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New member Username: OknessadPost Number: 9 Registered: May-04 | Well I'm sure I'll hear a bunch of told you so's on this thread but I'll share my story anyways. I got my shipment of NAD and PSB gear today and excitedly set it up. I turned on the NAD and tuned in a radio station just to make sure I wasn't dealing with a DOA situation. Worked fine, sounded fine, good deal. I moved on to a CD on a coax cable and nothing... Hmm, I must not be doing this right, its brand new. I looked in the manual and made sure all my digital settings were correct. Still nothing. Then I thought I'd throw in a DVD and see if maybe it was just some weird CD fluke. The dvd loaded and proceeded to output a odd digital noise type of sound. Well, that clued me in that something was quite awry here. At this point I called up David at DMC and he was there as always and extremely helpful. We tried a reset, unplugging etc etc and nothing. So he said ship it back to me and as soon as you give me the tracking number I'll have another one on the way for you. I was very pleased at this. I have no reason to be upset at DMC as they are just doing their job and a damn good job at it I'd say. As for NAD... I still am excited to hear it but the fact that I will have to get another unit is just sad. I was the one saying you can't trust everyone saying they don't work yadda yadda yadda and look what happens to me. How about that? It was a refurb unit, however, this makes me more scared to buy an untested new unit. I'll try and keep everyone posted on the situation and how it sounds when i get a WORKING one. On a better note, the PSBs arrived safely and are beautiful although I'd rather be listening to them right now instead of looking at them... Later! |
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TDK Unregistered guest | Does DMC pay for shipping charge both way or you have to pay for shipping it back? |
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New member Username: OknessadPost Number: 10 Registered: May-04 | No he didn't pay for them on the way back but he will pay for it coming back here. To make up for that he is throwing in a free Tara Labs Digital Coax which equals about the price of shipping for me. I should get the NAD back around next wed or so. David said he'll make sure and test out this unit before sending it out so I should have nothing but good things to say next week. |
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Gold Member Username: John_aPost Number: 1017 Registered: Dec-03 | oknessa, The "digital type noise" should never be audible, and to me suggests something wrong with the Digital Signal Processor. There is a history of T752 DSP problems on this forum, but I thought NAD, and the dealers, now had this nailed. I might have tried confirming the "digital audio out" settings on the DVD-player, and, just maybe, have tried an optical cable, or a different co-ax (an audio RCA will do for a test). But it sounds like Dave knows his stuff (wish all dealers did), and you are probably taking the only sensible route. If Dave is actually going to try out the replacement, then that is another sign of a good dealer. |
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Bronze Member Username: OknessadPost Number: 11 Registered: May-04 | I did all the above mentioned things. Tried optical, tried a different coax. It was definately the receiver. No doubts. The receiver was able to recognize that there was a stereo signal but never would play. And with the dvd, the noises made were like those you'd hear if you connected a dolby digital soundtrack to something not cablably of decoding it... just the 10001110101 of the digital bitstream heading right to the speakers I guess. I'd have to agree with you on hypothesis of a DSP problem. I thought these were solved too. Perhaps it got banged around too much in shipping? It was a refurb but I thought that meant they'd test it before sending it back out? On second thought, perhaps it was an unrelated problem (say a dead channel), they fixed it, tested the new channel and sent it out unaware of the other problem. All I care about now is getting the new one. This one better work or else its back to the drawing board on what receiver to buy. |
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Gold Member Username: John_aPost Number: 1021 Registered: Dec-03 | Ok, oknessa, I understand the position! Seem like you tried more than most to find the answer youself. What I would look for in a REALLY good dealer is for him to explain to me what went wrong. Good luck. Please let us know how it goes. |
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Bronze Member Username: OknessadPost Number: 22 Registered: May-04 | I got the new NAD today and I must say it works wonderfully. 2 channel stereo is superb and can drive those Image 6Ts like nobody's business. The only problem I've run into is that I decided I'd try out a dvd so I put in Ronin for its wonderful car chase scenes. Well, I plugged my sub in and plugged the sub cable in and immediately when I started up the disc a fairly loud hiss/humm (it's coming from the tweeter so hiss is probably more accurate... almost a clicking hiss). At first I started cussing out the NAD thinking the dolby digital was having a hum problem but after thinking about it I realized my sub might be the culprit. I unplugged the sub cable and the hiss vanished. The interconnect is a decent quality monster cable. It was 40 bucks or so and I'd hate to think thats the problem because I don't want to pay more for a cable... Could it be the sub itself? It's a Klipsch KSW-12 so its not a crappy sub. I found that after I unplugged the sub cable and then plugged it back in again a minute later the hiss had gotten quite a bit better. I don't know what this means but the DVD was then watchable as it was not audible from the listening position even in quiet spots with volume loud. But, the fact that the hiss was still there bothered me, I was just relieved it was not loud as it started with. Any ideas and thoughts would be greatly appreciated. I don't really have another sub to swap in to see if its causing the problem. One thing to note is i didn't unplug the sub cable from the receiver, just from the sub so it makes me think its not acting like an "antenna" as others have had problems with badly shielded cable. Seems like the sub might be the problem... Which sucks because I wasn't planning on replacing it as its a perfectly fine sub. Jace |
