Mobo main clock replacement...

[PeterSt]

My i7 - 2600s @ 2800GHz runs at 1,6 GHz, so at 400MHz per core.

Hi Stanley - It does not work like that. Just what TaskManager shows, but if you want to know per core, divide by two when Hyperthreading is active. And "our" 430MHz does not even take that into account.
Or I am wrong. Haha.

Regards,
Peter

[Nick]

Nick, give look at following link for a low phase noise jitter oscillator:

http://www.diyaudio.com/forums/digital-line-level/261651-well-tempered-master-clock-building-low-phase-noise-jitter-crystal-oscillator.html

Also give a look on ebay about used OCXO. These have great performances but are almost never used in audio due to high cost (about 500Eur each). Cost apart you will not find usual "audio" frequencies (11.2896 MHz and so on) and they have to be custom ordered.... minimum production batch is 5 pieces to complicate things even more.
Maybe for usb and mobo freqs. you'd find something!
 

Fralippo,

Thanks it's a very interesting post. Some real designer's working there.

I've looked at OCXOs but as you say they are expensive. There are some very good module oscillators about now at low cost. I think as mentioned before that there is a lower cost approach for USB and mob clocks that should give very good results without the cost of the dexas I have used.

kind regards,

Nick.

[fralippo]

Nick, if you're lucky enough to find the right frequency on a used industrial OCXO on ebay price will be very low (20 or 30 USD range). Unfortunately most of them are 10MHz. Anyway other freqs. are available.

Project at link I sent you is about getting much similar to a OCXO performances at a fraction of the price.

[toddn]

Hey Nick,

Interesting stuff. I happen to have a spare Dexa here(can't imagine why ) anyway where did you get the replacement oscillator for the Dexa and exactly what frequency are you using? Also, was there any fine tuning that you had to do on the Dexa adjustment trim pot or any other modifications?

Thanks,
Todd

[fralippo]

A little note.

Motherboards are NOT, NOT, NOT made to be modified!

Risks to damage them are VERY VERY HIGH!

Their reliability would be MUCH compromized even if you'd succesfully be able to replace a o/b x-tal with a external oscillator.
Fitting a coaxial cable would be very tricky and, again, reliability would be MUCH lower than before.

Furthermore, maybe Nick could add something on this matter, output voltages from "audio" clocks might NOT be optimal for mobos. Where even 1.2V rails are used...

In two words: be ready to get a NEW motherboard!

[toddn]

Hi Fralippo,

Thank for the warning, but a possible $270 to replace a motherboard is a small price to pay if we can give a separate opinion on whether there is merit to Nick's experiment in a different system. I assure you after some costly screw ups to my NOS1, which will never see any mods after the NOS1a upgrade!! I am not at all scared of modifying a computer. I already have a Dexa clock on my PCI Usb3 board, plus separate 12, 5 and 3.3 linear power supply's running the motherboard as it is.

Todd

[Nick]

Fralippo hi,

It's just a clock replacement nothing to get too worried about if approched correctly. I have test equipment to work out what is needed and all the relevant research done before hand. From my point of view the only risk I was concerned about was if the clock power-on timing sequence was important but it seems not. If the change had failed then the plan would be to revert back to standard or buy any replacement parts needed. Voltages etc are all fine.

I would not recommend doing this if you don't understand what you are doing or are bothered by the cost of replacement kit, but I'm fine with that.

Regards Nick.

[boleary]

Thought a pic of the PC might be fun. Poor thing has its guts all over but the SOUND haha

Best,

Nick.

Bit off topic, but seeing the guts of my PC is standard here. Putting the PS and HD outside the case on vibration damping footers provided a nice boost to SQ:

[christoffe]

Thought a pic of the PC might be fun. Poor thing has its guts all over but the SOUND haha

Best,

Nick.

Bit off topic, but seeing the guts of my PC is standard here. Putting the PS and HD outside the case on vibration damping footers provided a nice boost to SQ:

YOU ARE ALL  ( in a positive sense )

Joachim

[boleary]

Of course we're all crazy, that's why we hang out with you! 

[PeterSt]

I just wondered what those tissues are doing there, Brian.

[boleary]

Tissue box is simply a convenient cable riser that came with the upside down juice pitcher in a special AudiogoN auction. 

[Nick]

Hi,

I said I would post some more detailed impressions of the sound quality that the mobo clock upgrade produces. First before the sound impressions a couple of quick notes to bring the clock install up to date.

