Can anyone else replicate this?


#1

Imagine a scenario where a PWT transport is connected to a DSD dac running Yale Final firmware with an HDMI cable. The DSD screen shows a green light for the relevant i2s connector. The other i2s is inactive and therefore shows a red dot. The DSD plays for a few minutes. Then the HDMI cable is unplugged and music stops. But the DSD screen still shows a green dot as if there is an active i2s connection. Only after a reboot, the correct red dot appears. After plugging in the HDMI cable, the DSD plays better than before with improved dynamics, bass and musicality.


#2

While I can’t say I’ve noticed this, others have reported that shutting off the DS and restarting has resulted in improved sound. I believe Ted Smith has addressed this in the past, but I can’t recall his explanation well enough to paraphrase here. Perhaps he or someone who recalls it better will chime in.


#3

I could not find Ted’s explanation. I am very interested to know about both the nature of the problem and its remedy. It is very real and repeatable with my unit.


#4

@makfi, are you saying the whole thing is repeatable, including the quality of the music going from " improved dynamics, bass and musicality" back to some other ‘not quite as good’ sound that winds up getting better again with a power cycling?


#5

indeed


#6
makfi said I could not find Ted’s explanation. I am very interested to know about both the nature of the problem and its remedy. It is very real and repeatable with my unit.
I mentioned a reason that the DS might take a small regression in sound just after a software upgrade (but that would only last, say 10 - 30 minutes.) - the output transformer is subject to a small DC offset during the software upgrade and it takes a small amount of time after that to "degauss" after the upgrade. (The transformer is designed to be overkill and that temporary DC offset has no lasting effects.)

I’m not clear on your experiment itself. You say the music is better when the I2S cable is plugged in: were you talking about playing with, say, USB and while that was playing you plugged the I2S cable in and the sound from USB got better? Are you saying that you are comparing the sound from before removing the I2S cable to the sound after a reboot and adding the I2S cable back? Or something else?

I can easily believe that whatever causes the red/green light to stop working correctly also messes with sound quality and further that that could be in either the FPGA or the control processor. Also I can easily see why connecting a cable could change the sound quality whether it was being used or not - ground loops and all. The sound is usually worsened when that happens, but not always. Without being able to reproduce exactly what you are doing I would only be speculating about what’s happening and at the moment I don’t have any idea how I’d try to reproduce what you are experiencing.


#7

Hi ted,

i only have an i2s connection. can you please check

  1. whether you get green or red light when you unplug the hdmi cable?

  2. if you still get green, can you check if you get red after rebooting? (hdmi is still unplugged)

  3. if you get better sound after rebooting and plugging the hdmi back in?

Thanks in advance


#8

Which I2S input?

Are you unplugging while music is playing?

Are you plugging while music is playing?

Are you playing 44.1/16, DSD or something else?

You are saying that you don’t have any other inputs connected?

Right now isn’t a good time for me to be judging sound quality (noise in the neighborhood.) I’ll rearrange the work bench to get an I2S source in just a little.

I do see the light not going from green to red at times with multiple connections and disconnections. The FPGA doesn’t pay attention to what state the light is in, that’s just the control processor reporting a signal from the hardware. We have seen it missreported in the past, tho I don’t know what the problem is/was or if there’s a known solution to the light itself.

Also I should have asked what the display on the DS reports when this is happening. When the light doesn’t change I hear a little thump and the DS’s display goes to some random other value, e.g. DSD128 or 44.1/24…

At least so far I don’t hear changes in sound quality - but it’s not quiet here at the moment.


#9

thanks for looking into it. as for the questions:

Are you unplugging while music is playing? while music is playing or when the unit is on with no music

Are you plugging while music is playing? while music is playing or when the unit is on with no music

Are you playing 44.1/16, DSD or something else? red book from pwt

You are saying that you don’t have any other inputs connected? yes

Also I should have asked what the display on the DS reports when this is happening. 44.1/24


#10

Yep, the 44.1/24 with a redbook input is the kind of anomaly that I see too. I just don’t seem to have any problems with the sound quality when this is happening. We’ll look into it. Thanks.


#11

i will check over the weekend to see if the issue persists with other inputs (coax, xlr, optical etc) and report back. if incorrect red/green light is an isolated case for i2s (which i believe it is) then the control processor must be treating the inputs differently.


#12

No need. But of course you can if you want…

We can easily reproduce this with the Yale release and it doesn’t happen with Pike’s Peak’s FPGA code so it’s clearly the Yale software FPGA that’s doing something wrong - the fact that it doesn’t happen with USB or the bridge which look the same as the I2S inputs to the FPGA is a pretty good hint where it must be in the code.


#13

I wonder if there is a link between this and the problem I reported.
If the power cord is removed from the DS or the DS is switched off via the back with the I2s cable is still connected, the DS display flashes in light grey color. If I remove the I2s cable the problem is gone.
Seems like some sort of ground issue, but all equipment are powered from the P10.


#14

Hmm, I’ll think about that.


#15

I forgot to say that my problem also existed on the YB and PP.


#16

The bug contInues to exist in torreys as well: the i2s input thinks there is a connection even if the hdmi cable is unplugged until you reboot. And I continue to think/imagine that this brings sonic penalties


#17

makfi;

I am not sure if retaining the green source light is an unintentional flaw.

What happens if you switch off your DS from the rear switch with your HDMI cable still connected betweeen the I2s port and your source - do you also get a flashing DS display? If yes, PS Audio should clearly look into this issue with a higher level of determination because then it is not just my unit that is faulty. I also have the vertical striping that has been reported by many here, but this we all know is a recognized problem.


#18

nope. i dont have that one


#19

I had forgotten about this problem entirely. I just looked at the differences between Pike’s Peak and Yale and don’t see any obvious possibilities except that Pike’s Peek folds the input 24 bits down to 8 bits to save a little space while checking for changes on all of the inputs - I don’t know what kind of pattern this might hide, but there’s a chance that Pike’s Peak was wrong (at least in the FPGA) and that it covered up a bug somewhere else. The relevant code hasn’t changed much at all from Yale to Torreys so I’m not surprised that Yale and Torreys are the same for this problem. If we spin Torreys again I’ll see if I can figure this out, otherwise it will probably be another release. Still the possibility that there’s a sonic difference is intriguing.