Surge protectors/Line conditioners

[John Holmes]

I've been wondering, does the given protection from such a device ever wear down from normal use?

These items seem to get more of a workload than any other piece of equipment. I know living in WA., LA., and now FL., all of these places have power outages at least once a week or more. Not to mention, the constant power ups of refridgeration, AC, etc. So just how much or how long can you expect to do the job?




"I came here, to chew bubble gum and kickass. And I'm all out of bubble gum!!!" My DVD's

[ThomasW]

Devices that use sacrifical MOV's (metal ozide varistors) offer less and less protection over time. Virtually all low buck and some expensive devices use MOV's. They're cheap and do a fairly good job.

If you want to avoid MOV's then look at the products offered by Brick Wall

I had a in panel whole house surge unit installed last spring. It is a sacrifical unit. There's a green LED on the device. If the unit has clamped a big sipke and is dead the LED is off. The unit is unplugged an a new one is installed. Not cheap at ~$200 but it's chump change compared to the cost of the gear it is protecting




theAudioWorx
Klone-Audio

[brucek]

John,

I was just about to post an answer and Thomas beat me to it. :LOL:
I'll post my answer anyway......

Almost all surge arrestors use MOV's (metal oxide varistors) to shunt current, and will eventually breakdown. The varistor provides a low impedance path (shorts to ground) when it receives a spike over a certain voltage level. They react very quickly (sub-nanoseconds) and return to their high impedance state once the spike has finished. The problem is, there is a finite number of times the MOV will provide this service. Eventually it becomes ineffective. The lifespan, of course, depends on how much and how hard they've had to work, but they have a relatively long life. Certainly, the effectiveness of any surge protector to mitigate damages from a direct lightning strike isn't included in this discussion.
As the varistor device slowly degrades, because it's had to repeatedly conduct high current, its' turn-on voltage lowers. This of course, causes it to conduct more often, which lowers its turn on even lower. Eventually, as this slide continues, it shorts out, tripping a breaker or simply becomes an open circuit - now you're not protected. That's the bad news.

The good news is that most of these surge protector devices have a light that tell you the MOV's are open circuit and that your protection is lost. Time to replace the device (or the MOV's if you're so inclined). Since all these surge protector/line conditioners are basically the same except for bells and whistles, I wouldn't spend a lot of money, so replacing the device won't be a big deal.

A typical surge protector/line conditioner involves a low-pass filter as the first line of defense to attenuate the surge. This first-line EMI/RFI noise filtering in most "power conditioner" are simply low pass filters made up of inductor/capacitor ladders that attenuate high frequencies and transients. They do a good job, but most electronics equipment in your system have a very high EMI/RFI noise rejection built in already. The power supply transformer, bypass capacitors, the filter capacitors, voltage regulators and the chips themselves all provide a high frequency noise rejection. If this first line of defense is not sufficient, the MOV's shunt the remaining voltage to ground.

There are devices on the market (made Brickwall, Adcom, Zero Surge etc) that are called series mode protection. They don't employ MOV's in their design. They rely on a very large first line of defense inductor in series with the line and then use a smaller second line of defense using SCR's or some other triggering device. There is nothing to wear out, but now you have a rather large 'current limiter' in series with your equipment. Some audiophiles might suggest this has an audible effect when your power amp requires large amounts of current.
These devices are more expensive than the usual MOV design, but I suspect they're no more effective. I'm sure if you read the Brickwall site, they'll say otherwise.

Myself, I use a whole house surge suppressor and then cheap local suppressors at my equipment. This is quite effective for most transients. I understand in areas (like Florida) the local utilities will provide whole house suppression for a small monthly fee, and replace the device when and if it becomes ineffective.........

brucek

[ThomasW]

Probably should add that MOV's themselves are inexpensive and in many cases a fairly easy DIY replacement.




theAudioWorx
Klone-Audio

[George Bellefontaine]

Great educational thread here, fellas.




