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Old 3rd November 2010, 09:17 PM   #321
jkeny is offline jkeny  Ireland
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Quote:
Originally Posted by SY View Post
Unfamiliar with it.
Does it have an ASRC? Are you happy with it's performance? Do you not know the in & outs of your measuring equipment?

Quote:
I'll probably change over the analog output to the passive circuit published by Jan Didden as soon as I have a few weeks at home. With well-established levels, restricted bandwidth, and a healthy voltage level, I seriously doubt that the output section is the limiting factor; that's why 3/4 of Gary's page concentrates (rightly, IMO) on the input section where this is not the case.
He's fairly uncompromising & categorical in his condemnation of the analogue output stage!

Quote:
edit: If you're talking about the DCX input receiver (not the case for my other DAC), I have had problems at spdif levels, but far fewer with higher voltages. It's never done the "dull sound" thing, and I've only had it go frying eggs once. The high output of the Hiface is an advantage here.
Ok so you have issues with SPDIF input into the DCX - the attenuators will reduce the SPDIF level so might this be a problem for the DCX? for listening? Can I ask, if it doesn't sound right how can it be used to measure other devices?

So your M-audio 24/192 is impeccable?

Last edited by jkeny; 3rd November 2010 at 09:26 PM.
 
Old 3rd November 2010, 10:04 PM   #322
guido is offline guido  Netherlands
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Quote:
Originally Posted by Joseph K View Post
Guido,

Similar to your analyzer is the tipical TDC, time to digital converter, which is used a lot in physics.

And yes, it can be used to collect the same histograms, like the TIE histograms here. We used these to measure jitter in our experiments a lot of time. Typically these have 45 psec resolution, that is the finest binning.

But there is an important point: seemingly also the scope would have a similar resolution, 25 - 40 - 100 psecs. But. An interpolating algorithm is used, so the crossing time can be extrapolated by a much better precision.
The higher level scopes are good down to 1psec jitter resolution, the best ones are having like 500 femtosec jitter noise floor.

I have seen the built in 50psec rise time square signal generator's jitter: it was gaussian, 1sigma was 1.5psec. In the above histograms it would be a thin line.

Another point: a TDC like instrument collects only histograms, you loose the "private" information of the individual edges, so no time trend reconstruction. Also no FFT of it, no phase noise plots.

Again: a TDC has to be started / stopped at each time. That is, triggered. Also this procedure, producing the trigger, is producing it's own jitter contribution. Not by accident the discriminators used for it are a topic on it's own.
Also conventional scope "eye diagrams" are having the scope trigger jitter included.

In the plots above this is not existent: there was only one trigger at the beginning.

Ciao, George
Ok, ok. Here's one plus for my acient beast: it was only 80 euro's or so and not 35k
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Last edited by guido; 3rd November 2010 at 10:07 PM.
 
Old 3rd November 2010, 10:49 PM   #323
sendler is offline sendler  United States
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Default Any other SPDIF out?

Quote:
Originally Posted by Joseph K View Post
Of which the most educating is the TIE trend trace and the phase noise plot,
Does your M-Audio card have an SPDIF out or is there some other digital source that you have handy to test that we can compare to?
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Old 3rd November 2010, 11:30 PM   #324
jkeny is offline jkeny  Ireland
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Sendler, are you asking Joseph K to measure an M-audio 24/192 or do you just want another jitter TIE plot to compare the Hiface plots to?
 
Old 3rd November 2010, 11:42 PM   #325
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Quote:
Originally Posted by jkeny View Post
So your M-audio 24/192 is impeccable?
My understanding is that SY has proposed comparative measurement testing - DUT in circuit, DUT out of circuit. Given this, its largely irrelevant whether a source (or sink) is "impeccable" sonically - just that it is consistent.

More important is whether the test equipment can resolve at a suitable level to extract meaningful data, and then of course to logically analyse the data for causation.

As far as listening tests are concerned (and taking as a given that solo, heads-up listening is barely testing - more noodling...), barring gross errors, the same surely applies - the aim is to identify a difference.
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Old 3rd November 2010, 11:55 PM   #326
jkeny is offline jkeny  Ireland
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Originally Posted by aardvarkash10 View Post
My understanding is that SY has proposed comparative measurement testing - DUT in circuit, DUT out of circuit. Given this, its largely irrelevant whether a source (or sink) is "impeccable" sonically - just that it is consistent.
If it can't measure low level details how can it be irrelevant, otherwise why not just use the Realtek motherboard native sound output for measurements?

Quote:
More important is whether the test equipment can resolve at a suitable level to extract meaningful data, and then of course to logically analyse the data for causation.
Is that not what I'm asking above?

Quote:
As far as listening tests are concerned (and taking as a given that solo, heads-up listening is barely testing - more noodling...), barring gross errors, the same surely applies - the aim is to identify a difference.
Again, if the unit is sonically inferior how can sonic differences be identified?

I'm flummoxed - objective measurements surely must show that the measurement equipment is of a sufficient standard - are you saying that this isn't the case? I think we've already seen that the DCX2496 isn't up to the job even though SY has stated that it measured perfectly. Now he is changing the output stage after it came under scrutiny - an admission that it is not up to the job. He has also admitted that the DCX has a problem with SPDIF level signals. I'm really amazed that people so tied to measurement are now found to be using measurement equipment so unsuited to the task! - This really calls into question all the measurements previously performed with this unit.