First on clock speed. I don’t have a way (for now) to quantitatively measure clock speed so I cannot say if the set "sweat spot" speed described is the exact nominal frequency of the PCs master oscillator, however trimming the clock speed on the replacement now fitted shows that clock speed is extremely important to sound quality. The magic in performance can be dialled in or out by moving the absolute clock speed just a few 10s or hundreds of cycles per second. The range of sound characteristics that are heard as the sweet spot is approached include booming bass but clear mids, poor dynamics but reasonable balance across the frequency range, generally good but sharp highs, in short a range of “problems” that in my system I have frustratingly suffered at different times. Its very easy to trim speed by ear I really knew when the sweat spot was reached !!

Next point is that with the replacement clock the PC boot cycle can be erratic. The PC may try to start multiple times before the POST process completes. It retries automatically so I just let it get on with it. Once it has booted it’s completely stable and I would swear that things like screen redraws are snappier than before (might be imagining it). If the boot becomes a problem, I think I know what may be happening and have some ideas about how to address it.

So the sound.

First thing to say is that once the sweet spot is found that this in IMHO is an absolutely all upside change in sound quality. Everything improves by very significant step.

Some items that stand out are:

Evenness balance tone and detail across the whole frequency. Ever had that experience where say mids are well projected but highs are slight sharp and bass powerful but slightly boomy  or for that mater many combinations of some parts the music playing well but one or two being recessed or having hash problems and letting the show down ? Well the evenness and balance that come with upgraded and tuned clock result in all frequency ranges work together in harmony without so many incorrectly "highlighted", reassessed, boomy or sharp elements in the balance.

Having said that, what does stand out is that all elements of the music stand out equally, by this I mean each instrument, voice and synthesised effect or spatial reference etc etc are given the right amount prominence and lime light to play in. Everything is writ large like it would be in live music and because things are not getting lost or highlighted the effect is that you hear musicians playing off each other and together. The energy in the music is again more convincing, snap in bass, dynamics and substance of voices, the distribution of energy in the overtones coming from a guitar or piano sound realistic and just easy on the ear to listen to.

Final major point I wanted to mention is rhythm. When the sweet spot is hit (with the clock speed), then the music seems to really speed up. The speed is the effect of the rhythm being portrayed to great effect. Before the mobo clock maybe one or two instruments or a voice would be marking out and really driving rhythm and then not always in an entirely  life like way. I guess I was just used to this and good tracks would bound along and compel my toe to tap. Now all the instrument voices and sounds are equally participating and with the right energy attack and tone, the result is that as you expect from a live performance, everyone is playing their part to drive the music forwards. The results is that the music boles along like the musicians are having bags more fun playing together. This last quality of the sound comes together only with the last fine tweak of clock speed, but you really know when its there !

Having a NOS1a is a great privilege; it is so transparent that the improved PC performance is absolutely made available by the NOS1a to listen to. All of the observations above are only possible because the NOS1a is so stupendously good and the description applies to the sound quality of the NOS1a as much as to the PC with clock mod. It may be that in other peoples systems the audio “mileage” from this change may not be so great, but for me there  is absolutely chance at all of going back.

Final thought is that I have read about others on the net replacing mobo master clocks with OCXOs and other fixed speed clocks. My experiment here leads me to believe that using a clock with the ability to trim its speed is very important. By having this facility it possible to improve the odds that you will hit the "magic" spot (speed). Otherwise it’s Clock Audio Roulette as to whether your lucks is in and the speed of the fixed speed replacement clock happens to exactly hit the sweet spot speed for your system.

Happy to provide more information if anyone wants.

Nick.

[manisandher]

Hey Nick, thanks for sharing. For me, the mere fact that the sound changes with varying mobo clock speed is just incredible. It just goes to show that the 'computer audio rabbit hole' is so much deeper than anyone could have imagined.

As an aside, I've been really interested in the ADC side of things for a while now. Most (all?) studios use DAWs and I wonder how much SQ could be gained from the sorts of things we (I mean the pioneers on this forum, not me) are doing.

Mani.

[Nick]

Mani hi,

For me, the mere fact that the sound changes with varying mobo clock speed is just incredible. It just goes to show that the 'computer audio rabbit hole' is so much deeper than anyone could have imagined.

I think we have all experienced the frustration of getting settings that are good at many things only to find that there always seem to be some highlight or low light in the sound cannot be overcome. So start tuning again and get a slightly different combination of good and bad points.

Listening here now it feels like there IS a solid floor at the bottom of the rabbit hole after all. I say that with a real sense of relief.

I'm looking forwards to seeing what you and Paul make of my PC over the Christmas break. Also listening to this PC play through Orelinos is genuinely a mouth watering prospect.

Regards,

Nick.