Master Clock for your EtherREGEN

[MartinT]

Who here is using an external master clock with your EtherREGEN?  If so, what are you using and how would you describe the changes to sound quality compared with using the internal clock?

[MartinT]

Ok, I'm surprised no-one else is pitching in.  Meanwhile, I tried an experiment using a Chinese made BG7TBL OCXO to hear what an external master clock could do for both my ER and Mutec reclockers.  Here's what I wrote...

 

 

After testing that the BG7TBL OCXO was working fine with the EtherREGEN and Mutec MC-3, both set for external clock (the ER needs the clock switch set and to be power cycled, the Mutec needs the front panel setting for external 10M and reclocking), and giving it 6 hours to fully warm up, it was time to listen to what was going on.

I started with the ER alone and it was clear at first that the change was very little, if anything, depending on the track played. I couldn't hear anything obviously different in terms of dynamics, soundstage, bass to treble response or anything that I have a phrase for. Something was nagging me that it sounded different and, after a while, I decided that it just sounded easier on the ear.

My thinking was that the ER, with its notorious Crystek 575 oscillator, would be the better component to respond to an external clock although I have no knowledge of the clock used in the Mutec. So I expected little from this point onwards. I was wrong.

Jumping back a moment, I tried the Mutec on its own. I heard pretty much the same thing as from the ER: not a lot at first, then the slow realisation that this is nice and I’m enjoying the musical delivery. So far, so good and no step backwards with either component as I had feared. Proving that a stable crystal referenced sinewave master clock sounds at least the equal to, and actually better than, the internal clocks was a big learning moment for me.

So, without any further messing about, I connected the clock to both components and started a new session later on. By this time, the BG case was warm (and presumably the oven inside quite a lot warmer) and the LPSU feeding both the ER and BG was positively toasty. The ER consumes 10W and the BG about 18W max. so the 50VA LPSU is running at half capacity.

Listening to the sum effect of running the two sinewave outputs to the ER and Mutec, and allowing for some further warming up and settling, I was hopeful of hearing something more tangible. Well, I did, I heard a whole lot more music coming out of my system. Effortless, vivid, alive, right there, choose your own words, the delivery was wonderful. Ask me again to say what changed, and I’ll still struggle to define it. The bass is perhaps a touch more solid and potent. That’s it.

The best I can say is that my system is delivering music with new-found ease. Live music has phenomenal soundstaging, deeper than I have ever heard from my speakers (e.g. Nils Lofgren - Band Live), studio music has more immediacy and natural dynamics (e.g. Steely Dan – Pretzel Logic). Classical really benefits from the depth and low-level ambient sound of the recording space (e.g. Vivaldi – Four Seasons, Drottningholm). Nothing much has changed, but everything has changed, if you get my drift.

I am pleasantly in shock that £70 worth of Chinese made amateur radio clock (well, to be fair, a pretty accurate oven controlled clock made for telecoms use) could achieve anything very much, let alone what I’m hearing. My investment has been less than 1/20th that of the £1500 Teac CG-10M clock, one of the less expensive clocks on the market. I couldn’t be more pleased!

[MartinT]

Here's the inside of mine.  You can see it's a DAPU unit.

 

 

Apologies, I did not mean to insult your clock choice for the ER.  I said 'notorious' because I have an LKS MH-DA004 DAC and quite a few owners (including myself) have had the Crystek 575 replaced with something else.  The 575 gives it a hard edge to the sound, despite its excellent paper specs.  I know implementation is everything so, of course, it doesn't mean the 575 is always a problem.  With a Coherent clock in mine, the sound is considerably more insightful without that slight harshness.

 

Back to the BG7TBL, whatever is going on, it has made quite an improvement to my system's sound.  I cannot explain it, it was just an experiment for fun, but there you are.  The clock cables are Canare LV-61S, by the way.

[MartinT]

I found the specs for the DAPU OCXO. Would very much appreciate your thoughts on phase noise and the other specs.

 

http://dptel.com/products-detail.php?ProId=2895

[MartinT]

3 hours ago, Superdad said:

If the O55A is really the clock module in your box then it’s a good bargain for $100.

 

Yes, it's my photo of my unit.

[MartinT]

9 minutes ago, Ponkbutler said:

Would you mind posting where you bought it, if that's not against the rules...

 

From AliExpress.

 

https://www.aliexpress.com/item/4000152539910.html?spm=a2g0s.9042311.0.0.795e4c4dGTiyce

 

Mine is the latest BG7TBL variant, dated 2019-12-09 and contains the DAPU OCXO.  No guarantees that others will be the same!

 

[MartinT]

The output connectors are 50 ohm. I'm thinking of sourcing PCB mount 75 ohm sockets and swapping them.

 

Using short 75 ohm cables into 75 ohm ER and Mutec in sinewave mode doesn't seem to be harming the signal too much.

[MartinT]

I may be wrong but I deliberately did not select a GPSDO because the complexity is tenfold. All that digital circuitry and ground plane noise for the immaterial benefit of zero long term drift. I didn't want any more noise on the clock outputs than absolutely necessary. There is also the faffing around with a GPS antenna out to the window.

[MartinT]

I've not seen any of the BG7TBL designs with 75 ohms off the shelf. Even with 50 ohm output I'm getting a substantive improvement and I'm going to try adapting mine for 75 ohm operation.

[MartinT]

40 minutes ago, basillus said:

Hmm interesting... I have the same BG7TBL Connected to my Gustard U16 and haven't tried it on the etherregen, because I figured it wouldn't be an improvement there.

Ok, now it must be tried, but just needed one more bnc cable ;0) and a better psu...

