The Pin 1 Problem
Rather than clutter other threads, I though I would start one on the connecting of shields. Way back in 1995 Neil Muncy (RIP) wrote this paper "Noise Susceptibility in Analog and Digital Signal Processing Systems". Then 10 years later the Audio Engineering Society published standard AES48-2005.
It took the pro audio manufactures almost 20 years to get up to speed on this issue. The hi-fi industry still has a ways to go. If you do a search on the above title you will probably find it somewhere (it has no permanent home).
A better source is a reprint of the June 1995 AES Journal:
SHIELDS AND GROUNDS: SAFETY, POWER MAINS, STUDIO, CABLE AND EQUIPMENT, (special excerpt)
The June 1995 issue of the Journal was a definitive and comprehensive collection of information on this important topic. The seven papers by Neil Muncy and other experts in the field have been reprinted into a convenient guide for designers and practitioners.
It's about 85 pages long and has 7 great papers. Ont of the papers is the John Windt 'Hummer Test' only a shot summery of the paper is available on-line. The cost is $15 USD including shipping.
http://www.aes.org/publications/specialpubs/journal_issues.cfm
(I have to go to speedskating practice, be back later)
Rather than clutter other threads, I though I would start one on the connecting of shields. Way back in 1995 Neil Muncy (RIP) wrote this paper "Noise Susceptibility in Analog and Digital Signal Processing Systems". Then 10 years later the Audio Engineering Society published standard AES48-2005.
It took the pro audio manufactures almost 20 years to get up to speed on this issue. The hi-fi industry still has a ways to go. If you do a search on the above title you will probably find it somewhere (it has no permanent home).
A better source is a reprint of the June 1995 AES Journal:
SHIELDS AND GROUNDS: SAFETY, POWER MAINS, STUDIO, CABLE AND EQUIPMENT, (special excerpt)
The June 1995 issue of the Journal was a definitive and comprehensive collection of information on this important topic. The seven papers by Neil Muncy and other experts in the field have been reprinted into a convenient guide for designers and practitioners.
It's about 85 pages long and has 7 great papers. Ont of the papers is the John Windt 'Hummer Test' only a shot summery of the paper is available on-line. The cost is $15 USD including shipping.
http://www.aes.org/publications/specialpubs/journal_issues.cfm
(I have to go to speedskating practice, be back later)
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The Rane Corp article linked to in Post #2 is definitely a good one.
The AES48-2005 can be found floating around on various places of the Internet. Search for "AES48-2005 pdf" on Google/Bing and you shall find.
By far the biggest improvement in anything related to interconnects can be had by switching to differential connections. Pseudo-differential (described by Rane) works in a pinch. Or see attached figure.
~Tom
The AES48-2005 can be found floating around on various places of the Internet. Search for "AES48-2005 pdf" on Google/Bing and you shall find.
By far the biggest improvement in anything related to interconnects can be had by switching to differential connections. Pseudo-differential (described by Rane) works in a pinch. Or see attached figure.
~Tom
Attachments
Hi,
Very interresting, but maybe do not should all debates..
And if I use unshielded cable, how ?
With unbalanced :
Fig 20a is a wrong way for me, the signal does not go through shield.
Fig 23 and 24 are good ways (again for me, and at listening)..
Phil.
Very interresting, but maybe do not should all debates..
And if I use unshielded cable, how ?
With unbalanced :
Fig 20a is a wrong way for me, the signal does not go through shield.
Fig 23 and 24 are good ways (again for me, and at listening)..
Phil.
Some papers by Tony Waldron, Technical Manager, CADAC Electronics PLC on the subject:
(Note that Keith Armstrong contributed to some)
"A Practical Interference Free Audio System (Part 1)"
Designing for Interference-free Audio System Components
"A Practical Interference Free Audio System (Part 2)"
A Practical Interference Free Audio System (Part 2)
"Designing for Interference-free Audio System Components"
Designing for Interference-free Audio System Components
"Bonding Cable Shields at Both Ends to Reduce Noise"
Bonding Cable Shields at Both Ends to Reduce Noise
"Tony Waldron's Audio & EMC ranting and ravings"
Tony Waldron's EMC ranting and ravings
(Note that Keith Armstrong contributed to some)
"A Practical Interference Free Audio System (Part 1)"
Designing for Interference-free Audio System Components
"A Practical Interference Free Audio System (Part 2)"
A Practical Interference Free Audio System (Part 2)
"Designing for Interference-free Audio System Components"
Designing for Interference-free Audio System Components
"Bonding Cable Shields at Both Ends to Reduce Noise"
Bonding Cable Shields at Both Ends to Reduce Noise
"Tony Waldron's Audio & EMC ranting and ravings"
Tony Waldron's EMC ranting and ravings
Audio Engineering Society
AES48-2005
AES standard on interconnections
—Grounding and EMC practices —
'Shields of connectors in audio equipment containing active circuitry'
http://www.kirkeo.org/sites/default/files/pdfs/node15/aes48-2005-f.pdf
AES48-2005
AES standard on interconnections
—Grounding and EMC practices —
'Shields of connectors in audio equipment containing active circuitry'
http://www.kirkeo.org/sites/default/files/pdfs/node15/aes48-2005-f.pdf
Bill Whitlock is the AES committee chair on EMI/RFI.
