Balanced connections
Printed From: Graham Slee Hifi System Components
Category: Headphone Audio
Forum Name: High Fidelity Headphone User
Forum Description: Technical Q&A, hints and tips
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=5182
Printed Date: 20 Apr 2024 at 4:16am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: Balanced connections
Posted By: Ash
Subject: Balanced connections
Date Posted: 17 Mar 2021 at 9:42pm
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I guess it depends on the susceptibility to interference for the particular scenario. Short cable runs may not benefit from balanced connections. With balanced connections, you have three signal options to compare. Standard phase (single-ended/unbalanced), inverted phase (so-called R3) or balanced (both phases). Between DAC and amps, I use inverted phase Lautus 1.5m instead of balanced Libran 1.5m as the benefit of sheath ferrites probably outweighs the benefit of having both phases. Perhaps an ultra-short Libran might beat the 1.5m Lautus though, just because shorter is better? ------------- We do not see things as they are. We see things as we are. |
Replies:
Posted By: Graham Slee
Date Posted: 17 Mar 2021 at 10:32pm
What are you insinuating? ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
layercake1 wrote:Posted By: lfc jon
Date Posted: 17 Mar 2021 at 10:37pm
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I was told shorter is better if using RCAs, but XLR was better over long distances, that was said to me as a general rule ------------- Reflex M, Solo (both with PSU-1) CuSat50, Lautus, Spatia & Spatia links cables. Ortofon Bronze. |
Posted By: Graham Slee
Date Posted: 17 Mar 2021 at 10:39pm
 To be honest, my patience at my time of life is wearing rather thin. Especially after serving as senior engineer designing all-balanced professional broadcast mixing desks (the above being a stereo desk based on my BBC journalist workstation desk). Do I have to constantly fend off the bullsh*t brigade? ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: Graham Slee
Date Posted: 18 Mar 2021 at 12:08am
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Balanced is the feeding of phase and anti-phase signals down a twisted pair, from a 600-ohm source to a 600-ohm receiver (150 ohms using a transformer). Show me any modern hi-fi gear capable of sending at 600 ohms? OK then, I'll name one - the Majestic. 600 ohms is suitable for the telephone system and theatre snakes, whilst high-quality transmitter feeds will be 150 ohms via transformers. That is how program leaves a studio, connected to underground "BT lines," and emerging at a transmitter site some one to two miles away. Feeds to repeaters (AM and FM) might then be by microwave. Interesting fact: The Viking AM "Euro transmitter" is on the other side of the Humber estuary, so either the BT line goes the long way round or goes by an underwater cable. The transmitter site remains; although the station closed, it could be picked up anywhere in western Europe. The feed was line level. To obtain the required balance for noise cancellation, required a gain tweak in the non-inverting opamp input attenuator. The minimum signal gain is 2, although "noise gain" is unity. The reason for using opamps is their gain accuracy. The balance tweak was set on-test using an audio analyser measuring precision mixing resistors, such that the signal was reduced to an absolute minimum, below the noise floor. The arrangement used was designed by BBC engineer David Birt. Virtually all high quality feeds used NE5534 opamps. An improvement on Mr Birt's design is the all-inverting version because of it having no common-mode distortion. The conventional feed uses inverting and non-inverting stages for the phase and anti-phase signals. The non-inverting stage suffers common-mode distortion, which is compounded by the same occurrence in the receiving circuit. In most studios, balanced was mandatory only because it was used everywhere else in the station, and it is cost-effective to stock XLR's and TRS jacks rather than a mix and match of connectors. Some might think the XLR is used exclusively, but they'd be wrong. TRS features extensively in rack rooms for signal routing via jackfields. These tend to use the old-style PO jacks and sockets (the Majestic accepts both). My colleague, John C, has many years of experience wiring them into racks. The reason for using balanced is NOT to avoid grounding problems (although the bullsh*t hi-fi mantra goes like that). To say that balanced sounds better than a single-sided coax over a few metres is, in my experience, highly biased. It is marketing hype, and that is why I have so little patience when, after years of talking about balanced audio, another starts yet another topic about it. As I've said, please show me some balanced hi-fi unit which complies with impedance matching. Show me some hi-fi unit where the balance has been tweaked on a precision test to be actually balanced, and not just for boast! ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: BAK
