28 May
2010
28 May
'10
8:36 p.m.
On 05/28/2010 08:07 PM, Ralf Mardorf wrote:
Here's what I said:
"Well, it looks to me like this is caused by the fact that the audio cards
clocks are not in sync. When you loopback card A with itself, both input and
output are sampled with the same clock. But when you plug the output of card A
into card X, you're dealing with two clocks which are not synchronized, and that
result into these "artefacts". If I'm right then you should observe some
/similar/ issues when repeating the experience with the cards inverted."
Unfortunately, today my mails aren't posted on the lists, I don't know why. Some
days it works, and the day after it doesn't. So look at the second post from
Fons, there's my answer.
What I said is about syncing yeah. Maybe that Veronica is being more precise
mentioning clock instability or dither. But I'm very low in regard to theory
anyway, I'm the intuitive guy ;-)
--
Olivier
Ralf Mardorf wrote:
> Olivier Guilyardi wrote:
>> On 05/28/2010 07:36 PM, Ralf Mardorf wrote:
>>
>>> Folderol wrote:
>>>
>>>> On Fri, 28 May 2010 19:20:54 +0200
>>>> Ralf Mardorf <ralf.mardorf(a)alice-dsl.net> wrote:
>>>>
>>>>
>>>>
>>>>> Veronica Merryfield wrote:
>>>>>
>>>>>> You can't trust a loop back test.
>>>>>> Any instability or dither on the reference clock of card A (fifo
>>>>>> clocking say) is not going to show in a loop back test.
>>>>>> Vrnc
>>>>>>
>>>>> Is Veronica Merryfield the winner?
>>>>>
>>>> I'm highly suspicious of the USB link, but can't quite put my
finger
>>>> on why.
>>>>
>>> Card A is the USB card. For USB there could be several issues, but I
>>> don't have knowledge about buffering etc., but I guess it's card A
and
>>> that there's a "instability" = jitter. I don't know what
dither for
>>> CLK
>>> is. I guess the winner is Veronica Merryfield.
>>>
>>
>> I mentioned the clock problem first ;-) However, I thought it the
>> other way
>> around: I said that clocks being asynchronous that would generate
>> artefacts, but
>> Veronica seems to say that these are hidden when using a single clock.
>>
>> That's pretty much the same thing to me :p
>>
>> --
>> Olivier
>>
>
> Did you also say for what card? A or X? If so, is Oliver the winner?
I said that the problem should be the same with the cards inverted, see below.
Btw.:
Ralf Mardorf wrote:
And more:
Clock jitter would cause AM (<-- not my knowledge, somebody else wrote
it) instead of analog hum, that would cause an additive signal.
@ Oliver: Didn't you talk about syncing both cards? That's irrelevant. Gabriel Beddingfield wrote:
Is the jitter caused because of residual ripple?
Summarized:
Residual ripple for the DC could cause clock jitter and this for card A. On Fri, May 28, 2010 at 12:39 PM, Gabriel M.
Beddingfield
<gabrbedd(a)gmail.com> wrote:
> The 100 Hz (being 2x 50Hz, the power freq. in Italy)
> suggests that it is probably related to some manner of
> power supply. However, I have no theory why we're
> getting 2x 50Hz (and I think I need one :-)).
>
Doh! When the AC wave is rectified, it results in a signal that is 2x
the freq. because the negative part gets inverted. That's why we see
100 Hz instead of 50 Hz.
-gabriel
On card A or X?
Why AM and not additive signals?