What is common ground?

We often hear the term "common ground" when it comes to power amplifiers. But, what does Common Ground actually mean?

[@rakeshmahindrakar8866]

Paul keep posting videos. During corona outbreak your videos help us relax. And take care, God bless you.!!

[@NoEgg4u]

Common ground is what some people have been forever searching for in Washington DC.

[@carlosbauza1139]

It's the race...the human race.

[@GameTL]

I think this is a pretty great video, explaining how unbalanced(Single ended) and balanced works. Thanks! Nice release time. 1PM Thailand

[@gboates]

Got one of your amps and was loving it! Bought some new connect cables and they were a great improvement over my 25 year old connects. New speaker cables made it more veiled so reverted back to my OFC 12guage with your banana jacks sounded amazing. Was trying to phase align powered Pardigmn sub woofer and when I removed the cable from the amp and BANG the whole sound lit up with a wonderful brilliance yet unheard. Replaced the single rca sub cable and the whole system sounds much much better... who knew? The house ground is a real ground with a 4 ' copper rod driven into the earth. No floating grounds for me.

[@JingoLoBa57]

Something you hardly ever find in this hobby

[@thegrimyeaper]

lol

[@cuttinchops]

!

[@MrLuka10]

Paul, thanks to you I learned something today. It's always very interesting to watch your videos and learn from you. Thanks for sharing your valuable knowledge. Central Florida.

[@honeyken316]

Hello Paul, In commercial sound amplifiers there is the "Bridged Mode" where two amplifiers are out of phase and there is no "Ground". This has caused a few burned out amplifiers when someone connects the "Second Red terminal" to a common ground like the metal on a junction box. In that case, the output of one amplifier is essentially shorted. It also sounds pretty bad! There is the concept of having just one point be the ground to which all of the equipment is connected. That terminal may look like a star with all of the ground wires coming to that point. This deals with the "ground loop" problem in high gain equipment. Stay safe and healthy! Thanks for the videos. KEN

[@johnnytoobad7785]

Common ground is found in most high-end class A and AB amps, but not so much in class D amps. You can test with a cheap ohm-meter. Connect one lead to the middle (round) prong on the AC outlet or pre-amp ground, and the other to the black speaker leads on the amp. Should read 0 (or very low) ohms.

[@JoeJ-8282]

Most all "mid-fi" audio components, including almost all home audio A/V *receivers* DO have a common ground... Many truly *HIGH-end power amplifiers* , on the other hand, instead may have that type of balanced or "floating" output that Paul mentions here, but as far as most normal A/V receivers go, they are mostly all common ground... One way to tell for sure if an amp or receiver definitely IS a common ground speaker output, is to measure the resistance, (ohms), between the left and right channel *black* (-) speaker terminals on the output of said amp/receiver, with a good digital multimeter, and if the ohms measurement between the Left and Right channels' black (-) speaker output terminals is pretty close to 0 ohms, then your receiver DOES have a common ground... (MOST RECEIVERS DO)... Maybe this info will help *someone* out there who wonders about this topic.

[@terrywho22]

Great point.

[@cat-lw6kq]

Thx

[@backrack01]

I needed this. Thank you

[@mattgiunt]

I ran my polk SDA CRS+ speakers for thirty years using different receivers from Yamaha, Panasonic and Pioneer and never had a problem.

[@nicholascole4054]

Paul, back in the Seventies I built a Lindsey-Hood 75W amplifier from a kit and I had some problems with ‘motorboating’, a earth loop hum which I eventually solved by trial and error in connecting various components to a common ground. I had the same issue recently which I solved by trial and error by hooking up a common ground. I noticed you did a video recently on this subject. A suggestion: - maybe its time for a refresher video on earth loop hum and ‘motorboating’? Thanks, Nick Cole

[@paulcs2607]

I love your use of Post it’s :-)

[@benbryson6598]

did the later pin/blade connector polks resolve this from the earlier blade/blade SDAs?

[@brucevaughan1024]

Working in the professional constructing of recording studios there is great importance in setting a good central grounding rod

[@hansiangng2808]

I have a amp with A/B speaker outputs. One day when I tried to connect the speaker cables with spade ends in metal (carbon fiber) housing to output "B", as the binding posts are close to one another, it accidentally rests onto output "A". Therefore i could hear music when output A is selected. The question is what will happen if i toggle output to "A+B"?

[@genez429]

Keep posting, Paul! Whenever your new videos come out, the sale of toilet paper drops! (great video- explains why the manufacturer of my amp said not to use a REL sub)

[@juliaset751]

I would try two REL subs. Stereo subs are a huge improvement IMHO, and no common ground. I actually replaced one large sub with two smaller, less expensive REL’s, and the sound improvement was huge.