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Gold Member Username: John_aPost Number: 1137 Registered: Dec-03 | oknessaD, Try re-routing the sub cable, to keep it away from lamps etc and anything that might give off an electromagnetic field - its fundamental will be line frequency (50 Hz Europe; 60 Hz N. America). I think it can still be the cable, working as an antenna, even if it needs the sub at the other end in order to pick up the field. Fingers crossed with your receiver. You deserve a good one, this time! |
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Bronze Member Username: OknessadPost Number: 23 Registered: May-04 | by fundamental do you mean thats the frequency the hum would occur at on the speakers? I don't know much about hum and where it comes from other than I want to get rid of it! This is definately a higher pitch than 60 hz as it comes from the tweeter as more of a fuzz or hiss. It is much better now actually after listening for awhile. It seems to be getting quieter for whatever reason. I'll try rerouting the cable and keeping away from as many AC cords as I can. I appreciate the help as always John. |
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j. vigne Unregistered guest | Here are a few things to try if you like. First, simply change out the cable completely. Go get the cheapest interconnect you can find for the length you require and try it in place of your existing cable. Maybe a friend has one you can borrow. If that changes anything, you have a connection problem that may not be the cable. If the cable is picking up a stray 60Hz signal it would be coming from the subwoofer as that is the frequency where the sub is operating and depending on the hook up it would be coming from the woofer's in your front speaker(s). You don't indicate whether this noise is coming from both speakers or just one. I'm going to guess, since the noise diminished quite a bit when you made a disconnect and then a connection, that you have a dirty connection at one or both ends. This creates a diode effect that is responsible for all kind of strange apparitions and comings and goings in a system. An RCA connector is not what is known as a self wiping design (like an XLR) but by removing the connector you would have disturbed the offending substance enough to minimize the problem. The solution to this problem would be a Q-Tip and a bottle of contact cleaner. This can be anything from the stuff they sell at Radio Shack to something more exotic from a place like Audio Advisor. If you live in a city with a sound reinforcement company around you can check with them, most carry something like Contak since dirty connections are a common complaint in that business. Clean all connections according to directions on the container, use as little as needed to get the job done. Too much can create other problems. Clean both + and - connections. If this does not solve the problem tell us about what connections you are using on the reciever and sub (LFE, sub out with Y connector, low pass in, etc.). An unlikely but easy to try solution would be to reverse the direction of the cable as some cables have the shield connected at one end only and this could be responsible for picking up stray fields from all sorts of sources. I have a cable that every now and then will pick up a radio staion at a very low level. I can't get the signal to go away by anything I do but it will disappear on its own in an hour or a few days. It seems to be effected by humidity. I have learned to live with it since it is so low in level but when you first walk in the room you think someone is talking to you. |
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Gold Member Username: John_aPost Number: 1140 Registered: Dec-03 | oknessa, "by fundamental do you mean thats the frequency the hum would occur at on the speakers" Yes - the fundamental is the lowest frequency, but it always has many harmonics, they are higher. However, if the whole effect is more of a "Hiss" then I am not so sure this is the problem. I had the problem I describe, I found even changing a slide switch on a floor lamp, when it was switched on, would start off the hum. I moved the cable and the sub everywhere I could think of. Early T753 models were very sensitive to field-induced hum, and NAD changed one component to fix it. There is a history of this, here. Take a look at TCSmith's thread from last Oct NAD 752 V1.22 what are the improvements? and see if it sounds like the same problem. He gave a blow-by-blow account. First, though, do what Jan says. I bought the cheapest possible 15 meter sub cable a which ago (must be 75 OHMS) and it works better than any shorter and more expensive one i had before. Jan, You must live close to a radio transmitter. That would drive me crazy. Have you tried breaking the grounding of the screening completely, or having it grounded at both ends? I am very suspicious of this idea of having arrows on cables. Which way the "Signal" travels is in our minds, not in the electronics, I always think. |
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Bronze Member Username: OknessadPost Number: 24 Registered: May-04 | I appreciate the thoughts. I will try to obtain a contact cleaner. I will also try switching which end of the cable goes in which end and I will report back if either of those two problems fixes anything. I am glad that I have managed to isolate the only noise in my system to my sub/cable as that makes it a whole lot easier to deal with then looking blankly at a mess of wires and wondering which it could be etc. My question now is would replacing the sub help? There is another KSW-12 in my house (my dad's) so I'll try switching them out and see if the problem goes away. If it doesn't go away though I still haven't ruled out that its just a bad design somewhere in the sub since they are the same one... I also have one other sub cable I can try that happens to be less expensive as J. mentioned. I'll post back in an hour or so with any results. Thanks for all ideas and suggestions. |
