Page 2 of 4 FirstFirst 1234 LastLast
Results 16 to 30 of 54

Thread: Consumer and Pro-audio electronics: Connectivity

  1. #16
    RIP 2010 scott fitlin's Avatar
    Join Date
    Apr 2003
    Location
    Brooklyn NY
    Posts
    4,343

    yup

    Originally posted by Tom Loizeaux
    Maybe I'm just lucky, but I run my unbalanced sources into power amps or active crossovers and use either unbalanced 1/4" phono connectors or unbalanced XLR connectors, and have no hum problems! Eventhough I have the X-mods for my Crown PS power amps, I don't use them but run these amps in unbalanced mode - and I can hear NO hum from any of this.
    To me, this "balanced line" concern does not necessarily seem important in a home or studio setup.

    Tom
    Same here! My system is completely Unbalanced wiring! No hum here, either!

  2. #17
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142

    Rane BB44X

    Anybody know this...? Looks like a clever solution to a problem many of us do know...

    http://www.rane.com/bb44x.html
    Attached Images Attached Images  
    bo

    "Indeed, not!!"

  3. #18
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    9,720

    Hummmmmm

    During my college years, over a couple of decades, I moved quite a bit. I found that residential suburban and semi rural areas gave me no hum problems. Today living in an urban commercial part of San Francisco I have a constant battle with hum regardless of cable length. Most of my systems have a low level of background hum even after hours of changing cables and trying different circuits.

    I recently went completely balanced in one system and for the first time in years heard absolutely no hummmmmm!

  4. #19
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142

    Adcom GFP750

    ...and that was using this preamp, right?

    http://www.adcom.com/preamplifiers/gfp750.htm

    Did sound mighty fine.

    If I could only recall the active crossover you were using - sweet!
    bo

    "Indeed, not!!"

  5. #20
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    9,720

    Ashly XR-1001

    I have one on it's way! Paid a bit more than you did... thanks for the taste test and the tip! I hope I like it as much when my head clears.

    Widget

    PS. Yep that's the pre-amp.

  6. #21
    Senior Member JuniorJBL's Avatar
    Join Date
    Feb 2004
    Location
    Utah
    Posts
    1,723

    Ground loops! HA!

    I have been in the car audio install buis for 15 years and an electrician for about the same. Cars are more difficult then house's but you should use the same stratagies. First try to use only one circuit ( this means one ground/neutral) try to make sure that there are no motors on that circuit i.e. fridge ( if you need lots of current try a higher amp dedicated circuit to a single location. one high current outlet. more than one outlet can create this as well) use a good power filter/conditioner ( I use monster hts 5000's pluged into the same circuit on a single outlet 30A 10awg) I have also found that puting a transformer in-line with a signal cable can reduce signal-to-noise ratio somtimes very badly.
    I also make sure to stay away from ALL lights and motors and such when running power. Try not to make sharp bends in ANY cables or power lines.

    If you still have hum then you should look at your equipment to see if your RCA/XLR connectors have broken the solder joint on the PC board. Also some units are just badly designed and will have noise no matter what.

    I would not say I am an expert in this field but I have had a lot of experience. I hope this helps!
    Shane

  7. #22
    Senior Member JuniorJBL's Avatar
    Join Date
    Feb 2004
    Location
    Utah
    Posts
    1,723

    Talking Re: Adcom GFP750

    Originally posted by boputnam
    ...and that was using this preamp, right?

    http://www.adcom.com/preamplifiers/gfp750.htm

    Did sound mighty fine.

    If I could only recall the active crossover you were using - sweet!
    I use that pre as well and it is a great piece!!

    I also use the ashley 1001 for my sub 1500's
    Shane

  8. #23
    whgeiger
    Guest

    Grounding Notes and References

    BP,

    Quote: “Consumer gear is not grounded - it persistently has only the two-pronged plug, fat on one ear (for polarity purposes).”

    The neutral (white) wire (fat ear) is at ground potential (except for a small intervening resistance imposed by the wire run from the building entrance ground to the connected equipment). As a result, except for some improperly wired, unsafe equipment, all consumer gear is grounded when connected to ‘house power’.

    The third (green wire) protective ground replicates the neutral (white wire). Both are terminated to ground bar(s) in the service panel. When the green wire is present, it is used as a (protective) chassis ground; otherwise the neutral ground becomes the ground source. As both have some resistance and share a common cable sheath or conduit with that of the black (hot) wire, induced AC hum and line noise will be present at the chassis connection. For best results, a separate isolated, low impedance (signal) ground terminated directly at the building entrance (ground) should be used. If a UPS or isolation transformer is used to provide power to the technical load, then a local grounding system may be installed that is tied to the transformer secondary and provides separate signal, chassis and protective ground circuits that are free from noise resident in utility power circuits. This type of power and grounding system is typically used in well-designed computer (server) centers, telephone switch rooms, recording studios, process control rooms and other facilities that present technical loads that require a noise-free ground.