[@stephensmith3111]

A while back, I was checking out the Klipsch Heresy IV speaker on the company website and came across an internal link labeled history. Among the files available was the 'Heresy spec sheet - 1957'. This single sheet included a simplified schematic diagram for the Klipsch-Eargle circuit tor 2 track 3 speaker stereo with a single stereo or two monoblock amplifiers. The right (A) and left (B) Klipschorn or Shorthorn corner speakers are connected as normal to the 16 ohm and ground taps of the output transformers (1957, remember?) of the power amp(s), as normal. The (+) and (-) terminals for the Model H or HU center channel (A-B)/2 speaker are respectively connected to the left and right 4 ohm taps of each output transformer. There is also a connector between the ground taps of each of the two output transformers. I presume this is the common ground. Somewhat archaic, but still interesting to an Old Dude of the Old School such as myself. =//=OldDudesStillRock Note: this description is for information purposes only. I refer you to the klipsch.com website for specific details of the circuit diagram. I assume no responsibility for any damage to amplifiers and most strongly recommend consulting the manufacturer and/or trusted brick-and-mortar audio dealer first before trying this; if 3 speaker stereo is of any interest anymore. The original Heresy was designed primarily for use as a small-ish, low distortion, center fill speaker with the large corner horns doing the heavy lifting in the deep bass; although they could also be used as a less expensive regular stereo pair with the understanding that they were not designed to plumb the depths. As I said, Old School.

[@stephensmith3111]

errata: 'right and left 4 ohm taps' (might make a difference, or not; consistency may be the virtue of tiny minds, but it doesn't hurt where tech is involved). Also, I used "as normal" twice in the same sentence (the Dept. of Redundecy Dept. approves).

[@hugobloemers4425]

Which makes me think, if you have a balanced output amp (probably class D or a transformer output with a floating secondary winding) would it then not be better NOT to have a black connector but something else (Blue and green are even not good) so for instance purple?

[@williamlau7179]

My understanding is that the black is the return loop and as a grounding point for red signals return loop. Opening up amps showed that these black points are bridged together in the amps and components. Now, Paul said the blacks served as the out of phase signals. And out of phase between speakers for cancellation to enhance stereo effect!! What?? I am confused. I guess out of phase design is for high ends balanced components? Btw, to enjoy music, just sit back and relax after connecting the wires in a "normal" way. What else should I do with the casual components? :)

[@kalijasin]

Ground loops can happen when multiple devices are connected to a common ground via different paths.

[@dell177]

If you want to use the high level input on a subwoofer and you have an amp like the stellar that has output on both the red and black you CAN NOT wire the black outputs of those amps to the black binding posts of the subwoofer inputs. You have to run a wire from the chassis of the amp to the black sub input and then run wires from the red amp binding post to each sub red input binding post. Manufacturers of these class D amps should have ground tie point just for this. With my m700 amps I just loosened a chassis screw and ran a wire from there to the black binding post on the subwoofer

[@abelfonseca]

Great video! Stay safe Paul, you are a national hifi treasure.

[@m.9243]

Interesting! My Bryston monoblocks have a switch at the back which says: "Ground lift" I guess it gives the user an option, however, with music playing I can't hear any difference in the sound at all. And without music again, there's no increased noise or hiss audible switching from one to the other.

[@eliasbuebue]

Fat Rat... not quite. That makes sense that you donˋt hear a difference. The ground lift is mostly used if you have have a ground-loop somewhere in your system. Thet it can make sense to disconnect the grounds to get rid of the humming. But if you from the beginning havenˋt any ground loops, it doesnˋt make a difference in which position the switch is.

[@DrJLins]

Great video, Paul. Thanks!

[@denistyutin]

I thought that BHK is H-bridge too, isn't it? I remember Paul or Bascom mentioned it in one of the episodes...

[@carlosbauza1139]

AND...there are very interesting audible enhancements with "Dynaquad" speaker matrix, which works with a common ground. But thats another story altogether.

[@sundaru1]

Polk SDA only requires for common grounded amp if we will drive the speakers with mono block amp, the problem is how do we know that our amp is common grounded, any explanation will much appreciate , Pauls video only explain us the definition of common ground

[@chrisharper2658]

Two simple diagrams to show half bridge and full bridge outputs would sum it up.

[@maidak]

Perfectly explained Paul

[@sundaru1]

I had the same question long time ago since i use the polk sda signature series, still confuse with Pauls explanation, how do we know that the black channel in our amp is common grounded or not ..?