Some Bill Whitlock papers that touch on the subject:
*****************************************
"UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS"
CEDIA Class EST016
http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
***************************************************
A 2012 updated version of his seminary paper. more drawing & pictures.
"An Overview of Audio System Grounding and Interfacing"
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
*****************************************************
The 2005 seminar paper:
"UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS IN AUDIO & VIDEO SYSTEMS"
http://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf
[you have to register with Jensen]
****************************************
The Rod Elliott edited paper.
"Design of High-Performance Balanced Audio Interfaces"
Bill Whitlock - Jensen Transformers, Inc. (Edited By Rod Elliott)
Balanced Interfaces
Some Bill Whitlock papers that touch on the subject:
*****************************************
"UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS"
CEDIA Class EST016
http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
***************************************************
A 2012 updated version of his seminary paper. more drawing & pictures.
"An Overview of Audio System Grounding and Interfacing"
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
*****************************************************
The 2005 seminar paper:
"UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS IN AUDIO & VIDEO SYSTEMS"
http://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf
[you have to register with Jensen]
****************************************
The Rod Elliott edited paper.
"Design of High-Performance Balanced Audio Interfaces"
Bill Whitlock - Jensen Transformers, Inc. (Edited By Rod Elliott)
Balanced Interfaces
Jim Brown past AES committee chair on EMI/RFI has several papers, including:
Pin 1 Revisited
Neil Muncy called our attention to the Pin 1 problem (the improper termination of the shield of audio wiring to the circuit board rather than to the shielding enclosure) in his classic 1994 paper, reprinted in the June 1995 Journal of the AES. When he wrote his paper, most commercially available audio gear had pin 1 problems. It was, indeed, difficult to find equipment without it -- even the most prestigeous consoles had serious pin 1 problems! Over the next decade, the better manufacturers redesigned their products to correct their mistake, but sadly, many have not done so.
http://www.audiosystemsgroup.com/Pin_1_Revisited.pdf
http://www.audiosystemsgroup.com/Pin_1_Revisited_Part_2.pdf
**********************************************
"Power and Grounding For Audio and Audio/Video Systems -- A White Paper for the Real World"
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf
**********************************************
"RFI, Ferrites, and Common Mode Chokes For Hams"
http://www.audiosystemsgroup.com/RFI-Ham.pdf
**************************************
About 50 more Jim Brown papers:
Audio Systems Group, Inc. Publications
Pin 1 Revisited
Neil Muncy called our attention to the Pin 1 problem (the improper termination of the shield of audio wiring to the circuit board rather than to the shielding enclosure) in his classic 1994 paper, reprinted in the June 1995 Journal of the AES. When he wrote his paper, most commercially available audio gear had pin 1 problems. It was, indeed, difficult to find equipment without it -- even the most prestigeous consoles had serious pin 1 problems! Over the next decade, the better manufacturers redesigned their products to correct their mistake, but sadly, many have not done so.
http://www.audiosystemsgroup.com/Pin_1_Revisited.pdf
http://www.audiosystemsgroup.com/Pin_1_Revisited_Part_2.pdf
**********************************************
"Power and Grounding For Audio and Audio/Video Systems -- A White Paper for the Real World"
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf
**********************************************
"RFI, Ferrites, and Common Mode Chokes For Hams"
http://www.audiosystemsgroup.com/RFI-Ham.pdf
**************************************
About 50 more Jim Brown papers:
Audio Systems Group, Inc. Publications
AES48 was definitely a breakthrough read for me. Anyone ever read AES54-*-2008 standards on interconnections: Grounding and EMC practices ?
Henry Ott's Balanced vs. Unbalanced paper is pretty good, too. Don't think it's been referenced here yet: http://www.hottconsultants.com/pdf_files/Audio Interconnections.pdf
Henry Ott's Balanced vs. Unbalanced paper is pretty good, too. Don't think it's been referenced here yet: http://www.hottconsultants.com/pdf_files/Audio Interconnections.pdf
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