    For further information on grounds, shields and interconnecting cables, references to the following AES articles are provided:

    Regards,

    WHG

    Title: Grounding, Shielding, and Isolation
    Author: Arthur Davis
    Publication: AES-J, Vol. 1, No. 1, p. 103 (1953)
    Abstract: none

    Title: Considerations in Grounding and Shielding Audio Devices
    Author: AES-J, Vol. 43, No. 6, p. 472 (1995)
    Publication: Stephen R. Macatee
    Abstract: Abstract: Many audio manufacturers, consciously or unconsciously, connect balanced shields to audio signal ground. This is the source of many audio interconnection hum and buzz problems. The options available to manufacturers who follow this improper practice are …

    Title: Fundamentals of Grounding, Shielding, and Interconnection
    Author: Kenneth R. Fause
    Publication: AES-J, Vol. 43, No. 6, p. 498 (1995)
    Abstract: The ultimate performance of modern audio systems may be significantly constrained by signal contamination introduced by inappropriate grounding and interconnection practices. Fundamental principles of electromagnetism and linear circuits are reviewed.

    Title: Grounding Systems and Their Implementation
    Author: Charles Atkinson
    Author: Philip Giddings
    Publication: AES-J, Vol. 43, No. 6, p. 465 (1995)
    Abstract: The isolated star ground system is the most popular implementation of technical founding for the purposes of grounding sensitive electronic equipment. This approach has been in practice for many years, and while it is not the perfect solution, it is the …

    Title: Differential Technology in Recording Consoles and the Impact of Transformerless Circuitry on Grounding Technique
    Author: Author: Thomas M. Hay
    Publication: AES-P, No. 1723, Cnv. 67 (Aug-1980)
    Abstract: Possibly the least understood problem encountered during the construction of a recording studio is the powering and grounding of the equipment. While the arts of acoustics, monitoring, and equipment design have been studied extensively, it seems that the …

    Title: Differential Technology in Recording Consoles and the Impact of Transformerless Circuitry on Grounding Technique
    Publication: AES-P, No. 1748, Cnv. 66 (Mar-1981)
    Author: Thomas M. Hay
    Abstract: Possibly the least understood problem encountered during the construction of a recording studio is the powering and grounding of the equipment. While the arts of acoustics, monitoring, and equipment, design have been studied extensively it seems that the …

    Title: Technical Ground Systems Versus the Electrical Code
    Author: Philip Giddings
    Publication: AES-P, No. 3181, Cnv. 91 (Oct-1991)
    Abstract: Electrical codes impose rigorous restrictions on the equipment ground conductors that accompany 120-VAC power circuits feeding audio and other technical equipment. Many facilities and systems are in breech of the code. The issues surrounding requirement …

    Title: Considerations in Grounding and Shielding Audio Devices
    Author: Stephen R. Macatee
    Publication: AES-P, No. 3916, Cnv. 97 (Nov-1994)
    Abstract: Over the past decade, the declining cost of professional audio equipment has facilitated its use in more home studio environments. As home studios incorporate professional, balanced equipment into their systems, the unbalanced and balanced worlds collide

    Title: Grounding Systems and Their Implementation
    Author: Charles Atkinson
    Author: Philip Giddings
    Publication: AES-P, No. 3931, Cnv. 97 (Nov-1994)
    Abstract: The isolated star ground system is the most popular implementation of technical grounding for the purposes of grounding sensitive electronic equipment. This approach has been in practice for many years and while it is not a perfect solution, it is the …

    Title: A Transformerless Ground Loop Isolating Preamplifier-Introducing Current Balanced Circuit Technology
    Author: David Fiori, Jr.
    Publication: AES-P, No. 4849, Cnv. 105 (Sep-1998)
    Abstract: Current Balancedª technology is described with a circuit that achieves extraordinary isolation and CMRR characteristics without a transformer. The circuit is DC coupled, connects to unbalanced equipment, and provides signal gain without compromising CMRR. Like a transformer, it implements two-port audio signal isolation that is characterized by a balance in the currents flowing in and out of each port.

    Title: Amplifier-Loudspeaker Interfacing
    Author: R.A. Greiner
    Publication: AES-J, Vol. 28, No. 5 pg. 310 (1980)
    URL: http://www.aes.org/journal/search.html
    Abstract: Loudspeaker cables are investigated to determine if they exhibit transmission-line characteristics. Lumped representations of cables are suggested with consideration of the effects cable parameters might have on the audio signal being transmitted.

    Title: Effects of Cable, Loudspeaker, and Amplifier Interactions
    Author: Fred E. Davis
    Publication: AES-J, Vol. 39, No 6, pg. 461 (1991)
    URL: http://www.aes.org/journal/search.html
    Abstract: Loudspeaker cables are among the least understood yet mandatory components of an audio system. How cables work and interact with loudspeaker and amplifier is often based more on presumption and speculation than on fact. The literature on loudspeaker ...

  9. #24
    Senior Member JuniorJBL's Avatar
    Join Date
    Feb 2004
    Location
    Utah
    Posts
    1,723

    Re: Grounding Notes and References

    Originally posted by whgeiger
    BP,

    Quote: “Consumer gear is not grounded - it persistently has only the two-pronged plug, fat on one ear (for polarity purposes).”

