401 has older (presumably 2-core) cable so a rewire is in order then. Thanks.