Zenith Mk3 one channel low by 3 dB

[Zlone]

For some time I have thought that I was not hearing the same levels out of my left speaker as my right. I always figured it is either my room or my old ears. I am auditioning some new, more sensitive speakers that made it more apparent, and so I decided to do some testing. Using an iPhone dB meter and a 1 KHz test tone, I determined that the left channel is down by about 3 dB. First I swapped out interconnect cables and switched sides, etc. to see if it was a cable issue. It was not.

I figured it was my preamp which is a bit older, so I started there. I rigged up a dummy RCA cable and connected it to my Fluke meter to see how the output voltage varied by channel when playing the test tone, and it did, with the left channel consistently a lower value. I went up the chain and tested the DAC output, same issue. Aha, it must be the DAC, but I tested both balanced and RCA outputs, which are discrete on this DAC, and the issue was the same with both. There are trim pots on the DAC, so it could be adjusted, but since it is an issue with both balanced and unbalanced, the issue would be upstream from the the outputs, or both outputs are out of adjustment, which seems unlikely.

So I thought it might be the streamer, and just to be sure I swapped the USB cable, no difference there. It could still be the DAC, but it could be the streamer, and I am unsure how to confirm that one way or the other. All software on the unit is up to date. Any thoughts?

 

[Zlone]

For some time I have thought that I was not hearing the same levels out of my left speaker as my right. I always figured it is either my room or my old ears. I am auditioning some new, more sensitive speakers that made it more apparent, and so I decided to do some testing. Using an iPhone dB meter and a 1 KHz test tone, I determined that the left channel is down by about 3 dB. First I swapped out interconnect cables and switched sides, etc. to see if it was a cable issue. It was not.

I figured it was my preamp which is a bit older, so I started there. I rigged up a dummy RCA cable and connected it to my Fluke meter to see how the output voltage varied by channel when playing the test tone, and it did, with the left channel consistently a lower value. I went up the chain and tested the DAC output, same issue. Aha, it must be the DAC, but I tested both balanced and RCA outputs, which are discrete on this DAC, and the issue was the same with both. There are trim pots on the DAC, so it could be adjusted, but since it is an issue with both balanced and unbalanced, the issue would be upstream from the the outputs, or both outputs are out of adjustment, which seems unlikely.

So I thought it might be the streamer, and just to be sure I swapped the USB cable, no difference there. It could still be the DAC, but it could be the streamer, and I am unsure how to confirm that one way or the other. All software on the unit is up to date. Any thoughts?

New information. I forgot that I had another streamer laying around, an old Sonos Connect, not great but it works. I took the DAC output voltage measurements again using this streamer and the right and left channels, both balanced and unbalanced, were close to identical. So it seems that this is indeed an issue with the Innuos Zenith. Please let me know if anyone has some thoughts on how to further diagnose or solve this issue. Thanks.

 

[frank7036]

I’d be very surprised if the Innuos unit was changing the data values on the USB stream.
You don’t say what your dac or preamp are but I’d be looking harder at those components.
As far as I can ascertain the Sonus Connect isn’t USB compatible so the comparison isn’t apples-to-apples ?
In your comparison between the Sonus and the Innuos I would have thought your dac is using completely different circuits to process the data stream.
In the comparison between SE and BAL outputs, yes I believe the drop in L&R values would be similar in relative terms (BAL should be around x2 magnitude) because the INPUT circuit in the dac is common to both. Any processing of the data stream and conversion to analogue is UPSTREAM of the SE and BAL outputs.

I could be completely wrong about the above and I’m not an electrical engineer but something doesn’t seem to add up to me.
Good luck to figuring it out but if you want to further check you could borrow another USB Streamer/Server from a friend/dealer and compare that. In the worst case you could drop your unit back to the dealer for them to check and listen to music through the Sonus in the meantime.

 

[Stephen Healy]

As @frank7036 says, if the ZENith is sending a bitperfect output then there is in fact no channel differentiation from the source. Therefore, it could only be some kind of DSP at play.
Are you using Roon or Sense?

 

[Zlone]

Frank, I totally agree with what you are saying, and a very good point that the Sonos is bypassing the USB section of the DAC as it uses SPDIF. Also a good point about both SE and BAL being affected due to the issue being upstream. And yes, BAL voltage was consistently 2x of SE, but as mentioned on the left side it was lower than the corresponding right channel output for both types. I did originally test and see the issue on the preamp, but followed it up the chain to the DAC and now potentially the streamer. Since it is downstream in the component chain, the preamp is off the hook. For the record, the DAC is Merason. I also should note I am running Sense, not Roon, so no DSP at work here.