My Homepage!

[EMT]

Thanks for the informative posts guys. I'm wondering how balanced power isolation transformers, like those from Furman Sound, fit into the picture. Perhaps you technical experts can shed some light on these devices.

http://www.furmansound.com/IT-Series.html

http://www.furmansound.com/IT-REF.html

[ThomasW]

Ellen

Personally I think balanced power is wonderful. Furman is the Rolls Royce of balanced power and is priced accordingly

I use the devices from B-P-T They use the same or similar Plitron transformers as the big boys (Furman, Equi=Tech) but are much less expensive. If you're interested in these I have connections for very attractive pricing.

Balanced power transformers in and of themselves don't clamp spikes or surges. It does however significantly lower the AC noise floor. Caps, inductors and other devices placed in the AC path handle spikes, surges, etc.

Here's a link to the Equi-tech FAQ page for more info on balanced power




theAudioWorx
Klone-Audio

[John Holmes]

Thanks everyone for the great info and answers. So I should be ok until my "idiot lights" kick.




"I came here, to chew bubble gum and kickass. And I'm all out of bubble gum!!!" My DVD's

[brucek]

Ellen,

I feel there are indeed benefits to using balanced power, but I would advice getting your house in order first.
I'm aware that balanced power has merit in the correct application, particularly in somewhat reducing reactive currents, but I feel standard residential power doesn't really benefit from being converted to common mode as much as using sensible electrical practices in wiring and grounding an audio system.

I've seen too many poorly wired and grounded systems that produce a ridiculous amount of hum that the owners believe that throwing a balanced power or line conditioner at will solve.

I feel power manipulation of any kind is the 'fun' that comes after we have our systems as silent as they can be, while using standard residential differential power. The idea that there is always something fundamentally flawed with power from the wall is silly. Most AC power is fairly well regulated and generally free from noise. It can benefit from some surge protection and some RFI/EMI filtering.

The power supplies in our equipment will filter any small noise spikes and bypass most RFI to ground. The power supply regulators will make up for small line voltage changes. In fact, the noise rejection from power cord to DC at the chip in any piece of equipment today is extremely high and doesn't need any help.

If you feel that the AC power in your home is causing some problems with your system, then those problems should be tracked down to the source before resorting to converting all your AC to balanced mode.
If you're experiencing some sort of ground loop hum or noise in your system, perhaps you could isolate this problem and correct it before spending money on something you don't actually need.

Certainly one of the better things you can do for a system is to install one or two dedicated AC circuits ensuring they're on the same leg of your loadcenter. I don't think a dedicated circuit is a panacea, but I think in a lot of cases it can help. You avoid a lot of problems and eliminate any questions about your circuits quality. It's a great starting point. The benefits of a dedicated circuit are many. I highly recommend it.

Although there's nothing magic about dedicated circuits, it ensures a single run of cable from your power panel to a wall receptacle, with no interconnections between and nothing else plugged into the circuit except your system.

The receptacles in your room now may have up to 12 lights and receptacles on the same circuit. At each receptacle that the wiring runs through, there is a set of twisted connections inside covered with marrettes (wire nuts) that may be presenting a small resistance. The more of these connections, the more possibilities of poor, high resistive joints before the circuit reaches the receptacle that you are using. These connections can become highly resistive.
In addition, there are a myriad of things like motors, fluorescent lamps, and computers that may also be plugged into this same circuit shared with your system.
There's also a good possibility that if you are using more than one receptacle in your HT room, that they may be on a different leg of the loadcenter increasing the potential for ground loops.
All this can result in a loss of power and increased noise at the receptacle(s) you're using for your system.

