Have recently got my new T10, with one reason for upgrading from my previous T8 being the external clock connections which I wanted to use. The idea was to use an external master clock to link my network switch, the T10 and the downstream DAC (Hifi Rose RD160) with a synced click signal. The RD160 clearly locks onto the clock signal and indicates as such on its display. For the T10 it’s less clear. I have connected a 50 ohm BNC cable to the corresponding input and selected the appropriate menu option (50 ohm/10Mhz) via the Settings display. It would seem that there is no way of confirming that all is working correctly, such as the “lock” confirmation in the HiFi Rose display. So to test the status I disconnected the BNC cable completely, whilst keeping the menu setting for the external 50 ohm/10MHz clock input. The music played on, which I was not expecting. One conclusion is that the T10 never actually uses an external clock and that whatever the settings the clock signal comes only from the internal OXCO clock. Has anybody else tried this?
I have a T10 and use it with an external clock, the LHY Audio OCK-2S . I connect via a 50 Ohm BNC cable and use one of the sinewave 10 MHz outputs. Like yourself I select the clock source via the device main screen or via the control app. There is one small visual indicator on the top left of the standard home screen, it simply says clock inside a rectangle. If you disconnect the clock cable, then a small red x will appear on this area telling you it expects a clock but doesn't find one. If you try to generate music output from the T10 in this state, you simply hear nothing, it behaves as if muted. I hear a difference when I switch between internal OCXO and this external clock. So all works for me but what you describe is not right. I am on firmware 1.1.60 by the way.
Thanks for your reply. I have just done the 1.1.16 update and hoped that this might address my issue. I followed what your said and did see the small “clock” sign on the Home Screen (which I hadn’t noticed as before). When using the internal clock this symbol disappears - which suggests the symbol is indicating the use of an external clock. As you said, if I then unplug the BNC cable I get a red X on the “clock” indicator - but for me the music keeps playing! Starting a new track with this red X on screen I get normal playback. Very strange. Would you be able to try seeing what happens if you are playing music using your external clock connection and then select one of the other clock settings from the screen (or app), such as 75ohm/25MHz? Thanks again.
I have tried toggling the clock source options as music is playing, the music completely mutes if the wrong setting is selected. The now playing screen is still updating its progress bar and apparently playing but no actual audio is heard. I am using the I2S output and I have the x8 upsampling option in use. If I turn the upsampling OFF, then no change in the behaviour of the clock toggling occurs. Incidentally your firmware is not 1.1.16 as you say but 1.1.60 ?
I have about the same setup - T10, Hifi Rose RD160, LHY OCK-2p. I think the T10 just switches to default (internal) when no external clock is attached. When you switch with the app from internal to external, you should hear a change in sound (to the better), the RD160 is that resolving.
Well, I tried following your setup as closely as possible and found that using I2S (I had been on USB) I got the expected behaviour - music with either the internal clock or my 50Ohm/10MHz external clock, and no music playing if I selected any of the other clock options. Also there is a slight pause in the sound when switching from one to other, which is what I was expecting and was not getting previously. So I'm not sure if this is only a I2S thing (and I will go back and try USB again) but for now I'm happy that all is working correctly. Thanks for putting me on the right path!
So, I went back to test the USB connection from T10 to my DAC and found that the strange clock behaviour was back. When running in USB mode I can pull the BNC cable completely out of the T10 connection and the music will continue to play. The small red X does appear on the home screen "clock" icon but it makes no difference to the continuation of the music. In I2S mode, pulling out the clock cable immediately stops the music. So it appears that, at least for me, the external clock implementation only works correctly when using I2S to feed the T10 output to the DAC. Would be interested to hear anybody else's experience with this.
I checked with my T10/RD160/OCK-2p and have the same experience. Using 75 Ohm square for T10 and 50 Ohm square for RD160. With USB connection and clock disconnected, I get the little red clock label, but music still plays. Not with I2S, the sync immediately disconnects. In addition, I can easily hear a positive effect to soundquality with external clock on I2s, but not on USB. Seems to be buggy.
I suppose we could "explain" the USB effect by this being asynchronous so the clock is never being exported unlike for I2S. However I would have hoped that all the digital outputs could at least be impacted by an external clock even if the clock is not being directly exported. So with this reasoning the SPDIF digital outputs should also behave like I2S, as the clock is multiplexed onto the output. Maybe @Zidoo Support-Kim could comment on the situation ?
Two more data points. I tried connecting the T10 to my RD160 DAC via AES/EBU. The result was no interruption to music when the clock BNC cable was removed from its connection on the T10. The result was the same when using S/PDIF between the T10 and the DAC. So for me, the external clock only seems to be actively impacting music playback when outputting to the DAC via I2S.
I can confirm this, using AES the music is not interrupted when you switch external clock to a wrong setting or even remove the external clock cable entirely. So unlike what I predicted, the AES and I assume the other SPDIF outputs are behaving like USB. Only the I2S output is behaving as expected with regards to external clock source switching. This needs attention @Zidoo Support-Kim.
AES/EBU and S/PDIF : These are self-clocking protocols. The audio signal and the clock are combined into a single stream (using Biphase Mark encoding). When you connect an external clock to a device (such as a Zidoo network streamer), that clock is used to synchronize the internal converter or the main processor. If the external clock fails or is disconnected, the device instantly switches to its internal clock to avoid interrupting the data stream to the AES/S/PDIF output. The interface thus continues to transmit the signal. Unlike AES, I2S physically separates the data channels and the clock channels (Master Clock, Bit Clock, Word Clock) onto distinct hardware lines. If the external clock is removed or incorrect, the hardware clock line on the I2S bus is immediately interrupted or corrupted. This causes playback to freeze instantly or results in a total loss of sound. USB: Operates in asynchronous mode. The receiving DAC manages the clock and requests data packets from the T10.
Noted! Thank you for your detailed testing and thoughts. I'm waiting for the dev to confirm: Whether the different behavior is related to the clock architecture of each interface(impacted or not). When the external clock is disconnected during AES/SPDIF/USB output, whether the device is designed to automatically switch back to the internal clock source, or whether USB behavior is related to its asynchronous transmission mechanism where the DAC controls the clock. If any part of our understanding or summary is inaccurate, or if there are any additional details, please feel free to share.
Asynchronous USB is clocked from DAC side so source clock might not disrupt data transfer , but with SPDIF it is strange it is clocked from source. May be T10 has some fail-safe in design that switches clock source.
