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Question for the digital boffins ...

M

montesquieu

pfm Member
Question for the digital gurus out there ...

I had a Mutec MC3+ USB Masterclock-reclocker-usb interface which I mainly used to clean up SPDIF and AES connection.

I sold it and regretted it. Before I buy another is anyone aware of a cheaper reclock/digital signal regeneration box for spdif /aes?

I don’t need usb conversion or any of the fancy dsd-pcm conversion stuff: my transport is purely Redbook CD. I guess I could track down an old Genesis digital lens but there’s surely something more modern?

any ideas?
 
Zero experience of the product but has much of the functionality at less than half the price.

51NxBYffsSL._AC_SL1500_.jpg


https://www.audiophonics.fr/en/digi...-accusilicon-32bit-384khz-dsd512-p-14146.html
 
montesquieu said:
Question for the digital gurus out there ...

I had a Mutec MC3+ USB Masterclock-reclocker-usb interface which I mainly used to clean up SPDIF and AES connection.

I sold it and regretted it. Before I buy another is anyone aware of a cheaper reclock/digital signal regeneration box for spdif /aes?

I don’t need usb conversion or any of the fancy dsd-pcm conversion stuff: my transport is purely Redbook CD. I guess I could track down an old Genesis digital lens but there’s surely something more modern?

any ideas?
Click to expand...
What's it for? I take it you are taking a s/pdif or AES input from a cd transport- Then outputting something to dac? if so what inputs does the dac have?

I ask this because it's not clear from the blurb (or labelling at the back) that the Gustard will take a s/pdif input- on the face of it it's a usb to s/pdif (or whatever) converter. But maybe it can do S/pdif to S/pdif.
 
One of the options on the Mutec is that it takes in AES/EBU or SPDIF and outputs it as AES or SPDIF, reclocked and cleaned up. That's what I'm looking for. Output from CD transport, input to DAC.

I don't need USB but I guess most kit includes that these days.
 
montesquieu said:
One of the options on the Mutec is that it takes in AES/EBU or SPDIF and outputs it as AES or SPDIF, reclocked and cleaned up. That's what I'm looking for. Output from CD transport, input to DAC.
Click to expand...
Are you sure the signal benefits from cleaning in the first place? The receiver in the DAC will almost always be the limiting factor.
 
montesquieu said:
One of the options on the Mutec is that it takes in AES/EBU or SPDIF and outputs it as AES or SPDIF, reclocked and cleaned up. That's what I'm looking for. Output from CD transport, input to DAC.

I don't need USB but I guess most kit includes that these days.
Click to expand...
If you want somethign that takes a s/pdif in and gives a s/pdif out then this would do it. I don't think there's much call for it.
http://www.empiricalaudio.com/products/synchro-mesh
 
adamdea said:
If you want somethign that takes a s/pdif in and gives a s/pdif out then this would do it. I don't think there's much call for it.
http://www.empiricalaudio.com/products/synchro-mesh
Click to expand...
That device uses an ASRC, so it alters the audio data. I'm also doubtful it is of any benefit. In fact, it might actually make things worse. Any residual jitter from its PLL gets baked into the audio data (that's what an ASRC does), then the jitter of the DAC's receiver gets added on top. Unless the source is horrendous, this will be worse than feeding the DAC directly. A reclocker that doesn't use an ARC won't have this problem.
 
mansr said:
That device uses an ASRC, so it alters the audio data. I'm also doubtful it is of any benefit. In fact, it might actually make things worse. Any residual jitter from its PLL gets baked into the audio data (that's what an ASRC does), then the jitter of the DAC's receiver gets added on top. Unless the source is horrendous, this will be worse than feeding the DAC directly. A reclocker that doesn't use an ARC won't have this problem.
Click to expand...
Worse than the source ? I'm 99% sure we should not go there, but...... can you explain a use case in which it is worth having a reclocker at all, but where the ASRC reclocker of decent jitter rejection gave a worse result than no reclocker? Or to put it another way, if the dac has poor enough jitter rejection to need a reclocker, how would it be able to reject any jitter in the source ? and no cheatign by making the reclocker worse than the source.
 
adamdea said:
Worse than the source ? I'm 99% sure we should not go there, but...... can you explain a use case in which it is worth having a reclocker at all, but where the ASRC reclocker of decent jitter rejection gave a worse result than no reclocker? Or to put it another way, if the dac has poor enough jitter rejection to need a reclocker, how would it be able to reject any jitter in the source ? and no cheatign by making the reclocker worse than the source.
Click to expand...
An S/PDIF receiver, whether in a DAC or a reclocker, uses a PLL to generate a clock that tracks the average rate of the incoming signal. Any jitter below the corner frequency of the PLL is passed through while higher frequencies are attenuated though not entirely eliminated. Any jitter inherent to the local oscillator of the receiver is added to the mix. In the basic scenario of a source feeding a DAC, the receiver can be made as good as one wishes and is willing to pay for. With the commonly used receiver chips from Cirrus Logic and AKM, their own jitter tends to dominate the result regardless of source. That is because most sources use a crystal oscillator which is typically more stable than the simple VCO in the receiver chip.

