[MartinWT]

If it's power to s/pdif circuitry problem only, then usb input should work. Try that. Are you sure it's LKS. Have you try system with different dac. If it doesn't seem to be decoding, may be the clock. I would use multimeter to check if there is correct voltage to clock.

USB input DOES work! Yes, I'm sure it's the LKS having eliminated everything else and used a substitute DAC.

Thanks for the clock suggestion.

 

[b0bb]

I guess that S/PDIF is switched between the four inputs and then there is common receive circuitry. It appears to be receiving the clock but not decoding the music. If USB works, then I guess by the time the audio appears on the I2S bus all is well.

Could anyone give me pointers as to what may be the problem? Receive chip? Coupling cap? Something else?

It could be any of those components. Playback a 1kHz sinewave on the SPDIF input and observe the pattern on an oscilloscope, start at the input connector and trace until the pattern disappears.

The 2 rectangular chips near the 3 large red WIMA caps are either line drivers or multiplexors, you will have to locate the datasheet to determine this.
Check to see there is signal and that it is powered to spec.

ES9038PRO has 8 spdif inputs on pins 60 to 52, Pin60 is SPDIF0.
I expect the signal to be present on ports 0 to 7 on the LKS004.

There is a circle/dot on the chip, with that on the top left corner, the above mentioned pins are on the top edge, pin 64 is closest to the dot.

 

[MartinWT]

Thanks, b0bb. I decided to break out my old oscilloscope and look at the Coherent clock module output. There is only noise!

This is good news as it means the rest of the DAC is fine and it sounds pretty good from the Amanero USB input.

I shall return it to Coherent for repairs.

 

[oldearwax]

Thanks, b0bb. I decided to break out my old oscilloscope and look at the Coherent clock module output. There is only noise!

This is good news as it means the rest of the DAC is fine and it sounds pretty good from the Amanero USB input.

I shall return it to Coherent for repairs.

The Coherent clock is the system 100MHz clock. The system clock goes to ES9038 DACs.
If the system clock fails, you shouldn't hear anything ..... I am puzzled ???
I hope your oscope has sufficient bandwidth.

 

[MartinWT]

When I first tried to replace the 100MHz clock and botched it, the symptoms were exactly the same: clock lock with correct sampling rate shown but no muslc.

I didn't try USB at the time.

 

[xiamen]

That is strange. I would agree if the coherent clock is the problem, then probably USB shouldn't work too. Is it possible that with USB, it can use the Amanero clock instead of the coherent clock (that doesn't seem to make sense either). BTW, the upgraded version uses the same Amanero module but with upgraded clock. I guess check if there is any problem with the coherent clock.

 

[MartinWT]

Thanks. I'm somewhat confused about it, too. I'll be letting Coherent check it out soon.

 

[piaseczek]

Do you know if there is a "Ess hump" in a LKS 004?

https://www.audiosciencereview.com/...ow-to-fix-ess-hump-on-sgd1-and-la-qxd1.10502/

 

[MartinWT]

The ES9038Q2M is not used in the LKS.

 

[MartinWT]

Egg on face time. The LKS has been declared as working fine, no issues found. I'm happy with that and will take the embarrassment on the chin.

We discussed possible grounding problems (ground-based lockout happens with computers, something I come across working in IT). I shall start with a very straightforward hookup and build up the grounding box arrangements differently.

At least I'll have high quality music replay again. The loan NuForce DAC80 is somewhat restrained and average in presentation.

 

[mb3]

in case anyone is interested

https://www.ebay.com.au/itm/L-K-S-A...952510?hash=item1ce306b77e:g:lXIAAOSw~WpeNSJW

 

[MartinWT]

The DAC has been further modified while it was away with Tony of Coherent. I can't remember the detail of all the mods but the key areas were rewiring the mains input side with 3D cable and twisting the transformer pairs; lots of capacitor improvements using those superb K caps that Tony has specially made for him; some ultra high performance LT regulators to replace the standard ones; faster diodes in the rectifier section and trimming the balanced output DC offsets.

