PaceCar vs. LessLoss

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Brucemck

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PaceCar vs. LessLoss
« on: 26 Sep 2007, 02:04 pm »

Conceptually, does a PaceCar into an external Dac perform the same / better /worse than can be achieved by the master/slave approach advocated by LossLess? ( http://www.lessloss.com )

audioengr

Re: PaceCar vs. LessLoss
« Reply #1 on: 26 Sep 2007, 06:16 pm »

Conceptually, does a PaceCar into an external Dac perform the same / better /worse than can be achieved by the master/slave approach advocated by LossLess? ( http://www.lessloss.com )

Yes, same concept.  The only functional difference is that the Pace-Car supports multiple sample-rates and has deep buffering.  The implementation however is probably different.  I use a minimal number of discrete parts in the critical paths and use many isolated power supplies in order to minimize jitter.

I am surprised that they are advocating that the customer install the slave clock mods in the transport themselves, particularly with 33MHz clock.  This is tricky and bad signal integrity can easily result.  They dont talk about using impedance-controlled coax internally, which is a must, and what impedance it should be, as well as the outboard cable.  There are also length considerations for the overall cable.

Steve N.

slugworth

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Re: PaceCar vs. LessLoss
« Reply #2 on: 13 Feb 2015, 04:46 am »
An ancient thread I know. Why don't/can't dac manufacturers implement this internally within the dac.

audioengr

Re: PaceCar vs. LessLoss
« Reply #3 on: 19 Feb 2015, 01:15 am »
An ancient thread I know. Why don't/can't dac manufacturers implement this internally within the dac.

Slave clock requires that the DAC send a clock to the source device that synchronizes the source clock to the DAC clock.  The only thing that can be installed in the DAC is the clock output.  Does answer your question?

Steve N.

justubes

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Re: PaceCar vs. LessLoss
« Reply #4 on: 2 May 2015, 03:21 pm »
How does this compare with a masterclock approach , which output and feeding its clocks signal to both dac and transport( byassing both transport and dac clocks- even if frequencies are different but original from 1 clocking devices,  a little different from a mastering studio aster clock approach.

audioengr

Re: PaceCar vs. LessLoss
« Reply #5 on: 3 May 2015, 03:44 pm »
How does this compare with a masterclock approach , which output and feeding its clocks signal to both dac and transport( byassing both transport and dac clocks- even if frequencies are different but original from 1 clocking devices,  a little different from a mastering studio aster clock approach.

This is the worst way to do it, like dCs.  If you do an external clock, it should be master. clock, not word cloc kor some other frequency.

Steve N.

barrows

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Re: PaceCar vs. LessLoss
« Reply #6 on: 3 May 2015, 04:08 pm »
An ancient thread I know. Why don't/can't dac manufacturers implement this internally within the dac.

Actually, DAC makers do use this approach.  An asynchronous USB DAC when done well works like this:  Masterclock at the DAC chip, sent back through isolation to the USB interface, and the USB interface is running as "slave" to the Masterclock at the DAC chip.  The "source" is the async USB interface, and in this case it is directly clocked from the master clock at the DAC chip.  This is the low jitter promise of an asynchronous USB DAC, unfortunately, not all USB DAC manufacturers get all the details quite "right".

justubes

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Re: PaceCar vs. LessLoss
« Reply #7 on: 4 May 2015, 03:06 am »
Using a masterclock or oven clock to output the frequency directly in place of the internal oscillator .  Is this termed masterclock?

I considered the pacecar which reclocks, but want to clock both transport and dac with 1 masterclock component.

As the ocxo or rubidium having better phase noise figures, importantly feeding 2 or more components at once.

also what should we expect sonically when once clocking is done right, a lack of glare, harness and more nautralness?

Thanks

« Last Edit: 4 May 2015, 05:21 pm by justubes »

audioengr

Re: PaceCar vs. LessLoss
« Reply #8 on: 7 May 2015, 12:30 am »
Actually, DAC makers do use this approach.  An asynchronous USB DAC when done well works like this:  Masterclock at the DAC chip, sent back through isolation to the USB interface, and the USB interface is running as "slave" to the Masterclock at the DAC chip.  The "source" is the async USB interface, and in this case it is directly clocked from the master clock at the DAC chip.  This is the low jitter promise of an asynchronous USB DAC, unfortunately, not all USB DAC manufacturers get all the details quite "right".

We are talking apples and oranges.  I agree with you.  What I dont think is a good approach is an external lower than master clock frequency that feeds both source and DAC.  That is what I was talking about.

Steve N.

audioengr

Re: PaceCar vs. LessLoss
« Reply #9 on: 7 May 2015, 12:39 am »
Using a masterclock or oven clock to output the frequency directly in place of the internal oscillator .  Is this termed masterclock?