 

You must try it!  I found the effect of external clocking both my EtherREGEN and Mutec very impressive.  You should hear a similar doubling of the effect.

[MartinT]

I now have a set of 75 ohm connectors to install.  I will then need to find how the oven output reaches the connectors.  It may be a simple resistor change, I don't know yet as I've been unable to find a circuit diagram.  If in doubt, I'll leave it alone as it sounds very good already but I will change the connectors.

[MartinT]

I don't have variable output?  I use both sinewave outputs and am not using the squarewave output.

 

When I open it up to change the connectors to 75 ohm, I will see what I can find with regards to output impedance.

 

I'll say again: it's clearly not a major issue driving two devices using short 0.5m 75 ohm cables despite the clock being 50 ohms in stock form.

[MartinT]

35 minutes ago, k-man said:

Another consideration will be to exchange a 75 ohm EtherRegen with a 50 ohm version.

 

For me, that wouldn't solve the problem as my Mutec MC-3+ USB is also 75 ohm.

 

It works well now but I'll exchange the BNC connectors when I have a little free time.

[MartinT]

Either could potentially feed the BNC connectors, I would trace back using a meter to see whether they are the line impedance resistors.

I shall pull my board out soon, I'm just waiting for some ceramic decoupling caps to arrive.

[MartinT]

7 hours ago, Superdad said:

 

Actually, the EtherREGEN prefers squarewave input.  Since you have both, why don’t you go ahead and compare them? 

 

Thanks - I will try it once I've got the impedance sorted. I hope I'm right in thinking an impedance mismatch affects a squarewave worse than a sinewave.

[MartinT]

John, I do believe you're right. I've just switched the ER over to squarewave, leaving the Mutec on sinewave. There is a little more soundstage 'presence' and low level detail and the bass is a touch tighter. This is still with the mismatch at the clock socket/cable boundary.

 

When I receive a BNC T-connector, I'll be able to get my scope on the waveform and see how distorted it looks. My ears tell me that it's an improvement, though.

[MartinT]

Some detail of my BG7TBL PCB.  I have swapped two outlets to 75 ohm BNC connectors, leaving one sinewave outlet at 50 ohms.

 

Top side.

 

 

Underside.  Note the PCB is dated later than my rear panel, 2020-03-13.

 

 

Detail showing ceramic bypass capacitors added.  There is only just enough clearance in the case, it's a tight fit.

 

 

 

[MartinT]

I can say, in conclusion, that this inexpensive OCXO is really doing the business in my system, with the squarewave clock going to the EtherREGEN and sinewave clock to the Mutec MC-3+ USB.  For a tiny fraction of the cost of any 'hi-fi clock', it's giving a decent proportion of the attributes of running an external clock over using the internal clocks.  A good quality 12V external LPSU is essential, as is a decent DC cable (I'm using a Coherent modified Chinese LPSU to feed both the ER and OCXO, Coherent DC cable to the ER and MCRU DC cable to the OCXO).  Decent vibration absorbing footers are needed, too.  I also tacky-glued the two halves of the metal case to prevent resonances.  A trip to Coherent with it verified the decent performance (about 40ps jitter, reducing to 30ps with the LPSU) and good quality waveforms.  We saw overall phase noise drop with a low noise LPSU, too.  My Canare LV-61S cables also tested pretty well.

 

What I hear is a very low noise floor, deep soundstage with micro-detail, huge ambience and note decay (this latter a revelation in my system), natural 'shape' to notes, for instance guitar strings, highly focused vocals and an easy, liquid flow to the music while remaining highly dynamic with impressive attack and slam.  Steely Dan never sounded so good!

[MartinT]

6 minutes ago, zerung said:

 

 

@MartinT is this after the conversion of the clock to 75 Ohm? Incidentally the seller from Taobao is willing to change the system to use the Morion Clock and also change the connector to 75 Ohm, etc.

 

Yes, I'm getting a little more now but even in stock form it was worth the purchase.

 

If you can get it supplied in 75 ohm form then go for it as swapping those connectors wasn't easy.

 

How do you know the Morion clock is better than the DAPU?

[MartinT]

That's the frequency adjustable model.  Can they not provide 75 ohms in the fixed model, like mine?

You want the least complexity inside that you can go for.

[MartinT]

4 hours ago, Savolax said:

 

I ordered the same unit. Just received and opened it. The one I have is also 2019-12-09 and includes the same DAPU OCXO inside. I will be using it being connected to Magnafied Singxer SU-1 (sCLK-EX tweaked). I'm eager to get it compared vs the sCLK-EX clocks. 

This sCLK-EX mod provides me an extra DC-out via SU-1 which I will be using to power this clock unit. Modded SU-1 is powered by Farad3 12V.

 

Try both the sinewave and squarewave outputs into the ER and let me know what you think.  Don't forget to power up the ER after you're changed the switch to external clock.

[MartinT]

3 minutes ago, zerung said:

 

Is that an external filter? I am not sure how to do this? As far as I know this only come with square wave as a standard

 

 

Look at your front panel: from left to right, the BNC outputs are squarewave, sinewave, sinewave.

[MartinT]

Ah sorry, I was looking at Savolax's photo above, which is the same as mine.

[MartinT]

8 minutes ago, zerung said:

With my system, the ER and the clock make an alarming upgrade.

 

I completely agree.

[MartinT]

On 6/18/2020 at 3:19 PM, zerung said:

He is having trouble sourcing a 75Ohm BNC binding post that will fit his circuit board. 

 

https://www.ebay.co.uk/itm/RF-COAXIAL-BULKHEAD-BNC-Coaxial-RECEPTACLE-R-A-75-OHM-SOLDER/293400270378?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2648