AC Polarity and the reduction of noise and hum

[Steve williams]

oh and lest I forget, since Amir has chosen now to take on Lamm I must comment about when I was at ddk's house last year. David uses the same Lamm components as I do and has a speaker that is IIRC 115db efficient. In his room his interconnects are all SE and are all made personally by David from roll cable with lengths I am betting are at least 40 feet. Guess what. Not any extraneous noise. As quiet as any system I have ever heard. All SE cable

 

[bonzo75]

oh and lest I forget, since Amir has chosen now to take on Lamm I must comment about when I was at ddk's house last year. David uses the same Lamm components as I do and has a speaker that is IIRC 115db efficient. In his room his interconnects are all SE and are all made personally by David from roll cable with lengths I am betting are at least 40 feet. Guess what. Not any extraneous noise. As quiet as any system I have ever heard. All SE cable

+1

 

[amirm]

David uses the same Lamm components as I do and has a speaker that is IIRC 115db efficient.

Speaker efficiency numbers are just that: marketing numbers. They are done at frequencies that show the highest efficiency. Sometimes they are averages, other times single frequency. And at any rate they never use 50/60 Hz. There are also other cheats such as 4 ohm versus 8 ohm.

We once had these speakers that were rated at over 100 db efficiency. One day I noticed buzzing sound from them from 5 to 6 feet away. Took the same amps and hooked them up to a speaker with 89 db efficiency. You know what? The noise level did not change one bit!

This aside, sure, I believe there are many quiet systems out there with single ended connection. This we already said. It simply is the case that you did not hit the combination of cabling, power, location and equipment that causes them to hum. The circuit theory guarantees that this will happen in practice as is evidenced by reports of hum which can be very difficult to get rid of if you don't have the option of switching to balanced connection.

You want to foreclose your option to not have balanced, go right ahead Steve. Just don't advocate that as a good thing. It is not. As a customer I like to have choices. Reminds of when we moved to San Diego. The house we were buying did not come with AC. The real estate agent said the standard line of "San Diego has the most perfect weather in the world; you don't need the AC." Fast forward a couple of months later and we are moving into the house, there is Santa Ana winds and the thermometer hits 110 degrees. Could not get a wink of sleep that night in the second story bedroom!

So please don't tell me what I don't need. I like to decide that for myself. And other audiophiles should have the same choice. By constantly talking down balanced connection we reduce the availability of them in the product we use. Pro guys insist on it so it is standard equipment there. It should be the same in any high-end product.

 

[Steve williams]

we aren't debating balanced but rather your silly comment that XLR is the only way to go. Interesting when you see the nonsense of your argument that you are softening your stance and say you want choices. This was never part of the argument but rather you saying that balanced is the only way to go. To which I say BS

As to not finding the wires that cause the hum I would say "good on me'" and clearly helps to validate my comments. I am not debating the extra 3 db boost in signal but rather your comment that XLR is the only way to go. I say to you that's BS.

Some of the best systems I have ever heard use only SE wire so I guess their manufacturers were flawed in their thinking as well. So why don't you take the bull by the horns and enlighten us all about your system and better yet invite people over for a listen. I can't wait to hear their comments. Oh and IIRC as well Mike Lavigne uses a SE IC as well because he thinks it sounds better. And finally while we are at it contrary to the review you posted about Mike's system where you trashed it, I, as well as most everyone here, I bet would take his system over yours (whatever that may be) any day of the week.

 

[bonzo75]

we aren't debating balanced but rather your silly comment that XLR is the only way to go. Interesting when you see the nonsense of your argument that you are softening your stance and say you want choices. This was never part of the argument but rather you saying that balanced is the only way to go. To which I say BS

As to not finding the wires that cause the hum I would say "good on me'" and clearly helps to validate my comments. I am not debating the extra 3 db boost in signal but rather your comment that XLR is the only way to go. I say to you that's BS.

Some of the best systems I have ever heard use only SE wire so I guess their manufacturers were flawed in their thinking as well. So why don't you take the bull by the horns and enlighten us all about your system and better yet invite people over for a listen. I can't wait to hear their comments. Oh and IIRC as well Mike Lavigne uses a SE IC as well because he thinks it sounds better. And finally while we are at it contrary to the review you posted about Mike's system where you trashed it, I, as well as most everyone here, I bet would take his system over yours (whatever that may be) any day of the week.

