I agree. Back in the late 80s when I was in EE school, my music-enthusiast friends and I would take audio equipment to electronics class to ask questions about it in hopes of bridging theory to practical application. I remember my prof saying, “there’s no good reason to spend more than about $100 on a home stereo set.” We were disenchanted to say the least.
@Douglas Blake $1000 today gets you far better sound than same $1000 did in 1988 lets say. $100 back then gets you a small boom box or compact cassette and CD all in one plastic set. Not good sound let alone audiophile. $200 for a pair of speakers back then can not compete with modern $200 a pair speakers today.
Paul..... You should NEVER apologize for taking 8 measley minutes to explain something technical. This is great info that everyone here should know. Thanks for finally stepping UP to a white board. Please use it more often! Lesson 2 of this topic should be discussing the diffs between Active Balanced, Impedance Balanced, and Transformer Balanced. Oh that's exciting stuff!
Great to see an actual whiteboard being used for something during this pandemic where meetings have gone online and we lost the precious whiteboard human interaction.
To be honest Paul, 8 minutes is very good! There is a lot of (useless or time wasting or boring) content that isn't worth looking at unless you only have one hobby or passion.I have lot's.Thanks my friend (in a respecful and admiring way), Mark
Paul, great theory dissertation but may I suggest a part 2 where we can get into the specific practical problems mixing balanced and unbalanced signals. Sometimes there is no choice. 1) The level problem. Pro balanced signals are at +4db whereas RCA audio interfaces are loosely defined from -10db to 0db. 2) The transformer versus transformer-less minus side problem. When to tie the minus side to ground and when not to. 3) The professional converter box, why the best option but quite expensive.
What a great explanation, I’m watching this video knowing absolutely nothing about balanced and already have a good idea of what its trying to achieve, Thank you!!
What you said about more distortion in adding an invertor to create balance output is true for home use. However, if you are in a studio environment with very long cable run, there will still be some benefits of converting it to balanced.
Thank you so much for these videos Paul ! They have been a big help to me . I started building small transistor amps about two years ago . Soon I am going to build my first tube amp . It's so much fun building circuits ! In the same way you can play guitar a lifetime and never learn it all , there is always something new to learn in electronics .
Hi Paul. I am really enjoying your videos and the way you have of effectively explaining complicated concepts with a few squiggles on the white board. You’ve made a difficult topic very understandable at a level that gives enough knowledge without over complicating the whole thing. Great work and much appreciated.
Great job on your explanation many electrical engineers have a hard time understanding this concept. My dad was a ham radio operator and electrical engineering aficionado. One day we got a call from a recording engineer who needed this job performed and couldn't find anyone to do it for him. So my dad did the necessary modifications that he needed to his recording console. We then found out that this was the same recording console that was used in the recording studio that created the song Dream Weaver by Gary Wright.
Just what I needed, as a sparks I have run rca to amp( line in)...my problem is that every band uses XLR ..I thought we could convert...but now see exactly why we can't...new subscriber..cheers from Ireland
Years ago I used to have a bunch of unbalanced to balanced converters made by Switchcraft that got the job done with precision transformers. It seemed to perform well enough at the time but I expect that it probably striped some of the upper frequency spectrum from the signal. When we used them we knew we were using the equivalent of a bandaid. They saved us in a crunch. We were faced with an equipment incompatibility at a live performance and the show had to go on. And on it went thanks to Switchcraft. I remember there was quite a bit of loss through them.
Paul. In passive converters they take a negative signal from an audio transformer. Benefits: if you do it close to the RCA source and run the XLR for the rest of the distance you get the benefit of XLR noise suppression for this distance.
Wow that was brilliant thanks Paul. I used a balanced feed from an e-drum controller (brain) to my active monitors, I always knew it was better but not sure how. Wasn’t aware of how it removed any hum on the line but now I do. Thanks again and take care!
This is a great lead into another video discussing using 2 channel stereo amp as a monoblock. In that video he briefly mentions using XLR/Balanced cable and switching the pins. If your interested in this stuff, these 2 videos paired together makes a very interesting lesson. I always thought XLR/Balanced cable were just better for longer runs. I had know idea. Thanks, Paul.