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Bronze Member Username: OknessadPost Number: 25 Registered: May-04 | ok quick update. I went and grabbed the other Klipsch and plugged it in the same outlet and used the same cable and there was no noise until 0dB and that was right next to the speaker... take a step back and no noise at all. So my immediate thought was dammit, its my sub. I moved my sub back in place and plugged it back in and put the cable in and there is noise, but significantly reduced... I am now very much leaning with the idea that the contact is dirty. I'm now off to find me some contact cleaner. BTW, is there anything that can be used without going out and buying some audio specific product? |
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Bronze Member Username: OknessadPost Number: 27 Registered: May-04 | hmmm... Here's something that I probably should have mentioned earlier but never tested. This humm/fuzz/noise occurs even when the sub is unplugged or powered off as long as the sub cable is attached to the input. Now what are your thoughts? Does that mean that for sure the cable is just gathering surrounding interferrance? As soon as the cable is disconnected the sound is gone and the only noise that can be heard is when the receiver is turned to very high levels. But plug the sub back in, even when the sub itself has no power or plug attached and its back! The phantom hiss lives on! |
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Bronze Member Username: OknessadPost Number: 32 Registered: May-04 | Just to update before I forget to... After working with a couple different sub cables and subs for a number of hours the noise has gotten significantly smaller if not gone. I certainly can't hear it from my listening position anymore and have to get right on the speaker to hear it. That, to me, is within acceptable limits for some noise. Thanks everyone for ideas and help. I appreciate it much. |
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New member Username: JamespMansfield , TX USA Post Number: 4 Registered: Apr-04 | oknessaD-I am glad to hear everything is beginning to work right. I am curious as to what the final resolution was? Did you have to go to a different sub and cable? I do not have a sub yet and may need to borrow my neighbor's to test it out on my NAD T752 that I just got a couple of weeks ago from DMC. |
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J. Vigne Unregistered guest | John A. - In reference to the cable directionality: Though some manufacturers use the idea as a marketing device, it, to me falls into the category of throw it against the wall and see if it sticks. It would never be THE reason to buy a particular cable over another but if the manufacturer's logic and attention to detail convince me they have done a good job with their cable design and construction, arrows simply become another "benefit". Most commonly, though, the arrow is used to indicate a cable that has its shield lifted at one end (normally the input side) to try to eliminate stray hum feilds. As to my interference problem, I've tried everything I can think of to eliminate the problem included placing a braided 100% shield over the outside of the cable and RCA. Nothing has stopped the noise, but it is very intermittent, on one channel (mono amp) only and swapping cables side to side (L to R) has done nothing. It comes and goes at will, is very quiet until you walk right past the speaker and it gets your attention. I do live about ten miles from Signal Hill where 90% of our local antennas are located. Unfortunately it is a rock station that I never listen to on my own. Maybe the forty year old Macs are trying to relive their youth. Who knows? I've put it down to sun spots and stopped worrying. |
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Bronze Member Username: OknessadPost Number: 38 Registered: May-04 | The final solution ended up being... who knows. I cleaned the contacts and it was not immediately helpful, i switched cables, not helpful and did anything else I could think of. In the end it just started working. I can't explain it. Perhaps I inadvertantly moved an offending power cord or something without even noticing. So the moral of the story is, keep trying? It worked out for me I suppose and I am extremely pleased now that my sub is integrated seemlessly into my music system. In fact, I think i'll go give it a listen right now Jace |
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Gold Member Username: John_aPost Number: 1209 Registered: Dec-03 | jan, "the arrow is used to indicate a cable that has its shield lifted at one end (normally the input side)" I still think that "input" and "output" are in our heads and have no meaning in electricity, where there are just circuits. If someone with more knowledge can put me right on that.... Re unwanted radio reception, when I bought my first "system", a cheap Philips all-in-one-turntable-amp plus cardboard speakers (no tuner at all), I lived just about two miles from Crystal Palace radio transmitter in South London. After dark, there was no way to stop it pouring out multiple radio stations. I tried everything, and failed. The signal was so strong I could probably have wired in an accumulator and saved on heating bills. Going back to our perennial topic, I discovered some good music on that system, and look back on it with affection, though the sound must have been goddam awful by the standards I have now. Some of those LPs I have just got out of storage and they sound terrific 30 years on, by any standards, even after having been played many times, long ago, with that ceramic cartridge. I guess the stylus did not really penetrate the grooves, and any wear to the LP had no effect on the wonderful sound that is still there. |