What's the next thing to fail??? : ) Sean
You don't want to know brother. hehe
Cheers,
John
You don't want to know brother. hehe
Cheers,
John
balanced is inherently flawed
A recent post asking for opinions on balanced vs. single ended got me thinking once again about the inherent flaws in a balanced scheme.
A balanced signal has 2 parts called plus (+) and minus (-) that are equal in voltage but opposite in polarity. Therefore a balanced amp is really 2 single ended amps in one package, one for the + singal and the other for the - signal. So a balanced amp using the same quality parts as a single ended amp will be twice as expensive. Strike one.
That brings us to the "equal but opposite" notion. In order for this to work as planned, all of the + stages and cables connecting them must be exactly equal to all of the - stages all the way through the source, preamp, and power amp. Any deviation from the + stage being the exact mirror image of the - stage will result in an imbalance. Since perfect symmetry cannot be achieved, especially with tubes, distortions are introduced. Strike two.
Some think that balanced has to be better for various reasons that include:
1. If they hook up a balanced device using single ended cables they loose some gain.
2. They think a balanced system can achieve a lower noise floor.
3. They have balanced equipment and it sounds better when they hook it up with balanced cables vs. single ended cables.
4. It's used in recording studios by the pros so it must be better.
These arguments are flawed for the following reasons:
1. More gain does not equal better sound. Of course you need enough gain to drive your speakers to satisfactory levels, but the fact that one connection has higher gain than another has really nothing to do with sound quality.
2. This is the most misunderstood of all. A balanced amp CAN reject noise that is coming in through the interconnects. However, it can do nothing to reject or cancel the random electrical noise that comes from within the devices inside the amp. A balanced amp has no advantage over a single ended one when it comes to the major contributor of noise in the system, that which is generated inside the amp. The rejection of noise from cables relies on the fact that it is generally equal to both the + and - inputs and is therefore cancelled, but since the noise voltages generated by the devices inside the + and - stages in the amp are random and unrelated, they do not cancel and are passed on to the next stage.
Furthermore, since well designed, shielded interconnects of any type are very good at rejecting electrical noise from the outside, balanced has no advantage except in very noisy enviroments or when using very long runs, both of which apply to recording studios, not to typical home systems.
3. Since a truly balanced amp was built from the ground up to operate in a balanced mode, it makes sense that it will sound worse when fed a single ended signal. That doesn't mean that balanced is better, just that that particular amp sounds better when fed a balanced signal.
If you subscribe to the theory that more money can get you better performance, and since a single ended amp has 1/2 as many components as an equivalent balanced amp, it stands to reason that if the designer put as much money and effort into designing a single ended amp, it would sound better.
4. See 2 above.
And this brings us to our last point. ALL sound sources are single ended. Whether from a plucked string, blowing air through a horn, the human voice, or anything else; the resulting increses and decreases in air pressure that we perceive as sound are single ended. There is no "equal but opposite" waves of pressure. This is also true when the signal finally gets to a loudspeaker. There are no "equal but opposite" pressure waves coming from the speaker. It is a single ended device.
In a balanced system these pressure variations are picked up by a microphone and then some where along the line converted to balanced. A phonograph record is encoded single ended as is a digital disc. Your CD player may have a balanced output but the data that is read from the disc is single ended and then converted. In order not to introduce ditortions, this conversion from single ended to balanced has to be done perfectly. And since it can't be, strike three.
A balanced signal has 2 parts called plus (+) and minus (-) that are equal in voltage but opposite in polarity. Therefore a balanced amp is really 2 single ended amps in one package, one for the + singal and the other for the - signal. So a balanced amp using the same quality parts as a single ended amp will be twice as expensive. Strike one.
That brings us to the "equal but opposite" notion. In order for this to work as planned, all of the + stages and cables connecting them must be exactly equal to all of the - stages all the way through the source, preamp, and power amp. Any deviation from the + stage being the exact mirror image of the - stage will result in an imbalance. Since perfect symmetry cannot be achieved, especially with tubes, distortions are introduced. Strike two.
Some think that balanced has to be better for various reasons that include:
1. If they hook up a balanced device using single ended cables they loose some gain.
2. They think a balanced system can achieve a lower noise floor.
3. They have balanced equipment and it sounds better when they hook it up with balanced cables vs. single ended cables.
4. It's used in recording studios by the pros so it must be better.
These arguments are flawed for the following reasons:
1. More gain does not equal better sound. Of course you need enough gain to drive your speakers to satisfactory levels, but the fact that one connection has higher gain than another has really nothing to do with sound quality.