[@TheTrueVoiceOfReason]

Simplest way is to use a multimeter in Continuity mode. If you have Continuity between the left and right channel "ground" or "negative", then it is a "common" ground. You can use any multimeter. Even the cheapest ones from places like Harbor Freight or Ali Express have that feature, all for about the price of a coffee.

[@sailingaquarius23]

@@TheTrueVoiceOfReason Exactly. Doesn"t these common ground amps have more crosstalk?

[@TheTrueVoiceOfReason]

@@sailingaquarius23 That depends on the grounding scheme, the power supply rejection, and ultimately the quality of the power, most notably to the final stage. That's why the best (highest quality) amps have the most highly engineered power supplies.

[@sailingaquarius23]

@@TheTrueVoiceOfReasonThanks, what I've always wanted to do is eliminate the power supply and have 6 batterys that have stabllized at a full charge of 12.8. The rails are +36 -36. I would have 38.4 plus and minus. And dropping, That extra 3 volts shouldn't be a problem should it? I'm not an engineer or even much electronic background. So its just been a thought i've had for a long time. Its a 50wpc STK-0049 chip in a several Sanyo PA6100 car amps that i've had a long time. Decades and Decades. Got any thought's? Thanks again.

[@TheTrueVoiceOfReason]

@@sailingaquarius23 according to the datasheet, the max supply voltage is +-50 volts. The rated output is measured at +-35 volts. You should be safe. As for batteries, they "should" be the ultimate power supply, but even they have drawbacks. There's just way too much to go into, but if you have a big enough set of deep cycle batteries and a way to properly charge them between use, go for it. Isn't that what this hobby / lifestyle is all about?

[@beardedgaming3741]

i just bought an amp (not PS), cost about 500.00 for 500 watts a/b. the power wire is only a two prong (no ground).... why would this be?

[@terrywho22]

Very helpful. Now can you or someone explain higher ground? I think Stevie and Anthony are referring to the same thing, but UB40 may or may not be singing about a different thing.

[@Geerladenlad]

What about Highest Ground? I think Neal Schon and Jeff Scott Soto do a great job on that one.

[@sailingaquarius23]

Wow a flashback to 11 years old for me! First I thought you were talking Steve Winwood's Higher Love, then its actually Stevie Wonder's Higher Ground. There is so much good music to go back and relive.

[@terrywho22]

@@Geerladenlad Soul Sirkus?

[@terrywho22]

@@sailingaquarius23 YEAH MAN! Stevie Wonder, Red Hot Chili Peppers... I also love Higher ground by UB40 with Leroy Sibbles as the lead singer. That whole fathers of reggae album is an all time great (if you are into reggae...)

[@janinapalmer8368]

The BSK 250 ... correct me if I'm wrong ... uses BTL output topography.. so be very careful using the negative terminal ...

[@sailingaquarius23]

I thought thats what they called floating ground in car stereo.

[@scottyo64]

I think he knows it has a floating ground..........BHK

[@sailingaquarius23]

I'm thinking Billy Joel's "She's always a woman" Its nust a typo,....of course Paul has 132 speakers in his IRSV's.

[@janinapalmer8368]

STEREO JUNKY wtf ..?

[@janinapalmer8368]

STEREO JUNKY no no !!

[@ragu168]

I like watching but sometimes I am lost sorry Paul I didn't make it pass 3rd grade my teacher gave me something that is still causing flash backs 😁lol j/k did go all the way to 12 another good video.

[@UpgradingAsUsual]

Paul, keep your videos coming. They help a lot during these troubled times. Today, however, I learned nothing.

[@PebblesChan]

Ground is a place where carrots and potatoes thrive!

[@PebblesChan]

That's why they make people cry. Wombats eats roots and leaves.

[@skunk12]

Easy! "Common Ground" is what we DONT have in Washington DC. 🤣😂😆

[@skunk12]

@Тайбирияс Чайковский tell me how you REALLY feel. lol

[@HungryEatNow]

What about chassis ground?

[@eelcosterringa1374]

In many cases it can be used but it really depens. REL gives it as An alternate solution but they use high impedance cirquitry. For power impedance you can get return current which the design of the amp may or may not cope with correctly. Also possibly hum.

[@backrack01]

Is "system ground " the same as saying " common ground"?

[@jamesplotkin4674]

Well, that's a pretty crappy looking mains lead ya got there. It probably couldn't power my table lamp.

[@musicman195959]

It looks pretty solid to me. As long as it gets the job done is all that matters.

[@jamesplotkin4674]

@@musicman195959 Just sayin' it looks small for the HUGE unit it's connected to. My toaster/oven has a bigger one. So does my friend, but we don't quarrel over it.

