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SMSL G1 Review (Clock Generator)
- Thread starter NTTY
- Start date
OP
- Thread Starter
- #62
I ran complementary pitch error tests with 4 DACs and 4 CD players. I let all of them warm up 10min. The Accuphase was spot on at startup but deviated to -1ppm after nearly 15min. I used the Motu Ultralite mk5 for measurements, which stayed on for the last 24 hours.
The above tests are consistent with what I experienced for the last 2 years of testing CD Players. Their pitch error transition to the DAC(s), except with the D200 when it is fed by the G1 clock.
I might update this table with more CD players in the future, but that requires unreasonable time and I think the point is made.
| CD Player | Native Pitch Error out of the CD Player | Pitch Error out of SMSL D200 | Pitch Error out of SMSL PS200 | Pitch Error out of Topping D50III | Pitch Error out of ASUS ESSENCE STU | Pitch Error out of SMSL D200 + G1 |
| Accuphase DP-70 | -1ppm | -1ppm | -1ppm | -1ppm | -1ppm | +4ppm |
| Pioneer DP-D9 | -16ppm | -16ppm | -16ppm | -16ppm | -16ppm | +4ppm |
| Yamaha CD-S2000 | -16ppm | -16ppm | -16ppm | -16ppm | -16ppm | +4ppm |
| Revox B 226-S | +150ppm | +150ppm | +150ppm | +150ppm | +150ppm | +4ppm |
The above tests are consistent with what I experienced for the last 2 years of testing CD Players. Their pitch error transition to the DAC(s), except with the D200 when it is fed by the G1 clock.
I might update this table with more CD players in the future, but that requires unreasonable time and I think the point is made.
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"The smallest difference in pitch recognizable by the human ear is approximately 3–6 cents (where 1 cent = 1/100 of a semitone, or about 0.06% change in frequency) under optimal conditions for pure tones.
A JND of 0.3% = 3,000 ppm is more than an order of magnitude higher than the worst of the native pitch errors out of these CD players. So, isn't all this a largely academic discussion?
Besides, apart from the ritual of unboxing a CD, sticking into the transport, looking at the spinning disc, etc. which some find exciting, why not extract a FLAC copy from that CD onto a USB flash drive, plug it into a router which makes it visible on the network via DLNA, and play it directly via the DAC?
Explanation
- Just Noticeable Difference (JND): This is measured psychoacoustically as the smallest frequency change Δf that a listener can reliably detect (typically in >75% of trials).
- At mid-frequencies (e.g., 500–2000 Hz, where human hearing is most sensitive) and moderate sound levels (~40–60 dB SPL), the JND is roughly 0.3–0.6% of the base frequency f, or Δf/f≈0.003 to 0.006.
- Example: For a 1000 Hz tone, Δf≈3–6 Hz.
- In musical terms, this equates to 3–6 cents, since the cent scale is logarithmic: cents=1200×log2(Δf/f).
Supporting Evidence
- Classic studies (e.g., Shower & Biddulph, 1931; Wier et al., 1977) report JNDs of ~1–3 Hz at 1 kHz for pure tones.
- Meta-analyses and modern reviews (e.g., ISO 226 standard; Sek & Moore, 1995) confirm ~0.2–0.5% relative difference in the 1–4 kHz range.
- The Weber fraction Δf/f is roughly constant in this range, aligning with Weber's law for pitch perception.
Factors Affecting the JND
- Worse at extremes: Increases to ~1–2% below 500 Hz or above 4 kHz; up to 3–5% near hearing thresholds.
- Tone duration: Needs >100–200 ms for best discrimination; shorter tones raise JND.
- Complex tones/music: In real-world scenarios (harmonics, noise), JND can be 10–20 cents or more.
- Individual variation: Trained musicians may detect ~1–2 cents in familiar contexts, but average listeners are ~5–10 cents.
A JND of 0.3% = 3,000 ppm is more than an order of magnitude higher than the worst of the native pitch errors out of these CD players. So, isn't all this a largely academic discussion?
Besides, apart from the ritual of unboxing a CD, sticking into the transport, looking at the spinning disc, etc. which some find exciting, why not extract a FLAC copy from that CD onto a USB flash drive, plug it into a router which makes it visible on the network via DLNA, and play it directly via the DAC?
