EZDAC is singing now!!!

[6h5c]

You'd be surprised how much influence a good clock has on the sound... A crappy clock signal with lots of jitter doesn't sound nice, you should do a comparison some time.

The Nokia-guy is partially right; but the supply and load cap are the only differences you can see from the OUTSIDE. Inside the can, they are a world of difference.

A crystal will not do much by itself, it is a passive part with two pins (or three, and then it is called a resonator) and needs an active oscillator-circuit to work. This can be a simple CMOS inverter, or a JFET circuit. Basically anything that amplifies. Very often, such CMOS inverters are already integrated in a DAC or receiver IC. The crystal is part of the oscillator circuit and determines the frequency.

A clock on the other hand, or oscillator-module, contains exactly all of the above inside the metal can, so it holds a crystal and the active circuit. It puts out a neat clock signal if you connect is to a power supply and is a ready-to-use device.

Ray

[Erlend Sæterdal]

Thank you very much Ray . Nice homepage you have. I just bought the ACHL-24,576MHZ-EK from Mouser and I allready have a 3,3 V discret regulator.

I have built 3 more of the EZ dacs but the others with clocks from New Class D but I do not think they are good. Other clock I have used is XO XO2 and XO 3 from LC.Audio

[Erlend Sæterdal]

I will use your discrete output stage for one of the EZ dacs. I will be back.

[6h5c]

Hi Erlend,

Thanks! Good to hear you like my page.

I don't have any experience with commercial clocks, because I build a Flea if I need one . But one thing I noticed: all these manufacturers speak of jitter and how bad it is and that their clock is x times lower, but I don't see any measurements anywhere. Where are the numbers? So it all depends on how low that jitter actually is in practice. A nice low-noise power supply or a shiny SMA connector won't help with that if the oscillator is bad.

I think the outputstage is a very nice sounding circuit. How are you going to do the I/V conversion?

Ray

[Erlend Sæterdal]

Originally Posted by 6h5c

Hi Erlend,

Thanks! Good to hear you like my page.

I don't have any experience with commercial clocks, because I build a Flea if I need one . But one thing I noticed: all these manufacturers speak of jitter and how bad it is and that their clock is x times lower, but I don't see any measurements anywhere. Where are the numbers? So it all depends on how low that jitter actually is in practice. A nice low-noise power supply or a shiny SMA connector won't help with that if the oscillator is bad.

I think the outputstage is a very nice sounding circuit. How are you going to do the I/V conversion?

Ray

Passive I thought.

[6h5c]

Hi Erlend,

Passive is possible, but you may have to increase the amplification of the outputstage a bit. A 25R I/V resistor will give you only 200mV; you can lower the emitter resistors in the input stage to as low as 100R for 2Vrms output.

Regards,

Ray

[Erlend Sæterdal]

R 7 and 8 or 5 and 6 ? I have over 20 pcs 389 so I will try to use them on the board instead of 170.

[6h5c]

Oh sorry, that would be R7 and R8. With the CFP-transistors in place that's not obvious anymore

Ray