    The neutral (white) wire (fat ear) is at ground potential (except for a small intervening resistance imposed by the wire run from the building entrance ground to the connected equipment). As a result, except for some improperly wired, unsafe equipment, all consumer gear is grounded when connected to ‘house power’.

    The third (green wire) protective ground replicates the neutral (white wire). Both are terminated to ground bar(s) in the service panel. When the green wire is present, it is used as a (protective) chassis ground; otherwise the neutral ground becomes the ground source. As both have some resistance and share a common cable sheath or conduit with that of the black (hot) wire, induced AC hum and line noise will be present at the chassis connection. For best results, a separate isolated, low impedance (signal) ground terminated directly at the building entrance (ground) should be used. If a UPS or isolation transformer is used to provide power to the technical load, then a local grounding system may be installed that is tied to the transformer secondary and provides separate signal, chassis and protective ground circuits that are free from noise resident in utility power circuits. This type of power and grounding system is typically used in well-designed computer (server) centers, telephone switch rooms, recording studios, process control rooms and other facilities that present technical loads that require a noise-free ground.

    A much lengthier (and better! ) description than I was willing to write last night.

    This is the case! You are well versed in this area!!
    Take heed all, You SHOULD try this at home!
    Shane

  10. #25
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    Hey, Bill...

    Thanks for the tome! Extra effort, dood...

    In addition to your references, there frequently are sections on this topic within many of the Pro sound "Technical References" on the eponymous Thread. In-particular, the "Pro Audio Reference" by Bohn of Rane Corp. has a fairly exhaustive treatment of this, and includes some wiring / soldering charts cor creating proper cables.

    induced AC hum and line noise will be present at the chassis connection.
    which is why it is recommended to drop the shield at either end of a balanced cable interconnect.

    Too often "users" resort to dropping the AC ground, in hopes of stopping the hum. Bad behavior... All that is needed is proper cabling.
    Last edited by boputnam; 05-05-2004 at 07:03 AM.
    bo

    "Indeed, not!!"

  11. #26
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142
    Hey, Bill (II)...

    I had to await return home to dig these out, but figured these would be a worthy addendum to your post...

    Muncy, N.A., 1994, Noise Susceptibility in Anaolgue and Digital Siganl Processing Systems: presented at 97th AES Convention of Audio Engineering Society in San Francisco, CA.

    Muncy, N. and C. Perkins, 1994, Grounding, Shielding and Interconnections in Analogue & Digital Signal Processing Systems: Understanding the Basics: workshops presented at 97th AES Convention of Audio Engineering Society in San Francisco, CA.
    bo

    "Indeed, not!!"

  12. #27
    Senior Señor boputnam's Avatar
    Join Date
    Apr 2003
    Location
    northern california
    Posts
    6,142

    Drop shield at the INPUT end

    Originally posted by boputnam
    ...it is recommended to drop the shield at either end of a balanced cable interconnect.
    Pretty lonely when one quotes his own posts...

    But, this needs be remedied.

    It is common practice in pro audio to drop the shield on one end of balanced interconnects. However, in contrast to the convention adopted by Rane (ibid), it make more sense to drop the INPUT end. Why? The partially disconnected shield will likey act as an RF antenna. If the shield is dropped at the OUTPUT end (Rane convention) this leaves the shield connected at the INPUT and any RF can find it's way into the INPUTs. Makes more sense to drop the shield at the INPUT - that way the RF cannot enter the INPUT, resulting in lower noise floor.

    And remember, be consistent throughout your entire system interconnects.

    Always seeking a quieter quiet,
    bo

    "Indeed, not!!"

  13. #28
    Charley Rummel
    Guest

    I agree...

    Hi, everyone:

    More than once in my life I've seen (and heard) installations where everything appears to be by the book in cable settup, and then there's a very faint but present "strange voices" phenomenon comming out of the house mains and/or monitors.

    I haven't read the other posts in the string in depth, but the fact is any unsheilded conductor of any length (maybe longer than an inch or so for practical reasons) may serve as an RF antenna. Also, by shielding it - and from the INPUT side - the conductor has no opportunity to receive RF and feed it into the input circuit; capacitance in the input sheilded conductor cancels it to ground in the input device, whereas this is ability is absent if the sheld is grounded by the output device (and therefore introduces "strange voices" into the signal). This comes from first hand practical experience. (Defective guitar chords are a good source of RF).


    Regards,
    Charley

  14. #29
    Altec Fan
    Guest
    Perhaps this has been cited before but I've found it to be a useful reference when dealing with interconnection woes:

    Rane Note 110

    Later . . .

  15. #30
    Senior Member
    Join Date
    Apr 2003
    Location
    Colorado
    Posts
    311
    Rane's last shot is great!

    * Use balanced connections whenever possible.
    * Transformer isolate all unbalanced connections from balanced connections.
    * Use special cable assemblies when unbalanced lines cannot be transformer isolated.
    * Any unbalanced cable must be kept under ten feet (three meters) in length. Lengths longer than this will amplify all the nasty side effects of unbalanced circuitry's ground loops.
    * When all else fails, digitize everything, use fiber optic cable and enter a whole new realm of problems.

    John

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •