SuperNait 1 issue with deteriorating SQ
Posted by: winkyincanada on 22 August 2018
My SN1 has developed a bad habit. I run a SPDIF from my TV to a digital input on the amp that is mapped to a selector button as usual. What happens is that over about 10 or 15 minutes, the SQ deteriorates and becomes scratchy like a poor connection somewhere. Switching to a different input, then back to the offending one clears it up instantly, but after 10 to 15 minutes, there it is again.
Is the input switching on a SN1 fully solid state or are there relays? Any ideas? Time for a service? Amp is now 9 years old. I might add that I'm running it with an even older HiCap, which almost certainly needs a service.
Does it only happen with the TV connected? Is it optical or coax?
I'm wondering if the digital signal from the TV is drifting badly and causing the DAC difficulty.
Richard Dane posted:Does it only happen with the TV connected? Is it optical or coax?
I'm wondering if the digital signal from the TV is drifting badly and causing the DAC difficulty.
It's only with the TV. Optical.
I had the same with my Supernait. But sorry to say I did not find a solution, when i got an NDX I fed the TV optical into that & the problem was gone. During the time it was going on I came to the conclusion it was something in the DAC section, maybe Toslink related as other digital feeds via wire such as iPod sounded OK. .......... sorry not helpful as such but just some info to add to yours.
TV digital outs are often very poor - it may be that the Supernait DAC starts to find difficulty in synching clocks? Or, as mike speculates above, maybe TOSLINK related. Possibly one for an engineer to comment on.
Winky, as I suspected, the R&D technicians reckon it's the TV digital clock drifting badly (not uncommon with TV kit unfortunately - must cost them pence!). The Supernait's PLL only has a limited range before synching becomes difficult. If the TV clock drifts too far though then the Supernait DAC will automatically switch to bypass mode. Unfortunately you can't force this yourself. However, if you leave it long enough to get it to switch to bypass mode then it should stay in this mode. So have you tried leaving it for long enough to see whether the sound then suddenly improves?
Otherwise, they have recommended a better optical cable. Is it particularly long? That can cause similar issues.
The ideal fix is of course to have a TV with a better digital output...
Richard Dane posted:Winky, as I suspected, the R&D technicians reckon it's the TV digital clock drifting badly (not uncommon with TV kit unfortunately - must cost them pence!). The Supernait's PLL only has a limited range before synching becomes difficult. If the TV clock drifts too far though then the Supernait DAC will automatically switch to bypass mode. Unfortunately you can't force this yourself. However, if you leave it long enough to get it to switch to bypass mode then it should stay in this mode. So have you tried leaving it for long enough to see whether the sound then suddenly improves?
Otherwise, they have recommended a better optical cable. Is it particularly long? That can cause similar issues.
The ideal fix is of course to have a TV with a better digital output...
Thanks Richard. The Toslink connection at the TV is poor/loose. It doesn't click into place anymore. I'll bet that is what's causing it. I assumed that the Toslink was pretty much pass/fail (works or doesn't), but seems according to the advice form the techs, not so. I'll spend some time getting a more secure connection (somehow making sure it is square and pushed fully home) and see if that fixes it. The cable is a couple of metres long, and is certainly decent (well made), but not high-end. Interestingly, last night it was all fine.
winkyincanada posted:Richard Dane posted:Winky, as I suspected, the R&D technicians reckon it's the TV digital clock drifting badly (not uncommon with TV kit unfortunately - must cost them pence!). The Supernait's PLL only has a limited range before synching becomes difficult. If the TV clock drifts too far though then the Supernait DAC will automatically switch to bypass mode. Unfortunately you can't force this yourself. However, if you leave it long enough to get it to switch to bypass mode then it should stay in this mode. So have you tried leaving it for long enough to see whether the sound then suddenly improves?
Otherwise, they have recommended a better optical cable. Is it particularly long? That can cause similar issues.
The ideal fix is of course to have a TV with a better digital output...
The Toslink connection at the TV is poor/loose. It doesn't click into place anymore. I'll bet that is what's causing it.
I have had quite a few bad connections using Toslink. I've had more cables that don't click in to place, than one's that do.
Quite often fumbling around trying to align the male plug to the female socket. Not always that easy.
Meerkat posted:I have had quite a few bad connections using Toslink. I've had more cables that don't click in to place, than one's that do.
Quite often fumbling around trying to align the male plug to the female socket. Not always that easy.
I'm going to make a small plastic(?) bracket to hold the cable dead square to the socket, and to both take the weight and to provide firm upward pressure. (Cable plugs in vertically upwards, so it wants to fall out).