NOSValves Posted April 9, 2014 Share Posted April 9, 2014 I think the main problem here is we have too many Chiefs instructing one Indian and its causing confusion. This type of problem needs to be handled methodically one step at a time. And the METHOD is in the Jensen Transformer doc. I'm sure it is probably documented other places as well. I will resist the temptation to add my suggestions if that is what Eth2 wants. Yea the Jensen doc is a good read to help someone understand what is going on......But in the end its really an advertising piece to sell you Jensen products. I have talked to a number of people that use them with great results. I myself have my AC in my entire shop wired with GFI outlets and have none of my gear grounded. I make the least little mistake while working on hot audio gear the GFI goes snap and I'm safe as can be.... my system is dead quiet to boot! Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 Mono block A is connected to power supply A using a power cable (you are calling "XLR") and a ground strap. YES Mono block B is connected to power supply B using a another different power cable and another different ground strap YES Power supply A and B have their own 3 prong power cords. YES And absolutely nothing, no cables or plugs of any kind from anything, are connected to either of the RCA or XLR inputs on the mono block CORRECT the inputs are bare YES If that is correct, then--- 1. Is there any kind of direct connection of any kind between power supply A and B? NO 2. Is there any kind of direct connection of any kind between mono block A and B? NO If the answer to 1 and 2 is "no" you do not have a condition for a ground loop. A loop is a circle. Without connecting power supply A to B with some sort of wire, there is no circle, no ground loop. WHAT ABOUT THE CIRCUIT INTO WHICH THEY ARE PLUGED? Also, if you DID have a ground loop, and you did something that fixed it on one outlet in the house, it would also be fixed on other outlets because the outlet doesn't matter. MAKES SENSE I CAN EASILY MAKE THE SHORTING PLUG AND WILL TRY THIS WHEN I GET HOME TONIGHT. THANK YOU Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 Ok so each power amp has a separate power supply unit. Each chassis is grounded through the third prong on the power plug(with no cheater) and then the two power supply chassis are strapped together? Or are the power supplies strapped to their respective amp units? Just for clarification. Each front end has a different power supply - The power supply chassis are NOT strapped together. One power supply goes to one front end. So each power supply goes to its own front end. There is no connection anywhere between the two mono blocks (except that each power cord goes into the same outlet.) Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 I have a question with regard to the shorting plug. What is the difference between stripping two RCA plugs and twisting the wires together then using the red plug in one amp and he white plug in the other amp, from just taking one RCA plug and inserting one end into Amp A and one end into Amp B? Quote Link to comment Share on other sites More sharing options...
Don Richard Posted April 9, 2014 Share Posted April 9, 2014 I have a question with regard to the shorting plug. What is the difference between stripping two RCA plugs and twisting the wires together then using the red plug in one amp and he white plug in the other amp, from just taking one RCA plug and inserting one end into Amp A and one end into Amp B? If you do it that way you will be connecting the two amplifiers together. You are trying to separate the amps temporarily for a test to see if the noise changes. Make 2 separate shorting plugs. Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 Don, I am missing something. I take two separate RCA cords. One cord is white on each end, and the other is red on each end. I cut them both about 4" from one end. I then strip the wire from each plug (I now have four stripped wires. I twist all four wires together I then take one red end and put it into one amp. I take a white end (from the other end) and plug it into the second amp. I now have one red end and one white end not plugged into anything. I listen for noise Is this correct? Quote Link to comment Share on other sites More sharing options...
Cut-Throat Posted April 9, 2014 Share Posted April 9, 2014 (edited) Not sure if anyone has mentioned this, but the main solution to my Ground Loop Problem was to have both Monoblocks Plugged into the same outlet, not the same circuit. Even though I had a completely separate dedicated circuit. I would get a ground loop hum with the amps plugged into different outlets. All it takes is a couple milivolts of different potential between outlets and that is enough to magnify and pass it on to your speakers. The monoblocks were 12 feet apart, so what I did was run an extension cord to plug the other amp into the same outlet. Luckily I built cabinets along a wall where I could hide the cord under a false bottom of the cabinets. I'll attach a picture of my room, where you can see how far apart the Monoblocks are. The base of the wall cabinet is open for running cables etc. Edited April 9, 2014 by Cut-Throat Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 Initially I had them plugged into the same outlet, but they were not more than 4 feet apart. Quote Link to comment Share on other sites More sharing options...
