Cables
tmartin2 -- Wed, 01/25/2006 - 22:37
Any comments on whether balanced interconnect cables are worth it? Are they obviously better, and if so how?
Any comments on whether balanced interconnect cables are worth it? Are they obviously better, and if so how?
It is my understanding that they make a difference on long cable runs. Short cable runs between power amp and pre-amp are unlikely to provide any auudible improvement. On the other hand if one has self-amplified speakers or monblocks positioned very close to each speaker but quite a length from the pre-amp it may be a good investment. My pre-amp has both balanced and unbalanced but since it is only 2 feet from the power amplifier I'm using the unbalanced.
Bryston 2BLP Parasound Halo p-3
Infinity Kappa 400 M&K MX-70
NAD T-533 Yamaha MCX-1000
Thorens TD-185 Monarchy 33
Is the circuitry for balanced outputs/inputs more complicated and therefore likely to sound worse?
To the best of my knowledge I have never heard anyone say that balanced connections sounded worse than unbalanced. However, for many of us it is an unncessary expense. Bear in mind that I generally mock the cable elite.
I,ve found that some decent belden cables are all I need. Video may be a different story.
Bryston 2BLP Parasound Halo p-3
Infinity Kappa 400 M&K MX-70
NAD T-533 Yamaha MCX-1000
Thorens TD-185 Monarchy 33
I want to let all AVGuide forum participants know that the editors and writers of The Absolute Sound and The Perfect Vision will be engaging in the forum on a regular basis. Bring on your questions, comments, thoughts about the magazines. We'd love to hear from you.
We will also publicize this forum in the magazines so that we get more participants and generate some interesting and stimulating threads. I look forward to seeing you on the forum.
To reply to the balanced/unbalanced question, in my view balanced is a better connection method only if the source component is inherently balanced (a CD player that splits the signal in the digital domain, for example) and the entire signal path is balanced. In many "balanced" preamps, the balanced input is converted immediately to unbalanced (with a differential amplifier) and then processed as an unbalanced signal. This unbalanced signal is then converted to balanced at the output with a phase splitter. This topology adds two additional active stages to the signal path. A truly balanced preamplifier is expensive because it must have four identical signal paths (+/- Left, +/- Right). You can look at a preamp's volume control to see if the preamp is balanced; a fully balanced preamp must have a four-element volume control.
Robert Harley
Editor-in-Chief
The Absolute Sound
The Perfect Vision
Thomas, You now have it from the definitive source. Most of the little I know of high-end was learned from Mr. Hartley's book. Thank you for taking the time to repspond, Mr. Hartley.
Bryston 2BLP Parasound Halo p-3
Infinity Kappa 400 M&K MX-70
NAD T-533 Yamaha MCX-1000
Thorens TD-185 Monarchy 33
Does this "inherently balanced" idea mean that if I have mix of components (unbalanced turntable, balanced CD player), I better off with unbalanced connections? Also, how do I tell if the CD player is inherently balanced?
Thanks.
Subject to correction from the experts, I believe you can mix balanced and unbalanced connections as desired. Neither my Sony Cd changer or NAD DVD player has unbalanced outputs so the point is moot, for me. A physical inspection of the back of the unit will indicate whether balanced outputs are supported. In fact, I have never known anyone with a high enough quality digital source to have balanced connections (Although I'm sure they exist outside my mid-fi world). My thorens turntable has an attached unbalanced RCA as most turntables that I have seen. I don't know about the turntable connections on high-end models.
My Parasound does have one set of balanced outputs for connecting the power amp. However, my Bryston is the consumer version with RCA unbalanced inputs. I do believe that cables with balanced on one connector and unbalanced on the other connector are readily available from Blue Jeans cables and other cable sellers. Perhaps someone will chime in with better knowledge of the advantages of these 'mixed' cables.
Hopefully, as the forum gains traffic you will get a better answer from someone actually utilizing the balanced approach.
