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Suncoast Audiophile Society Message Board Main discussion area (visible to non-members) › Ground loops, cable isolation, and dedicated lines

Ground loops, cable isolation, and dedicated lines

Philip R.
inline_phil
Brooksville, FL
Post #: 13

I do know 2 things. A lightning bolt arcs 40 miles and nothing impedes that jolt. Surge protectors are laden with MOV's and they are adversely detrimental to the sound of an audio system. My audio rig suffered minor damage because it was located at the other end of the house. I suspect that a surge protection device is benefictial if the surge is a mile or more away.

Lightning is an interresting and sometimes misunderstood phenomenon. A good-sized bolt of lightning can contain about 5 billion Joules of energy (5x10e9 Watt-seconds total energy before losses). The average lightning bolt has a duration of 0.2 seconds and contains "pulses" in roughly 20mS segments over its duration (it's NOT constant as you can sometimes notice by a slight flicker). If you were ever able to capture all of this energy, you could snag about 1.4 million Watt-hours of power from each bolt. Real-time measurements of up to 200,000 amperes have been made (NASA measured 100,000 amps during a launch) at of hundreds of millions of volts, all in DIRECT CURRENT (sorry Tesla).

Yes, lightning can do damage and a lot of it in the blink of an eye. But if the total power in a bolt was not dispersed to some degree before it reached the ground, golfers (et. al.) would never survive lightning strikes. Part of the misunderstanding is that lightning - to the eye - appears to follow a few well-defined jagged lines. In truth, lightning randomly dances in whatever path and as many different routes as it can find since there is no solid conductor (e.g. a wire) for it to travel through. These smaller branches are obscured by the bright flash of the main bolt limiting the eye's ability to detect them (the dynamic range limitation - we need a bigger sampling word size). Photos of strikes on bridges and towers demonstrate some of this invetred tree path a bolt of lightning actually takes (there are literally millions more paths but even the most sensetive photographic films and optical instruments cannot capture the full effect).

Spark gap surge protection is common at substations to help protect step-down transformers from exploding from nearby strikes (look for the balls on rods spaced close together). If you subscribe to TECO's lightning insurance, you have MOVs on your line before power reaches the breaker box.

Lightning hunters, as mentioned earlier, have conducted experiments in directing and measuring discharges before a bolt begins by sending small rockets into potential clouds towing a single thin wire (much like casting a fishing line into the surf). On occasion, such experiments can artificially create lightning by tapping into the "source terminals" of the cloud before the voltage potential is high enough to create cloud-to-ground lightning. The wire and rocket are vaporized in the process but instruements can be placed at the point where the lightning reaches the ground to make these measurements. Understand that the measurements are somewhat misleading since even this tiny wire in its vaporized plasma state is a much better conductor than air.

Attempts to divert the energy in a lightning strike is the best we can hope to do, given the huge numbers involved of voltage and current. Usually, this means that whatever device is used to accomplish this diversion gives up its life in doing its job. One problem is the "turn on time" where those that last longer also take a longer time to turn on. During this "off time," the power of the strike reaches the attached devices (here your home entertainment system). Another problem is the amount of time it functions before it dies. Again those that endure more stikes can be less effective. The industry has created standards in which to test for these abilities to survive and all surge protection products are tested to these minimum requirements. Some work better than others; some sound better than others.

The problem is that literally nothing mankind can produce to date can survive a direct hit by a main bolt. All we can hope to do is slow the hit down before it reaches your house by draining the excess energy off along the way (spark gaps, MOVs, passive chokes, etc.). However, some of this energy reaches your home when a nearby power line or transformer takes the hit.

When the grounding in your home is improper, there is a much greater chance for lightning to enter despite the technology you choose to suppress this unwanted energy. I personally would first make sure that house grounding is working as assumed. You know what they say about assumptions...
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 275
Got an unexpected tweak from TECO the other day. Doorbell rang, and a TECO service guy told me he was here to replace/upgrade my 10 year old "ZapCap" whole house surge protector (installed at the meter). Maybe it's just placebo effect, but I swear my system sounds significantly better ever since!