2. This is the most misunderstood of all. A balanced amp CAN reject noise that is coming in through the interconnects. However, it can do nothing to reject or cancel the random electrical noise that comes from within the devices inside the amp. A balanced amp has no advantage over a single ended one when it comes to the major contributor of noise in the system, that which is generated inside the amp. The rejection of noise from cables relies on the fact that it is generally equal to both the + and - inputs and is therefore cancelled, but since the noise voltages generated by the devices inside the + and - stages in the amp are random and unrelated, they do not cancel and are passed on to the next stage.
Furthermore, since well designed, shielded interconnects of any type are very good at rejecting electrical noise from the outside, balanced has no advantage except in very noisy enviroments or when using very long runs, both of which apply to recording studios, not to typical home systems.
3. Since a truly balanced amp was built from the ground up to operate in a balanced mode, it makes sense that it will sound worse when fed a single ended signal. That doesn't mean that balanced is better, just that that particular amp sounds better when fed a balanced signal.
If you subscribe to the theory that more money can get you better performance, and since a single ended amp has 1/2 as many components as an equivalent balanced amp, it stands to reason that if the designer put as much money and effort into designing a single ended amp, it would sound better.
4. See 2 above.
And this brings us to our last point. ALL sound sources are single ended. Whether from a plucked string, blowing air through a horn, the human voice, or anything else; the resulting increses and decreases in air pressure that we perceive as sound are single ended. There is no "equal but opposite" waves of pressure. This is also true when the signal finally gets to a loudspeaker. There are no "equal but opposite" pressure waves coming from the speaker. It is a single ended device.
In a balanced system these pressure variations are picked up by a microphone and then some where along the line converted to balanced. A phonograph record is encoded single ended as is a digital disc. Your CD player may have a balanced output but the data that is read from the disc is single ended and then converted. In order not to introduce ditortions, this conversion from single ended to balanced has to be done perfectly. And since it can't be, strike three.
73 responses Add your response
Herman. I really apologize for your computer mishap. I should of stated that the first link is an Adobe PDF file. My bad. I have provided the actual web link below in hopes that you may read the white paper contained within. It is some fascinating and extremely insightful reading. http://www.jensen-transformers.com/an/an003.pdf I agree that we all tend to experience a "slant " or "bias" when absorbing information being provided by manufacturers. I try to negate the sales portion of the information and concentrate on the rational scientific or factually supported portion of the information. Remember. Remove the sales portion, and in most cases the information is still being provided by brilliant and very well acomplished designers and engineers. Let's mentally remove the corporate logo's, and give them the credit and respect that they deserve. Driver. My background and formal education was mechanical engineering. Throughout the time I was attending school, I was an avid listener and musician. So, I had exposure to the prosound industry. Two of the most brilliant designer engineers I ever aspired to due to that exposure were Robert Heil and James B. Lansing. These gentleman could be considered modern day pioneers of audio research and design. I hold tremendous respect for both of these individuals. If one was to read Robert Heil's white papers on sound reproduction, my feelings would be reinforced. And now the absolute bottom line (for me at least). When I put together my last system I had initally hooked everything up with LAT IC-200 interconnects utilizing RCAs, as I had no balanced interconnects. I ordered new ICs (same exact cabling) in balanced configuration. Upon switching all IC cabling to the balanced wires, (transport to dac, dac to amp, all TRUE balanced) the difference in quieting factor was astonishing. And my system was already extremely quiet from the start. It's very simple. More quiet. Lower noise floor. No impedance level mismatch. (TRUE balanced) Equals: Wider dynamic range. Higher level of detail (less noise). Happy components. (VERY scientific) These are MY results with MY system. Respectfully, Ed. |
El: I'm not nearly as opposed to IC based circuitry as one might think. One of my favourite preamps is IC based. So long as good quality parts are used and the engineer / designer knows what they are doing, an IC based component can sound quite good. Problem here is that many products are based on the "sample circuit" that the manufacturer of the IC provided. Most of those circuits are designed to demonstrate the basic functionality of the IC, not exploit it to its' fullest potential. Driver: Thanks for reminding me who i was talking to about what : ) I'm not even 40 years old yet and my memory is going. What's the next thing to fail??? : ) Sean > |
Ed, that is SO COOL that you have that info on Bob Heil. I got my start in St. Louis running sound & made the trek over to Marissa many times, both for equipment repair & to get in on some seminars on running sound. The main thing I learned almost 30 years ago was that AC could give you more problems than you can imagine. Seems to hold true still. |
