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Professor Dave Unregistered guest | Hello I have a brand new NAD T773. I just noticed that when I have a digital input running (either coaxil or toslink)I can hear the radio turner through the speakers. Doesn't matter if it is toslink 1,2 or coaxil 3,4,5. I've tried messing with all the setting and turning off and on, unplugging. I guess it would be a radio hiss, but since the default station is actually a station, that is what I am getting picked up (88.5). Any idea what is wrong? Thanks |
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Silver Member Username: EramseySouth carolina United States Post Number: 393 Registered: Feb-05 | Return it professor Dave. Take some of your speakers and a digital cable and a component which has a digital output, cd.dvd,etc. If the dealer gives you any problem with you wanting to do this or another t773 does the same thing promptly get your money back and shop elsewhere. |
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Silver Member Username: Riches1Atlanta, GA US Post Number: 194 Registered: Apr-04 | You might be picking up some RFI (radio frequency interference) through an input to your receiver. From what I have read about NAD receivers, they are extremely sensitive to this, to the point of becoming problematic. Speaker wires are relatively immune to RFI, but interconnects are susceptable. Consequently, my first suspect would be either the Toslink or the Coaxial cable. What brand of Toslink and Coaxial cable are you using? This article may be helpful as well: http://www.bluejeanscable.com/articles/humrejection.htm |
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Silver Member Username: EramseySouth carolina United States Post Number: 395 Registered: Feb-05 | Yes this is a possibility although rather unlikely in my opinion. In the dozen or so receivers I have owned over the past decade I have never encountered this problem. PD we need to know is this a "hiss" or actual radio-music and voice coming through the digital inputs. Cables can be bought now for as little as $10-15 with often 2 copper woven shields and another foil shield. This has been proven by the industry to reject over 95% of RFI and provided equipment is not used in strong magnetic field area, over 95% of EMI as well. Inputs on a receiver should not suffer noise problems from stray RF signals. This almost completely preventable in a $15 cable and highly unacceptable in a receiver of that pedigree and price. Of course this leaves the other 5% of rare cases, perhaps PD falls into this category. PD try reorienting your radio antenna further away from the receiver taking care not place the ant. near power cords. If this does not help then you should do this. Unhook everything from the receiver except one source component and make a optical digital connection between the source component and the receiver. Optical digital cables are plastic fiber or glass so they are not conductive or inductive and thus immune to RFI or EMI. The only other thing that should be hooked to your receiver is your speakers . Play the source component and have the volume low but high enough to hear material. If you still hear the radio,voicesand music through the speakers when the digital source is playing then their is a "leak through" signal inside the receiver between the tuner section and the preamp. In this case return the unit promptly and get another and check for this problem again with the same setup. If this noise is a mere "hissing" sound then this points to noisy preamp or analog section in the unit, very dissapointing for an $1800 receiver which should have a dead quiet noise floor. Either way I would return the unit and give another one a final chance but draw the line after that. |
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Professor Dave Unregistered guest | Thank you all for the replies I use Ixos brand as well as bettercables brand of toslink and digital cable. So, they are not cheap cables. My sense is that there is a "leak through" in the unit. I own 3 other NADs and have not had this problem before. Go figure it is with the flagship. It is an actual radio station that is leaking through. I don't even have the FM antenna attached. I will swap it out for another and see what happens. I also recently bought an NAD C372 and the entire left channel ( A + B ) came Dead on Arrival. If you think of anything else this might be, then please contribute. I'm pretty positive that this is a "leak through". Is that what I call it when I return it? |
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Silver Member Username: Riches1Atlanta, GA US Post Number: 195 Registered: Apr-04 | OK, it's obviously not the quality of your cables. Those brands should all have adequate RFI foil shielding. What about the way they are situated behind the reciever. Eric makes a good recommendation about isolating your antenna, but also consider all of your other interconnects that could act as an antenna. Here is a good link that may also be valuable: http://www.audioholics.com/techtips/audioprinciples/interconnects/connectiontips 101.php I have implemented about 90% of the measures recommended in this article. All of my speaker wires, power cords, audio interconnects, etc. are individually segregated using various diameters of split loom tubing. What about a power conditioner? Are you using one of those? The wiring in your walls is one giant antenna. |
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Bronze Member Username: DarySao Paulo Brazil Post Number: 73 Registered: Apr-04 | Professor, When I had a 773 I solved this problem using a ferrite core on the subwoofer cable, placed as close as possible to the receiver. |
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forgotten username Unregistered guest | Search on the board for nad and hum you'll find pages about is it... - a ground loop? - "faulty" cirrus dsp's on early production of the T753 (a quote from a nad engineer somewhere from memory) - other specific comments on the dsp and humming - power supply capacitor upgrades - I've returned 8 units, NAD is rubbish - I've never had a problem I love NAD |