Clock experiments

[SCAudiophile]

Originally Posted by custodian

Thanks for posting an interesting and comprehensive summary.

A point you raise early on needs a bit of clarification; generally the better ocxo clocks have better short term stability and phase noise than any rubidium clock. I'm not sure why rubidium clocks can sound as good as they do in the right system.

I think pursuing picking the best possible ocxo and providing a top quality power supply is definitely a good path. With my home made clock using the amazing Oscilloquartz 8607 BVA ocxo. I spent some time experimenting with power supplies to wring out the last drop of performance. I still would like to put it all in a case like Sforzato used for their commercial clock using the same 8607 ocxo but for the time being it has to stay in an off the shelf case plus HRS damping plate.

Excellent clarification,...thank you! I learned that in the past 6 months from my forays into these 10 mHz 50-ohm based clocks.

Esoteric Rb-based clocks cause music to sound as good as they do (in my experience iwth them) I believe due to the quality of the Rb circuit they use PLUS every other level of excellent design improvement they implement around it from the chassis and base plates to the outstanding power suppliers. Interesting project you made happen with the BVA. That module/circuit has a great reputation!

[SCAudiophile]

Originally Posted by chessman

Outstanding post!

Thank you very much....

[custodian]

Originally Posted by SCAudiophile

Excellent clarification,...thank you! I learned that in the past 6 months from my forays into these 10 mHz 50-ohm based clocks.

Rb-based clocks cause music to sound as good as they, particularly Esoteric I believe due to the quality of the Rb circuit they us PLUS every other level of excellent design improvement they implement around it from the chassis and base plates to the outstanding power suppliers. Interesting project you made happen with the BVA. That module/circuit has a great reputation!

Not sure I buy your comments on Rubidium circuits. Generally they have comparatively poor phase noise which should be critical. Also some of the commercial offerings use very ordinary switched mode power supplies. The rubidium unit is self contained and bought from an OEM supplier; not something fabricated by the audio equipment manufacturer. Certainly casework and wiring help but I'm not convinced any of the rubidium units do this any better than companies such as dcs do with their ocxo oscillators. But in spite of their quantitative performance shortcomings and often mediocre implementation, they can sound very good. As a cheap experiment, try buying one of the ex China Telecomms rubidium units ($1-200 on EBay) and a cheap 15v switched mode PSU and a simple case. it can still add something when used to provide a reference clock signal to a DCS or similar.

[SCAudiophile]

Originally Posted by custodian

Not sure I buy your comments on Rubidium circuits. Generally they have comparatively poor phase noise which should be critical. Also some of the commercial offerings use very ordinary switched mode power supplies. The rubidium unit is self contained and bought from an OEM supplier; not something fabricated by the audio equipment manufacturer. Certainly casework and wiring help but I'm not convinced any of the rubidium units do this any better than companies such as dcs do with their ocxo oscillators. But in spite of their quantitative performance shortcomings and often mediocre implementation, they can sound very good. As a cheap experiment, try buying one of the ex China Telecomms rubidium units ($1-200 on EBay) and a cheap 15v switched mode PSU and a simple case. it can still add something when used to provide a reference clock signal to a DCS or similar.

Thanks for the note and feedback plus ideas; I was not as clear as I had hoped to be....my post should have read like this;


A point you raise early on needs a bit of clarification; generally the better ocxo clocks have better short term stability and phase noise than any rubidium clock. I'm not sure why rubidium clocks can sound as good as they do in the right system.

I think pursuing picking the best possible ocxo and providing a top quality power supply is definitely a good path. With my home made clock using the amazing Oscilloquartz 8607 BVA ocxo. I spent some time experimenting with power supplies to wring out the last drop of performance. I still would like to put it all in a case like Sforzato used for their commercial clock using the same 8607 ocxo but for the time being it has to stay in an off the shelf case plus HRS damping plate.[/quote]

Excellent clarification,...thank you! I learned that in the past 6 months from my forays into these 10 mHz 50-ohm based clocks.

Esoteric Rb-based clocks cause music to sound as good as they do (in my experience with them) I believe due to the quality of the Rb circuit they use PLUS every other level of excellent design improvement they implement around it from the chassis and base plates to the outstanding power suppliers. Interesting project you made happen with the BVA. That module/circuit has a great reputation!

==>I do agree with you based upon the last 6-9 months where I learned alot more on this topic and was no longer buying/using blind based upon a glitzy marketing spec (PP/B versus PP/M). Through some very expensive learning over the years and with finding a high-quality OCXO-based implementation that quite simply makes my system sound a whole hell of a lot better using a sub-$2K clock with a great OCXO implementation than the best Rb I ever owned or heard, for the reasons you state above. What I am very eager to see though is what will Esoteric pull off with their all-10 mHz/22.xx mHz true master clock, the Grandioso K1. I have to believe they are aware of the importance of all these factors. Wondering how this Grandioso-level rig will perform. I'm also looking forward to my next all-OCXO > OP15/17 level implementation (current tested modules are OP20) to be designed and made available in the future.

Hope this helps...let me know if I solved the confusion from my post or just created more!

[custodian]

I think it helped (a bit, anyway)

[jpspock]

Dear scaudiophile, or zephyr you changed your name I think, and custodian. I have read your reports with great attention and it is very helpful, thank you.

So scaudiophile, you are in contact with cybershaft and it seems they are serious and propose with the new OP 11-14 very competitive clock 10MHz compred to antelope, sforzato or perf10. I didn't receive any information concerning op 17 or upper, i will ask.