Thanks for all of the considered responses. The points about ground loops, rejecting internal EMI, cost of common components such as cases, systems in a noisy enviroment, the ability to closely match stages if willing to spend the money, everything is imperfect anyway, and several others are all well taken. If you are having hum problems from ground loops and going balanced gets rid of it then it is hard to make a case against it. I read the links from Buscis and they make good arguments but since they come from manufacturers of balanced equipment I would expect no less. BTW, the first link tried to load some stuff on my computer and locked it up, but I appreciate you taking the time to create the links. I did not mean to imply that balanced systems can't sound good. I've heard some that are among the finest. They were also among the most expensive. I guess my main hypothesis is that since sound is inherently a single ended phenomenom, it's reproduction should be also. Of course, I am in the "simpler is better" camp also. Although there are some strong arguments for going balanced, I'm sticking with the basic idea that taking a single ended source, inverting it and then trying to take both the original and the inverted and treating them exactly the same through a long chain of cables and amplification is going to cause more problems than it solves. As for noise and hum, I have a single ended system hooked up to 103 dB speakers and the only noise is a very faint hiss that you have to put your ear to the tweeter to hear. It uses Naim electronics and they are not balanced as someone suggested above even though they do use din connectors. Everything plugs into the same outlet strip so I'm sure this is one reason the noise/hum is so low. BTW, I'm listening to $19,000 Avantgarde Duos connected with a few hundred dollars of Naim speaker cable to a $1,350 Naim integrated so I may not be exactly mainstream with my audiophile preferences, but it is the best sound I've ever had in my room. If you haven't heard the latest generation of Naim stuff you should check it out. |
What a strange coincidence Herman. That's exactly what this designer said. And this designer. And this engineer. And this prosound company. I don't know Herman. I respect your opinion, although almost all of what you wrote, even though beautifully articulated, is opinion. I would very much enjoy seeing, reading and evaluating the contrary to what information I provided above. If you could substantiate what you stated with some scientific facts, I would enjoy discussing this further. Until that time, we all have our opinions. I respect yours, and I hope that you will reciprocate. Great post Herman, Regards, Ed. |
Herman- I read your post several times but I fail to see what point you are (attempting) to make. Plus, you make many wrong assumptions. For example: 1- A balanced amp will not necessarily be twice as expensive as a single ended amp, and typically will be far from twice as expensive, as the cost of a typical high-end balanced amp (Jeff Rowland, Krell, Mark Levinson, BAT, etc.) is driven by the cost of the mechanical parts (the solidly damped chassis, the fancy front panel machining, the front panel display and controls, etc.) and not the parts on the circuit boards or the output devices. 2- The two halves of the amplifier can be close too or exactly perfectly matched using many techniques (local feedback, resistor trimming, potentiometer adjustment, etc.). IÂ’ll admit though, this does add expense. 3- A balanced amp may, or may not reduce the noise floor, but in general will provide an increase in S/N ratio, as the noise remains constant while the output signal doubles in amplitude. Higher S/N ratio is always better. 4- A balanced amp in some instances CAN reject spurious noise within the amplifier. For instance, the input power transformer is radiating EMI throughout the chassis. An equal amount, or almost amount of noise will get into both halves of the amp and thus be cancelled, or almost completely cancelled-out at the output of the amp. 5- Lastly, and this is my input, a COMPLETELY balanced system, from the source through the power amp, effectively does away with all the various problems that can arise from the difference in ground potential from box to box. That's exactly why Naim (their stated reason) uses DIN connectors for box-to-box connections. And of course, a DIN connector is just another form of a balanced connector. If you do not wish to use balanced components (your point?) that is your prerogative. However, balanced components, particularly a fully balanced system, can afford many advantages over a single ended system. That does not mean the balanced system will sound better but that it has the ability to do so, particularly in a system where the units are plugged in all over the place. And, as always, IMHO. Russ |
Sean...I know how you feel about Op amps. I halfway agree with you on this subject, but only because Op amps are so often used in unsuitable applications. However, a unity gain buffer (which you need two of for a balanced line output) is an application wheren the Op amp is entirely satisfactory, and use of discrete circuitry would be a waste of money, and probably yield inferior performance. I have done a lot of amplifier "bridging" before that term was coined, in particular as a way to drive a center speaker from a stereo amp by inverting one channel's signal. It seems to me that an amp in bridged mode would exhibit many of the advantages cited for balanced lines, yet it is commonly reported that amps in bridged mode don't sound so hot. Finally (?) why do the two sides of a balanced line need to be matched? The whole idea is that the signal is floating, and can be received with a differential input amp that rejects common mode noise. If you ground one side of a balanced line (the extereme case), I think that you just revert to single ended. |