A friend has a Zenith Mk2 and I am going to ask him to bring it over and see if we have the same results. I agree, something does not add up, the streamer is the last place that I would expect this to happen.

As @frank7036 says, if the ZENith is sending a bitperfect output then there is in fact no channel differentiation from the source. Therefore, it could only be some kind of DSP at play.
Are you using Roon or Sense?

Stephen, I agree. As Frank noted, my test with the Sonos was not sufficient to rule out the DAC as it did not use the USB port, faulty thinking on my part. I am starting to think the issue is in the USB portion of the DAC.

To answer your question, I am using Sense, so there is no DSP at work here. I will be testing a friend’s MkII today, if it exhibits the same behavior, then I will have to take a closer look at the DAC.

 

[Stephen Healy]

Thanks for clarifying Zlone.
On the deeper setting of LMS, there is actually deeper audio configuration that does include a balance bias, so it is quite possible that somehow this has been altered. This seems unlikely, however, if you have never gone into the backend LMS settings. However, if you did buy your ZENith pre-owned then its possible this could be a left over setting from the previous owner?
You can check it by following our guide on how to access LMS, then go to Settings, then the 'Player' tab, change the drop-down to 'Audio'. Under this you will see a Balance slider, which you need to make sure is set to dead-centre '0'

 

[Zlone]

Thanks for clarifying Zlone.
On the deeper setting of LMS, there is actually deeper audio configuration that does include a balance bias, so it is quite possible that somehow this has been altered. This seems unlikely, however, if you have never gone into the backend LMS settings. However, if you did buy your ZENith pre-owned then its possible this could be a left over setting from the previous owner?
You can check it by following our guide on how to access LMS, then go to Settings, then the 'Player' tab, change the drop-down to 'Audio'. Under this you will see a Balance slider, which you need to make sure is set to dead-centre '0'
View attachment 419

Thanks, I checked this out and it is set to 0. That would have been an easy fix!

 

[Stephen Healy]

Thanks, I checked this out and it is set to 0. That would have been an easy fix!

Okay, good to know.
Do you have a basic laptop or PC that you can try running via USB into the same DAC?

 

[Zlone]

Okay, good to know.
Do you have a basic laptop or PC that you can try running via USB into the same DAC?

I do. That would be something to try before another Zenith.

 

[Zlone]

Okay, good to know.
Do you have a basic laptop or PC that you can try running via USB into the same DAC?

Okay, I just ran a 1khz test tone via usb to through the DAC, same issue. So this rules out the Innuos. Thank you for your help!

 

[Stephen Healy]

A masterclass in 'process of elimination' @Zlone ! A curious issue though, not one i have encountered before.

 

[Zlone]

A masterclass in 'process of elimination' @Zlone ! A curious issue though, not one i have encountered before.

Indeed. I will get some more data and talk to the DAC folks. Thanks again for your help.

 

[frank7036]

Thanks for clarifying Zlone.
On the deeper setting of LMS, there is actually deeper audio configuration that does include a balance bias, so it is quite possible that somehow this has been altered. This seems unlikely, however, if you have never gone into the backend LMS settings. However, if you did buy your ZENith pre-owned then its possible this could be a left over setting from the previous owner?
You can check it by following our guide on how to access LMS, then go to Settings, then the 'Player' tab, change the drop-down to 'Audio'. Under this you will see a Balance slider, which you need to make sure is set to dead-centre '0'
View attachment 419

Stephen,
For people who have purchased 2nd hand does a reset to factory defaults also reset all the options within LMS or are they separate? It seems to me that if one did purchase a 2nd hand unit this might be the 1st thing to do??

 

[Stephen Healy]

Stephen,
For people who have purchased 2nd hand does a reset to factory defaults also reset all the options within LMS or are they separate? It seems to me that if one did purchase a 2nd hand unit this might be the 1st thing to do??

LMS is separate, so a Factory Reset in Sense does not reset everything to a set standard on LMS currently, which is why we generally prefer users not to tinker in LMS too much, because there is not an easy way to snap it all back to defaults - any settings change, adjustment, plugin etc all need to be manually reversed and undone to get back to factory standard.