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Phono Cable Shielding.

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Posted on January 9, 2017 at 07:34:40
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002
 I need to come up with a RCA to RCA IC to go between a tonearm junction box and a phono preamp. I was wondering about just sliding the copper braid over my already built V-H Audio V-Twist and or his Fine Silver wire recipe? One thing it would accomplish is spacing the shield a bit away from the signal wire which may reduce capacitancestors I think. Thoughts?

 

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RE: Phono Cable Shielding. , posted on March 23, 2017 at 09:20:49
sayntjack
Audiophile

Posts: 109
Location: North Vancouver, BC
Joined: July 4, 2005
 I earlier posted in this thread that when I put a braided shield over my I/C to remove hum it very negatively effected the sound. Since this time I have built the VH Audio DIY cable using #28 cotton insulated silver wire by Jupiter over a cotton stuffed Teflon tube. The sound was impressive (better than anything that I've heard up to $600 (my cap)) however it did hum with my Grado 3mV high o/p cartridge. So, after wrapping 3 layers of Teflon tape, I installed a soft flexible braided outer jacked which I then wrapped with Teflon tape. Following this I took kitchen aluminum foil cut into 3/4" strips joined together and completely wrapped the Teflon layer making sure that the foil did not contact the connector at either end. I then ran a small gauge plated copper wire from one end to the other over the foil making two turns over the 1M length. To one end of the wire I connected a 7" insulated wire with an alligator clip (half of a common electronics jumper wire). Over this I wrapped two more layers of Teflon and then applied the heat shrink over the connectors / cable ends with the insulated wire coming out of the back of the heat shrink.
Results: Zero hum, dead quiet black blackground to the music, no degradation in the sound quality whatsoever. (Aligator clip attaches to the preamp chassis.) Interestingly after burning the cable in on my burner for 24 hours I noticed a slight brassiness to the highs which I thought may be a characteristic of the silver but after a few albums it has gone away (yes I compared it to my old interconnects to be sure).

Jack

 

Two comments, posted on January 12, 2017 at 09:53:49
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 1. I doubt you will need any shielding. I have used unshielded wiring for my tonearm wires for years with no hum whatsoever (and with a 0.25mv MC cartridge). I would definitely try the wires first without shielding and only resort to shielding if there is hum. In my experience, unshielded wires sound better.

2. I recommend you try something other than V-Twist wire. I have some V-Twist interconnects and I just don't find the sound to be very good. Sure, it checks the boxes on the audiophile evaluation list (smooth tonal balance, decent detail, decent dynamics) but it always sounds synthetic or artificial as opposed to natural and musical. I have tried several RCA plugs all of which sound different but nothing so far makes me want to leave them in the system. By the way, V-Twist needs lots of hours to break in fully. Mine have over 1000 hours.

 

RE: Two comments, posted on January 12, 2017 at 10:01:30
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002
 What wire do you find that sounds musical to you? I intend to try unshielded first especially since this is in my basement without a lot of RFI or EMI that I'm aware of.

 

RE: Two comments, posted on January 12, 2017 at 10:34:24
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 For line-level interconnects, there are many cables I would choose over the V-Twist. Just from ones I have owned or used extensively, these would include Wireworld Eclipse (all versions), Wireworld Polaris 5, and Discovery Essence and Plus 4. On a more expensive level, I like Audio Note AN-Vx and Ocellia Silver Reference. And on a very cheap DIY level, the Belden 8402 wire is certainly a decent sounding cable.

For phono wiring such as tonearms, I like 1877 Phono (sold by Parts Connexion) and Discovery Plus 4. For several years, I used some twisted 22g stranded copper wires (sold by Cary Audio) as the hard-wired connections between an outboard SUT and my phono preamp, and they sounded really good. I ended up replacing them with a hard-wired section of Discovery Essence which sounded even better, but not dramatically so. The Cary wires were unshielded and had no hum problems.

 

the Belden 8402 specs doesn't seem to be so great, posted on January 16, 2017 at 20:36:45
lovetube
Dealer

Posts: 3008
Location: Melbourne Australia
Joined: June 8, 2003
 impedance is 52 ohms and capacitance is 55pf/ft , why this cable is recommended ? i'm confuse . isn't the 52 ohms is not deserve in audio ( hifi ) interconnect ? 75 ohms is standard for audio as we all know.

 

RE: the Belden 8402 specs doesn't seem to be so great, posted on January 18, 2017 at 14:14:46
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002
 The capacitance is indeed quite high, while the 52 ohm characteristic impedance is okay for line-level applications, but not for 75 ohm S/PDIF digital or 75 ohm video applications.

 

Break in with only a 0.25v signal must take years and years?, posted on January 12, 2017 at 10:31:02
3+4=5
 The tiny signal from a low output MC would IMO take years to 'break in' any wires... Just sayin'!
I would think one would need wires that sound great not broken in.. Otherwise the wait for them to break in will be a killer.