Date Posted: 18 Mar 2021 at 12:46am
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Graham quote: "To obtain the required balance for noise cancellation, required a gain tweak in the non-inverting opamp input attenuator. The minimum signal gain is 2, although "noise gain" is unity. The reason for using opamps is their gain accuracy. The balance tweak was set on-test using an audio analyser measuring precision mixing resistors, such that the signal was reduced to an absolute minimum, below the noise floor." Balanced signal will not be truly balanced unless the + and - signal components (XLR pins 2 and 3) are exactly equal. When the designer makes the effort to make the + and - signal components exactly equal and makes them able to drive a 600 ohm load, this is a sign of a true professional. Not all balanced outputs are equal. Many cut corners for cost only to say they have balanced outputs. ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Ash
Date Posted: 18 Mar 2021 at 7:08am
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I think the rationale behind having two phases of equal/matched amplitude, one inverted and one non-inverted, is that when both signals are overlaid, the interference common to both can be completely eliminated. ------------- We do not see things as they are. We see things as we are. |
Posted By: Graham Slee
Date Posted: 18 Mar 2021 at 11:30am
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Let us not get confused with "bridged," and I'm now beginning to realise this topic might be about bridged headphone amplifiers??? Unless you have my "dark" sense of humour, as a qualified person, you'd call bridged bridged - you'd not call bridged balanced. However, the thick marketing guys do a great job of misleading the hi-fi buying public. They should be locked-up, preferably in a bottomless pit, for at least 1,000 years! ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: Graham Slee
Date Posted: 18 Mar 2021 at 12:02pm
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"OK, look into my eyes, the amplifier you are about to hear is balanced. As we all know, balanced is totally silent, and so you will hear complete silence, until the music starts. Instead of the crappy one sided sound of a conventional amplifier, you'll hear the complete music - both sides. When I click my fingers, you will trash anybody who doesn't advertise balanced." We only have the ASA in Britain - it only applies to us. It's difficult for the ASA to prosecute Americans and the Chinese for what they're good at (fake ads). ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: BAK
Date Posted: 18 Mar 2021 at 12:56pm
And the eagle swoops down to take us out of our trance! That hype that hypnotizes! It is brain-washing! Good one for Graham! 
I agree with Graham
Ash, you are correct.
Jon, you are correct. Any signal cable less than 8 feet (about 2.5 meters) is not going to benefit much from the common mode rejection properties of a balanced connection. At about 10 feet the difference will start to be noticeable, but just barely. With high impedance microphones (>1k ohms) single-ended RCA or UHF connectors were used up to 10ft long without a problem ... sometimes up to 25 feet, even. With low impedance dynamic microphones (50 to 150 ohms) the signal coming out of the MIC was balanced by the transducer directly or transposed with an internal balanced line transformer, that was then able to traverse up to 150 feet. With the use of "fantom power" on the MIC cable, the MIC could have its own preamp built in to drive longer cables with more clarity... balanced cables are not new... they are as old as radio used them in the 1940's !!!! and nothing newer has been made to improve the concept using wire cables. Only newer uses of old technology. Even the + and - signal balancing was 1st done in the early years (1940's). Don't be brain-washed! RCA cables are very good, and double-shielded, triple-shielded, even quad-shielded coax cables are the choice for most industrial and military signals... except armored ethernets which require twisted pairs and extremely low capacitance. ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: BAK
Date Posted: 18 Mar 2021 at 3:58pm