Master clock is the highest frequency clock used and is comprised two or more frequencies in order to generat all sample rates, therefore, there is not just one MC frequency.  It can be located in the source, the DAC or external to both.

Quote
I considered the pacecar which reclocks, but want to clock both transport and dac with 1 masterclock component.

Why?  Best jitter is achieved with the master clock in the DAC, usually in a USB or Ethernet interface.

Quote
As the ocxo or rubidium having better phase noise figures, importantly feeding 2 or more components at once.

These caliber of clocks can be qchieved inside the DAC, and at the optimum frequencies.  Rubidiums are usually 10Mhz or some other non-optimal frequency.


Quote
also what should we expect sonically when once clocking is done right, a lack of glare, harness and more nautralness?

Its like cleqning the dirty window qnd now you can see all of the light and detail through that window.  Like comparing a cheap pair of binoculars to a Zeiss when looking at birds.  Much more gratifying.

Steve N.

barrows

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Re: PaceCar vs. LessLoss
« Reply #10 on: 7 May 2015, 01:45 am »
We are talking apples and oranges.  I agree with you.  What I dont think is a good approach is an external lower than master clock frequency that feeds both source and DAC.  That is what I was talking about.

Steve N.

Yeah Steve, totally agreed.  I really am not in favor of a totally external clock (be it master, or word) feeding separate components, all we get then is more jitter due to distribution issues.

I have done some listening tests with measured low jitter (lower phase noise masterclock at low frequencies) vs higher jitter, and one should listen for the following:
With lower jitter, generally there will be hightened sensation of details, especially details associated with protraying physical spaces (ambience), but unlike some ways of enhancing detail retrieval, lower jitter sounds more at ease at the same time.  Very low level details will sound more fleshed out.  In complicated music, it can almost sound like the music is slowed down some, allowing one to hear deeper into the music, while at the same time being very relaxed in presentation.

justubes

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Re: PaceCar vs. LessLoss
« Reply #11 on: 7 May 2015, 04:38 am »
Thanks for your responses.

It just happens i just go back from a shootout.

The effects described seem to mirror a  shootout test i just attended.

I have just heard a masterclock feed both source and dac. It was calm, no brightness and fuller.  It would seem tonally darker with no heightened sense of detail.

Just the clock feed the dac, there was a slightly leaner sound which actually sounded a little more lively but brighter, but not as in "bright" or sharper sound. Funnily, bass had less depth but more snap with just 1 clock connection.

So possibly with some jitter is good, but to an extent, zero jitter could be very natural but loose what i call brilliance to the sound.

Masterclock using an OCXO or rubidium unit still goes through PLL and VCXO/TCXO to geenrate the frequencies from the 10M  unit, so what is the audio purist so hung up on the rubidium clock feeding dacs, transports etc. Is it still flawed as opposed to a reclocker?

 

path73

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Re: PaceCar vs. LessLoss
« Reply #12 on: 10 May 2015, 07:02 am »
I run a SynchroMesh reclocker feeding an SPDIF input of my DAC (internal PLL clock recovery) with absolutely fantastic results!
Swapping the Dynamo power supply and Steve's BNC coax cable into the mix makes their positive effect on reducing jitter immediately apparent. Low jitter puts high requirements on cable connections.
Dynamics are less "in your face" but more organically attached to the instruments in the auditory scene. On good recordings, dynamics are really foot tapping. Bass is better defined as well.
There is more subtlety, refinement and a sense of "density" that triggers emotional connection to the rendered musical event.
SynchroMesh does one other thing really well: it upsamples everything to 96kHz (in the version I use) which makes my DAC really shine, without any audible artifacts. All other ASCRs I tried (often seen inside DACs) soften the sound and make it a bit dull.
/path

steve in jersey

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Re: PaceCar vs. LessLoss
« Reply #13 on: 10 May 2015, 04:33 pm »

With lower jitter, generally there will be hightened sensation of details, especially details associated with protraying physical spaces (ambience), but unlike some ways of enhancing detail retrieval, lower jitter sounds more at ease at the same time.  Very low level details will sound more fleshed out.  In complicated music, it can almost sound like the music is slowed down some, allowing one to hear deeper into the music, while at the same time being very relaxed in presentation.

Wow, very astute observations  :thumb:

This is the first time I've seen mention of the "music seeming to slow down, allowing one to hear deeper into the music" . I would expand
this a bit further than deeper however, & describe this as hyper realistic views of minute ambient detail that has you wondering what seat you're occupying on stage with the Orchestra !

Until the digital music you're listening to starts to sound like it could actually be a time domain governed format (analog) you most likely
have a bit further to go in getting the jitter in your system under control. Once you've broken through the timing issues that exist in Digital, musical detail becomes readily available as the information that wasn't being completely developed is so now before further information overlaps it.