OP
- Thread Starter
- #64
Indeed, I am one of some
Been there, done that, boring. Easier to subscribe to whatever online music streaming.
Besides, appart from the unreasonable time that would be required to rip 5’000+ CDs, and I did try to go for it, the library got too slow at 3’300 albums. No hardware updgrade made it reasonably faster (iTunes), so I went back to enjoying spinning the silver disc. It is also a pleasure to go through a real physical library, a true offline activity. But I get not everyone will be into it.
Thanks for the tips. The difficulty for the DIYer is to implement the input word clock. Now there is the new Cirrus Logic CS2600 that, at least on paper, makes things much easier as it is a one chip job.You could daisy chain the word clock output from one device to the other, this method work fine if you don't have several equipement to synchronize.
The best approcah is too use a Word Clock Distrubution amplifier as this one from Ross Video.
WDA-8409
The WDA-8409 is a distribution amplifier designed specifically for Word Clock distribution. It features 8 75Ω word clock outputs with full 5Vp-p swing. The card supports a looping input, with an optional 75Ω termination, and supports remote monitoring through DashBoard.www.rossvideo.com
Some advices:
Use proper video cable with 75 Ohms connectors and wire, don't mix with 50 Ohms BNC connectors. BNC connectors must be crimped not soldered.
Always put a 75 Ohms terminator on the last output.
It's a good pratice to monitor the word clock output with an oscilloscope.
The square signal should be pristine with but minimum noise, measure the output of the clock and the last output.
Mutec specifies its MC3+ clock accuracy as <0.1ppm
MUTEC – Digital Audio Equipment – High End | Professional Audio - MC3+
MUTEC Germany - Manufacturer of Digital Audio and Video Studio Equipment
mutec-net.com
Well, you don't know your ADC impact here.
It's very possible it introduces this 4ppm shift.
Your 1ppm result being, in that case, a -3ppm error added to the same 4ppm shift.
Well, nowadays, audio networks are pretty much everywhere in pro studios.
And the protocols used have to include efficient clock sync.
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Thanks for the review.
The bottom line of it, as I read it, is that this 500€ device is useless.
The bottom line of it, as I read it, is that this 500€ device is useless.
and
" And the protocols used have to include efficient clock sync."
results into what final conclusion ??
VientoB
Addicted to Fun and Learning
Why does it have to cost so much? And is there any reason, apart from aesthetics, it needs as large a box as the DAC and CD player in the same line?
Jimi Floyd
Active Member
Please, don't tell this to people spending 50k for a dCS clock!
Is the dCS CD player any more tellable?
Indeed. (Or, in fact, a -5 ppm error, since it was -1 ppm.) We are talking about differences on the order of normal sample variation here.
The ADC is not pulling its reference clock out of thin air, it's got an internal oscillator of finite accuracy. Without an external reference that is slaved to an official atomic clock directly or indirectly (like a well warmed-up GPSDO), you won't know how accurate it is in absolute terms.
There's this joke that goes: A man with a clock knows what time it is. A man with two clocks never knows what time it is exactly.
Realistically, nobody truly cares about a few ppm of absolute clock inaccuracy in audio. What matters in a recording studio is that the whole gaggle of ADCs and DACs running around is synchronous, so either all of them need to be sync'd to an external master clock or one must be the master that all the others sync to. Now I would think that wordclock sync would be more common in this field than a 10 MHz reference (which requires a full-blown DDS/PLL clock generator to obtain wordclock), but things may have changed.
Because they can charge that much for it? Also, this has to be a fairly low-volume item in a fancy case, and I can't imagine that an OCXO is that cheap either given its usual fields of application. (I just checked, and you can buy a small 10 MHz OCXO board for less than 20€ on Amazon. That's actually not bad. If you want to buy just an OCXO at a distributor, you're looking at the 30-40-50€ range, though even 10 ppb parts can go over 100, and if you insist on 0.2 ppb it'll be over 1000. Those cheap boards may be sporting used OCXOs from decommissioned telecoms equipment or something. All of that old 2G and 3G gear must have gone somewhere after all, and for a smart recycler an expensive part like an OCXO means easy profit.)
I would think that matching aesthetics is exactly the point. It's not a bug, it's a feature.
