Pop/click in transporter playback with recent firmware

[fredgoodman]

I've been experiencing very soft pops or clicks when playing music on an (original) transporter with recent firmware (87).

Further info: my music is all apple lossless. I use a Mac, OS X 10.6.8. SBS 7.6.1. Connection from server to transporter is ethernet (with switch/router in the chain). I have sync (with a SB3) turned off.

The effect is subtle (not loud) and intermittent, not associated with any particular place on any particular track, i.e. not reproducible. It occurs maybe once in an hour. I have never noticed the noise when listening on an SB3 with current firmware.

There was a previous thread about noise on transporter when playing high density (e.g 96/24) files, but this is not my problem; I am playing ordinary CD quality files. Also I already implemented suggestions in that thread to reduce the demand on the transporter CPU by turning off the VU meter and scrolling.

The effect is new, but I'm not exactly sure when this started, so I am now trying previous firmware versions, while keeping SBS 7.6. Right now I am trying firmware 84.

I don't know enough yet to submit a bug report. The purpose of this report is to check if anyone else has noticed the same thing.

[slate]

Just to put some more details onto this....

- Does it happen in the shift of two tracks or while the music plays?
- If in a track can you rewind and hear it again?

Typically when one experience pif/crackle/puf is in the space between two tracks. Especially when the tracks are of different resolution.
From your information it isn't any of the above...

- Are you using an external DAC?

[fredgoodman]

It happens while the music is playing, not between tracks. It cannot be reproduced by rewinding and playing the same place in the track. I am using an external DAC.

I have not done a lot of testing of variables, e.g. different firmware versions, removing the external DAC, etc. This would/will take a lot of time since the problem is so intermittent.

Thanks for your interest in the problem.

[Mnyb]

Alac is transcoded by the server to flac or pcm depending on settings in advanced > filetypes.
As the player does not handle applelossles natively.

try both setting ?

Try another fileformat ,flac to see if it is the serverside handling of alac that is at fault ?

You can not see anything common to these files is it completely random.

No supicius activity in the server.log
No rebuffering, yes ethernet cables and switches can have problems to.

[cliveb]

It happens while the music is playing, not between tracks. It cannot be reproduced by rewinding and playing the same place in the track. I am using an external DAC.

The fact that it happens about once an hour, at random and non-reproducible points, and you are using an external DAC all points to an obvious possibility: the DAC has its own free-running clock which is slowly drifting out of sync with the TP. Eventually there is a buffer over- or under-run in the DAC and it has to resync.

I have not done a lot of testing of variables, e.g. different firmware versions, removing the external DAC, etc. This would/will take a lot of time since the problem is so intermittent.

The first thing to do is remove the external DAC and run the TP's analogue output into your system for a while. After a few days, ask yourself whether you've heard any pops. If you haven't, you know the problem is in the TP/DAC interface. If the DAC has a word clock output, use that to drive the TP. Otherwise, find a way to configure the DAC to slave its clock to the incoming SPDIF signal.

[Phil Leigh]

What is the DAC?

[Craig]

What is the DAC?

It's a box where bits go in and sound comes out!
Soz couldn't resist

Craig

[Phil Leigh]

It's a box where bits go in and sound comes out!
Soz couldn't resist

Craig

ouch ouch my sides are splitting...

[fredgoodman]

Thanks for the helpful suggestions.

I was using the same TP --> DAC setup for perhaps 15 months with SBS 7.5.x or 7.4.x without noticing any noise. This suggests returning to a previous firmware version could solve the problem for me. I'll have to run the experiment for some time to be able to report anything.

The DAC is Berkeley alpha, which does not have clock input or output.

[cliveb]

I was using the same TP --> DAC setup for perhaps 15 months with SBS 7.5.x or 7.4.x without noticing any noise. This suggests returning to a previous firmware version could solve the problem for me. I'll have to run the experiment for some time to be able to report anything.

The correct experiment to try first is not to revert the firmware, but to remove the DAC from the signal path. If the pops remain even after that, *then* you can conclude the problem is the TP firmware. If not, then the problem is in the TP/DAC interface, and lucking on a specific firmware that doesn't exhibit the problem isn't really a solution.

I appreciate that your DAC is probably closer to your heart than the TP, so if you really can't find a proper solution to the TP/DAC interface issue, then perhaps the simplest course of action would be to replace the TP with a Touch.