Love your videos Paul. If interconnecting preamps and poweramps, speakers, etc,. Impedances are more important. But if you have to run audio cables at any length, they will pick up noise if not balanced, balanced audio, the design has a ‘reason for rhyme’.
Randy Slone (RIP) covers this topic extensively in his excellent book: "The Audiophiles Project Source book". (2001). Basically you do it with Op-amps. I believe you do need the ground connection to shield the audio cable from noise and tie the two devices to a single ground. The reason you're using balanced connections in the first place is to minimize "induced" noise.
Fantastic explanation. I have an electronics background and understood you completely. You CAN change the end of a cable from RCA to XLR however it's only a connector type change with no sound quality "improvement".
Yeah, but you just need to add/splice a second RCA cable to carry the duplicate, flipped sigal. This video is correct only if you don't add a second conductor. Add a second conductor and all that's left is to flip it.
Don't mind longer, detailed videos when there is something good to learn. I love to learn and will spend hours comparing individual opinions to get to the truth. So, don't apologize if your videos go over the alloted time.
There are actually some benefits Paul when using a longer balanced cable to a DAC and a very short XLR to RCA cable to the amp. Not all units allow for a direct signal from balanced inputs to RCA outputs. In this case you absolutely do gain better quality, because a direct signal sounds much better.
XLR is very useful for stage setups as hum and noise can kill the whole show. In my opinion it would help to convert RCA to XLR as a sales concept to new bands who didn't think about this yet and suffer by it.
Take as much time as you want Paul. Would much rather watch a long video with a useful and comprehensive answer, than a short one with a superficial answer that doesn't really explain anything!
Oh boy. Balanced may tend to be quieter when cables run near stray magnetic fields. But balanced does not sound better. Unbalanced sounds equally good. Bill Schnee's custom audio console was unbalanced and had passive summing. Also, pretty much any audio console these days can see a balanced or unbalanced input without changing anything.
The diagram for the unbalanced to balanced conversion isn't strictly correct. First, the amp stages as shown are working in open loop and would give a very high gain. Typically, buffer amplifier stages (op-amps) used for such purposes would be having feedback from the output to the input not receiving a signal to make them unity gain. And then, I don't think it's correct to use the output from the first buffer to feed to the inverting one. There are usually phase delays in the output and that would make the inverted signal lightly out of phase. It's more practical to use the two buffers in parallel and use the inverting input on one and the non-inverting input on the other, and use their outputs as the two out of phase signals.
I totally agree that there is no benefit to converting RCA to XLR in an enviornemnt where you have control of the setup. Though sometimes even professionally you MUST do it. I am a wedding videographer. I record audio from various speaker systems, wireless mic recievers, and DJ sound boards. My audio recorder has XLR inputs. MOST of the time, I can take audio from a source that uses either XLR or 1/4" TRS as an output, and that works just fine. Balanced signal. But just recently I came across a DJ that had an old sound board and they ONLY had RCA outputs on thier board. I had a simple RCA to XLR unbalanced cable. It sounded ok I guess but I can't help but wonder if there's a better way.
Balanced adds complexity and cost that are not necessary for a vast majority of home systems, and it sounds worse to boot as it has a negative effect on the distribution of harmonic distortion resulting in more odd-order distortion and a clinical, sterile sound that is further away from a psychoacoustic ideal and therefore most folk's preferences. Also, mixing balanced and single ended components is not ideal either, but it's forced on many of us as most modern DACs are supplied with inferior RCA outputs while the best preamps and amps are single ended. This results in a massive number of systems that are not optimally set up, and to top it off the component manufacturers will not be honest about this with their own customers, and generally instruct them to hook up their system the easiest way, and not the best way. You don't even mention this issue, but the fact is many folks need real, honest information about using balanced source components with single ended amplification.
Long signal pathways by their cable lengths and connections can introduce unwanted noise. Nullifying out the these disturbances will give you a much cleaner signal. I believe this is mandatory with long cable runs used in bands for stage performances, indoors or outdoors.
I think balancing in pro audio is most important for mic level signals, as the signal is so weak. Noise on a Line level signal is much less noticeable. Keep your RCA cables short as possible and away from power cables and electrical equipment and I think you would struggle to find noise any differences even if analysing electrically.
