XO question for Guido

[georgehifi]

Hi Guido, a customer asked me if one of your XOsupplies can run 2 x XO2 clocks.

Cheers George

[Fin]

Hi George

In Guido's documentation, it says that each XO2/XO3 board requires 9 to 35Vdc with about 30mA...and the XO supply can provide 16Vdc under 50mA load conditions.

Not the definitive answer you were looking for...but it might help.

[HiFiNutNut]

Thanks George and Fin. That George's customer is me.

I am thinking about adding the XO clock(s) to my NAD542. The NAD542 has two crystal oscillators (16.9344mHz), one for the PCM1732 and the other for the DSP CXD3017Q. According to George, I need two XO2 clocks instead of one.

From Fin's figures, it does not seem like a single XO Supply can drive two XO Clocks. I don't think the NAD has sufficient space to fit in two XO Supplies and two XO clocks, not to say that is also too expensive for the NDA542.

Does the XO2 clock really benefit that much from a quiet supply as good as the XO Supply? I am not so sure as I am not experienced. The digital ground can only be as clean as the existing D+5 supply ground, which is taken out after a 7808 then another 7805.

So this is perhaps the only option for me: build a separate 5VDC supply using the LM317. If this is quiet enough for the XO2 clocks then I will just get 2 clocks, otherwise forget about the clock upgrade.

Your input will be appreciated.

Regards,
Bill

[Fin]

Knowing Guido, he has probably been quite conservative with his figures - so it still might be possible..................

There is also a thread around here somewhere in which Guido describes what would make a nice DIY supply for his XO2 board. From memory, it was nothing too fancy - a small transformer, schottky diodes........it would be worth doing a search for it.


Update:
Found the thread - here it is....
http://www.diyaudio.com/forums/showt...210#post689210

[HiFiNutNut]

Thanks Fin.

Quido: "In stead, you may want to build a copy of such reg, but my experience says a seperate transformer / diode / filter does a most effective job. Those not wanting to buy XO supply, use a nice small 15Vac transformer, 4 pieces diodes like SB150, a 400mH/100mA choke and a 1000uF Black Gate......."

So what is after the ......? I don't think Quido refers to the schematic George posted.

I guess I can build the one suggested in Tentlabs site in the Application section: http://www.tentlabs.com/Products/Com.../XO/index.html

Will this one be good enough to supply 2 x XO2?

Regards,
Bill

[Fin]

No - the one on Guido's site is a supply for a bare XO. If you are using XO2 modules, then you already have that bit.

What you need it the part that comes before the XO2 board or before the circuit on Guido's site. You need to build what Guido described:-

".....Those not wanting to buy XO supply, use a nice small 15Vac transformer, 4 pieces diodes like SB150, a 400mH/100mA choke and a 1000uF Black Gate......."

Thta's all you need. The "......." indicates the connection to the XO2 module.

However, as you would be connecting this directly to the mains supply in your cd player, you really need to know what you are doing. What you would be building is a device that will be supplied by the 240V AC mains supply, stepping it down to about 15V with a transformer, rectifying it to DC with the diodes and filtering it with the choke and capacitor. This would then be used to supply the XO2 modules. If you are not sure how to do this, please get someone who does know to help you. It can be very dangerous and illegal.

If all of this sounds too hard, you could power the XO2 modules from an external power adaptor via a 2.5mm DC input connector. This would not be as good or as neat as an inboard solution, but it would have to be better than using the existing power supplies in the CD player. Just make sure it is a linear supply (not switchmode) and that it supplies enough current. You could even get a regulated one but it is not necessary as the XO2 modules are regulated anyway.

You could get really kinky and power the XO2s from the existing supplies - through the 2.5mm socket - so that this supply is interupted when you plug in the external supply

[HiFiNutNut]

Fin,

Thank you for your detailed description. Yes I can build that as I have designed and built my own tube preamp and a pair of 400W SS monoblocks. I did not know the XO2 module includes the regulator.

So All I need is to build such that circuit then hook up with the XO2 boards.

I think I will give it a try.

Best regards,
Bill

[Fin]

Well - that sounds good. If you have space, it might be a good idea to get a transformer with two secondary windings at about 12V to 15V. That way you could build separate circuits for each XO2.