Master Clock Talk
Dec 29, 2022 at 2:53 PM Post #421 of 3,361
Don’t worry about the center hole in a BNC cap. The cutoff frequency is so high nothing is getting in or out that tiny hole. A 1mm circular waveguide has a high-pass cutoff freq of over 450 Ghz.

Terminate unused outputs or not necessary? A good experiment connect one clock output with 1m coax cable to an oscilloscope (terminated). Measure clock signal with all other outputs terminated and again unterminated. See any difference? Something to consider is the terminated outputs will draw additional current from the power supply and possibly create more noise. Each design is different and may not behave the same way. I like Mutec’s Ref 10 approach which allows users to turn off unused clock outputs.

For LHY clocks Alvin may have some thoughts.
 
Dec 29, 2022 at 4:04 PM Post #422 of 3,361
Don’t worry about the center hole in a BNC cap. The cutoff frequency is so high nothing is getting in or out that tiny hole. A 1mm circular waveguide has a high-pass cutoff freq of over 450 Ghz.
That is. An audiophile with engineering HF knowledge. Estimating the same, just didn't look at exact numbers.
 
Dec 29, 2022 at 4:17 PM Post #423 of 3,361
I received my OCK-2 a week ago and have had it on 24/7 to let it burn in.

My chain: 2go/2Yu Streamer > Gustard U18 / OCK-2 > M Scaler > TT2

Gustard U18 internal clock sounds good on its own, but in comparison there's more body and richness to the sound with the OCK-2 external clock engaged. Though I have no experience with other clocks, I can heartily recommend based on relative cost and effect alone.

I'm running a 75 Ohm stock Chord Electronics BNC Cable at the moment because a Canare 50 Ohm cable is currently enroute. Will be interesting to hear what the cable impedance differences does to the sound.
 
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Dec 30, 2022 at 10:15 AM Post #424 of 3,361
If you really care of a quality of a signal you don't 'consume', then perhaps you have a reason.
I also care about the signal to "consume". Which is why we were discussing how to prevent reflections from interfering.
If you don't or will try evasive tactics again, then I will consider your comment about my pseudoscience as an ordinary, primitive troll.
For one thing I will apologize, as I understand how you feel it was a personal attack on you when I first quoted you and then went on about pseudoscience. I should have made it clearer that this was not about you specifically. It was not, my apologies.

For some pages I thought to notice inaccurate explanations. I will be happy to contribute where I know a thing or two, then anyone can make up their minds themselves.

Other than that, do as you will. I am sad to remember other threads where you have tried painting me to be some bad guy when we did not see eye to eye on some topic. So yes, I have decided to not be drawn into any of that anymore and instead be selective in my communication with you.
Don’t worry about the center hole in a BNC cap.
I agree not to worry on RF leakage (the radiated power is very low) and mostly not for susceptibility either. We're not listening in industrial environments next to a MW-sized variable frequency drive. Same time it's becoming recommended practice to terminate unused CATV ports in the presence of 4G networks. Those F-type connectors are not so different from the BNC's for the intent we are discussing here. Though in most homes it won't make a difference.
The cutoff frequency is so high nothing is getting in or out that tiny hole. A 1mm circular waveguide has a high-pass cutoff freq of over 450 Ghz.
Again I agree with you but for academic purposes: how did you come to that number? For Fc = (1,8412 x c) / (2 * pi * r) I am finding 175 GHz for a diameter of 1 mm. Female BNC barrels are somewhere around 2,1 mm which puts it around 82 GHz. Still well in the realm of "not to worry" but to understand how you are getting to 450.

One thing to note is that a circular waveguide may not be enough to model a BNC barrel. Many barrels are not continuous cilinders, but formed by several parts that are interspaced so the plug and jack can actually mate. Typically this may be a metal sheet folded into an almost-closed circle, or two halves or four quarters of a circle forming a "beak". This can easily be seen with the naked eye. Some barrels like the Neutrik NBB75DFIX are exceptions and indeed are continuous.

Where the barrels are not continuous cilinders, they will also exhibit RF properties of dipoles or even halo antennas, depending on their construction. The RF susceptibility of such antennas may be distinct from a waveguide.

For RF radiation I would still not be bothered as the radiated power is very low.
Something to consider is the terminated outputs will draw additional current from the power supply and possibly create more noise.
True but at 3,3V and 50 ohm only 0,22W right, and for 75 ohm less so.

Your advice to measure is the best that one could give. I am sorry that I don't own a OCK-2 yet so can only theorize. I would be surprised if the effects would be audible in any case (cap, no cap, terminator) but am looking forward to forum members to report their findings.
Each design is different and may not behave the same way. I like Mutec’s Ref 10 approach which allows users to turn off unused clock outputs.
Indeed. For the OCK-2 mk2 just one dipswitch per port extra? :)
 
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Dec 30, 2022 at 12:32 PM Post #425 of 3,361
@roderickvd
Thanks I saw the circular waveguide cutoff formula after posting and just guessed at the 1mm hole diameter. Still 82Ghz is beyond real world so the hole is no practical consequence. if it still bothered me I would just put a blob of solder across the hole to plug up.