[@musicman195959]

@@jamesplotkin4674 Well good for you and your friend.

[@keeferdog5617]

Who’s still confused? God, how I hate electrical crap-

[@JessHull]

IDK Paul that power cord doesn't seem very BHK worthy :-P

[@eelcosterringa1374]

Heb already explained on that. In short it is safety basic function only costing close to nothing so customers can add their power cable of preferece and whenever they want. Adding a serious cable would increase the price and many customers would still prefer a different power cable in their system

[@curtchase3730]

common ground, or chassis ground IS the norm w/most home amplifiers of conventional push-pull design. An area where common ground is NOT the norm, is cheaper car stereos. They commonly use what I call "floating" ground. The instructions will say

[@sailingaquarius23]

Yes but go further back and all car stereos were common ground.

[@ETA555]

Car audio is a different story. But ground means the same thing. A neutral potential. Why is this so hard to understand? Is it me? Because I am from Sweden? Thor and Odin has told me what potetial is. Tor och Oden in Swedish.

[@str1xt]

The wife watches tv and I listen to music. That’s common ground

[@TheTrueVoiceOfReason]

You call it balanced, most others call it bridged. Here's a thread that helps explain it. toidsdiyaudio.com/community/diy-preamps/simple-amplifier-bridging/#post-959

[@voiceofreason9238]

Balanced and bridged are two different concepts in amps.

[@TheTrueVoiceOfReason]

Yes, they are different. The description given in the video was of bridged outputs rather than balanced. Very big difference in the final stage.

[@ashtongrist]

Does that include the plo. What about people right here who fought for you so long ago. And jessie your inside my thoughts as the ruthmic words subside my common ground invites you in or do prefer to wait outside oh is it true my common ground includes you too

[@BojanPetrovicvft]

So if you put black wire in black and you DON'T BLOW YOUR(500 $ or more) AMP than you're good.

[@MrJules39]

I was the 551st person to leave a like! Wooooh! Yeah Buddy!!!!!!

[@jeffmlane]

Excellent video Paul. As always, I learn something new or I am refreshed on what I have forgotten. If you do not mind me going a bit COVID-19 on you, licking one's fingers to flip a page is an unhygienic habit that we need to drop. When in the doctor's office or Emergency waiting areas, I cringe when I see folk doing this as they read magazines previously rifled through by someone who may have an contagious condition. It happens at 0:47. Please Paul, take care of yourself. 99% of folk come here not only for information but for a dose of Paul, even more so in this, the Great Reset. Stay safe. Sorry for the lecture.

[@googoo-gjoob]

Polk.... not Poke

[@giangvu7902]

You NEED to know this information before hooking up a REL subwoofer using high level input.

[@Geerladenlad]

Why?

[@giangvu7902]

@@Geerladenlad REL subwoofers usually use speaker terminal input, which feeds into their high level speakon connector. If you have a balanced amplifier, then the black wire CANNOT be connected to the black speaker terminal. You will have to ground the black wire somewhere else on the case of the amp. But if you have a non-balanced amplifier, then the black wire can be connected to any of the black speaker terminal since it doesn't carry any signal. Hope that helps!

[@DaveSHarris]

Yep. I have a rel connected to an s300. There is no common ground so the rel hums when the amp is off

[@cat-lw6kq]

Place show a diagram next time some of us are familiar with service manuals.

[@ericelliott227]

It is something not found in the US....oh, amplifiers...my bad. LOL!

[@davidcroteau510]

You must be board

[@Aswaguespack]

Common Ground is rare. Just look at Washington DC. They show us daily that a Common Ground no longer exists in this country these days.

[@stephensmith3111]

They should resign in disgrace; forswear all pensions and benefits (especially heathcare); and spend the rest of their mortal existence cleaning out manure spreaders. But hey, I'm a live and let live kind of guy.

[@Aswaguespack]

Stephen Smith they certainly enjoy luxurious perks they have awarded themselves and that would absolutely horrify our Founding Fathers who never intended that as a function of Service to the Nation. What hypocrisy they tout as they proudly claim a list of accomplishments developed at the expense of their constituents who continue to struggle daily while they relish in their Elite Country Club Benefits courtesy of the voters.

[@stephensmith3111]

@@Aswaguespack Not to mention their well documented expertise in spreading manure.

[@Aswaguespack]

Stephen Smith fertilizer should be our #1 product and more than enough to replant our forests

[@stephensmith3111]

@Fat Rat An old class mate of mine said, "The are two types of politicians: the honest ones and the ones that get elected."

[@nsfeliz7825]

unless your gonna fool around inside your amp such terms are irrelevant.

[@NeilDSouza7]

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