A proper "passive" converter would be a transformer. Good ones are expensive. But if you really need to convert unbalanced to balanced--such as a long run between pre and power-- it is arguably the way to go. Like an active converter, it degrades the signal. With a really good transformer, maybe not by much. It also offers certain advantages, such as an ideally limited pass band--way beyond what is considered audible--when terminated properly. Jensen makes good quality transformers, with ideal Butterworth responses. They also make ready made adapters for those not wanting to add enclosures and connectors. Not trying to write an ad, but I have auditioned Jensen transformers carefully and not found them wanting. They are widely used in professional audio equipment and studios.
Learned a lot. However in the application it is typically a 1 meter component connection. A high quality rca cable isnt going to induce much noise if it is decent shielded cable. Leaving the advantage of the xlr not so much. I have both types of 1 meter inputs on my home systen and hear no difference. However in a pa system with great distances between source and loudspeaker it is neccessary to use balanced inputs most times.
I think the person was wanting to actually change the port on the unit itself to balanced. I have seen this sort of hack in Japanese equipment. I remember seeing an old Pioneer amp that had been converted to XLR and even a Sony TA-D88 crossover network completely converted to XLR. I'm pretty sure they would not do this unless there was a very good reason and/or a noticeable quality bump in doin this.
Balanced lines are a must in professional audio. Where RCA level might be 1 volt, microphones can be only a few millivolts. When your mic lines are 300 feet and are surrounded by noisy stage stage equipment, even a little interference can be heard through the speakers. The whine of a switching power supply and the hum of an AC unit can be really distracting!
I can listen to this for 30 minutes, don't need to excuses yourself! What I'm wondering: this balanced vs. unbalnced version: would the balanced version be twice as "loud" compared to a non-balanced signal? Does that mean the you have to turn up the volume control when you use the passive convertor?
All thing being equal, then YES one leg of a balanced signal has half the voltage swing, compared the the difference between the two legs. If the signal on each leg is 2 volts, then the difference is 4 volts. Double the voltage means 6dB louder. However, if a component has both RCA and XLR outs, that doesn't always guarantee this relationship. There might be different gain stages feeding each output, so the output voltages might not be exactly the same. Lots of pro audio gear has -10dBv level on the RCA, and a much higher +4dBv on the balanced output. Pro audio gear runs at 14dB higher level than consumer gear.
consumer standard -10dBV (base unit is 1V) = 10^(-10/20) * 1V ~= 0.3162V pro standard +4dBv (or +4dBu, the base unit is "1mW into 600ohm", which is sqrt(0.6) ~=0.775V), therefore +4dBv or +4dBu = 10^(+4/20) * sqrt(0.6)V ~= 1.228V the pro standard is higher than consumer standard by ~0.9114V or 20 log(1.228/0.3162) ~= 11.78dB
My SACD plyer has XLR out for two channel the only way to get that to work to use balanced XLR to an amp that has XLR inputs . Its a NAD player. your right balanced is better. I do use unbalanced XLR to RCA that one is made by audioquest. It has those lovely batteries at the end.
While most "passive converters" are probably just cross wired connectors, as Paul noted, a transformer would also be a "passive" device and would give the benefit of common mode rejection if the conversion was made close to the RCA output and appropriate impedance matching was considered. This is how an instrument DI box works. However...in HiFi applications, a very high quality transformer would be required and would probably cost more than an active circuit !
Hey Paul, thanks for the explanation. But shouldn't the noise be cancelled out in the RCA too? The ground wire would pick out the same noise as the signal wire and the Amplifier should cancel that out too.
You can use a 2-conductor + shield cable to connect RCA outputs to balanced inputs. Use one conductor for the signal side of the RCA output - goes to non-inverting side of balanced input. Use the other conductor to connect the RCA ground side to the inverting side of the balanced input; add a series resistor at the RCA end of this conductor which matches the source's impedance, to achieve balance. Connect the shield normally at each end.
for the original question: I doubt the center conductor will pickup same level of noise as the shield in a coaxial cable, which is required to cancel out the noise
A white board? Go on Professor! Ok Pail, now this. I wanted a home theater before there was such a thing. I found an article on Hall effect wring for the rear speakers of a quasi surround system, where you take the two rear speakers and attach the positive leads to either side to them, then you bridge together the negative speaker wires together at the amp, and run a wire from each of the speakers negative input to each other. The only thing that was supposed to come out of the rear was what was common to both sides of the thing your listening to. And for a long time I only had simulated stereo for the input from the VCR to the amp.