The clock output terminations draw little current ? At 50 ohms each output current draw is 66mA. That is quite a lot as all outputs switch simultaneously. So in the case of the OCK-2 with 6 outputs that is a total power supply current demand of 396mA and has to change state (0 to 1, 1 to 0) in 1nS or less. Requires very good power supply design to have power in reserve at each output driver. Every design is different.

I think with the knowledge above I will just leave unused outputs unconnected or capped. No loads.

75 ohm is an easier load to drive than 50 ohm. On a given clock design you may have faster clock edges with 75 ohm vs 50 ohm. That would be a good experiment to change loads from 50 to 75 ohm termination with source/ cable impedance swap.
 
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Dec 30, 2022 at 12:54 PM Post #426 of 3,361
Ever wonder what happens when you feed a CDplayer the wrong clock frequency on purpose?

I came across a DHT master clock mod (i have many types of these modules) where i could change the frequency in real time while the unit is playing as a digital transport. As you can see, the CD-880 requires clock (square waves) for digital overhead to run the decoder and controller boards, but the clock also effects the playback end result directly and i believe this section sounds better when fed Sinewaves. I overclocked the CDP to about 17mhz for a few seconds and then i put it back to stock speed at 11.2mhz. Changing frequencies on a CDP is like changing RPM on a turntable. Using a master clock based upon a tube is very interesting as it is not weak like unbuffered Quartz (it is strong... too strong and must be dialed back). Absolute accuracy and stability is not the point here (because honestly that just makes it sound more digital like a cheap dvd player), but simplicity of circuit and and whatever natural imperfections exist (i cant see it on the scope nor do i care) make for a much more natural sound and PRAT akin to analog. The digital controller obviously accepts the clock or it doesn't, but it will still function even if completely wrong frequency is the key observation to note. Obviously the internal CDP dac does not function at 17mhz, but i am playing back via an external dac via SPDIF output. The master clock is my favorite CDP mod.

7h82vD1l.jpg

IeMqelvl.jpg

 
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Dec 30, 2022 at 3:11 PM Post #427 of 3,361
@roderickvd
if it still bothered me I would just put a blob of solder across the hole to plug up.
Ah, but then you would have created a whip antenna which would be quite sensitive around the clock frequency :)
The clock output terminations draw little current ? At 50 ohms each output current draw is 66mA. That is quite a lot as all outputs switch simultaneously. So in the case of the OCK-2 with 6 outputs that is a total power supply current demand is 396mA. That has to change state (0 to 1, 1 to 0) in 1nS or less. Requires very good power supply design to have power in reserve at each output driver. Each design is different.
I will admit that I did not consider that point yet, lol. So used to working with a properly sized class A that I almost forgot!

Does anyone know which LDO's are used on the LHY's? From the pictures I can't make it out. On the net I find something about TI LDO's but not which ones. Betting on the TPS7A4700 I found it interesting in the datasheet that it likes a good constant current loading: https://www.ti.com/lit/ds/symlink/t...=https%3A%2F%2Fwww.ti.com%2Fproduct%2FTPS7A47. In figure 22 the noise at 50 mA is lower than for 20 mA almost across the board.

Figure 19 shows the load transient which very much resembles the leading and falling edges of the clock. Instantly drawing an extra 835 mA gives an overshoot and undershoot of 2 mV -- am I reading that right? There is your noise _but_ not by the 396 mA you might expect, but from the increase in capacitor charging duty cycle because the reservoir is drained more quickly. This voltage misregulation is then smoothed by the capacitor bank, which will be less than that 2 mV for 835 mA, but greater than zero.

Pick your poison: interference from reflections, or greater power supply noise from increased loading :xf_cool:

How much I am looking forward to these measurements both by oscilloscope and ear.
 
Dec 30, 2022 at 3:59 PM Post #430 of 3,361
@jh4db536 that thing looks beautiful. What is it?

It is a master clock based upon the CX371a (type 71 kinda like a lower power 45) Directly Heated Triode and powered by UX280 full wave rectifier tube (type 80). It's basically a sinewave generator circuit which is adjusted like a radio tuner to get the desired frequency. It can output in excess of 4VRMS amplitude of a clock signal and output via coaxial into a CD player and/or DAC's (modified of course to accept external clock). All my gear is 11.2896Mhz so that's what i use for master clocking my entire chain. Changing the tubes with identical frequency will change the sound of the entire chain. The way it interacts with the gear that is slaved to provides major tuning opportunities.

xpAAfTxl.jpg


I also have EZ11/EF11 master clock and it's fixed at one frequency so i was never able to demonstrate before. This is my daily driver that i use for my CDT and DAC's and for me gives me the sounds i want which is making CD880 sound like a Garrard Idler drive without motor rumble pops and crackles. All the convenience of digital.

rZrrkK6l.jpg


Should also mention, i have Tricord4 on my VRDS-25 which collects dust after i got into these. Have the tentXO on my diy shigaclone

Edit:
I borrowed the 71 DHT clock so i could figure out how to implement and install it in my friend's CDP. These were custom made point to point back in 2014.
They can be bought as standalone boxes or PCB in various stages of assembly. Schematics were always available. It is always up to the user to implement and mod the downstream gear to accept it so this is intermediate level diy stuff to some degree.
My friends did huge group buy a long time ago and we only just received this stuff recently.
 