The "ZapCap" is actually TECO's name for the "MeterTreater" line of protection products, which I presume other local FL power utilities offer as well. The version he just installed is their 575-1SL-A (spec sheet here... (http://www.metertreat...­)

It's a MOV-based device, so I'm wondering if the old one might have taken a couple hits over the years, or perhaps the new one sounds better just by virtue of having a new tight connection.

For any of you who have an older version of the device, might want to check with your utility company to see if they offer an upgrade. BTW, the old device carried a 10-year protection warranty, and the new version has a 15-year warranty.
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 633
Since reassembling my system (after our recent remodeling), I've encountered WORSE ground loop issues than ever before. Most of the problems stem from connecting video sources to my system (Oppo BDP-95, Sony HDTV, or Denon surround receiver), and I've ruled out cable/FiOS, and Ethernet/WiFi, as the source. All gear is now running off a single dedicated 20A line, so all should have the same ground potential. In the past, I found an Ebtech HumX device (or cheater plug) worked well when connected to the Oppo (or my preamp). Now, that solution doesn't work as well. I've ordered another HumX (just in case the original is kaput), along with a Stinger SGN20, which is an isolation transformer (ostensibly for car audio) that works with analog RCA connections. I'm hoping one, or both, of those will bring peace and quiet back into my system! Will keep y'all posted!
Philip R.
inline_phil
Brooksville, FL
Post #: 81
Since reassembling my system (after our recent remodeling), I've encountered WORSE ground loop issues than ever before.
There is a methodical, scientific approach you should use to assure proper grounding and eliminate ground loops. Call me when we can get together for a few hours and truly figure out what is going on. Remember, I wrote 5 books on this subject. 3 of which deal with issues above and beyond the wall outlet. I believe you know my number. Phil
Phil
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 634
Thanks Phil! If the HumX and/or isolation transformer don't solve it, I'll give ya a ring. Maybe I'll even host the Aug meeting with a Ground Loop Redux theme! biggrin
Grant P.
gjposner
Tampa, FL
Post #: 34
Good luck Alan, let us know how it all turns out. I have had serious issues with grounding, which gets worse when running a Tesla Coil in my side yard.. And yes, the coil has its own dedicated 8ft ground rod, my issue, I believe, is that my house ground is poor..
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 635
A Tesla Coil? Talk about RFI! biggrin
Grant P.
gjposner
Tampa, FL
Post #: 35
A Tesla Coil? Talk about RFI! biggrin
Yea, it is an issue. Only running 4kv in currently, looking to upgrade it to 12kv in which should triple the arc output as well..
Alan N
user 13931748
Group Organizer
Tampa, FL
Post #: 636
Finally got the ground loop issue solved! It's actually two separate issues, but a potential common fix. Connecting my Oppo BDP-95 analog RCA outs to my preamp creates low-level hum, which is partially removed by running the Oppo power cord through a HumX. However, connecting HDMI from the Oppo to my Surround Receiver or HDTV results in more hum (even if the Oppo is unplugged!!). Using the Stinger SGN20 alone interposed between the Oppo and preamp eliminates ALL noise, including that from the HDMI signal. Next test will be spinning some SACD's in the Oppo to see if the SGN20 has any audible effect. Thus far, the SGN20 looks like a pretty nifty device for $11! Unfortunately, my C-J preamp and amp don't have balanced inputs, so I can't test if the Oppo's balanced outputs are also noisy.
Russ G.
user 13947780
Sarasota, FL
Post #: 31
I don't think the Oppo is the culprit, just the carrier exposed by the cj equipment. I used a cj pre-amp and amp for 5 years and cj pre-amps for 10 and, while I appreciated the sound, I always had issues with grounding and hum. Since changing out the cj system, problems have been few and far between, if any.
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Founded Feb 3, 2011

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