Fast choppy thrashing noise from new 4k blu ray player

HiFi Dave

Novice Member
I bought a new Panasonic DP UB9000. Worked fine for several days with HDMI lead to TV. I then connected an optical lead from TV to my DAC then to amps and speakers. This worked for a bit but now mostly gives a horrible distorted noise instead of audio from disc, not even close to being music or speech etc., just sheer noise but mid/high pitched not mains hum. But sometimes it works! What the hell could be causing this? I already posted an issue with this system several months back with no known cause where I couldn't place a component to the right of my preamp/power amps but could on the left! This is doing my nut in. How is it possible to have such a problem when noone else seems to have had it?? Is it the blu ray that's defective? Is it the optical lead? Is it the placement of the bluray player? Is it the disc? Is it a power problem? Is it my TV? All components are less than 2 years old except my amps.


The three cheapest and easiest things to try is a factory reset of the player, a replacement optical cable - under a tenner, and test the DAC with another digital source


Distinguished Member
Since your unnamed DAC probably doesn't know how to decode Dolby / DTS / whatever (very few do, but check the manual anyway) you need to ensure the signal being sent from the TV to the DAC over the optical lead is PCM (2.0). This can and must be configured in the TV, but depending on the unnamed TV may also need to be configured in the DP UB9000 (so try it there too).

You should also check that the optical cable is properly seated at both ends. The TosLink connector does not have a particularly reliable clamping mechanism and tends to come loose fairly easily. Optical cables have a minimum bending radius, if not respected the cable will suffer damage. If neither of the above suggestions work, try a new cable and be careful with it. Better cables will indicate the minimum bending radius.

BTW, when asking questions, it always helps to fully identify all involved components - it takes the guesswork out of answering.

wine man

Active Member
Nail on head Mark.Yudkin. A 2 channel system can't decode multi channel so the DVD source must be changed to PCM.

HiFi Dave

Novice Member
Thanks. I was able to change Blu ray out to 2 channel Dolby Digital (stereo), but that didn't work either. The wierd thing it did work for a bit then stopped and gave this horrible noise. I'll check TV settings.

DAC is Jay's Audio DAC 2 Signature, so can take very high res digital stream
TV is curved UHD 4k Samsung (about a year old)
Amps are MF a308CR Pre and 2 powers.

Also, I understand that all components need to get power from the same wall outlet, but if you use an extension lead in the room to plug components in at different points in the room, does this have the same chance of causing a ground loop? I don't think this specific problem is a ground loop, but that's another issue I have with components on right of amps (but oddly not on the left!).

Hifi when hiend can be complicated enough but home cineme is something else!
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Distinguished Member
If you have it connected like this: Blu-ray > HDMI > TV > Optical > DAC

Then you need to apply settings in the TV to ensure that it is outputting Stereo PCM. It may be one setting, or it may be two like in my LG TV, which had me foxed for a while the other day.

The setting could be called audio/sound, format/output etc. If in doubt take screen shots and people will help.


Distinguished Member
Thanks. I was able to change Blu ray out to 2 channel Dolby Digital (stereo), but that didn't work either. The wierd thing it did work for a bit then stopped and gave this horrible noise. I'll check TV settings.
Dolby Digital cannot be decoded by your DAC (see the specifications at DAC2-MK3 | Jays Audio) and hence it will sound exactly like you describe it if you do feed it Dolby Digital.

You need to switch your TV and BD player to stereo PCM, as accepted by your DAC. The good news is that every TV and every BD player necessarily supports stereo PCM output, but it can occasionally be a bit messy to find the setting in the menu.

A ground loop sounds as a 50Hz hum. You may or may not have one, but first you need to set your sources to PCM so that you can find out if you have a hum.

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