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Any questions about cables would ultimately be answered by a cabling engineer who has made cables of all types for many, many years... for broadcast radio, staging music venues, mixing boards "rats nests", etc... John C on the forum, take a bow. John hand makes and tests every cable. ------------- Bruce AT-14SA, Pickering XV-15, Hana EL, Technics SL-1600MK2, Lautus, Majestic DAC, Technics SH-8055 spectrum analyzer, Eminence Beta8A custom cabs; Proprius & Reflex M or C, Enjoy Life your way! |
Posted By: Graham Slee
Date Posted: 18 Mar 2021 at 4:55pm
Not forgetting the London Planetarium! ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: Graham Slee
Date Posted: 18 Mar 2021 at 5:11pm
And most of Bush House (World Service). And Hallam, Pennine, Viking, Buzz FM, Red Rose, CN FM, Pulse FM, Red Dragon (Cardiff), and stacks more. Plus BBC local radio stations. Red Tape and Human League recording studios. (he can't remember anymore - he's getting on you know...) ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: Fatmangolf
Date Posted: 18 Mar 2021 at 7:07pm
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That's quite a CV. I buy John's cables because they sound and look better than the ones I make. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: lfc jon
Date Posted: 18 Mar 2021 at 7:41pm
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This person also told me the same also applied to speaker cables the shorter the better but he did say to me that you do if you can, need to have your speakers a fair distance away from the system, specially if you have a turntable. He also said that putting your system between the speakers was not good, But this I can only take his word on that as I have not read anything about it any where (but I do it anyway)
------------- Reflex M, Solo (both with PSU-1) CuSat50, Lautus, Spatia & Spatia links cables. Ortofon Bronze. |
Posted By: Graham Slee
Date Posted: 19 Mar 2021 at 6:59pm
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An elementary block diagram of a so-called "balanced" HPA.  The only thing balanced about it is the input ("Birt" configuration shown). The amplifier is bridged, and there are two options. 1. One side receiving the signal from the other's output (via attenuator not shown), and both amps are inverting. 2. Both sides receiving the same signal with one inverting and the other non-inverting. The first suffers the second amp receiving the first amp's error signal and its propagation delay. The second suffers common-mode distortion on the non-inverting side, where there is none on the inverting side. Even with "perfect match" components, the bridge amplifiers can never be considered genuinely balanced. The other snag is that headphones with a common return short out one of the amps. Separate return headphones have to be rewired to a four-pin plug. ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: Ash
Date Posted: 19 Mar 2021 at 7:56pm
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It would be great if you were to write a whole book about electronics design Graham. I would buy it. ------------- We do not see things as they are. We see things as we are. |
Posted By: Graham Slee
Date Posted: 19 Mar 2021 at 10:14pm
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Far better people have written far better than my abilities allow. The Art of Electronics - Horowitz & Hill Valve Amplifiers - Morgan Jones Just to name two that give a wonderful insight into how things actually work. However, the reader must have the commitment, enthusiasm, and more importantly the staying power to stick with it. ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: Sylvain
Date Posted: 20 Mar 2021 at 1:38pm
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For what it is worth.....I perceived 'Balanced' as ''professional design'' and though my DAC offered a Balanced Output and Proprius accept 'Balance' and John subtly advised upon my repeated request and his patience would worn thin though he seems much younger that !!!!!!!! ''' balanced' for long length. I my naivety ask him to provide nearly 3 metres pairs balance Libran to connect Proprius across my living room now that Propertius allows positioning speakers further apart. It cost much. I tried a 1.5 metre pair in Single ended when John suggested a year later that I also introduce a Single ended cable. Well, single-ended in 1.5 metre pair to Proprius (at more than half the cost )and you do not need three wires save very Much money and the sonic difference at my 66 age well hardly noticeable but yes 'balance' mode in Phono Pre amp and headphone may have a subtle sonic difference.