I'm not sure I understand your question.
Audinate Dante, as an example, distributes accurate clock signal. So even in a multiple devices setup there is no need for such a device.
Which isn't very smart. Because, as everyone should know, the power cable is the most critical component in the audio chain. Beginners
It’s even sillier when you for that money can get new balanced audio gear and run xlr cables instead
solderdude
Grand Contributor
One really only should use a word clock with sources that actually have a clock input.
This synchronizes the clocks of the source and DAC/DAW with that of the source.
This has many advantages especially when more than 2 digital devices are being used.
When using a source without clock input (or output) it is absolutely pointless to use the source on SPDIF/Toslink as the clocks are NOT synchronized which inevitably will lead to buffer under-/over-run which means samples will be discarded/lost.
This won't be audible but is likely measurable.
When using any SPDIF/Toslink output best to let the DAC 'sync' on that SPDIF signal.
Note: not all SPDIF/Toslink receivers are created equal.
For the SP200 and G1 this external clock actually works but only because the player has a clock input.
Ironically it would have been cheaper to simply let the DAC or the player have a clock out and the other device a clock input as the internal clocks seem to be more than good enough already... but SMSL would make less money, you would not have another 'matching' device in your stack either.
It's great that it is reviewed and tested but is pointless for other devices than the 2 SMSL devices when 1 of the devices does not have a 10MHz clock in- or out-put.
This synchronizes the clocks of the source and DAC/DAW with that of the source.
This has many advantages especially when more than 2 digital devices are being used.
When using a source without clock input (or output) it is absolutely pointless to use the source on SPDIF/Toslink as the clocks are NOT synchronized which inevitably will lead to buffer under-/over-run which means samples will be discarded/lost.
This won't be audible but is likely measurable.
When using any SPDIF/Toslink output best to let the DAC 'sync' on that SPDIF signal.
Note: not all SPDIF/Toslink receivers are created equal.
For the SP200 and G1 this external clock actually works but only because the player has a clock input.
Ironically it would have been cheaper to simply let the DAC or the player have a clock out and the other device a clock input as the internal clocks seem to be more than good enough already... but SMSL would make less money, you would not have another 'matching' device in your stack either.
It's great that it is reviewed and tested but is pointless for other devices than the 2 SMSL devices when 1 of the devices does not have a 10MHz clock in- or out-put.
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With less than 500 bucks the target customers wouldn't accept it as serious. Basically even 500 is already too low.
As @AnalogSteph mentioned atomic clocks: if you (with special hint to @NTTY and upcoming measurements
) really want to have a perfect as possible reference you don't need to spend kilobucks of money. Atomic accuracy clocks are everywhere - received via GPS. I use this little unit for less than 140 bucks to calibrate, check and sync my whole lab:
www.leobodnar.com
Quote: Frequency stability of its output is defined by the accuracy of GPS satellite onboard Caesium references and approaches 1x10-12 or 0.000001 ppm.
Prices have changed a bit and they now sell a newer version, see link. Via Windows (and Mac) software one can set its output to any desired frequency, but still stable as a rock.
Stuff like this made laboratory units obsolete that had cost as much as two cars.
As @AnalogSteph mentioned atomic clocks: if you (with special hint to @NTTY and upcoming measurements
) really want to have a perfect as possible reference you don't need to spend kilobucks of money. Atomic accuracy clocks are everywhere - received via GPS. I use this little unit for less than 140 bucks to calibrate, check and sync my whole lab:Mini Precision GPS Reference Clock : Leo Bodnar Electronics
Leo Bodnar Electronics Mini Precision GPS Reference Clock - Low jitter GPS-locked precision frequency reference 400 Hz to 810 MHz output mini version We recommend a newer version of this product: LBE-1420 GPS locked clock source This device outputs low jitter reference clock frequency-locked to...
www.leobodnar.com
Quote: Frequency stability of its output is defined by the accuracy of GPS satellite onboard Caesium references and approaches 1x10-12 or 0.000001 ppm.
Prices have changed a bit and they now sell a newer version, see link. Via Windows (and Mac) software one can set its output to any desired frequency, but still stable as a rock.
Stuff like this made laboratory units obsolete that had cost as much as two cars.
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