babadono Posted April 9, 2014 Share Posted April 9, 2014 Don, I am missing something. I take two separate RCA cords. One cord is white on each end, and the other is red on each end. If you only want to sacrifice 1 cord just cut it in half. I cut them both about 4" from one end. Or cut both ends off 4 inches long. These are test plugs who cares what color they are. I then strip the wire from each plug (I now have four stripped wires.You will have two connectors, one for left, one for right, each with a stripped center conductor wire and another bare wire that is the shield if you have done it correctly I twist all four wires together No twist the center conductor of one to its shield wire. Do the same with the other. You now have two shorting plugs one for each amps input. I then take one red end and put it into one amp.They will both be red or white now, who cares. Plug one into each amp. I take a white end (from the other end) and plug it into the second amp. No I now have one red end and one white end not plugged into anything. I listen for noise Yep Is this correct? Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 Got it THANKS!!! Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 Not sure if anyone has mentioned this, but the main solution to my Ground Loop Problem was to have both Monoblocks Plugged into the same outlet, not the same circuit. Even though I had a completely separate dedicated circuit. I would get a ground loop hum with the amps plugged into different outlets. All it takes is a couple milivolts of different potential between outlets and that is enough to magnify and pass it on to your speakers. The monoblocks were 12 feet apart, so what I did was run an extension cord to plug the other amp into the same outlet. Luckily I built cabinets along a wall where I could hide the cord under a false bottom of the cabinets. I'll attach a picture of my room, where you can see how far apart the Monoblocks are. The base of the wall cabinet is open for running cables etc. Beautiful room, Cut-throat! 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted April 9, 2014 Share Posted April 9, 2014 I think the main problem here is we have too many Chiefs instructing one Indian and its causing confusion. This type of problem needs to be handled methodically one step at a time. And the METHOD is in the Jensen Transformer doc. I'm sure it is probably documented other places as well. I will resist the temptation to add my suggestions if that is what Eth2 wants. Yea the Jensen doc is a good read to help someone understand what is going on......But in the end its really an advertising piece to sell you Jensen products. I have talked to a number of people that use them with great results. I myself have my AC in my entire shop wired with GFI outlets and have none of my gear grounded. I make the least little mistake while working on hot audio gear the GFI goes snap and I'm safe as can be.... my system is dead quiet to boot! Yes Jensen Transformers wants to sell Jensen Transformers. But I have spoken to the president Bill Whitlock on a few different occasions and he was very helpful. He genuinely wanted me to get the best lowest noise performance out of my system whether I needed to use their products or not. I still have not had to use any of their products. Imagine me a little home audio enthusiast talking with the president of small company and he really wanted me to understand what was going on and how to fix it. Says a lot to me about his personal integrity and probably the whole company. Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 OK - the results are in! I made the cables and tried them out. Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 9, 2014 Author Share Posted April 9, 2014 Oh sorry-----I forgot to tell you the results. (NO cheater plugs are being used) When I put the cable in the one amp there is no effect. The hum remains. However, when I put it in the other amp everything is silent. So what does this mean? Quote Link to comment Share on other sites More sharing options...
Schu Posted April 10, 2014 Share Posted April 10, 2014 I'd like to see what would happen if the two konos were bridged. Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 10, 2014 Author Share Posted April 10, 2014 Mark Whichever amp I short out becomes silent. Also, if I plug in the preamp (even if it is unplugged from the AC outlet) the noise gets louder. If I turn the preamp on, the noise gets quieter, but it is still there. If I move cords around (either RCA or power cords to the preamp, CD player etc., it has an effect on the volume of the noise. Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 10, 2014 Author Share Posted April 10, 2014 Also, the noise from the left amp is always a bit louder than the right amp. Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 10, 2014 Author Share Posted April 10, 2014 Lastly, the noise is significantly louder in the living room than in the den or library. No other amps are behaving this way Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 10, 2014 Author Share Posted April 10, 2014 When you short the inputs and noise stops, it means the noise is RFI (airborne) coming in on the high impedance input as I suggested a few posts back. This is a different kind of problem than a ground loop So now the 64k question - Why is this happening and how do I fix it? Quote Link to comment Share on other sites More sharing options...
eth2 Posted April 10, 2014 Author Share Posted April 10, 2014 Thanks, Mark. I will call them tomorrow. Quote Link to comment Share on other sites More sharing options...
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