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Posted By: Ash
Date Posted: 20 Mar 2021 at 5:43pm
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I chose single-ended 1.5m Lautus cables between Majestic DAC and Proprius amps, after quite a bit of thinking. If the cable has excellent EMI shielding and RF suppression already then the need for eliminating interference by two phase superposition becomes quite unnecessary, especially as this cable length is quite short so the cumulative interference along its length would be small. The main benefit of balanced input and output capability is that the inverted phase can be used instead of the standard phase. The inverted phase is not subjected to common mode distortion like the standard phase is. ------------- We do not see things as they are. We see things as we are. |
Posted By: Fatmangolf
Date Posted: 24 Mar 2021 at 7:50pm
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To be fair it does help on long cable runs with low signal levels. Otherwise I can see your reasoning that choosing the 'live' or 'return' output and connecting it to your choice of 'live' or 'return' input offers subtle options on the sound, depending on the pieces of equipment. But if one stereo channel is out of phase with the other you'd definitely hear that. Also some people can hear the absolute phase of reproduced music and that would be a factor too, for them. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Ash
Date Posted: 24 Mar 2021 at 8:38pm
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I agree with low level signals over long distances. That really hits the nail on the head. ------------- We do not see things as they are. We see things as we are. |
Posted By: Graham Slee
Date Posted: 25 Mar 2021 at 11:29am
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I'm with Doug Self on absolute phase. He states that for most frequencies, there is no detectable difference, but with one exception. I don't want to misquote him, so this is my interpretation. Any very-low-frequency single "thud" creates a pressure wave, which is first outgoing, its decay - which is almost as loud - starting at the almost as instantaneous pressure "suck back." The successive vibrations could be in either direction as our hearing cannot discern direction on repetitive back-forth air movements. He says that the original "thud" would have been face-on to the microphone capsule and suggests the only instrument recorded that way is a kick drum. He then discusses possible phase reversals that might occur in the recording chain, especially as the sort of music featuring a kick drum is quite possibly rock and/or "commercial" and might have been misphased in the wiring somewhere due to the number of recording stages. For the sake of the occasional fleeting "thud", the loudspeakers would have to be capable of creating the pressure wave, and the volume would need to be set pretty high to make a reasonable facsimile of the pressure wave. Even then, the listening room acoustics might "mangle" the pressure wave. However, he notes that the purists argue so much about this, and the "average" customer believes them that it is best to design for absolute phase, even if that is at the cost of adding complication. So, unless we're equipped to listen for that ephemeral "thud," what else could make us sensitive to phase? It cannot be imagined because sensible reviewers can detect a difference when swapping phases - something I discussed at length with Scott Faller. I, too, was able sometimes to notice a difference. What I found is something that makes sense, and that is the difference between inverting and non-inverting stages. Inverting stages do not suffer common-mode distortion! Therefore, I surmise that absolute single-sided phase might not sound as good as a mixture of inverting and non-inverting as found in balanced send and receive circuits. At that point, I decided to do an experiment, which was to connect an antiphase output to an antiphase input - single-sided - and compare it with both a fully balanced connection and a phase to phase single-sided connection. I also "recruited" a few customers to try an R3 interconnect between their Majestic and Proprius pair. They might remember? To my ears, the antiphase to antiphase connection sounded best, and that can be substantiated objectively because both use inverting send and receive circuits. These exhibit no common-mode distortion. The worst was the phase to phase connection, and from an objective viewpoint, it could be substantiated because non-inverting stages suffer common-mode distortion. The balanced connection was a little better than phase to phase, but antiphase to antiphase was best. This was further substantiated because although the receiving circuit - in the Proprius - is an all-inverting series input, the non-inverting input passes both, and the inverting input passes only once. What has this to do with the absolute phase of the music? Nothing! ------------- That none should be able to buy or sell without a smartphone and the knowledge in how to use apps |
Posted By: Ash
Date Posted: 25 Mar 2021 at 7:22pm