Firstly, I tried the DAC driving the power amp direct, but this time from the XLR outputs. Decidedly better than when I had tried it from the phono outputs some time ago, but there was still something lacking, it all sounding slightly lightweight. Then I reinserted the buffer between DAC and power amp and the potency and slam were back.

The LKS still has its detail and dynamic potency (strengths of the ES9038 chipset) but somehow seems calmer now, delivering the music without effort and with even lower levels of harshness than before.

Then I played with the grounding boxes. There are almost infinite permutations so forgive me for not trying them all. I did try, at one point, grounding the reclocker with all four leads from the SGS-1s but that wasn't as good as I had heard the system before.

I've now settled on this arrangement, but being very careful to route cables hanging in the air rather than touching each other:
SGS-1 to the router (via the power plug)
SGS-1s to the DAC (two cables to analogue and digital grounds) and the buffer (two cables to output grounds)
BR Eflos USB to the streamer
BR Eflos phono to the reclocker (S/PDIF ground)

Something I’ve noted, a clue that there is less system noise and better grounding, is that the Mutec locks faster than before. I often missed the start of a song while it sync’d with the blue LED flashing. Now the music starts even before the LED has stopped flashing.

I think the DAC still needs more hours to complete its burn-in but what Tony has given me is the best of the LKS' abilities – detail, impact, bass extension and power – without any Sabre hardness or treble tilt. What I also notice is a whole wealth of extra texture and new sounds now brought to my attention. The power of Kraftwerk's Minimum-Maximum is still there but I'm hearing a lot more from this amazing live album while the overall potency has taken another step up.

 

[Xoverman]

The DAC has been further modified while it was away with Tony of Coherent. I can't remember the detail of all the mods but the key areas were rewiring the mains input side with 3D cable and twisting the transformer pairs; lots of capacitor improvements using those superb K caps that Tony has specially made for him; some ultra high performance LT regulators to replace the standard ones; faster diodes in the rectifier section and trimming the balanced output DC offsets.

Firstly, I tried the DAC driving the power amp direct, but this time from the XLR outputs. Decidedly better than when I had tried it from the phono outputs some time ago, but there was still something lacking, it all sounding slightly lightweight. Then I reinserted the buffer between DAC and power amp and the potency and slam were back.

The LKS still has its detail and dynamic potency (strengths of the ES9038 chipset) but somehow seems calmer now, delivering the music without effort and with even lower levels of harshness than before.

Then I played with the grounding boxes. There are almost infinite permutations so forgive me for not trying them all. I did try, at one point, grounding the reclocker with all four leads from the SGS-1s but that wasn't as good as I had heard the system before.

I've now settled on this arrangement, but being very careful to route cables hanging in the air rather than touching each other:
SGS-1 to the router (via the power plug)
SGS-1s to the DAC (two cables to analogue and digital grounds) and the buffer (two cables to output grounds)
BR Eflos USB to the streamer
BR Eflos phono to the reclocker (S/PDIF ground)

Something I’ve noted, a clue that there is less system noise and better grounding, is that the Mutec locks faster than before. I often missed the start of a song while it sync’d with the blue LED flashing. Now the music starts even before the LED has stopped flashing.

I think the DAC still needs more hours to complete its burn-in but what Tony has given me is the best of the LKS' abilities – detail, impact, bass extension and power – without any Sabre hardness or treble tilt. What I also notice is a whole wealth of extra texture and new sounds now brought to my attention. The power of Kraftwerk's Minimum-Maximum is still there but I'm hearing a lot more from this amazing live album while the overall potency has taken another step up.

@MartinWT
Can you please share with us the buffers you are yousing?
I am also thinking off yousing buffers after the conversation I/V conversation stage.
Op amps from "Sparko Labs" to drive the XLR outputs.

 

[MartinWT]

I am using an external buffer, a Burson AB-160 XLR buffer, from the LKS' XLR outputs. The FET outputs are good (and a lot better sounding than the phono outputs) but they do still need buffering for best grunt and slam into my power amp.

 

[Lennym]

The SQ of my LKS seems to vary according to the day and hour. It does this much more than other sources, like analog. As I live in a large city, it is probably a local power issue. Has anyone found a small power filter or re-generator used in front of the LKS alone to be an effective device? Other solutions? Thanks.