New guy w/question.

 

New member
Username: Voodoosg

Canada

Post Number: 1
Registered: Mar-07
Hey, I'm new here, and I've recently upgraded my setup, but I'm not 100% on all of the technical aspects of A/V, so I', looking for some input. I'm running the pre-outs on a consumer-type (Harman/Kardon) receiver to a pair of commercial-type studio amps, with one running each of my consumer-type (Cerwin-Vega) speakers. All wiring and cables are sufficiently thick (with the exception of my speaker leads, which I'm replacing asap), the amps are running at 8 ohms, and the speakers are rated for 8 ohm amps. I have a Monster power filter deal for the power. However, I seem to be getting a bit of hum/buzz from the setup. I'm told this may be because of a ground loop problem (...?). I am curious to find out A)how I can fix this ground loop issue, and B)could my mix of commercial and consumer equipment be adding to this problem, or for that matter, detrimental in any way? It's not a loud hum/buzz, but it still irritates me. Any ideas?
 

Gold Member
Username: Frank_abela

Berkshire UK

Post Number: 1984
Registered: Sep-04
Pro-units tend to be a bit ruggedised for hostile environments. They sometimes also don't have certain features since they don't need to be as flexible as domestic units, for example most pro amps do not have single-ended inputs. Other than that you should be able to mix and match as much as you like.

The problem does sound like a ground loop. The Monster power filter could actually be causing the problem since the filtration could be keeping the earth at a significantly different level to the rest of the kit. If all the kit is plugged into it then it shouldn't be causing the problem. If only the power amps are plugged into it, try plugging them straight into the wall and see what happens. You can work your way around the system, unplugging (not just switching off) one source at a time, then preamp then power amps to find out where the loop is being caused. Once you find the unit that causes the problem, try plugging it into another socket etc. FWIW, the power filtration unit is probably not helping the system, particularly as it's on the one thing that tries to draw power dynamically from the wall (the power amp). I am one of the few here who doesn't rate those things and recommend they don't get used, except in areas where electric storms are a probability.

Regards,
Frank.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 10098
Registered: May-04
.

I agree with Frank regarding AC line conditioners not being good for a system's performance - with very few exceptions. Most AC conditioners limit the available current draw for medium to large power amplifiers and even some very low amperage devices such as turntables. The better the system, the more the effect will be noticed. There are some very good line conditioners and surge protectors but they tend to be quite expensive and sometimes, when compared to the relative cost of replacement, not worth the money other than for peace of mind sake. Despite their disadvantages many conditioners contribute to the system performance in one area, they are sometimes beneficial in reducing line induced noises that are all too common in the majority of urban environments. You have to weigh the benefits to the disadvantages and decide which is greater for your system and location. That said, I don't think the Monster units are the best device for any function other than providing flashing lights to watch while your music plays. As line conditioners go they are mediocre at best.




So, yes, it sounds as if a ground problem is at hand in your system. Ground problems are typically identified by a constant 60Hz "hum" while frequencies higher up would be a "buzz" and not typically related to AC ground loops. Since the problem will not be resolved unless you are trying to fix the correct noise, you'll have to identify which sound is coming from your system. If you have a 60Hz ground loop problem and this is a home theatre installation a likely culprit would be your cable box. The cable companies have a ground point that is referenced miles away from your home and many installations need the ground lifted to operate without noise. Unplug the cable box from the AC and listen for improvement. If this solves the problem, contact your cable company and have them supply a ground lift for your gear.



If your amplifiers or any other component is supplied with a three pin AC plug, you might have the polarity of any two pin units reversed. Try swapping the orientation of the two pin AC equipped pieces one at a time and listen for improvements. If this fails, the solution begins with identifying which component is causing the problem. As Frank suggests this is best accomplished by unplugging units and replugging them until you can say which unit is at fault. If the units are plugged into different circuit breakers, this could easily be your problem.



You can get more assistance by entering "solving ground loop problems" into a search engine. It is difficult to resolve ground loops over a forum since the route to solving the problem isj ust a logical prgression of plug and unplug while noticing any changes in the system sound. This is difficult when we are sitting here and the problem is at your house. Try the above suggestions and read the results from the search engine then get back to us if need be. If the problem is not a ground loop and the noise is higher in frequency, you might need to move your equipment on their shelves to elminate RF and EM interference. Redressing your cables could also solve the problem. All power cables, line elvel cables and speaker cables should eb dressed in groups separate from each other and only crossing at right angles when necessary. Placing "dressing audio cables" in a search engine should get a better explanation of how to do this procedure.



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Gold Member
Username: Nuck

Post Number: 6513
Registered: Dec-04
Ryan, try searching out your GFCI circuits first.
Another member, John, tracked down his problem to an outside rcepticle on tyhe same circuit.

Be sure of the circuitry!
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