When you use a dedicated circuit, and noise is introduced on a different circuit in the house, even though they return to a common point at the loadcentre, this noise tends not to travel down your dedicated circuit because of the extremely low source impedance of the mains at the panel .This noise induced on other circuits is "sunk" once it arrives back at the loadcenter and is not passed to the dedicated circuit. It acts like a pass filter to this induced noise. The noise rejection is quite high. This is one major advantage of a dedicated circuit. You know that there are no other noisy devices plugged into this circuit.
Some whole-house or local surge protection is also a good idea to try and help protect that expensive equipment. Beyond that, not much else is necessary as far as AC power is concerned.

If I use my own system as an example. I have two identical dedicated 20 amp circuits feeding my system. I don't have any noise making refrigerators or fluorescence or anything but my system plugged into them. I only use some simple whole-house surge protection. I have ensured my safety grounds are installed from my loadcenter properly and are properly bonded to neutral.
I have to press my ear up against my speakers to hear even the slightest thermal hiss. There is zero hum at full volume on my preamp. What is a balanced power unit going to do to my system? If you have a hum coming from your speakers, find the fault before purchasing anything else.

Once you're satisfied that your power for your system is in good order, a balanced power unit may be an interesting addition. A balanced power unit is basically a very high quality isolation transformer with a center tapped low impedance secondary. So instead of a hot of 120 volts and neutral return, you have two 60 volt lines with a center tapped ground. Across the 60 volt lines which are 180 degrees out of phase you have 120 volts, with each 60 volt lead referenced to the ground at the center tap. There are a lot of benefits in this configuration. Any reactive currents developed in the load arrive at the common center tap and are cancelled. Any noise that would normally travel on the safety ground are cancelled at the center tap. The ground is basically re-defined and becomes very close to a true zero reference. This does a good job in helping to reduce ground loop currents which can cause hum. There's not much chance of a ground loop. The other benefit can be a lower noise floor. Some people claim excellent results.

Large current balanced power units aren't cheap, although the ones offered by B-P-T are fairly reasonable. The trade off you have to realize and accept is that a 20 amp wall plug can supply approximately 2400 VA's and this available power will be reduced by the size of the balanced power unit you choose. If you get units that supply this and can afford it, that's good, and you'll also realize the benefit of the EMI/RFI filtering the unit provides. Of course on the down side, you just added another device (transformer) in the chain. :roll:

Anyway, those are few thoughts on it.....

brucek

[ThomasW]

My experience with balanced power devices is that in every system where we have auditioned them, there has been a significant improvement in sound quality. Now this is not the music itself getting better, it's the noise floor of the AC dropping.

I realize that some people think balanced power is some kind of 'tweak'. It's really not, I've taken my devices to other people's house plugged them in and they heard the same level of improvement. The differences are not subtle. So I don't think the system needs pristine power to achieve the benefits that balanced power has to offer. But I certainly agree with Brucek that all attempts should be made to eliminate ground loops and use a dedicated circuits when possible.

My AC is pretty clean, whole house surge, dedicated 20 amp line, Tice Titan/Power Block II. Added to this are 2-BP-2.5's ,1-BP-2 ,1-BP-1 and 2 BP-4's. This covers all the A/V equipment in two rooms. I had no ground loops/hum prior to installing the balanced devices. And my electronics are clean enough that the noise floor of the playback electronics themselves is virtually inaudible.

As a test I started out with a single BP-2. Where ever I put it in the signal path there was an audible improvement. I moved it to the power amps and added a BP-4 for the front end equipment. This resulted in even more improvement. And no it's not placebo effect. I've taken it in and out of the system with a dozen people here for amp testing, and all heard how the system changed.

Having used these devices for ~10 months now I quite literally don't want a system that doesn't have this type of line conditioning. I believe the saying is that 'the blacks are blacker'

Personally I have no issues with adding additional devices in the AC line; as long as the addition is results in an improvement to the performance of the system.

As I said in an earlier post the B-P-T devices are available at a nice discount. We have a group buy set up, email me for details if interested...BTW this isn't a situation where I have any financial gain from sales......




theAudioWorx
Klone-Audio