AV system sound problems
Posted by: Neil Bennett on 23 June 2007
The set-up is an all Naim one of DVD5, AV2, 200,175, Allae fronts, Axess centre, NSats/stands rears and an N-Sub. Just added the DVD5 recently (upgrade from an Arcam DV88). Had problems with the DVD5 DVI settings originally (now resolved), but just got a DC1 cable to upgrade from a chord cable and reconnected everything after a couple of weeks of inactivity. Unfortunately now there's a crackling all the time (whether or not any music/speech is coming through them, though when it is sound is thin/poor as well as the crackling) from the Allaes which is only alleviated by switching off the 200. Sound through the centre is fine. I've tried re-making all the connections but to no avail. Switching N-Sats to the front has no effect (i.e. still crackling). So is it the 200, the cable, have I blown both speakers somehow or what?
Any ideas?
Neil
Posted on: 23 June 2007 by AV@naim
As a diagnostic step, if you connect your surround outputs from the AV2 (remembering to power down the 200 or remove the speaker cable and assuming the 200 is on the front channels), to the 200 rather than the fronts, does it still have the same problem?
This will tell us if the AV2 or 200 is the faulty unit
Posted on: 25 June 2007 by Neil Bennett
OK, thanks. I will try when I get the chance and let you know. Even with the AV2 in standby, it there is a humming/buzzing from the Allaes.
Neil
Posted on: 25 June 2007 by David Dever
If you disconnect the TV or projector from the DVD5, does the problem go away?
Posted on: 25 June 2007 by AV@naim
quote:
Originally posted by Neil Bennett:
OK, thanks. I will try when I get the chance and let you know. Even with the AV2 in standby, it there is a humming/buzzing from the Allaes.
Neil
Its prob not the AV2 then...
follow Dave's advice, you may have an earth issue. Is your aerial to your TV earthed or isolated?
Posted on: 26 June 2007 by Neil Bennett
Will try tonight, but last night's experiment revealed that the Allaes were fine with the rear sound from a DVD when I connected the surround out cable from the AV2 to the 200, which itself would imply a problem with the AV2, wouldn't it?
I powered everything down before dis/re-connecting, and initially on re-switching on, it was fine and the problem only re-emerged after ~20 mins, implying it's only an issue after warming up?
Any further suggestions?
Neil
Posted on: 27 June 2007 by Neil Bennett
Further detail. When connecting the fronts cable to the 175, the humming/crackling transferred to the N-Sats, agian implying an issue with the AV2 (?). No difference when disconnecting the DVD5 from the TV, althought the effect seemed less bad when also disconnecting the aerial from the TV and only using Sky HD. I should know about the aerial earth/isolation, but I don't. How do I check?
Neil
Posted on: 27 June 2007 by AV@naim
-are you using a naim 4:4 lead or other brand?
-you may have an oscillation issue on the front channels of your AV2.
If you "borrow" a 4:4 active lead from your dealer, this may help. failing that you may need to get your current 4:4 lead slugged
Most aerial boosters/amplifiers are isolated these days, so unless you live somewhere where the signal is distributed (i.e. blcks of flats etc), it should not be an issue.
Posted on: 27 June 2007 by Neil Bennett
All the cables are Naim ones as supplied with the AV2/175/200/DVD5 (+ a DC1 and all NACA speaker cables/mostly Naim plugs). The only non Naim cables are the DVI-HDMI one from the DVD5 to the TV, the Optical one from the HD to the AV2 (both QED) and a couple of phonos for analogue sound (Chord), which Naim don't make AFAIK. The aerial/amplifier was put in new 4 years ago and it's a detached house
What exactly do I need to ask the dealer for/how do I get a lead "slugged"?
Thanks,
Neil
Posted on: 28 June 2007 by AV@naim
quote:
Originally posted by Neil Bennett:
What exactly do I need to ask the dealer for/how do I get a lead "slugged"?
Thanks,
Neil
Is it the lead?...
a slugged lead has low-ohm resistors in line with the signal (normally 22r). This is to "load" the lead slightly to stop the setup picking up interference. Chord co can probably do this or contact naim direct.
Try borrowing an active 4:4 first though as this has a slightly different capacitance over the standard version. This will hopefully clarify if the issue is caused by interference/oscillation and not something else.
Is it the aerial?...
Checking aerial installations can be slightly tricky in some setups. If other TV's connected to the amplifiers "float" chassis-wise and your aerial is not mains earthed, then you can get 1/2 mains potential shocks from the aerial lead! The advice here is get a competent person to check if your aerial setup is mains earthed or not if you are not sure.
If the coax outer is earthed, and its causing the issue, then you can get in-line isolators from various electrical vendors
