Drawmer D-Clock

[space2012]

purchased a Drawmer D-Clock.
looks pretty, that was the reason i bought it for...but it turn out it was verry annoing to see how flawed diferent clocks are.

my Drawmer M-clock was a out of tune!, it was drifting,
was verry annoing. to see: 43.0997 or 47.9999.

i was about to freak out!!! sell everything and cry!

the good news:
i knew that M-Clock has 2x EQZAL TCXO that can be calibrated!!!
i wrote to Drawmer, and they told me: they were factory calibrated, but i can purchase new ones.
one for 44.1khz x2 & x4, the other for 48khz x2 x4.

instead of selling & buy another clock, or replacing with new TCXO crystals.
i decided to open the M-Clock turned-on!, and used the D-Clock to visually callibrate the M-Clock to AES Grade1.

inside the M-Clock has two 22/24Mhz TCXO EQZAL, each has an small philips screw to calibrate!...,
dont know if its for input voltage or for temperature.
verry tiny adjustements, and it worked!, now they work like charm:
44.1000Khz 00000ppm 0.00000% 48.0000KHz 00000ppm 0.00000%

i think that maybe, shipping vibration changed factory calibration or really bad dirty 140v AC power i had.
D-Clock was a good purchase, more than just a pretty face, i just love those down&up experiences.

another good news: was my old Alesis Ai-2, what a surprise!,
the .pdf manual say it has +-50ppm,
but... with a Furman AR-15 series ][ + true 99.997% OFC cables.
realtime measurement of the D-Clock gives +-12ppm!!, far from a calibrated M-Clock, but way better than any internal clock ive heard/seen so far.
it was a surprise.

[mobius.media]

Damn man you're hardcore.

Let the clock tests begin.

and what's ppm? shouldn'r it be picoseconds?

[space2012]

Originally Posted by mobius.media

Damn man you're hardcore.

Let the clock tests begin.

and what's ppm? shouldn'r it be picoseconds?

ppm = particle per million,
ppb = particle per billion,
_______________
http://lib.store.yahoo.net/lib/yhst-87604201054931/clocksync.pdf
http://www.antelopeaudio.com/en/products_iso_10m.html
"Swiss-made Rubidium core with accuracy of 0.03 parts per BILLION
Ultra-precise Atomic oscillator with stability of 1 second in 1,000 years"
_______________
some clock manufacturers measure accuracy in picoseconds, like: RME, Mytek, EMU, etc...

other manufacturers use: ppm like Drawmer, Antelope, Teac, rosendalh, Mutec, Lucid, etc...,

Atomic clocks; Teac Esoteric & Antelope Audio 10M are measured in: ppb
...
like a zipper: clock + data.
digital signals were designed to avoid phase problems, and to be able to extract clock signal from the data signal.
Clock must be twice the data rate, and thats called the BiPhase Mark Code.
for 44.1KHz x 24 Bit x 2 - S/PDIF, AES/EBU or Wordclock.
it should be 4.233.600MHz exactly each second.

most clocks drift around 4.2Mhz,
that oscillation "error" is measured in +/-ppm or ppb, D-Clock can also measure in +/-0.0000%, and freq.

a common technique in digital clocks is to use a higher frequency and divide that to minimize jitter and clock drift.

for example: M-Clock can generate 192Khz clock signal,
192.000 x 24 x 2 = 9.216Mhz but the TCXO inside its over 24Mhz.

anyway... some clocks jump; "randomly"
one second are 44.1003 the next second 44.1090, the next second 44.1050.
and thats a form of jitter.

creating tuning problems.
but is also related to the other jitter between clock pulses.

if you create a 440Hz Sine wave mathematically perfect,
any decent software.
much more accurate than tunning forks, or Led Strobes.

if you play that 44.1khz 16Bit sine wave .wav file in WMP, QuickTime, WinAmp or any other player

and connect the output of the soundcard to the input of the same soundcard. DA--to-->AD , and disable monitor input in the "Sound and Audio Devices" or DSP of the Soundcard,

and with a Tuning software like AP Tuner 3 to analize the tone the more accuratelly possible at the input of the soundcard.

when the clock is low quality, for example the soundcard in my laptop,
the mathematically perfect 440Hz wont return/measure 440Hz,
each note divided in 1/100cent steps. some clocks will have 10% error.

the AP Tuner has a "calibration feature" with 2 decimals, but 2 decimals and just one measurement point is not enough.

when i create higher frequencies and loop test/measure them,
they drift even with the software calibrated with 2 decimals; for example: 436.45Hz
....
some manufacturers claim that in theory clock drift and clock jitter can be verry diferent,
but in reality, they seem to go hand & hand. like clouds and rain.

so far ive only seen 1 clock with drifted freq. & medium jitter.
but always ive seen/heard that a better ppm clock sounds bettter
"less jitter" in a converter that can follow ext.clock.

thers also cable added jitter:
the clock signal travels verry high/fast., and tiny, making it sensible to EMI & RMI & CMRR interference.

the clock is just an Square wave, but an AC Square wave, that has lots of harmonics over the fundamental frequency.

just create a 440Hz sine, and a 440Hz Square 50/50, and see them in WMP Bars & Waves FireStorm or with Izotope Ozone4 demo, or any free frequency analizer.

those harmonics determinate the Square wave quality/shape.
the more harmonics the more perfect the Square wave will be.

the shape raise and fall, or slew rate, is verry important for the accuracy detector circuit of the receiving device.
capacitance and resistance, by the purity of the copper or silver.

only true pure cables can transfer those harmonics over the: 4.233.600MHz for S/PDIF 44.1Khz 24Bits x 2 channels accuratelly in realtime.

each digital/clock cable Brand&model affects the Square harmonics diferently, making the Converters to detect & react diferently to the same 1 & 0s, reproducing or recording a diferent sound.

that the only way i could explain such big diference between:
Apogee Wyde Eye BNC vs. Philips PXT1000 RCA with rca-to-Bnc adapters.

in the end its personal taste... but i like much more the Philips cable, over any other non silver cable ive tested so far.
...
also thers another variable:
the PLL TTL circuit inside the clocks.
the clocks oscilators generate a Sine wave originally, but that Sine wave must be converter/transformed into an Square wave.

.. it happens that diferent clocks manufacturers use diferent methods/techniques for creating the Square Waves, resulting Diferent harmonics & Square Shapes, that afects diferently the converters.
something similar to how cables affect the signal but inside the machine.

another thing ive noticed its the AC power noise & ripple.
the Cleaner the AC power i give to the external clocks,
the more accurate clock they generate.
i wish i could test my M-Clock with Furman IT-20 Series 2, Balanced power to see if or how much improoves over my furman AR-15 series 2, i just want to hear how low can i go in jitter, with the same clock.

[fweqy]

hi space2012

wow nice post. ( regarding the variables that can alter clock speed)

i read somewhere a guy upgraded his sound card clock with a rubidium reference clock bought from ebay by doing a little soldering. looked like a fun thing to try out. I supose you would need a a square wave and the right frequency. i'm thinking of moding my rme raydat. i just cant find that article now. i would have thought many people would have given this a go and posted blogs. perhaps its not so easy? have you ever heard of this?

peace