Balanced vs. Unbalanced audio

[Music] balanced versus unbalanced cables great subject let's get to it Tom in Durham North Carolina tell me what the difference between a balanced and an unbalanced cable is and what are the advantages of each near and dear to my heart first off let me be clear I like balanced and I recommend anybody using our products to go balanced with with few exceptions I think the only exception is our little sprout integrated amplifier which does not have balance but other than than sprout every product we make has a balanced in and out and it's true bounce which I will explain in a minute so let's let's look and see what are the differences the standard consumer interface is RCA unbalanced and and and you've seen that I gosh darn it I should have something here to show you some kind of connector well here let's I can show you this all right hang on we're getting closer there all right so this guy is as a balanced connector and you've seen it's got the three prongs over here and we should have some RCA ones here somewhere well anyway it looks more like this this is a three-and-a-half millimeter plug sorry I should have been prepared but you know which ones I mean it has the the RCA connector has the the single hot lead and the the outer shell so RCA not even sure how that got that name but anyway that the single-ended is basically a ground and a hot and a balanced is two hots and a ground plus a shield okay so you actually have four connections in a balanced cable and you only have two in an RCA connector so what let me explain the difference between that so in an RCA we have what we call the hot lead which is your your Center and then around it you have the little dingus that plugs in and that's that is ground and the shield so around the outside of your RCA cable is usually a mesh of metal that is intended to stop interference from external sources of hum and and noise which we would normally call EMI or electromagnetic interference and it carries both the signal and ground and tries to get rid of any kind of noise and that plugs into your system and if it if it is typical that outer shell will be just shunted off and connected to ground and then the only thing left is the hot lead which is where the signal is rising now this is what most of us wind up using it's not the best and the reason is because it despite the outer shield it isn't great for eliminating noise also anything that is passed from the receiving unit or the sending unit to the receiving unit goes through the cable and if anything is picked up along the way like noise or there's any distortion problems that are common along that cable you're you're not going to have any benefit of another thing that I will tell you about which is common mode rejection and common mode rejection is concerned on balance cable so these balance cables I say if you I don't know if you can see there's in here there's three and there is a hot lead to hot leads one who's non-inverting that means as the signal is going up and down like this it's following exactly the way it was sent and an inverting which is now the opposite of that so that between the two as one is going up the others going down and we have like that and then the third prong is actually ground a signal ground and then out here we have that same shield that mesh shield that we had on our RCA cable but that is grounded separately through the shell and sometimes tied to the ground depends on how its wired so this is a very low noise cable and it's well shielded and you have the two hot leads and the ground within it that are protected by the shield now let's get to common mode rejection before this gets too long and I objects we're not being more prepared common mode rejection means that the circuit which is typically either a transformer and audio transformer or a differential input amplifier which is what we use it will amplify only the differences between the two hot leads remember I said there was a hot - hot leads and inverting in a non-inverting the non-inverting being the actual signal in its proper polarity and the inverting is the same signal but out of phase so the difference between those two is what's amplified in the difference as this one's going up this one's going down right so now we have a difference and it amplifies that but here's where it gets really cool if those two wires you're too high signal wires the inverting and non-inverting pickup the same signal at the same time like let's say there was a transformer closed and it had hum that was coming in and both of them picked it up which they're likely to do because they're all bundled within this one cable right they're all sitting here close together I put that close to a source like nipper you know putting out hum they're both gonna get the hum my differential circuit on the other side is going to eliminate that hum because it pays no attention to anything that is common between the the two hots and if it's common like if there were common distortion coming from the transmitting unit or if there was a common noise picked up like nippers bad breath it's going to ignore that and it will only amplify those differences and so that's a much cleaner signal much better sounding and that's why I always recommend balanced as opposed to unbalanced and the last part I'll tell you about is well is about true balance so a number of companies especially in low-cost products they will actually just use an inverting op-amp that the output of their signal at the output of their device to create that that inverted signal okay it's not actually a balanced circuit it's putting out a balanced signal but it's not a balanced circuit and then when it takes it in you have this this differential pair which does help with common mode rejection but then it's converted back to a single ended signal and that works it absolutely works it's not the best way to go the best way to go is to have a fully balanced circuit feeding and a fully balanced circuit receiving and that's called true balanced which is what we do thank you for the question bye [Music] [Laughter] [Music] you

Channel: Paul McGowan, PS Audio

Views: 146,731

Keywords: Ask Paul 6, Ask Paul 1

Id: PzEmKPTb18g

Length: 8min 41sec (521 seconds)

Published: Mon Dec 18 2017