Embedded Systems Conference
Breaking News
Comments
Guru of Grounding
User Rank
Author
re: Don't Let the Headphone Jack Ground-Return-Path Impedance Threaten Compliance with Vista Windows Logo Program (WLP) Crosstalk Requirements
Guru of Grounding   9/19/2009 9:38:15 PM
NO RATINGS
I think this is a very dubious (and certainly not a new) technique. It begs all kinds of grief for the customer when ground loops occur (which is nearly always, except with an actual headphone). Imagine the effect of several mA of 60 Hz "harmonic soup" flowing into the jack's ground when it's connected to external audio gear. It's bad enough that the connection is unbalanced (making for inevitable noise due to common-impedance coupling in the cable itself). Computers in general, and laptops in particular, almost always have internal grounding issues severe enough to make an audio professional recoil in horror. Adoption of "compensation" techniques like this one only makes matters worse. PCB designers of these products should learn from AES48-2005 about recommended grounding practices for audio I/O ports. Kick the "artsy-fartsy" industrial designer out of the room and put the audio driver where it belongs! Bill Whitlock, Fellow of the Audio Engineering Society and IEEE Senior Member

SpatialKing
User Rank
Author
re: Don't Let the Headphone Jack Ground-Return-Path Impedance Threaten Compliance with Vista Windows Logo Program (WLP) Crosstalk Requirements
SpatialKing   10/19/2009 5:07:16 PM
NO RATINGS
Bill, I like your comment about kicking the artsy-fartsy engineer out of the room but it will take a very large boot indeed. Of course, if headphones had four wires instead of three and the ground currents only mixed at the amplifier output ground, then the whole ground current mixing would be moot.

bcarso
User Rank
Author
re: Don't Let the Headphone Jack Ground-Return-Path Impedance Threaten Compliance with Vista Windows Logo Program (WLP) Crosstalk Requirements
bcarso   2/11/2010 6:14:10 PM
NO RATINGS
Do you know what the threshold is for detecting that some fraction of a signal is emanating from a two-channel system's lower-level channel, rather than 100% coming from the louder one? Absent time-delay effects, in the region of highest perceptual acuity the answer is about minus 13dBr---that is, at less crosstalk than that the listener hears the sound as coming entirely from the louder channel. Bear this in mind when you struggle to achieve truly impressive crosstalk numbers. The extremes to which some go in this pursuit border on the ludicrous, including the audiophile's abiding respect for "dual-mono" designs, even extending to separate mains inputs!



Radio
NEXT UPCOMING BROADCAST
Why Connect a Car?
May 11, 1pm EDT Monday
Overview: Battle-hardened veterans of the electronics industry have heard of the “connected car” so often that they assume it’s a done deal. But do we really know what it takes to get a car connected and what its future entails? Join EE Times editor Junko Yoshida as she moderates a panel of movers and shakers in the connected car business. Executives from Cisco, Siemens and NXP will share ideas, plans and hopes for connected cars and their future. After the first 30 minutes of the radio show, our listeners will have the opportunity to ask questions via live online chat.
Top Comments of the Week
Flash Poll
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Special Video Section
LED lighting is an important feature in today’s and future ...
Active balancing of series connected battery stacks exists ...
After a four-year absence, Infineon returns to Mobile World ...
A laptop’s 65-watt adapter can be made 6 times smaller and ...
An industry network should have device and data security at ...
The LTC2975 is a four-channel PMBus Power System Manager ...
In this video, a new high speed CMOS output comparator ...
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...
General-purpose DACs have applications in instrumentation, ...
Linear Technology demonstrates its latest measurement ...
10:29
Demos from Maxim Integrated at Electronica 2014 show ...
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
STMicroelectronics demoed this simple gesture control ...
Keysight shows you what signals lurk in real-time at 510MHz ...
TE Connectivity's clear-plastic, full-size model car shows ...
Why culture makes Linear Tech a winner.
Recently formed Architects of Modern Power consortium ...
Specially modified Corvette C7 Stingray responds to ex Indy ...