Fine Phono !

[CrowDaddy]

Completed my build a few weeks ago, and have been enjoying it since.  Spouse commented on how realistic singers sound. 
I lined the wooden base with copper tape ( cheap, because it's so thin) folded over into the rabbet for electrical contact. 
Glued small wooden blocks into the lower corners of the base so I could mount Vibrapod feet.

Suggestions for instructions:  on p.74, values which take a while to settle are not marked with asterisk.
On p. 76, I suggest you note that these values are to be measured on the CCS board; I started on the shunt board since it also has IA and IB.

Question:  I think I need to replace the cables from my ancient AR XA turntable, to get better grounding.  Would you suggest Belden RG-59 coax or Cat 5 cable, or something else?  Thanks!

 

[Paul Birkeland]

For turntable to Eros cables, I would recommend STP wire, definitely not coax.  You want shielded twisted pair with the shield either connected to the phono plug shell on the Eros end or brought out to its own wire that can go to the ground post. 

 

[grufti]

Mogami star quad or Canare star quad is my favorite. Benchmark Media has a demo on their site that is difficult to ignore/refute.

 

[CrowDaddy]

Thanks to both for your replies.

So, Paul, do I leave the shield floating at the turntable end?

grufti, the Benchmark folks urge balanced connections; just using star quad cable doesn't get you there.
However, Stuart Yaniger argues convincingly in one of his articles that the only place balanced connections make sense in a typical home system is between the cartridge and the phono amp; almost no one does this.  Doc, Paul and Paul, can we look for a balanced input option on the Eros3?

 

[Paul Birkeland]

So, Paul, do I leave the shield floating at the turntable end?

Yes.

Doc, Paul and Paul, can we look for a balanced input option on the Eros3?

You can use a moving coil and step-up transformers in the Eros 2 and with a little tweaking have balanced inputs.

 

[CrowDaddy]

Hi Paul,
Well, I removed the original 1970s cables from my AR turntable; they had chassis ground permanently wired to the left RCA shield.  Installed RCA jacks with twisted-pair running inside the table from the arm-cable terminal strip to the RCAs.  RCAs are not connected to the internal ground system.  Between the table and the Eros2 I used Pro-Ject star quad phono interconnects :
https://pro-jectusa.com/product/connect-it-e-rca-1-23m/
I connected the cable's ground lug to the ground post on the Eros2, and left the other end's ground lug unconnected.
Result:  terrible hum! 
When I connected the 'table-end lug to the arm ( which is connected to the other grounds) hum mostly disappeared.
I can hear both channels quite well, so I think the basic signal connections are OK.
So. something is still not quite right; any suggestions?
Thanks -- John

 

[Paul Birkeland]

If you set your meter to measure resistance, what's the resistance between a grounding wire on those cables and the shell of an RCA cable?  (You'll need to take this measurement with the cables unplugged from the Eros and your TT)

Can you post a photo of how you've connected the RCA cables inside the TT?

 

[Doc B]

Do we know what cartridge you are using? I didn't see it in the thread.

 

[CrowDaddy]

Paul, thanks for your help.  I installed a ground post on the TT, connected the other ground lug to it, and now noise is unnoticeable when playing music.
However, hum returns when I disconnect ground on amp end.
My old Fluke meter sees infinite resistance between ground lugs and RCA shields, even on its highest ( 60 Meg) setting.
Attached are pix of inside of TT; terminal lug closest to camera is ground ( plinth, arm, suspended chassis, and braided shield of wires from arm).
The TT was built assuming its ground would be connected to left channel shield; also has no power ground ( it has an unpolarized 2-prong plug). 
No difference in hum when I reverse plug.
Cartridge is a Stanton 681eee with a new "Vivid" stylus.
Have not checked whether cartridge shell is grounded; will do that when I'm rested with a steady hand.
Treated the lugs with Deoxit before installing the twisted pairs. 
Unless you can see something to try, I'm content leaving it alone; sounds good and I enjoy it.
If I get a new TT some day can try different grounding scheme.
Again, thanks for all your help.

 

[Paul Birkeland]

Paul, thanks for your help.  I installed a ground post on the TT, connected the other ground lug to it, and now noise is unnoticeable when playing music.
My old Fluke meter sees infinite resistance between ground lugs and RCA shields, even on its highest ( 60 Meg) setting.

That's what I was after. Having a completely separate earthing wire is a very good idea.