It sounded like a review just to give a context to future and past web exchanges, otherwise admitting an uber big spend audiophile who does not measure indeed has a system that is good would not make him look cool. While I totally understand we have subjective tastes and not everyone needs to think that Mike's system is up there, to write the way he did made it a very defensive review.

 

[DonH50]

I really like Vladimir and now have even more respect for him for using his sales acumen to get you past your objection. Thankfully we are all so deaf in low frequencies that even when hum is electrically there, we don't hear it until it gets to elevated levels.

Here is the deal though and there is no getting around it. Ground loops can occur when you change cables, equipment, distance between gear, etc. If you develop such a problem three years from now, you really think a dealer will give you your money back and have the salesman cough up the commision he made to go to Hawaii? I don't think so.

Advocate excellence and I will be with you Steve. Advocate good enough for you and you will have to go it alone.

You're getting even funnier. Keep it coming

FWiW I choose never to go with you. Why don't you spew your so called acumen over in your little spot of the Internet. I'll take my system over yours any day. Oh but lest we forget no one knows what your system is let alone ever heard it. Keep on trucking. You've convinced a little over 200 people in your middle earth. I suggest you hang out there where the chosen few seek your so called knowledge. You add nothing here.

Seems harsh. WBF has by and large, just in my opinion, become more of a subjectivists' place to be, while Amir started ASR as an objectivists' site. Denigrating each other just seems, I dunno', lame though I understand given the history. But in my opinion (and perhaps that of no other person) the personal animosity between you two is really distracting and painful to watch. Especially when it devolves into purely personal insults and spills over to all others, on either site, by association.

So for now, before I say something I will really regret, I'll toddle off to my trumpet site for a bit...

 

[Steve williams]

It is painful Don but when they are aimed at me on my website I will reply. People hang out here for obvious reasons and those reasons are not the same as those who hang out at ASR.

 

[microstrip]

Seems harsh. WBF has by and large, just in my opinion, become more of a subjectivists' place to be, while Amir started ASR as an objectivists' site. (...)

It would be great if they stay so, with just an occasional mix of both in frontier subjects.

IMHO we have a lot of disagreement at WBF about the subjective matters, mostly friendly with occasional more passionate swordplay, and we know we will never agree. Panels, boxes, horns, SETs, SS, tubes, push-pull, silver, copper, gold, rhodium, treated rooms, untreated rooms, close listening, far listening, price, analog, digital, THD or not THD - we debate everything with passion. But most people can not be happy when someone comes here telling us that most of us are just a band of ignorant consumers and the guys supplying our equipment are ignorant and dishonest manufacturers, tries to prove it with his "objective science" and even insists on telling us how the high-end should run.

And yes, I insist, the single ended versus balanced discussion, without the hum arguments, would be a great subjective thread in WBF ! I hope we can have it someday.

My 2 cents of an euro on the subject.

 

[DaveC]

This aside, sure, I believe there are many quiet systems out there with single ended connection. This we already said. It simply is the case that you did not hit the combination of cabling, power, location and equipment that causes them to hum. The circuit theory guarantees that this will happen in practice as is evidenced by reports of hum which can be very difficult to get rid of if you don't have the option of switching to balanced connection.

Amir, you are good at taking a fact and twisting it to fit your views. But, your views don't seem to be complete or tempered by actual experience in the real world.

At this point I've had A LOT of experience helping people with system setup and addressing noise and hum problems. What I bolded is a great example... The actual number of people who have issues with noise and/or hum in their single ended systems is miniscule and when people do have issues they are generally not difficult to solve, as in just about everyone manages to address the issues they come across. You make it seem like it's a forgone conclusion that people will eventually have issues and this just isn't true. I'd also say that plenty of people have problems with balanced systems too, they aren't as immune to issues as you think.

Part of the reason SE is better is the simple fact SE amplification sounds better, more natural and more believable, they image and soundstage better and simply recreate music with a competency other amps just don't have.

It is true most DACs are moving to balanced but it's not an amp, it's a source component and there are good reasons for doing it that way, using trafos to convert to SE or grounding pin3 through a resistor of equal value to the input impedance of the component work just fine and then you can proceed with superior SE amplification.

 

[DonH50]

My experience differs in that the number is small but I would not say "miniscule", we just have different experiences. Subwoofer hum and hum due to cable boxes (which generally ground through the cable input) seem fairly common if you follow HT forums. Music-only systems are often simpler with fewer "extra" connections, and even there folk have issues now and then.

Part of the reason SE is better is the simple fact SE amplification sounds better, more natural and more believable, they image and soundstage better and simply recreate music with a competency other amps just don't have.

That is a very broad statement. Except for tube amps, the majority of systems I have seen are SE, but that may be for other reasons than subjective impressions (see previous list) -- or not. In any event there is no technical reason either should be superior or inferior assuming no issues with EMI, ground loops, or other things that might corrupt the SE signal, and assuming the gain structure or excess noise does not impact the differential circuit.

Most DACs are differential for technical reasons, it is easier to implement the circuitry and performance is better, but most outputs are single-ended because the output buffers are generally single-ended. That is true in the RF world, too, FWIW.

In any event, my apologies for side-tracking this thread, and I'll try to keep out of it. - Don

 

[DaveC]

My experience differs in that the number is small but I would not say "miniscule", we just have different experiences. Subwoofer hum and hum due to cable boxes (which generally ground through the cable input) seem fairly common if you follow HT forums. Music-only systems are often simpler with fewer "extra" connections, and even there folk have issues now and then.



That is a very broad statement. Except for tube amps, the majority of systems I have seen are SE, but that may be for other reasons than subjective impressions (see previous list) -- or not. In any event there is no technical reason either should be superior or inferior assuming no issues with EMI, ground loops, or other things that might corrupt the SE signal, and assuming the gain structure or excess noise does not impact the differential circuit.

Most DACs are differential for technical reasons, it is easier to implement the circuitry and performance is better, but most outputs are single-ended because the output buffers are generally single-ended. That is true in the RF world, too, FWIW.

In any event, my apologies for side-tracking this thread, and I'll try to keep out of it. - Don

Your posts are always welcome, Don!

I do agree subs and cable boxes are often problematic but the solutions are well known... subs are often plugged into a different circuit and cable has a different ground. If you except subs and cable boxes the number of issues shrinks considerably. If the entire system is plugged into one power distribution device, or if multiple devices fed by multiple lines are bonded together the problems mostly go away.

As for SE amps, there are some technical reasons such as zero-crossing distortion, fast slew rates, better distortion spectra wrt psychoacoustics, simpler circuit design with no feedback necessary... all these things add up to a better amplifier imo.

It seems many high end DACs have balanced outputs that sound better than their SE outputs, not always, but sometimes.... obviously a result of inferior SE output circuitry, but it's semi-common. And I agree it's done for technical reasons and should not be a reason to insist the amplification components must also be balanced.

 

[DonH50]

Thanks.

Yes on power, and there are signal and cable isolation devices that are fairly inexpensive as well, though they won't solve every problem. But, most folk do not have problems.

SE amps have no crossing distortion only if they are class A and not a push-pull output, which I suspect is a pretty small number... Not everyone's speakers are suitable for a SET amplifier, and I would guess the vast majority of amplifiers today use push-pull (complementary) outputs. As for the rest, again our experience differs. Differential drive generally provides higher slew rates, I do not see how SE obviates the need for feedback (that is a design decision, and even "zero feedback" designs typically have some local feedback to stabilize the gain and frequency response), theoretically a differential design has clear advantages over a SE design, etc. The audible benefits clearly aren't enough to justify the higher cost of a fully-differential design, natch, and I suspect that is a larger reason than audibility or noise rejection.

I have no input on the psychoacoustics, but distortion is awfully low in any decent design these days.

I was speaking in general and I think you must be referring to specific amplifier topologies, that may be where we crossed wires.

Note I was referring to the actual DAC itself, the chip inside the device, not a component that includes the chip that we as audiophiles call a DAC. I certainly have not seen them all, but almost all the ones I have seen use a differential DAC circuit and follow it with a conversion stage to get to single ended outputs.

Have a good day, I have to eat and go to rehearsal, where I have to play in tune despite my obvious ears of clay. - Don

 

[microstrip]

(...) It seems many high end DACs have balanced outputs that sound better than their SE outputs, not always, but sometimes.... obviously a result of inferior SE output circuitry, but it's semi-common. And I agree it's done for technical reasons and should not be a reason to insist the amplification components must also be balanced.

Althouh, as Don referred, the currents coming from the two differential DACs inside the chip are summed inside it, most (not all) of the best DACs are balanced. As the DAC chips are inexpensive they generate the inverted phase signal digitally and use one more chip to generate the opposite phase signal (-Vout). As the manipulation of phase is done digitally they can even use one complete dual DAC per channel - something that results in an even better quality signal.

Some balanced DACs generate the SE signal differentially from the two phases +Vout and -Vout - a good thing - but others just use the +Vout as single ended output. In this later case you are paying for something you are not using ...

Please see the attached diagram of the PCM1792, an old well known DAC chip of high performance, still used nowadays in top electronics, such as the famous Devialet. In this case one chip creates two SE signals. With one more chip you can have two truly balanced channels.

 

[amirm]

Amir, you are good at taking a fact and twisting it to fit your views. But, your views don't seem to be complete or tempered by actual experience in the real world.
[...]
Part of the reason SE is better is the simple fact SE amplification sounds better, more natural and more believable, they image and soundstage better and simply recreate music with a competency other amps just don't have.

Hi Dave. You say that with complete conviction and I get that is your conclusion but it just isn't a universal truth. As I mentioned and you know, almost all of our music is produced through balanced connections. Do we really think the talent heard less fidelity music than we somehow hear when we play that through unbalanced connections?

But maybe you are making a point only with regards to playback system. I am a data driven guy so I went to the stereophile Class A recommended amplifiers and looked at how they were evaluated in their reviews to get that status. Didn't have time to go through them all and just did a sampling: http://www.stereophile.com/content/2016-recommended-components-power-amps#P7k2QXcuAdXxZzgE.97

Dan D'Agostino Momentum monoblock: $65,000/pair
Here is the business end of that amp:

As you see, it only has balanced connection. Under the specs it says, "Inputs: 1 balanced XLR."

The Momentums produced a seamless overall sound, with slightly reserved highs, a tube-like midrange, and an authoritative bottom end, said MF. "With the darTZeel NHB-458, it's one of the two most satisfying power amplifiers I've ever heard," he concluded.

I hope you agree that calling anyone who owns this amp to have an experience that is less natural or believable, etc. would get you a fist fight in a hurry.

Dan's amps last year were the most popular one I saw at audio shows. So it reasons that there is no concern as you mention.

Lamm Industries M1.2 Reference monoblock: $27,390/pair
"The 110W M1.2 with tube front end and MOSFET output stage, comprehensive short-circuit protection, and high/low impedance settings, offered "unflinching honesty in conveying the true nature of the music that passed through it," said PB. "Utterly continuous and coherent from top to bottom," the M1.2 combined resolution and transparency with harmonic completeness, timbral richness, and glow. JA concurs."

This amp has both inputs. So I looked up the review and found this in the equipment list used to review it:

Cables: Digital: DH Labs Silver Sonic. AES/EBU: AudioQuest Coffee, Belkin Gold USB. FireWire: AudioQuest FireWire 400 (prototype). Interconnect (balanced): AudioQuest Wild.

That's a $4,500 XLR cable.

The review again fully confirms that amazing fidelity can be had with balanced audio.

mbl 9007 Noble Line monoblock: $42,800/pair

"The 440W Reference 9007 can be used as either a balanced monoblock or a single-ended stereo amplifier and has provisions for biwiring and biamping....Sacrificing bloom and suppleness for crystalline transparency and offering tightly focused imaging, shimmering highs, and well-damped bass, the 9007 was one of the most exciting and engaging amplifiers in MF's experience."

Method of connection is again in the equipment list:
"Interconnect (balanced): Kubala-Sosna Elation!, Transparent, AudioQuest Wild Blue."

I could keep going but as you see, superlative performance according to these reviewers was achieved using balanced connections.

And a few other quick ones:

As you see there is no unbalanced connection.

So while I believe that is your conclusion, there is a mountain of evidence that balanced connections provides superlative performance in the hands and ears of others.

 

[Steve williams]

what you fail to understand about Lamm is that there is NO balanced connection. Its is a SE connection using an XLR connector. You like to throw things out with total lack of knowledge of Lamm. But once again you obfuscate and deflect

 

[853guy]

Hi Dave. You say that with complete conviction and I get that is your conclusion but it just isn't a universal truth. As I mentioned and you know, almost all of our music is produced through balanced connections. Do we really think the talent heard less fidelity music than we somehow hear when we play that through unbalanced connections?

Hi Amir,

Do you really believe the physics behind converting sound waves to electricity shares the same equivalency as converting electricity into sound?

Yours in curiosity,

853guy

 

[amirm]

what you fail to understand about Lamm is that there is NO balanced connection. Its is a SE connection using an XLR connector. You like to throw things out with total lack of knowledge of Lamm. But once again you obfuscate and deflect

Before I answer you, do you understand this post by Ken?

Balanced interconnections are the surest way to reject ground noise coupling between mains powered system components, which is why studios use them. As far as sound quality, if you prefer the sound of SE circuits, balanced signal interfaces can be established between SE drive circuits as effectively as between differential drive circuits. The signal interface is not dictated by the drive mode.

 

[ddk]

Stereophile Recommended Buying List , hardly the factual evidence you're asking Dave for!

For obvious reasons I won't enter into an argument about the other products but as far as the Lamms are concerned, given the same decent wiring SE input sounds far more musical than the balanced one, this is based on a 20 year continuous personal & professional experience with them.

david

Hi Dave. You say that with complete conviction and I get that is your conclusion but it just isn't a universal truth. As I mentioned and you know, almost all of our music is produced through balanced connections. Do we really think the talent heard less fidelity music than we somehow hear when we play that through unbalanced connections?

But maybe you are making a point only with regards to playback system. I am a data driven guy so I went to the stereophile Class A recommended amplifiers and looked at how they were evaluated in their reviews to get that status. Didn't have time to go through them all and just did a sampling: http://www.stereophile.com/content/2016-recommended-components-power-amps#P7k2QXcuAdXxZzgE.97

Dan D'Agostino Momentum monoblock: $65,000/pair
Here is the business end of that amp:

As you see, it only has balanced connection. Under the specs it says, "Inputs: 1 balanced XLR."

The Momentums produced a seamless overall sound, with slightly reserved highs, a tube-like midrange, and an authoritative bottom end, said MF. "With the darTZeel NHB-458, it's one of the two most satisfying power amplifiers I've ever heard," he concluded.

I hope you agree that calling anyone who owns this amp to have an experience that is less natural or believable, etc. would get you a fist fight in a hurry.

Dan's amps last year were the most popular one I saw at audio shows. So it reasons that there is no concern as you mention.

Lamm Industries M1.2 Reference monoblock: $27,390/pair
"The 110W M1.2 with tube front end and MOSFET output stage, comprehensive short-circuit protection, and high/low impedance settings, offered "unflinching honesty in conveying the true nature of the music that passed through it," said PB. "Utterly continuous and coherent from top to bottom," the M1.2 combined resolution and transparency with harmonic completeness, timbral richness, and glow. JA concurs."

This amp has both inputs. So I looked up the review and found this in the equipment list used to review it:

Cables: Digital: DH Labs Silver Sonic. AES/EBU: AudioQuest Coffee, Belkin Gold USB. FireWire: AudioQuest FireWire 400 (prototype). Interconnect (balanced): AudioQuest Wild.

That's a $4,500 XLR cable.

The review again fully confirms that amazing fidelity can be had with balanced audio.

mbl 9007 Noble Line monoblock: $42,800/pair

"The 440W Reference 9007 can be used as either a balanced monoblock or a single-ended stereo amplifier and has provisions for biwiring and biamping....Sacrificing bloom and suppleness for crystalline transparency and offering tightly focused imaging, shimmering highs, and well-damped bass, the 9007 was one of the most exciting and engaging amplifiers in MF's experience."

Method of connection is again in the equipment list:
"Interconnect (balanced): Kubala-Sosna Elation!, Transparent, AudioQuest Wild Blue."

I could keep going but as you see, superlative performance according to these reviewers was achieved using balanced connections.

And a few other quick ones:

As you see there is no unbalanced connection.

So while I believe that is your conclusion, there is a mountain of evidence that balanced connections provides superlative performance in the hands and ears of others.

 

[Steve williams]

Myverror. The M 1.2 and M 2.2 have balanced inputs. However my question is why Lamm chose not to include Balanced inputs on his other amps and why he neglected it in his $140,000 amp. Speaking to him it is his strong opinion that SE sounds better

 

[ddk]

Myverror. The M 1.2 and M 2.2 have balanced inputs. However my question is why Lamm chose not to include Balanced inputs on his other amps and why he neglected it in his $140,000 amp. Speaking to him it is his strong opinion that SE sounds better

Lamm tube amps are SETs and that's what Vladimir believes sounds better than other topologies, a balanced input on these amps is counterintuitive. His hybrid amps are a different story, they've been used in many applications that demand balanced electronics, so he offers both SE & Balanced circuits on M1.2 & M2.2. Lamm's L2.1 has balanced outputs too.

david