What about the M-Audio 24/192 - what should we know about it's shortcomings?

Last edited by jkeny; 4th November 2010 at 12:13 AM.
 
Old 4th November 2010, 12:30 AM   #327
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Quote:
Originally Posted by jkeny View Post
If it can't measure low level details how can it be irrelevant, otherwise why not just use the Realtek motherboard native sound output for measurements?
Absolutely what i said - just further down the post.


Quote:
Originally Posted by jkeny View Post
Again, if the unit is sonically inferior how can sonic differences be identified?
To put it crudely, the inferiority or otherwise of a device "sonically" (generally a VERY arbitrary and subjective test) is irrelevant AS LONG AS IT CAN REASONABLY RESOLVE AND IS CONSISTANT.

Try this line - take a plastic trumpet. Play it, and listen to it. Its awful sonically of course, but thats the nature of the beast. Now take a standard trumpet mute and put it on the plastic trumpet. Can you hear a difference? Can you describe the difference?

If you can hear a difference, then its reasonable to conclude that the change is due to the use of a mute. The "quality" of the instrument is irrelevant to our test here.

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Originally Posted by jkeny View Post
I'm flummoxed - objective measurements surely must show that the measurement equipment is of a sufficient standard - are you saying that this isn't the case?
Absolutely - and if you have concerns about the equipment, it behoves you to state really clearly what those concerns are, preferably including a set of minima for specs that are required. Hectoring about perceived qualities of the equipment is unlikely to satisfy you or SY.

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Originally Posted by jkeny View Post
I think we've already seen that the DCX2496 isn't up to the job ...This really calls into question all the measurements previously performed with this unit. What about the M-Audio 24/192 - what should we know about it's shortcomings?
See above. If you think the device is incapable of performing satisfactorally, explain CLEARLY why and give some guidance for the specifications required to satisfy you.

Disclosure here - all this stuff is technically MILES above my head. I wouldn't know a SPIDF from a spliff. In fact the latter may well be the cause of my inability in this area. None-the-less, i can follow a line of logic and I'm trained in conflict resolution and mediation which requires me to see both sides of any argument, hence my interest here.

Cheers!
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Old 4th November 2010, 12:41 AM   #328
jkeny is offline jkeny  Ireland
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Quote:
Originally Posted by aardvarkash10 View Post
......

........

Absolutely - and if you have concerns about the equipment, it behoves you to state really clearly what those concerns are, preferably including a set of minima for specs that are required. Hectoring about perceived qualities of the equipment is unlikely to satisfy you or SY.
No, I'm not the one that is making the claim that I can measure anything that can be heard - it behoves those that do to prove it! I'm not hectoring, simply querying the equipment being used or should this not be done in your opinion?



Quote:
See above. If you think the device is incapable of performing satisfactorally, explain CLEARLY why and give some guidance for the specifications required to satisfy you.
Obviously the equipment isn't suited - both the analogue output stage & the SPDIF input stage are found wanting? Again, it's not up to me to specify what the specs should be BUT when I see agreed inferior equipment being used for measurement it makes me query the veracity of the measurements being proposed.

Quote:
Disclosure here - all this stuff is technically MILES above my head. I wouldn't know a SPIDF from a spliff. In fact the latter may well be the cause of my inability in this area. None-the-less, i can follow a line of logic and I'm trained in conflict resolution and mediation which requires me to see both sides of any argument, hence my interest here.

Cheers!
I hope you can follow the line of argument & the logic.

Really, all the measurements that show the effects of attenuators have been already given with the equipment used & test set-up. This is the direct measurement of the effect. This was rejected & analogue measurements proposed. It is not unusual to query the equipment being used & those that proposed the analogue measurement to be able to stand over the equipment (or at least understand the parameters & limitations of it).

Last edited by jkeny; 4th November 2010 at 12:50 AM.
 
Old 4th November 2010, 12:49 AM   #329
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well then if you are unwilling to state what IS required to carry out the test to your satisfaction you can expect to be dissatisfied with the results SY brings back.

Moreover, you won't have any comeback. Just like its not enough for someone to stand on the sidelines and sling accusations at you about your device, its not enough for anyone to rubbish a test without clearly and unequivocally stating what IS required to carry it out properly.

This shouldn't be a ******* contest - it should be a quest for answers. That means everyone involved has to make positive input surely?
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Old 4th November 2010, 01:01 AM   #330
jkeny is offline jkeny  Ireland
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Originally Posted by aardvarkash10 View Post
well then if you are unwilling to state what IS required to carry out the test to your satisfaction you can expect to be dissatisfied with the results SY brings back.

Moreover, you won't have any comeback. Just like its not enough for someone to stand on the sidelines and sling accusations at you about your device, its not enough for anyone to rubbish a test without clearly and unequivocally stating what IS required to carry it out properly.

This shouldn't be a ******* contest - it should be a quest for answers. That means everyone involved has to make positive input surely?
Look I'm not the expert in analogue measurement - others claim they are - it is up to them to say what they use & how it does the job. Sorry if you don't want to understand this but this is a typical tactic!

The DCX is inferior & all it's measurements are in question - so I suggest you revisit any results from this equipment!

You are now trolling so no more answers from me!
 

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