 

RE: Break in with only a 0.25v signal must take years and years?, posted on January 12, 2017 at 10:41:04
Salectric
Audiophile

Posts: 1358
Location: East Coast
Joined: February 23, 2003
 I break in my wires with a line level signal (FM or CD on repeat).

 

you only need "Phono Cable Shielding" if without it you have HUM... Just a thought. , posted on January 12, 2017 at 00:05:49
3+4=5
 If without any shielding.. you have NO HUM. then you are all set.
Why bother with shielding.
If you have only a tiny amount of hum.. You could reroute the wires.. And that may remove the hum.

It certainly could be possible to have unshielded wires from a cartridge to a phono preamp..
(Particularly the sort of 3wire woven style like Kimber PBJ etc.)

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 19:10:00
sayntjack
Audiophile

Posts: 109
Location: North Vancouver, BC
Joined: July 4, 2005
 I tried the same thing in the same application as your are proposing with my mids 90s MIT 330 Musiclink I/C (no boxes). Result - sounded like I had replaced my I/C with a dollar store I/C, as in loss of air, depth, detail and highs - no hum though. I connected the shield at the preamp end only and did not try any other variations.

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 23:40:41
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002
 So what did you end up doing ?

 

RE: Phono Cable Shielding. , posted on January 10, 2017 at 17:37:12
sayntjack
Audiophile

Posts: 109
Location: North Vancouver, BC
Joined: July 4, 2005
 As it turned out with the MI330 cables there is a drain wire in the cable connected at the preamp end which is in partial contact (intended or unintended I don't know) with a kind of metalized plastic sheath. Cutting the cable end and reapplying the connector to the fresh end making sure that the drain wire was in contact with the metalized plastic sheath reduced the hum enough that it was not a problem. There were no negative effects to the sound. Perhaps this was the manufacturer's proprietary method of implementing a sheath without negatively impacting the cable's performance.

 

If you use MI or MM cartridges the capcitance of the cable can play a very large part.... , posted on January 9, 2017 at 13:10:22
viridian
 in the resulting frequency response of the cartridge. The cartridge sees the aggregate capacitance of the arm cable, the internal tonearm wire and the input capacitance of the phono stage.

 

RE: If you use MI or MM cartridges the capcitance of the cable can play a very large part.... , posted on January 9, 2017 at 14:46:21
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002
 True, but the VH Audio V-Twist is a low-capacitance 11.13 pF/ft cable, so adding a braided shield that's naturally spaced away from the twisted pair conductors is not likely to affect the capacitance of the phono-level cable in a particularly severe manner.

See link:

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 12:46:37
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002
 Yes, that would be fine. You might want to experiment by grounding the braided shields at the phono preamplifier end of the cables (not the TT end) to the phono preamp ground binding post. You can do this by soldering a drain wire to each braided shield at the phono preamp end of the cables, then secure them to the ground binding post of the phono preamp. Since a phono cartridge is a passive device, grounding the drain wires at the phono preamp end is a better method. However, if hum is still an issue, try soldering the braided shields to the rca connector grounds at the phono preamp end of the cables. Cover the braided shields with Techflex sleeving to protect the stranded wires of the exposed braided shields.

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 13:22:02
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002
 That is what I was intending reading your and other's other posts on the subject. So I could just slip the copper shield on with the jumper wires soldered and try it both ways. Will it be detrimental if the braid touches the metal ferrel on the RCAs?

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 14:34:52
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002
 If you connect the drain wires to the ground binding post of the phono preamp, you should insulate the braided shield from touching the rca connector in any manner. Just wrap the very end of the braided shields with heavy-duty PTFE Teflon plumber's tape as an easy and effective insulation method.

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 11:51:40
dee eye why
Audiophile

Posts: 1148
Location: so. ohio
Joined: March 20, 2003
 The braided shield would need to be grounded to (-) terminal of the I.C. to be effective at shielding. Preferably at the source end only.


.
Freak out...Far out...In out....

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 12:48:47
WntrMute2
Audiophile

Posts: 782
Location: Detroit
Joined: September 16, 2002
 I'm aware of that but any opinions on the overall idea or should I work on either a purpose built DIY phono cable or store bought model?

 

RE: Phono Cable Shielding. , posted on January 9, 2017 at 13:00:02
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002
 BTW, the VH Audio V-Quad is said to provide hum-free performance without a braided shield for a phono-level application. Even though the cross-connected star quad geometry of the V-Quad is a self-shielding design, I'm still surprised to hear that it does not require a braided shield for a phono-level turntable application. Another option that may help to reduce hum is the use of a shielded power cord for the TT motor.

 

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