Sy, you have been told, by those who know, that your plots are meaningless, if you want to be credible, just show your equipment can plot the jitter differences in the analogue waveform between two known low jitter devices. Do something to prove your test set-up rather than trying to bluster your way out of it.
And while your at it show the attenuators in a signal path with reflections!
And while your at it show the attenuators in a signal path with reflections!
Totally uninteresting. It's trivial to use the right cable and right impedance termination (can you name any commercial DACs that have an incorrect termination impedance?). I'll let you and George play around with that.
If you believe in this mod, you ought to test it with units other than the one you're selling. Have you tried putting a level shifter at the spdif output of a 0.5V unit, then attenuating it? Have you examined the effects of jitter in the USB line?
Of course you are not interested in showing how the attenuators work - quelle surprise! It's already shown by George & Mike's plots.
Again, I'll state that I started this thread so others, better suited than I, might experiment & find out the parameters of these attenuators. Anecdotally they seem to offer benefits in circumstances other than the one I suggested, high SPDIF signal level. Is this not of interest? There may well be factors at play here other than the jitter reduction that I premised but who knows - we are certainly no wiser with your set of tests - sorry, you showed that the attenuators show no effect on your reflection free signal path - so I guess this fits the premised theory of their operation!
Last edited:
'I am beginning to believe now that the best attenuation is the MAX attenuation that can still have the dac in a stable lock'
Why not write to the manufacturers of a few DACs and SPDIF interfaces, and I mean ones with a standard output, because this quote comes from a guy using a SB3, and see if you can get them to endorse this recommendation. I noticed another quote from somebody using standard equipment in there.
'I found that the attenuators improved the sound from a Marantz CD5001 CDP as a transport into a AVA Vision DAC.'
Ask ThorstenL, or Joseph K, or that well known supporter of listening impressions, abraxalito, or for that matter anyone who isn't just an end-user of hi-fi equipment.
Good luck.
w
Why not write to the manufacturers of a few DACs and SPDIF interfaces, and I mean ones with a standard output, because this quote comes from a guy using a SB3, and see if you can get them to endorse this recommendation. I noticed another quote from somebody using standard equipment in there.
'I found that the attenuators improved the sound from a Marantz CD5001 CDP as a transport into a AVA Vision DAC.'
Ask ThorstenL, or Joseph K, or that well known supporter of listening impressions, abraxalito, or for that matter anyone who isn't just an end-user of hi-fi equipment.
Good luck.
w
Last edited:
@Waki
You really show no inquisitive bone in your body whatsoever, do you? Instead preferring to cite engineering & standards & manufacturers, etc as if they are all sacrosanct & unimpeachable. I know let's all buy Bose equipment then we would all have excellent sound forever! How about a bit of investigation - Fran said that you should try these attenuators (he has tried on a SB3)!
Maybe you should ask Thorsten about Cirrus SPDIF receivers & learn a thing or two?
You really show no inquisitive bone in your body whatsoever, do you? Instead preferring to cite engineering & standards & manufacturers, etc as if they are all sacrosanct & unimpeachable. I know let's all buy Bose equipment then we would all have excellent sound forever! How about a bit of investigation - Fran said that you should try these attenuators (he has tried on a SB3)!
Maybe you should ask Thorsten about Cirrus SPDIF receivers & learn a thing or two?
Last edited:
That's not generally true. Input transformers and/or input caps will screw up a DMM measurement. A much better way to determine it without a network analyzer is to see the effects on the level of an spdif signal from changing the source impedance. All that takes is a scope.
As for return loss, at what frequency and what level?
And what would that be, Mr. T?
I wasn't measuring jitter, nor did I claim to in that post. I was just showing that it is possible to measure lower than -120dB. And that although some artifacts are indeed below -120dB, many rise above that.
So remind me, what exactly is your point?
No.
I refer you back to my post #709. 3rd paragraph. 2nd 3rd and 4th sentences. Please, do one or do the other.
@waki
with stable lock there is no dropouts and no bit errors. Yes, if you attenuate too much, your DAC won't lock.
But how much is too much?
Depends on your circuit before receiver chip in your DAC. If you remember Post #174, real commercial DAC with this circuit inside will maintain stable lock with 0.3V p-p incoming signal (unterminated) and 0.15V p-p (terminated into 75R). Way bellow SPDIF standard.
Yes, signal is attenuated, but unwanted reflections are attenuated more. Even with 3dB attenuator you will improve your return loss.
with stable lock there is no dropouts and no bit errors. Yes, if you attenuate too much, your DAC won't lock.
But how much is too much?
Depends on your circuit before receiver chip in your DAC. If you remember Post #174, real commercial DAC with this circuit inside will maintain stable lock with 0.3V p-p incoming signal (unterminated) and 0.15V p-p (terminated into 75R). Way bellow SPDIF standard.
Yes, signal is attenuated, but unwanted reflections are attenuated more. Even with 3dB attenuator you will improve your return loss.
@SY
yes, with DMM you can measure only terminating resistor. Capacitor will block DC and transformer will show you short circuit.
Frequency for measurement? I think bandwith is more appropriate word.
How much bandwith?
Depends, how much square wave should remain square.
Ideal square = infinite number of odd harmonics. How much harmonics you want?
Download Square wave simulator and play with number of harmonics.
yes, with DMM you can measure only terminating resistor. Capacitor will block DC and transformer will show you short circuit.
Frequency for measurement? I think bandwith is more appropriate word.
How much bandwith?
Depends, how much square wave should remain square.
Ideal square = infinite number of odd harmonics. How much harmonics you want?
Download Square wave simulator and play with number of harmonics.
Yes, I'm fairly familiar with the Fourier decomposition of square waves, Gibbs and all that, but what bandwidth do you need to transmit spdif? One of the posters (who seemed quite focused on gigahertz) pooh-poohed the Chinese unit I was using because of a slower rise time than the expensive jkeny-modified Hiface, but the system locks, data is accurately transferred to the DAC, and frankly, the square waves look a whole lot less cluttered.
- Status
- Not open for further replies.