Concerning my approach, my search through the net showed me a lot of discussion with custodian. I discoverd you had a scarlatti stacks before. So you have for sure the experience of what is happened when a 10MHz clock is added to a scarlatti clock. Can you develop this for me? As you have a specific clock, unavailable for us, what do you think about cybershaft clock? So just for the fun.

And for both, the bnc cable must be a 50ohm, for the cybershaft, where can i get one, and does it make a problem with the scarlatti that has an entry of 75ohm.

Already many thanks guys.

[custodian]

With dcs Scarlatti stack, I have run several rubidium clocks from a cheap and simple China Telecom surplus unit from eBay, up to Quartzlock module. All of the rubidium clocks are designed to output via an SMA connector to 50 ohms. In all cases, sound changed from standard Scarlatti clock, generally to produce a better imaging result. The 50 ohm SMA in some units just goes through a short jumper to a BNC connector.

Working on a project with Quartzlock, I had an opportunity to try any type of frequency standard. The advice of the Quartzlock engineers was to try the 8607 BVA ocxo because it had the best available results in phase noise. Initial tests were with a simple set up with a 24v switched mode supply and the same sma to bnc jump lead to a 50 ohm bnc on the rear panel. Connecting this to the Scarlatti clock with a 75 ohm cable produced a very good result.

Trying to get even better performance, I used a 50 ohm lead direct from the sma on the ocxo case to a 50/75 ohm converter at the dcs clock reference input. Again a noticeable change for the better.

Final upgrade was to build a high performance power supply and fit clock in a decent case with mechanical damping: results outstanding!

Cybershaft clock? I can't comment because I've not had the opportunity to try one although the specs look very good at a very attractive price.

The end of production of the BVA Oscilloquartz 8607 was a great pity however it was difficult to make because of low yields. I understand that there might be an alternative sometime soon but no firm details yet.

For me, the next steps are to do more work on optimising the 50 ohm cable.

[SCAudiophile]

Originally Posted by jpspock

Dear scaudiophile, or zephyr you changed your name I think, and custodian. I have read your reports with great attention and it is very helpful, thank you.

So scaudiophile, you are in contact with cybershaft and it seems they are serious and propose with the new OP 11-14 very competitive clock 10MHz compred to antelope, sforzato or perf10. I didn't receive any information concerning op 17 or upper, i will ask.

Concerning my approach, my search through the net showed me a lot of discussion with custodian. I discoverd you had a scarlatti stacks before. So you have for sure the experience of what is happened when a 10MHz clock is added to a scarlatti clock. Can you develop this for me? As you have a specific clock, unavailable for us, what do you think about cybershaft clock? So just for the fun.

And for both, the bnc cable must be a 50ohm, for the cybershaft, where can i get one, and does it make a problem with the scarlatti that has an entry of 75ohm.

Already many thanks guys.

Let me know how I can give you a call tomorrow to answer your questions if that is acceptable to you.

[Masterlu]

Originally Posted by SCAudiophile

Let me know how I can give you a call tomorrow to answer your questions if that is acceptable to you.

Mark... without him being a Subscriber, he cannot send nor receive PM's.

[SCAudiophile]

Thank you Ivan....did not notice that.

JPS: OP levels for OCXO modules above OP14 (from what I am told, remember, I'm just an owner of their clocks out of Japan) were exhausted and the Limited level of the clock that could range from OP15 to OP17 is not being produced any longer. I am told design revisions and new module acquisition are firmly under way. The process apparently is that hundreds (or more) of candidate modules are tested rigorously and this OP rating (which I don't know the source of, could be their in-house rating nomenclature) then assigned to each for any module that is not discarded. When they have a lot produced that scores highly, they apparently buy up the remainder of the entire run from the vendor, test them, assign levels and shelve them for future builds. Hope this answers the question in a more thorough way.

Having 2 clocks in the system right now at OP14 level (lower strata and one upper strata of the range), I can tell you that OP14 is more than sufficient to have the wow-factor. I cannot imagine what an OP17 or above would behave like; it must be truly special. I hope they wind up having these made and certifying them at a > OP15 and above level. I will definitely grab one....

As for 50-ohm cables,

- Shunyata is entering a testing phase per Caelin recently on a beta version of one of their high-end BNC:BNC cables certified for 50-ohm. My personal bet knowing his work is that this cable will be amazing

- I've talked at length to Sergeui at STEALTH; he definitely makes and will certify a pure 50-ohm version of his VARIDIG SEXTEX V16 or V16T cables...

- Esoteric/Mexcel made one in the past, the 8N-A2000 which is like "unobtanium" to find these days. I am extremely fortunate that there was one left locally and I was able to grab it from a good friend(!)

- Acrolink I believe also makes one that is either 6N or 7N

- I have an extra Kubala-Sosna 50-ohm 1.5 meter custom-made cable < 6 months old; if interested, let me know and I'll post it

- You can get a $35 USD cable that is absolutely certified for 50-ohm off Amazon; I tried one initially and it was a good start (for me)

- Other manufacturers may make them; I did not exhaustively research the topic...

- Many people have found no noticeable difference at 1-meter and 1.5 meter length using high-quality cables like Wireworld Platinum Starlight v7; Ivan can definitely tell you more

JPS: Become a subscriber; it's the best $25 USD you will ever spend :-) !!!

Let me know of other questions...have a great day!!!