To my ears having had a completely balanced home audio system sounded wonderful with XLR cables. For grins I switched to RCA cables & although still nice, it didn't have the fullness as before. This particular gear sounded better balanced & that's how I ran it. I also do pro audio sound & of course all our gear is balanced for the simple reason of noise reduction. Also there's the bennie that the connections are more solid & although one is not likely to go running past the back of their rack, there's comfort in knowing the connection is secure. I also wouldn't use pro audio gear in a home stereo because it's not the best amp for the job, although it will work. Don't take this the wrong way but if someone wants to buy a balanced piece of home audio equipment, there's not much you can say that will dissuade them. As an aside, I've used both types with very good results over the years & using XLR connections has proven to me that apart from the topology, XLR is the way to go. Why does somebody prefer SS to tubes or analog over digital? It's a matter of preference because even though you've heard it a thousand times, it bears repeating-if everybody did the same thing, audio (as well as anything else) would be very boring. Sean, it was me that you were emailing a few days ago about why I was selling my Ayre & I did enjoy our "talk". |
Herman, Thank you for a detailed report on this subject. However, I am not convinced of a few issues made here. Issue 1: I wired a phono cable in both SE and Balanced configuration to feed an Aesthetix Io phono stage. This was a SilverAudio SilverBreeze cable. There was indeed a gain difference which I compensated for to get the same level. In some cases, at this stage in a system, this extra gain can be very valuable. But there was also more low-level detail with the balanced cable. I do not know if this was due to the nature of the cable in this configuration or the Io's inherent design but in my case, it was very clear of the sonic improvements. I have been eager to try this with the Manley DAC into my line stage but I do not have RCA and XLR cables of the same brand/model to do a fair test. Issue 2: The situation where noise rejection from within the interconnects is achieved, I find this valuable in itself. My system is in a very noisy environment, sump pumps, cable company transformers, furnace, etc., and any kind of rejection simply has to be of value. My pre-to-power length is 20' and so perhaps is not a big issue, but again, until I can compare an RCA vs. XLR cable of the same brand/model, the jury is still out for me on the benefits or not here. Perhaps the issue of "filtration" is something I need to attend to, but why do I need to go through so much effort to condition my power? Should not components be designed to resolve this for me? Issue 3: I am unsure of your conclusion here. You point out that in theory the two phases of a balanced circuit can not be equal. So if a product has been designed to its best ability to have two "matched" phases, I would think that grounding out one of these and running single-ended should be an improvement. Afterall, one of the compromised phases is out of the loop and the power supply should ultimately have more headroom as well. It most likely is not as good as another product of the same price that was a single-ended design, but the balanced product with one phase grounded should be better than with both phases if there is indeed no benefit to the 2-phase implementation. And yet, I suspect the engineers at ARC, BAT, Aesthetix would not think so of their products or they would have dismissed the balanced implementation and focused their attention to putting all their money into single-phase designs. Of course this is what CJ, Lamm, CAT and others have done. What we all would need here is to hear the comparisons of these company's designs throughout their R&D efforts when they made these balanced vs single-ended decisions at those times. Issue 4: You award balanced designs 3-strikes because the conversion from single-ended is not perfect. I think we all can agree that the world of audio electronics and music reproduction is not even close to perfect. But we are also in an analog world. So do we assign 3 strikes to digital recordings because the analog to digital conversion is not perfect? As a long time phono fan, I have come to like the sound of much digitally recorded music. I understand that many products have XLR connectors, step-up transformers, etc., to give the user a false claim of balanced benefits. But I simply have to believe that there are benefits of truly balanced designs for home audio or a number of talented audio engineers would have abandoned this by now. And in the few limited comparison tests I have made, there is indeed benefit. John |
Sean, circuit balancing not neccessarily can be achieved through so not favorable larger negative feedback, but electronically by the diode blocks between a complementary pairs of amplification (that's how it's usually done on SS amps) involving no extra negative feedback. The same could be applied to tube amps and it won't be a "violation of a tube purity". In terms of distortions, noise, bandwidth it's always dealing with gains and losses in any of the above said cases. |
