Below are the highlights of todays experiment, I’m not going to give too much away, however I felt you may appreciate what actually goes into product investigation/ review and new concept implementation.

The first few are of the basic clock design with various voltages and currents applied, same probe, same scope, same settings all warmed up for 90 mins before any measurements taken.

It was quite obvious in the first hour or so, that the wall wart and Ali express LPS were acutally making matters WORSE, totally counter intuitive, given one was a genuine LPS with twin outlets, totally unmolested just very noisy electrically, the much better SMPS with the fancy DC filter was actually OK as in it didn’t degrade the sound at all, compared to the other two!

I stuck with the bench PSU as it was the most ‘linear & stable’ which is what is required when you are looking at consistency of results.

This is also interesting, below is the measurment readings taken with a traditional passive probe and flying lead, this adds inductance so if you are not aware it will cause you much head scratching and frustration, you can reduce this inductive loop by using the spring clip, below is the flying lead image.

Below exactly the same set up but just using the spring clip instead of the flying.

Last one looking at the best supply rail numbers for this particular device

Differential active probes are like two probes in one. Instead of measuring a test point in relation to a ground point (like single-ended active probes), differential probes measure the difference in voltage of a test point in relation to another test point.

These probes provide transparent probe attenuation so signals are always optimized for the display. The differential range is 18 Vp-p with a differential offset of ±8 and common mode range of ±10 V, making this versatile for every probing application.

The wide dynamic range of 16 Vp-p and offset range of ±8 suit this probe to a wide range of applications and signal types. The ZD differential probes are ideally suited for Automotive, Serial Data, power, and general-purpose use. The differential input capacitance is only 1 pF to minimize loading distortion on the highest frequency signals under test. System noise of only 4 mVrms allows accurate measurement of the smallest signals.

Probing with long leads or accessories is sometimes necessary to reach the test points, but it comes at the expense of reduced bandwidth, increased capacitance, and added noise. The ZD accessories are engineered to provide the best signal fidelity without ringing or distortions commonly introduced with tip accessories.



The last scope images are after I have completed removal of long flying leads, installed a new comparator circuit, one circuit bypass, five capacitor changes plus a small ref board underneath to bypass the O.E. voltage reference. Again, I tried with various V/I’s.

On this particular clock I did find a sweet spot for voltages, the original ‘clock’ oscillator is still present and like Martin T found out a few years, its not the ‘best figure of merit version’ either, but that’s for another day.

Sorry for the long post, but the take aways here are, the power supplied to the clock itself is AT least as important or more so than the clock device itself imho

Also that specific voltages and currents can and do make more than insignificant differences, the end result which was ‘measurement wise preferable’ ended up @ 7.85Vdc pulling a 16.314mA load.
The original figures for frequency deviation from 16.934Mhz were 1.45Khz, rise time around 50pS and 18pS for fall time. After the design changes were made the frequency deviation was reduced to 1.260Khz reduction of around 14%.5.35However, the positive and negative widths ended up being rather gopd at 6.635pS for (+ Ve) and 6.932pS (-Ve) there are more reductions in the others individual traits as well, but I have only listed a few.

below are the screen images from the scope after the updates were performed and the active diff probe set up and installed. I have also thrown in a jitter kiot analysis and some serial data in depth clock eye pattern and noise track measurments

How does his sound, well given the clock has to really have around 200hours of use, I can’t say right now, but I have another untouched clock with the same older configuration, both are now being exercised, so by this time next week I will be able to make a judgement call.

Its all hands to pumps this week with the superb North West Audio Show happening this weekend, we really rate and like this show and have supported it since it's inception. Lots to see and do, good food sensible costs, great grounds and hotel plus one of the few shows that exhibitors make a good effort for. Right in the heart of Whipper thrasher & toe tapper land, its the anti-thesis of Bristol. Great atmosphere & a relaxed musical environment with very little hifi pap imho.

Over the weekend I thought I'll just try and see if I could cajole W25 into giving some more  of its rather special musical moxy, recently while working on some aerospace project, so I felt it was worth a try.

Also gave me change to try out a new set of H & E field sniffer probes, so while you chaps were enjoying the superb weather yesterday I was playing hunt the RF noise lol

Anyway the upshot is quite noticebale even after 14 hours of use, the sheer presence this dac now exudes is most grin inducing like a honey badger taking a chunck out of a lion's ball sack

Depth on this dac has always been one of the strongest traits in stock form, it never disappoints big wide and DEEP now its plain old intoxicatingly cavernous in the least, also the noise floor has reduced a little (lol) not that it was high in any way, I have managed to reduce the noise between the fudemental harmonics to deep, deep in the mud. Even Qoboz sounds like the old days with files now, quite listenable.

I did spot some mains coupling from 50 to 500Hz, although this was between -88 & -115 dBc with the ref level @ +20dBc and that was with the lab supply and not the system power supply. Given this is the stock Tx I'm quite please with this

Here you can see how we  look at the dac while on the analyser & using the EMI spurrious location app on the spectrum analyser at the same time.

Also a new lens for the Nikon as well, the H field prove is virtually sat on one of the clocks this is purely for illistration, you can see the probe holder in the background but the shot didn't look right so some artistic license was used! However not shabby a result i  any way.

As I am having a lab re arrangement currently I thought I would dust off the VNA (Vector Network Analyser) these are used for cable measurments  S11/S12 & S21/S22 return loss (dynamically), antenna seting up (SWR). circuit pathway measurments/ base and broad band emmission monitoring and 5/6G & higher communication rf transmission decoding etc

So I found an appropriate 'N' terminated 50Ohm T-flex 405 cable, let the instrument warm up for a hour or so, calibrated then looked at the results of investigation.

Now on this unit only looking up to 1.5Ghz (not quite DC to daylight lol) anyway these imahes are of the Smith chart/ phase response / Polar chart and S11 reflection coefficient (gamma) ideally as close to one is the goal. Phase response here looks odd but is actually very good. With the DUT (cable) showing just over 3.2 cycles in 1 GHz, that's equivalent to an electrical length of about 3.2 feet, the actually cable length is 90cm so pretty close I feel. light tarvels at about 1 ns per foot or in a typical plastic-insulated cable a physical length of about 2.2 ft / .67 m in that time period.

The botom line is the 405 measures very good and sounds fine as well, is that always the case............. er No! but with the T-flex it is.

Hello Damien

That's the back up VNA, we have more exotic versions for slightly more trickier situations and dynamic cables measurements are not really (at this level & frequency) are not taxing.

Now the cable I use personally don't read anything like that and there are reasons for this. Also I have a few cables which are improved over the 405 measurment wise but do they sound the same? As I mentioned in pervious post back in the annals of time (it feels like it anyway!) make the 405 sound like bell wire, however you need to have the full inforstructure in place to really expliot these cables along with the price tag.I would suggest that utilising your funds in other areas first will bring far more benefits all round.

I have some other technical features planned over the next few months plus some insight as to why certain equipment works 'better' with certain other types of brands.

Plus a new feature Big W's video-casts on basic electronic skills and how to improve them.

Well lab upgrades have been progessing well in the last few months, and shortly I will be inpocession of one of the very best signal anaysers on the market with full phase noise & noise figure abilities up to 26.5Ghz. Its a bit good

What this means is ultra accurate zero bullshit clock measurments for jitter & phase noise in the real world and end user testing.