The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator

Status
Not open for further replies.
Jump to Latest
#2,281
gentlevoice said:
@andrea: ... thanks for outlining why the Pierce has re-entered your selection - I have to admit that I really do look forward to seeing what you have arrived at ... 😉

One suggestion - and please don't see this as not recognising that you are already doing a lot and fine work - but have you considered to also include your "best solution" for a frequency divider? Unless your preferences have changed I remember your being very interested in R2R DACs and here I reckon that a splendid frequency divider may be helpful ...

@JohnW:



Hi John ... Might I ask you a question in relation to this? Using lower value resistors increase the effective bandwidth of the track transmission, however, unless the resistor's value leads to critical damping or over-damping of the track response, might the overshoot of the digital pulse (slight or more pronounced) not transfer back into the digital circuitry's power supplies and thus cause more general noise on the PSU line - and eventually potentially more phase noise in the digital transmission?

I reckon this may be what you imply with your 100 ohm suggestion but essentially where would you say that the "sweet spot" speed wise vs overall circuitry stability/noise is?

About terminology: You call the resistors "termination resistors" which pops up in my mind as "resistors close to where the digital transmission line ends". We may of course just use different words for the same resistor - but just to clarify - do you use both a sending resistor & a termination resistor? Don't know if this makes sense ... 🙄

BTW - and this is just meant to be very briefly off-topic - over time I have tried out & listened to some SMD resistors (e.g. TNPW-vishay, Susumu-RG, MMA0204, PFC-vishay) and to my ears these resistors SQ wise are not really close to the sound quality of the better "regular" resistors. Might you/others here have experience with a really good sounding SMD resistor?

Cheers,

Jesper
Click to expand...
Hi, gentlevoice.
This page is useful for your question. (written in Japanese)
特性インピーダンスとドライバの駆動能力 - 半導体事業 - マクニカ
Google translated
Characteristic impedance and driver drivability
Damping resister is to match to transmission line impedance to prevent reflection.

BTW, I surprised LVDS clock deliverly.
LVDS included termination requirements in their specifications.
LVDS isolator (Analog Devices ADN465x) has much better sound quality than single-ended isolator (smaller jitter).
Molex TwinMax is very stable transmission wire (Skew: <10 ps/m).
I posted here.
https://www.diyaudio.com/forums/equ...-adc-project-ltc2380-24-a-24.html#post6142273
LVDS reciver (FIN1002M5X etc) can convert LVDS to CMOS at near the DAC.
I surggest sine to LVDS converter.

Edit: Fix my post url and add mention of jitter.
 
Last edited:
#2,284
laserscrape said:
Do the clocks have a standby function like most standard XOs have?
Click to expand...

All the oscillators don't have output enable funtion, the clock is always present at the SMA output connector.
They don't have any standby function, we suggest to keep the oscillators always power on.

Clock selection has to be implemented in the device that uses these oscillators.

Our announced FIFO system provides the selection using relays in "T" configuration, no multiplexer in the clock path.
 
#2,288
TNT said:
Your upcoming DAC project, would you say it's basically a theoretical approach or a "listening" approach?

//
Click to expand...

Neither and both, let call it "the SOTA approach".

I prefer a different classification, as an example about clock:
- low-fi approach: Si570
- midi-fi approach: Crystek
- hi-fi approach: older oscillators of this thread and similar commercial devices
- SOTA approach: new Driscoll and Differential oscillators
 
#2,297
It would be interesting to know if there is a benefit of higher or lower voltage supply, so to speak should I aim my battery powered voltage at the upper end (18v) or at the lower end (12v) implying I can guarantee that I have a stable voltage.

Also if I would switch between two "power banks" to have the oscillators constantly running, so to speak one loading while the other one running. would it be important to have no or minimal voltage swing when switching between them or would this not matter as long as the voltage is in the specified range. Or would such a swing bring instability and "unsettle" the oscillators.

Greetings oli
 
#2,299
Hifoli said:
It would be interesting to know if there is a benefit of higher or lower voltage supply, so to speak should I aim my battery powered voltage at the upper end (18v) or at the lower end (12v) implying I can guarantee that I have a stable voltage.

Also if I would switch between two "power banks" to have the oscillators constantly running, so to speak one loading while the other one running. would it be important to have no or minimal voltage swing when switching between them or would this not matter as long as the voltage is in the specified range. Or would such a swing bring instability and "unsettle" the oscillators.

Greetings oli
Click to expand...

The oscillators are stable from 12V to 18V power supply.
Higher voltage tipically means higher drive level of the crystal and higher output voltage. Difficult to say what happens at phase noise level.

All the measurements was done with 12V power supply (to be precise 13.2V battery supply), so I suggest to use that. BTW, if you can easily set the power supply to higher voltage you could give it a try changing the voltage and listen to the sonic result.

If you use 12V there is no transient problem, while with 18V it could be a problem if the transient voltage overcomes 18V.
 
Status
Not open for further replies.
Top Bottom