Herman, I'm glad you took the time to write this post. I have made numerous short comments on the Single-Ended vs. Balanced issue, and I generally agree with you. However, I think it is more of an issue of what people think, that is flawed, than the flaw of the cables themselves. Balanced cables are what they are, which is a design borrowed from pro audio to keep external noise lower on long runs of cable. The problem is that consumers have begun to get the notion that balanced is the better technology because it has "pro" applications, and looks "heavy duty". It strikes me as rather ironic, since most "pro audio" gear is generally not considered fit for home audiophile use. And as far as the often quoted 6db gain increase is concerned, it is the result of the step-up transformers on each end of the line driver circuit that is providing this, and not the balanced cable. These line drivers are there to provide the extra "kick" needed for long cable runs that are expected with balanced lines. But these transformers also place additional parts in the circuit path that have signal losses and phase-shift associated with them. These are not present in the Single-Ended connections. Just like with anything else, you have to use technologies where they are most applicable, and not generalize. For home use, my opinion is that Single-Ended is most often the right choice, unless the entire topology of the amplification chain is true balanced. |
I prefer single ended interconnect for my 38 foot run between my balanced preamp to amplifiers. My turntable looks to be running balanced from the appearance of the cable. I had a custom built balanced cable terminated as single ended. The purpose of this was to obtain the superior cryo treated balanced locking connectors for use in a tight, high stress situation. Between the two (true balanced) Aesthetix pieces, there was some sonic gain with balanced runs, provided identical quality cable was used in each test. I concluded that cable design, shielding and termination were at least as important as the differences between SE and balanced. In extremely long runs such as microphone cable the results would likely be very different. In some situations microphone cable is over a hundred feet and in proximity to electrical connections, sound reinforcement equipment, other signal cables and possibly television and computer gear. In this difficult situation, a true 600 ohm balanced has advantages and is the reason pro gear is set up this way. |
Herman: All i can say is "great minds think alike" : ) I just posted or emailed someone stating much the same thing. Sometimes i do so much typing that i get confused whether what i sent was public or private. The part that stuck out in my mind about balanced operation was primarily the fact that you have four amps ( or four circuits ) doing the work of two ( for stereo ). Most manufacturers have a hard enough time building two channels that match, let alone four that perfectly match. Not only does this increase the potential for a channel to channel ( left to right ) imbalance, but also that of inter-channel imbalance ( positive to neutral vs negative to neutral ). It is hard to achieve cancellation of spurious external noises when the amplifier circuit itself may not be properly "nulling" the offsets. Then again, some of these problems would show up in S/N ratio measurements if they were severe. If the amplifier were not properly nulling the differenctial signal, the distortions produced from such a mismatch could be corrected relatively easily though by using more negative feedback. As many of us have heard though, this can make for a product that measures better but sounds worse. What got me to thinking about this was the fact that i purchased an old amp to run the subwoofer i just finished modifying for my Father. This amp is internally bridged, which means that there are actually four mono amps making up the two stereo channels. This provides twice the voltage potential, making for a pretty potent amp in what is a pretty compact chassis. This type of approach shares similar design strategy to balanced operation, which is what got me thinking about the potential for internal imbalances. As to El's comments, most of the Pro Sound reinforcement gear that accepts / works with balanced gear are simply using quad op-amps running in complimentary fashion. These cost next to nothing and one of these IC's can do both stereo channels. Most high end audio gear are using discrete components of ( hopefully )higher quality, making the parts count and cost of production measurably higher. My thoughts are that balanced operation has the potential to work better, but like anything else, it has to be properly designed and implimented with good quality control. Otherwise, there's just more to go wrong. Sean > PS... Lower grade circuitry may benefit more from balanced operation than state of the art single ended designs. At least with balanced operation, you've got some form of internal "checks and balances" without having to resort to GOBS of negative feedback. |
Although I think that balanced lines are unnecessary in the home audio situation, it is wrong to say that they are "inherently flawed". Balanced lines will do no harm, except to your pocketbook. My main complaint is that home audio manufacturers charge exorbitant prices for the little bit of extra circuitry involved, and make exaggerated performance claims to justify the price. Pro sound manufacturers routinely provide balanced interfaces at no great cost. |