Now add the ASRC based reclocker. Like any S/PDIF receiver, it uses a PLL to track the incoming data rate. However, instead of passing the residual jitter through to the output clock, it uses a fixed oscillator and resamples the audio data to compensate for any discrepancy. The residual jitter is thus irrevocably baked into the data before it is transmitted on using a low-jitter clock. When this reaches the DAC, the clock recovered there will have jitter dominated by the receiver chip while the data has the jitter of the reclocker. When fed to the DAC chip, these two jitter sources are summed.

The only situation where an ASRC reclocker can be of benefit is when the source has extremely high jitter _and_ the receiver in the DAC has poor rejection of incoming jitter but adds little of its own. This is very unlikely to ever occur. In reality, we can expect one of three possibilities:
  • DAC receiver is much worse than reclocker: no benefit since the DAC dominates anyway.
  • DAC receiver roughly equal to reclocker: total jitter approximately doubles.
  • DAC receiver much better than reclocker: result dominated by reclocker, DAC efforts wasted.
This gadget is a flawed solution to a non-existent problem.
 
Another option you could look at is a used Meridian 518 - they come up on ebay every now and again and cost between £200-£300. I used to have one many years ago and in my view made my system sound better. It will handle upto 24/48 - so fine for CD. It also has some digital filters built in and works as a digital pre-amp if you want to.
 
mansr said:
The only situation where an ASRC reclocker can be of benefit is when the source has extremely high jitter _and_ the receiver in the DAC has poor rejection of incoming jitter but adds little of its own. This is very unlikely to ever occur. In reality, we can expect one of three possibilities:
Click to expand...
To be honest this is obviously the only sensible use case. But it would be the case whether reclocker uses ASRC or not.
 
Just to be clear on what the need is here, I have an Audio Note CDT2/II transport, and an Audio Note kit DAC that's been maxed out, pretty much taken as far as it can go in terms of available components, including upgraded I/V transformers, the top end Audio Note balanced output transformers available to buy, and some major power supply enhancements including reams of black gates etc, extra tube regulation etc. I would say it's the equvalent at least of a DAC4.1x, probably better as my PSU would be superior.

This is a pretty decent setup, albeit in a non-oversampling, non digital filtering, all redbook kind of way, which might not suit hi-res believers. (It does, however, suit me pretty well). I do have a Macbook dedicated to streaming and a reasonable USB-SPDIF converter as well as an Uptone Audio USB-Regen on the USB input. It sounds pretty good, but I don't use streaming in any major way as I hate the idea of interfacing with music using a computer. Only in extremis, when something I want to listen to something I don't have on vinyl (preferably) or CD, then I'll stream it. And then decide whether it's worth buying on physical media.

I had the Mutec in (reclocking the AES) in the system for a while, and felt it made some small difference though very hard to pin down. But it's £900, I don't use most of its functionality, and it's actually quite complicated to set up and use. I was just looking to see if there was something simple and equivalent in terms of the reclocking function to take its place. I appreciate it's a very old-fashioned request.
 
+1 for the Meridian 518, cleans up things nicely, you can resolution enhance red book to 24 bits, which if nothing else will reduce the dither noise to inaudible levels, play with the dither types etc.

Cheap too.
 
seyles said:
+1 for the Meridian 518, cleans up things nicely, you can resolution enhance red book to 24 bits, which if nothing else will reduce the dither noise to inaudible levels, play with the dither types etc.
Click to expand...
Increasing the bit depth can never lower the noise level of an existing signal. Besides, S/PDIF is always 24-bit anyway.
 
apart from the empirical audio
https://wyred4sound.com/products/digital-converters/remedy-reclocker
https://ifi-audio.com/products/spdif-ipurifier/
no idea whether they will help- and you might want to watch out for unwanted sample rate conversion which is probably heterodox within an audionote belief system.
[Edit the ifi claims
"We pride ourselves on giving you Bit-Perfect signal transfer. This means the signal remains original and unchanged.

This device ensures a Bit-Perfect transfer which is highly unusual for SPDIF devices. It can handle 44.1 / 48 / 88.2 / 96 / 176.4 / 192kHz; 16 to 24 Bit, DSD, DoP, and even Dolby Digital and DTS."
so that seems promising]
 
The jitter seen by the DAC chip is _always_ determined by the S/PDIF receiver immediately preceding it unless both the source and receiver are excruciatingly bad.

The iFi device might help break a ground loop if the source and receiver don't have transformers for the S/PDIF signal. Of course, any optical connection will do the same, as will a simple passive transformer.
 
mansr said:
... a simple passive transformer.
Click to expand...

Audio Note use a line transformer in and out. My DAC doesn't have optical in, only AES and SPDIF (BNC and RCA connections).

adamdea said:
apart from the empirical audio
https://wyred4sound.com/products/digital-converters/remedy-reclocker
https://ifi-audio.com/products/spdif-ipurifier/
Click to expand...

Fab - I've looked at the ifi but I think the remedy-reclocker is exactly what I was looking for - got to be worth a try at that amount of cash. As you point out they can fix it to 44.1 out which is what I need.
 
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