 Proprius - 1.5m Lautus-R3, anti-phase to anti-phase, switched mode power supplies Solo Ultra Linear - 0.6m CuSat50, phase to phase, PSU1 linear supply Both combinations sounded pretty much the same but Proprius had more power available and may have even sounded slightly better if I had to choose a winner. ------------- We do not see things as they are. We see things as we are. |
Posted By: Fatmangolf
Date Posted: 25 Mar 2021 at 8:40pm
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Thanks Graham. I have some true balanced sources like microphones but know the subsequent preamp electronics are often a balanced receiver then unbalanced circuits followed by the generation of a balanced output. Whether that is transformers or extra stages they add something else to the sound as Ash said and that can be bypassed. I still have my R3 cables just like Ash but in my setup I slightly prefer the balanced cables. Yes I agree about absolute phase but respect some are very committed to getting the "polarity" right saying the sound is wrong otherwise. In live music the effect of out of phase amplified sound is more obvious as larger drums sound thin (the 'thud' is cancelled out) and it can reduce feedback on some acoustic guitars as I found. Hi-fi playback of studio recordings is harder to rationalise, especially when you think of the wavelengths involved in the 'thud' compared to normal room dimensions. That said I think turning off the rumble filter helps, as it brings phase delay to audio frequencies is much as altering amplitude of sub-bass. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Ash
Date Posted: 25 Mar 2021 at 9:32pm
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I had been considering a very short Libran between Majestic and Proprius for a while, to replace my 1.5m Lautus-R3. I had been weighing up the pros and cons and was thinking along the lines of what Graham just said, that the inclusion of the regular phase alongside the inverted phase might not actually improve things compared to the inverted phase alone. Depending on the application, I was thinking that the presence of the regular phase could introduce more distortion than the phase/anti-phase pairing would remove, thus not actually being a superior connection in certain circumstances. Perhaps the only connection that might beat the Lautus-R3 is a very very short CuSat50-R3, without the ferrites, like Jon had. If I were to house the Majestic and Proprius close together in a sealed metal box, I would probably go CuSat50-R3. ------------- We do not see things as they are. We see things as we are. |
Posted By: Fatmangolf
Date Posted: 27 Mar 2021 at 5:44pm
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I still have the 0.6m R3 Cusats if you would like to buy them second hand, Ash? It is five vears ago so I had forgotten the details of the R3 cable wiring beyond the Ring to XLR pin 3. I checked whether the 2 or live pin on the R3 cable's XLR plug is grounded but it isn't. So I just need to unsolder (and heatshrink) the live signal wire from XLR pin 2 on my balanced cables to listen to the 'R3' option. I shall try it again when time permits and share any revelations. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Ash
Date Posted: 27 Mar 2021 at 8:00pm
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Thanks for the offer Jon but if I go for the CuSat50-R3, it would be shorter than 0.6m, maybe a third of that length, down to 20cm. Still not decided whether it is worthwhile just for tidier cabling. I would have to really weigh up the pros and cons vs the Lautus-R3. Yeah, the R3 connectivity is just a single-ended interconnect that can only be used between balanced output and balanced input. ------------- We do not see things as they are. We see things as we are. |
Posted By: Fatmangolf
Date Posted: 27 Mar 2021 at 8:18pm
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Fair enough Ash. You'll know The coax cable in the Cusat50/Lautus cables has a minimum bend radius so you may find 200mm means the gear is back to back to avoid kinking the cable. Anyway I am not claiming you'll hear any difference between the 1.5m Lautus and 0.6m Cusat. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
Posted By: Ash
Date Posted: 27 Mar 2021 at 8:45pm
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Even with MySphere and a long power-on time, any sound difference would probably be so subtle that a comparison would be inconclusive. 0.3m might be more sensible for equipment placement then. Although the 1.5m Lautus-R3 is better for using speakers as the speaker cable could be very short. ------------- We do not see things as they are. We see things as we are. |
Posted By: Fatmangolf
Date Posted: 28 Mar 2021 at 11:07am
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I agree Ash, 1.5m x2 could work in a near field setup with the hifi in the middle of the speakers. but probably not for a larger listening room (lucky people!). I appreciate the Lautus R3 could be longer than 1.5m as my digital cables are, but any audio cables probably would need to be several meters long or more if the amps are next to the speakers and the rest of the hifi equipment is well away from them. ------------- Jon Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |