noise with keyboard input

It sounds like you've got a ground loop between the S80 and your computer.  The VS-100 floats with respect to ground, but your computer and the S80 don't, so you get a loop when you connect them to the VS-100.

The simplest thing to do would be to use a DI box to connect the S80.  Unfortunately, a good stereo DI box like the Radial JDI is expensive.  If you don't own a DI box, you should borrow one, even if its a single channel, and test it to make sure it solves your noise problem.

There are also audio isolation transformers, but low-cost isolation transformers will affect the frequency response of you keyboard.  A cheaper alternative is to build special cables to connect the S80 which don't connect the S80's ground to the VS-100's ground.  But this is difficult to explain and doesn't always work.

Murray

Then what do you do in the event of a fault?

Thanks to all for your comments.  I decided to test the laptop ground theory by simply unplugging the AC and allowing it to run on battery - voila! no noise.  The grounding issue appears to be the culprit.  I may look for some more complicated solutions, however the simpler one seems to point to running the laptop on battery power if noise is a problem.  It's interesting, however, that I'm also running a Roland TD-20 drum kit on AC and I don't seem to have the same problem.  Ideas?  Thoughts?

I agree with the solution of using a 3-prong to 2-prong adapter, which lifts the ground off from the power supply of the laptop.

As to concerns on the needs for the ground, do see that various of the laptop makers DO NOT use a ground in their power supplies.

HP laptops I had did, Lenovo does not and they are IBM designed.

Also the vast majority of wall-warts do not use a grounded plug..Typically cellular phone chargers, and so forth.

I use one of those plugs on an HP I still have, and have it like that for years for the reason of ground-loop noise, and if I did not have one of those plugs, I would chop the grounding off of the plug, specially after the thing is out of warranty. But that's me.

The laptops work on D.C. anyway, and when they are running off-batteries, they are floating.

MurMan

NoKey

I agree with the solution of using a 3-prong to 2-prong adapter, which lifts the ground off from the power supply of the laptop.

To quote rabeach, "Then what do you do in the event of a fault?"  Issue an apology to the forum? 

Of course I'm being sarcastic, but electrical safety is serious business.  You are camparing various laptops as if you understand the internals of their electrical designs.  In a former lifetime, I designed and submitted hardware for UL and CSA approvals.  There's a lot that goes into this, much of which is not obvious from the outside looking in.

It is a real mistake to suggest defeating safety devices.  There are several other ways to solve this problem that are safe.

What fault, or type of fault would he be talking about?

Lightning from the sky does not fall inside of a house, there are no overloads on a loptop , and as to short-circuits, the laptops work on DC voltage and they have no more power than the battery themselves hold, typically 5 volts or so...And as to ground faults, most household outlets do not have ground-fault circuit breakers any way, and those that have them are in bathrooms, or kitchens, and they are not mandatory, any way.

As someone says above, grounding all electronic consumer gadgets is kind of old fashion..Heck, even so many power tools DO NOT USE a grounding plug any more.

There are "other  ways" that are "fail-safe"? ...Like what for instance?  An isolation transformer? It basically lifts off the ground, anyway, from the equipment, plus you would be introducing ONE MORE component that can ALSO fail, in a bigger way, even.

What about this solution: "Buy a laptop that DOES NOT use a power supply with a grounding plug"? Would that be OK to you? Would that be a Fail-safe solution?

So what's your fail-safe solution Mur-Man?

Now if you submitted hardware for UL in former times, that does not necessarily carry-over to the topic, would say...Not all medicine is good for all situations...Plus learning evolves.

Ha!

The example that you chose for a fault, which you say "puts line-voltage to the ground of a laptop", happens to be one that would need, not just one fault, but a multitude of faults, due to the number of components in the power supply. Besides, laptops are floating, so they have no real ground. If they were required to be "grounded", then they would not be portable.
    
Anyhow, if we take the same convenient criteria of the fault, or type of fault that you chose to bring, we can certainly apply it ALSO to the power supply of my Lenovo laptop; and THAT ONE does not have a grounding prong, as said.

So, with the type of fault that you offer, my Lenovo could also have line-voltage at "one of its metallic parts", but my Lenovo has UL, CS, and NOM logos in the bottom sticker, meaning that type of fault is EXTREMELY unlikely.
    
And, as I say, there are so many devices even in the kitchen (and I mean MODERN devices) that do not use a grounding plug, such as coffee pots, mixers, even toasters in metal casings, and the irons that ladies use, and even use WATER inside!

So WHAT WOULD YOU SAY keeps them from having a fault that would put line-voltage to their "ground" or metal parts?
    
Makers of older tools and devices did all follow the school of using ground plugs, as per your criteria. Well, even so,  I did see a fellow get electrocuted in the far past with a drill that had a grounding plug!....Luckily, he did not die, but was hospitalized to recover.