@ken cohagen This is referred to as "Differential Rear Fill", or (L-R) + (R-L). Some car audio DSPs have this capability in their input-to-output routing matrix, and a few car audio SQ competitors use this type of "differential rear fill" to widen, deepen, and raise the perceived soundstage. If done correctly, it presents a larger overall soundstage and it seems as if you are listening to the music in a larger "room" than the small and confined cabin of a vehicle. However, it is very recording-dependent, and the results will vary and sometimes cause center images to be placed behind you depending on what techniques were used during the studio mixing process.
The ground in an rca wire is still a wire so if the amplifier is doing all the differential comparing the noise will still be in both wires and it will still get rid of it really the only noticeable effect this will have is the audio will be reduced for the same input voltage
Thank you for your explanation of the difference between the two. I have a question however. If you have a source, that has both L and R outputs (lets say a subwoofer output on a receiver). Is it possible to take L and R and convert that into a single XLR using the 2 signals? Would that work to connect to a Professional powered subwoofer and feed it a clean signal? Or would I have to ensure that the source has L and R each 180 out of phase of each other?
Those who find this interesting should check out the line inputs and line outputs section in Small Signal Audio Design by Douglas Self, where he talks about a few different topologies for these circuits.
While balanced is technically better, I don't think it will make much difference in home audio, when your interconnect is only about 1m long. Balanced audio lines are essential when you cable is more than about 10m and in electrically noisy environments, such as for microphones on a stage. Balanced audio lines let you run audio over hundreds of metres.
Thank for such a great simple explanation. I need to run line-level 40ft out of my AVR into an amplifier. Both are not balanced should I just use a well shielded coaxial and not convert to balanced?
Paul explains what an active converter does to RCA signals to convert it to XLR by drawing the circuitry on the whiteboard in the final minutes of the video. My question is this: : on PS Audio's fully balanced equipment, how is the negative (inverting signal) generated if not by some sort of circuitry like the active converter?
That's not what a DI box is used for. It not a matter of impedance. Single ended and balanced signals are not electrically compatible. In your example of a guitar amp, the DI box would be used to convert the single ended signal from the guitar to balanced so it can then be plugged into a balanced mixer. Depending on your needs, you can get DI boxes in active or passive configurations, but the main function is not to boost the signal. Its a compatibility issue.
@@solarfall2728 Read this: en.wikipedia.org/wiki/DI_unit . A guitar pickup has an impedance measured in kilo-ohms and will not properly feed the 200 ohm microphone input of a mixing desk. You lose a lot of high frequencies through a long unbalanced cable. An unbalanced cable can be plugged into a balanced input by connecting the cable ground/shield to both the cold and ground pins of the input (pins 1 and 3 of an XLR socket) but you do lose the advantages of balanced signals. Trust me, I've been doing this for over 20 years. Did you know that you can even use a passive DI box in reverse to connect a balanced signal to an unbalanced input? These are of course a matter of last resort when you are doing sound for a gig and your client turns up with all sorts of weird gear.
@@MrFlint51 I really don't know why 20 years experience has anything to do with facts, but if it makes you feel better, I have over double that. You're just reading simple definitions off of Wikipedia, put there by anyone who wants to post. Your guitar example isn't even relevant. No one would ever plug a guitar directly into a mixing board. It first goes into some type of preamp. Any impedance issues will be dealt with in that component, and will leave as a line level signal. Most of the time that line level signal will not be balanced. That's where the DI box comes in. And yes, all other things being equal, when you convert the signal, impedance will change. Its not something you have to mention. And if all you need to fix is an impedance mismatch, you don't need to use a DI box. So I'll say it again. The main reason you use a DI box is to convert a single ended signal to balanced, and as you correctly pointed out, to convert a balanced signal to single ended. This is done because the 2 circuit topologies are not electrically compatible. Any features the DI box offers in addition to its core function, are just features.
