John Swenson tutoring paper: "Considerations regarding usage of external reference clocks" (EtherREGEN and other): Sine vs. square, impedance, cables—and a money saving surprise at the end.

[MartinT]

6 hours ago, LowMidHigh said:

Regrettably, the Canare and the  Belden measurements don't fully overlap, but where the do, the 1694A does measure better. 

 

 

But the Canare LV-77S sounds better!  Trust your ears, it's not just about measurements.

[MartinT]

I heard quite clearly the upgrade in sound quality between LV-61S and LV-77S.

 

It's a surprise playing with different cables. The Belden 4694R sounds different again.

[MartinT]

19 minutes ago, LowMidHigh said:

I have a question fo my own here to John. Given we have the figures for both the Bedlen 1694A and Canare LV-77S, which of the two would he recommend over the other?

 

It's really the Belden 4694R that should be compared with the Canare LV-77S.  And they sound really close albeit slightly different in character.

 

1694A is a lesser cable and sounds inferior.

[MartinT]

My Mini-Circuits BLP-10.7-75+ has just shipped.  Running sinewave into the ER, this seems well worth trying.

[MartinT]

2 hours ago, soares said:

Also I am not sure why just the 10MZ output is working. Do you know what is the purpose of the other outputs? 

 

Jorge, it looks like you have the RS-232 programmable version. Those two other outputs have their frequency programmable via the serial port.

[MartinT]

Sound quality is going to be dependent on the consistency and noise at the exact trigger point threshold of the clock receiving equipment.  Whether the clock is square or sine doesn't matter at that level.  At the point of crossing the trigger point, how much jitter and phase noise there is superimposed on the signal (remember, it's an analogue signal) will count for a lot, because it will determine the amount of uncertainty.  Also, consistency from one crossing point to the next, which depends on the receiving circuit design.

[MartinT]

I can only say that sine with the filter sounds better than square with my BG7TBL clock.  Same (good) cables.

 

Not just a bit better - it's quite noticeable.

[MartinT]

That makes sense. The Belden 4694R cables are pretty well shielded and show it in the results.

[MartinT]

All DACs will claim jitter reduction by dint of input buffering. It doesn't stop any ground plane noise from getting in, though.

[MartinT]

11 hours ago, GMG said:

Thanks Martin, 

Sure, but are saying that the clock adds to the clean up of the ground noise?

 

Via a reclocker like ER or Mutec, the output will have less jitter and phase noise.

 

You can't reclock to better than the clock accuracy.

 

Getting rid of ground plane noise requires very good grounding connection or grounding boxes.

 

Both of these contribute to the ultimate sound quality.