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Dec 30, 2022 at 4:42 PM Post #431 of 3,361
@jh4db536 you built these yourself?
In OCK-2 is LT3042
OK same trick, different datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/lt3042.pdf :)

Initial thought: oh wow, that LT3042 really is a different beast. For a 190 mA step, the voltage output first dips by almost 9 mV. Then on the trailing edge it has this huge see-saw, first overshooting by over 20 mV before undershooting by 5 mV. Just look at that "Load Transient Response" graph. I never spent so much time looking at it, but wow. Next time I'm making a BOM for a PSU I'll be sure to look beyond just the absolute µV noise figure, and think harder about current deltas.
 
Dec 30, 2022 at 4:55 PM Post #432 of 3,361
@roderickvd
Thanks I saw the circular waveguide cutoff formula after posting and just guessed at the 1mm hole diameter. Still 82Ghz is beyond real world so the hole is no practical consequence. if it still bothered me I would just put a blob of solder across the hole to plug up.

The clock output terminations draw little current ? At 50 ohms each output current draw is 66mA. That is quite a lot as all outputs switch simultaneously. So in the case of the OCK-2 with 6 outputs that is a total power supply current demand of 396mA and has to change state (0 to 1, 1 to 0) in 1nS or less. Requires very good power supply design to have power in reserve at each output driver. Every design is different.

I think with the knowledge above I will just leave unused outputs unconnected or capped. No loads.

75 ohm is an easier load to drive than 50 ohm. On a given clock design you may have faster clock edges with 75 ohm vs 50 ohm. That would be a good experiment to change loads from 50 to 75 ohm termination with source/ cable impedance swap.
Unconnected and uncapped?
 
Dec 30, 2022 at 5:16 PM Post #433 of 3,361
For one thing I will apologize, as I understand how you feel it was a personal attack on you when I first quoted you and then went on about pseudoscience. I should have made it clearer that this was not about you specifically. It was not, my apologies.

For some pages I thought to notice inaccurate explanations. I will be happy to contribute where I know a thing or two, then anyone can make up their minds themselves.

Other than that, do as you will. I am sad to remember other threads where you have tried painting me to be some bad guy when we did not see eye to eye on some topic. So yes, I have decided to not be drawn into any of that anymore and instead be selective in my communication with you.
If you had bad past experience with someone, it is better to avoid comments on the beginning of the conversation which can be perceived as a derogatory generic characterisation of the respondent. It looks like looking for the automatic stamp of approval from the audience on your point of view or bringing support from individuals with wrong intent. Happily trolls didn't come up this time, but it is observed in many other places.

I accept your apology that your comment was not directed on me, but not the explanation. If you read the above paraghaph, you will understand it is all wrong. Mutual respect is neccessary for the positive outcome. Any indication of disrespect stimulate pointless aguing or turns discussion into unnecessary drivel.

I am trying to start new topic clean, as those who participate may don't know our past. Those who know, don't want experience it all over again. I am not free of limitations or mistakes, but you can not accuse me for a bad intent. It is on the conclusion, I am hope we are now fine.
--------------------------

Coming back to the topic, discussion inevitable leads to the conclusion which is consistent with my initial evaluation. @OCC7N can you hear? :)

1. Open port is fine, but may rise question of interferences.

2. Pin-less cap is harmless and cures suspicions of interferences.

3. Terminating cap (a) takes care of the shape of the signal we don't 'consume' (pointless), (b) gives a solution for the reflections that may not occur at all (short leads), (c) is not free of negative consequences.

I am convinced that additional switching load on power and ground planes cannot be ignored even in a good design. It is a first place where noise appear. Regression of filtration capabilities of the power supply at increased load has been covered as well, it is a second place.

Yes, I read that LDO power supply has to be current loaded for optimal filtration. Designers know well about this issue, even if they don't, the associated components draw enough current to bring LDO out of the idle zone. We don't need to investigate design level details. It looks to me brought in purpose of arguing.

Now is a time to verify our finding in practice. Some members had ordered terminators and pin-less caps, looking after test results.
 
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Dec 30, 2022 at 6:08 PM Post #434 of 3,361
I thought the ock-2 master clock had selectable dip switches for 50/75 ohms.

It seems alot of sellers are offering 50 or 75 ohm options.

Can anyone shed some light on that?
 
Dec 30, 2022 at 6:21 PM Post #435 of 3,361
I thought the ock-2 master clock had selectable dip switches for 50/75 ohms.

It seems alot of sellers are offering 50 or 75 ohm options.

Can anyone shed some light on that?
It has for all outputs yes. Who said it does not?

I talked with the europe seller. He confirmed it is user configurable. 50 and 75 on ALL ports.
 
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