I've read the recent posts about Hum and noice on NAD receivers in the 7x2 line. I recently had a NAD T742 of my own. It had a clear low-frequent hum in center speaker in all sound modes - this was also present if all devices (excluding speaker ;0) had been disconnected the receiver. It had a peeping tone especially in the right speaker, when DVD was on. This tone was present in all modes with a coax (digital) connection between DVD and receiver - and in all surround modes if the DVD was connected with phono cables to the receiver. There was no peep tone in stereo/phono connection mode.
I tried a different T742 at the dealer - same s..t !
I swapped it for at T743 - dead silent ! No hum no peeping tone, and they lived happily ever after.....
But something is bugging me. I think the 743 is sounding harsher/harder than the T742 - it isn't as warm sounding as its predessecor IMO. It is so far just a theory, as I havn't heard them back-to-back.
I am no Hi-Hi expert, but from what I understand, one of the reasons for NAD quality in sound on their surround receivers is, that they use analogue components for stereo sound, and not IC's, where the competitors often use the the IC of the DSP to give stereo signal also.
This reduces risk of noice, but gives a more cold/digital sound.
My theory is this: NAD has ackowledged the problems with the T742 (in silent that is, nothing official has been posted to my knowledge). But they have had problems getting the analog / digital components working together without some noice problems, so they have "digitalised" some of the stereo processing, giving less noice, but not as authentic a sound in stereo mode.
Does someone have experience with swapping a NAD T7x2 for a T7x3 receiver, and could you give me a comment on my theory . Maybe I am just crazy - I am getting a bit paranoid after the problems I have been having
Hi I have had the 742 since September 2003 and have not seen either of the problems you mention. In fact the 742 has not even had a software upgrade since it was released.
Did you change/rewire anything in your setup when you switched to the 743? Also when you say "dvd was connected with phono cables to the receiver" do you mean RCA connectors?
Speaker wires touching the body on the receiver and power quality and cable path can be reasons for hum...
I havent heard a 743 yet, so cant respond to your comparison query.
I've also had a 742 since last fall. I do have a small hum coming from the center speaker if my TV is on (10 year old 32" tube). In fact, the hum is present with the receiver off and TV on, presumably because of wiring paths...I haven't done anything about it since I'll be moving my system to the basement very soon and it's not noticable unless I put my ear about 8" or so away from the speaker anyway. There is no noise if I turn off the TV. There is no noise in stereo mode or any noise coming from any of the other speakers, other than a small hiss if I put my ear right up to the speakers, this was the same with my previous receiver (H/K AVR30).
If I were you I'd give the 743 a few weeks or so and see how you like it. I'm sure my 742 sounds a bit warmer than when I first got it but of course that could just be my imagination, or maybe it was those expensive directional bi-wired speaker cables I bought a while ago .
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