ESS9018 - try new, try more...

[Joseph K]

Ok, for example this is more real, and probably not too bad:

http://depnerlabs.hu/wp-content/uplo...datasheet2.pdf

Ciao, George

[barrows]

George. It looks like the Depner is an entire clock/power supply which must be applied externally. I wonder how much additional phase noise will be caused by having to distribute the clock signal?
Nice thing about the Crystek CCHD-957/950 is that they can be placed directly adjacent to the DAC, and with good board layout, should not degrade much.
These (CCHD Series) clocks are still looking pretty good to me from a practical standpoint, consider the ability to implement them in existing products/boards in mostly non-compromising ways. In direct comparision to the Depner, the phase noise is pretty close, and considering the degradation which may be caused by distribution, in practice, the Crystek may perform equally as well.
Of course, we muct consider the power supply as well...

[Bunpei]

TAD-D600 CD player
???????TAD-D600?TAD (in Japanese)
uses this oscillator. This is not OCXO. However, its technology is of OCXO and manufactured by NDK. (TAD people thought the need of "warm-up" in OCXO does not satisfy a requirement in a consumer product.)


Phase noise plot of the oscillator;

[barrows]

Cool. That looks pretty good. Out of curiosity, do you know what the blue reference is for comparison?

[Coris]

OK guys. I see that it started up a little discussion here about OCXO. I feel the need to come with some clarifications about my previous post on the same theme.

First I have to repeat that the producer names of those OXCO I used in that post was quite by chance. Just those names came in my mind at that moment... I will not say that one is better than another. It may be, it may be not... I did not made a close research about yet.... Else both companies produce very good and very expensive oscillators, as very standard ones...
When I think at an OCXO I have in mind an 100Mhz oscillator. As I know, is very hard to find an OCXO usable directly in audio. I mean about the standard clock audio frequencies. As I know, and got some informations about, those OCXO are made mainly for radio range control frequencies. That because the most known and sold OCXO frequencies have quite strange range for audio domain. Is quite by chance that an 100Mhz OCXO can meet today the audio field by clocking this ES9018. So, the phase noise is to talk about at this frequency. This I meant and had in my mind when I`ve posted may previous post. A phase noise level at this frequency is quite good, and have to be very good at an 100Mhz OCXO.

Maybe I`m wrong, but I have this logic in this case: a jitter/phase noise is directly connected to the frequency stability of that clock. An standard oscillator (for say 100Mhz) with a 100ppm stability, have to have quite big phase noise level. Another one with an 1ppm have to have a better phase noise/jitter. An 100Mhz OCXO clock with 50ppb (f. ex.) have to have a much lower phase noise. I actually think that is an very close correlation in between this two parameters of an oscillator: stability and phase noise/jitter. I in fact just noticed in few cases that one face a much lower jitter when is about less ppm, or in ppb range.
If I`m wrong, please correct me...

[qusp]

Originally Posted by Coris

Such devices as OCXOs are made and meant to be used in extremely stable systems, where phase noise levels and frequency stability is much more sensitive/important than in audio field...
The only problem with those type oscillators is that are quite expensive...
If you intend to state that a Crystek which costs 30$ or less is better than an f.ex. Abracon OCXO which is happen to costs more than 200$, in its phase noise level or/and about stability, than one have to doubt seriously about such logic...
(I`ve used here different companies names only by chance, but both those producers have all kind of oscillators for sale, cheap or expensive...)

i don't know how, but you missed the point. they are built to be stable averaged over long time intervals, incredibly stable even, but that is of no real relevance to audio clock quality. average accuracy over long periods and a second could be considered long here does not automatically translate to high accuracy over very short periods. then we have the practical concerns, especially as most are physically large, requiring less than optimal routing and grounding of the clock output and many(most) require some sort of secondary clock division to be useable.

being expensive is meaningless, it can be very good for its intended purpose, but if that purpose is not audio it could very well be less ideal than a 10 dollar clock specified for audio

[NicMac]

Originally Posted by qusp

i don't know how, but you missed the point. they are built to be stable averaged over long time intervals, incredibly stable even, but that is of no real relevance to audio clock quality. average accuracy over long periods and a second could be considered long here does not automatically translate to high accuracy over very short periods. then we have the practical concerns, especially as most are physically large, requiring less than optimal routing and grounding of the clock output and many(most) require some sort of secondary clock division to be useable.

being expensive is meaningless, it can be very good for its intended purpose, but if that purpose is not audio it could very well be less ideal than a 10 dollar clock specified for audio

Quite right qusp. In fact, there are 'in principle' even better XO's around that lock onto the GPS network. Nevertheless, probably the crystal they put into the OCXO's is of good quality considering the cost of the external constant thermal 24/7 correction system. I have a suspicion that an XO package actually qualifies as an OCXO simply because of its thermal conduction characteristics.....

[Bunpei]

Originally Posted by barrows

Out of curiosity, do you know what the blue reference is for comparison?

They just say "Common CD player" for the blue reference.

[Bunpei]

Originally Posted by Coris

It will be interesting for me after those last experiences, to go back to an 100Mhz, but with an OCXO...

I have an OCXO of 100 MHz sine wave output at my hand. If you want to evaluate it, I can send it to you.
The model is 9325D(Fixed Communication)/Oven-Controlled Crystal Oscillator (OCXO)/NDK

Its list price is approximately 1,000 Euro. Phase noise measurement chart for the individual device is available.
As the output is sine wave of +-0.9 V(1.8 V p-p) amplitude, I applied an adjustable DC bias using batteries and fed the biased sine output directly to XI pin of ES9018. The idea of the direct input was given by Dustin.
You need +12V power for the device.

I felt the sonic result of this OCXO was definitely better than the standard Crystek oscillator used on Buffalo II. However, the cost performance was not so high enough. After I once knew the superior performance of synchronous master clocking scheme, I decommissioned it.

[barrows]

I am more interested in synchronous clocking of the ESS 9018, hence my desire for more standard (audio) clock frequencies.

Bunpei: it is nice to hear that you find synchronous clocking to produce better sound than using the ASRC/DPLL-I assume this is as long as the master clock/bit clock provided are very low jitter. I am looking forward to trying synchronous clocking when I get my hands on the CCHD-957 oscillators.
The NDK which TAD is using-do you know if that is a custom part, or is there a series available from them with that level of performance, and if so, can they be purchased in single unit quantities somewhere?