Regards
Bryston 2BLP Parasound Halo p-3
Infinity Kappa 400 M&K MX-70
NAD T-533 Yamaha MCX-1000
Thorens TD-185 Monarchy 33
If you have a mix of unbalanced and balanced sources, you'll have to live with the additional active stages introduced into the signal path for unbalanced signals if you have a truly balanced preamplifier. Conversely, if you have an unbalanced preamp, you'll have to live with the additional active stages introduced into the signal path for balanced signals. If these active stages are executed well, however, they don't significantly degrade the signal.
Robert Harley
I received this reader letter and wanted to share it with our group on the AVguide forum. It's a common (and natural) question with a very interesting answer.
Editor:
First, I'd like to say I'm a long-time subscriber to "The Perfect Vision". I also own & have read Robert Harley's books.
I have a question though. In the Winter 2006 issue on page 15 in regards to "How can I get the best possible sound quality from my theater system for music listening?", Robert Harley states that "we" should use the coaxial digital connection for audio from a DVD player because the optical (TosLink) connection introduces timing variations (called "jitter") in the clock that degrades sound quality.
I posted this info on a forum & got this response:
Go to any studio, even the very studios producing the DVDs we watch at home. You will find a large number of Toslink connections for digital audio as well as some XLR connections (AES/ABU) for digital. Toslink is a common standard for 8 channel, 24bit, 48kHz audio called ADAT. That is 6.5 times more bandwidth than we use Toslink for at home. Why would they use it so often if it were inferior in every way?
I respect Mr Harley alot. Is this "clock" in controllers bad in some and good in others? Is the same "clock" in the controllers used for coaxial & Toslink? Can you or Mr. Harley expand on this statement?
Thanks for your time & hope to learn more.
JF
Dear Mr. F:
TosLink is just fine for connecting two digital devices so long as the receiving unit is not a digital-to-analog converter. TosLink accurately gets the bits from one place to another, but the problem with TosLink arises because the clock embedded in the signal (it's more accurate to say the audio data are embedded in the clock) loses its timing precision in the TosLink interface. This clock is recovered in the digital-to-analog converter (usually by a PLL, which, by its very nature, tracks variations in the incoming signal) where it becomes the master reference clock for the DAC. The "word clock" (352.8kHz in an 8-x oversampling DAC) that controls when the samples are converted to analog is derived from the clock transmitted in the interface. Jitter in the interface translates to jitter in the word clock, unless heroic efforts are employed. This is why some high-end digital products use a separate clock line, or use the DAC as the reference for the source. Humans are extremely sensitive to tiny timing variations in the reconstruction of digital samples into music. Note again that if the data are not being converted to analog, interface jitter is not an issue.
The exact mechanism by which interface jitter affects audio quality is spelled out in great detail in the Audio Engineering Society paper "Is the SPDIF/AES-EBU Interface Flawed" by Chris Dunn and Malcolm Hawksford. It is a fascinating and pioneering piece of work, available at www.aes.org. What's particularly interesting is that the jitter is highly correlated with the audio signal. In experiments I performed with a custom jitter analyzer (it acts as an FM tuner, with the clock as the carrier frequency and the jitter as the modulated component), I could listen to just the jitter component on the interface and identify the music.
This AES paper finally quieted the engineering types who insisted that if the bits are the same, the sound must be the same. By the way, the first audio writer to discover that TosLink sounded inferior to coaxial connection was J. Gordon Holt in the first published review of a separate DAC and transport back in the mid-1980s. He new nothing about the technical issues, but simply reported what he heard.
Robert Harley
was worth the price of admission, folks. I guess I can cross "learn something new" off of my list of things to get done today. ;~)
Thanks, RH!
The question of whether a digital source is "inherently balanced" can be answered by looking at the DACs and output stage. A CD player or digital processor can have balanced outputs created in the analog domain by a phase splitter. The better way, and what I meant by "inherently balanced," is to split the signal into two phases in the digital domain before the DACs, and then convert those four signals to analog with their own DACs and analog output stage. This second technique obviates the need for an additional active stage (the phase splitter) in the analog signal path, and confers other advantages. When the two phases of the balanced signal are eventually summed, any noise or distortion common to both phases (those introduced by the DACs) will cancel.
Robert Harley
Editor-in-Chief
The Absolute Sound
The Perfect Vision
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