And let me tell you that it only takes 20 milliamps or so to kill a fellow, so there is no circuit breaker, fuse, or whatever that can be said to reliably give those levels of protection, specially when the current can flow from the hand of a person to locations other than that of the grounding prong.

In other words, if line-voltage gets to be present in any device, and you touch it, don't ever believe that the grounding plug will save you...Current can flow through your hand, through your heart, and through your feet, or other part of the body to actual real ground, not necessarily to the grounding plug, even  if there's one.
    
And, don't count either on breakers tripping when insulation or components fail, because most of the ground faults are of the arching type, where there's not enough current to trip a breaker, but enough milli-amps can still flow to kill or harm a fellow.

As to lightnning not being a prolblem to worry about, you ought to know that people have been killed simply from using a telephone, inside of their house, during a storm..

And, I will mention that I have personally seen an electrical outlet spark when lightning stroke during a storm, and have had a modem, and a monitor fail and have actually heard the sparks in them when so they failed, also when lightning fell from the sky.

But power supplies of laptops have plenty of internal components to pretty much avoid that type of external faults, and DON'T DISCOUNT that inside they do have protection against surges!

Even so, many people use surge-suppressors in their equipment.

As to line-voltage, fortunately, laptops and electrical devices are pretty safe now-days, and even more laptops, which use voltages in the order of 5 volts of D.C. current, as said.

And, for your clarification, I am not giving advise to anyone..
    
I am just stating known facts an my own personal decision on how I fixed the problem that is being asked about in this thread.

And I am not the only one that has come to the same solution, I have found, for I did not read my solution in the web. When I found out what the problem was, the solution was obvious.

And so, my laptops an myself are OK years after doing that.

MurMan


This conversation is a waste of time.

Better to waste time than money in buying an isolation transformer as you say, for the problem in question.

And I am glad I did not buy one, for, when I researched my situation a few years ago, THAT was indeed the recommendation I found on the web!

Fortunately, thinking is of an independent nature...And so is decision-making..

And I am not keeping anyone from making his own decisions.

Thanks, I really appreciate that.  Hopefully, someone will be more careful as a result.

Murman - 

Thank you for your knowledge and patience.  FWIW,  I am an Electrical Engineer and I understand, agree and appreciate what you stated here.
Regards, Dan

DPTrainor


Murman - 

Thank you for your knowledge and patience.  FWIW,  I am an Electrical Engineer and I understand, agree and appreciate what you stated here.
Regards, Dan

DPTrainor


Murman - 

Thank you for your knowledge and patience.  FWIW,  I am an Electrical Engineer and I understand, agree and appreciate what you stated here.
Regards, Dan

Underweriters Laboratories Inc DOES NOT mandate that ITE equipment be grounded, so most ITE equipment is not grounded nowdays, specially mobile ones. Those are standards based on electrical engineering also, and beyond.

So, let's not see that people go nuts grounding devices that do not have a 3-pin plug, including laptops, in order to "avoid line voltage being present in any of its metallic parts".

I will also say that it should not take an electrical engineer, a PHD, or even UL to establish that if a piece of equipment, even if it comes with a grounding plug, RELIES ON THAT PRONG in order for it to be safe from line-voltages, it is altogether an unsafe device, and not fit for UL listing.

People who shout "wolf", "idiot", "hero", or  "gentleman" here, ought to be more unbiased and realize that the same power supplies and laptops that we are talking about are ALSO suitable for operation up to 220 volts, with two prong plugs. If in doubt, do read the specs on the labels those power supplies..These are not old-fashioned transformer types....so they even work even in 50 volts.!....So, old school and fixed mentalities do not necesarily hold water on this. Bottomline,  laptop power supplies are approved by UL to work in up to 220 volts, and even 10% above, due to norms...Just read the label on your power supply!

Don't forget that people just use an ungrounded adapter when they go to another country; ... and if you buy a "replacement" power supply for your laptop, in the USA, it will be UL listed and  not grounded...And it will state "good for HP", etc., regardless if your original was or not grounded...So defenders of old traditions regardless of where and how, go and fight Walmart, if you want to save the world.

Just google for "adapters" for use overseas on your "grounded" laptop, if you still have doubts on safety, on wheter or not to use an adapter plug to get rid of the ground loop for audio use in a laptop.

Heck I still have some of those from my world-wide travels. I got those there, but they can be bought at any USA Radio Shack,  if going oversees and taking your "grounded" laptop over.

A ground-lifting adapter is  a much better solution for solving the ground-loop audio problem than an isolation transformer.

And, by the way, one you should not use a USA 60HZ transformer in Europe, or where electricity is 50 HZ or other, for they happen to be voltage and frequency specific.

Isolation transofrmers can also fail, evenso more, than lifting the ground as discussed as a solution,  and cause real safety problems that, however, am not willing to discuss here.

rabeach


NoKey there are so many inaccuracies in your statements that the three electrical engineers posting on this thread are reluctant to address them. best regards.

Would you mind listing even one or two of those many, rabeach?