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Delay measurments and sampling + buffer
PostPosted: Tue May 08, 2012 10:23 pm Reply with quote
Nicola
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I run systune 1.2 with a TC asio desktkonnect. I use systune to adjust the delay in multiple drivers loudspeakers with active digital filter. I notice changes in the measurements if i reduce the buffer of the interface (tc konnekt) - shorter distance - or if i increase the sampling rate fro 44.1 to 88.2, 96 or 192 on both the interface and systune. Are there best practice set up or more advisable ? (shorter delay, increased frequency (which seems to improve signals reading above 20khz)

Is there a way to store the delay measurment method ? By default the measurment is ms and i want to set it to m only so i do not have to bother when launching systune.

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PostPosted: Tue May 15, 2012 8:36 am Reply with quote
Waldemar
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What changes do you see, if you change the bufferlength and what do you see if you change the sample rate? We would like to investigate the files, if you send them to me directly: <WRichert>.
For SysTune you do not need a short latency of the device. We recommend to use a long latency. Use a higher sample rate than 48kHz only if you have to investigate higher frequencies (for electronic measurements?).
ms is the default unit. Unfortunately you cannot save this as setting for opening SysTune.

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PostPosted: Tue May 15, 2012 8:39 am Reply with quote
Waldemar
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Nicola, the email address was cut while submit. It is WRichert@afmg.eu

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PostPosted: Fri May 18, 2012 6:02 pm Reply with quote
Charlie
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Hi Nicola,
Are you using a loop-back from the output of the sound card back to one of its inputs & selecting this for the reference in SysTune? Doing this should normalize the measurements to the internal latency of the sound card regardless of the buffer settings or sample rate. Hope this helps.

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PostPosted: Sun May 20, 2012 8:10 pm Reply with quote
Nicola
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Charlie wrote:
Hi Nicola,
Are you using a loop-back from the output of the sound card back to one of its inputs & selecting this for the reference in SysTune? Doing this should normalize the measurements to the internal latency of the sound card regardless of the buffer settings or sample rate. Hope this helps.


No, i've been thinking recently that might be the cause. I'll need a Y cable to test this.
Thanks for the advise anyway
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PostPosted: Sun May 20, 2012 8:19 pm Reply with quote
Nicola
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Joined: 19 Apr 2012
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Waldemar wrote:
What changes do you see, if you change the bufferlength and what do you see if you change the sample rate? We would like to investigate the files, if you send them to me directly: <WRichert>.
For SysTune you do not need a short latency of the device. We recommend to use a long latency. Use a higher sample rate than 48kHz only if you have to investigate higher frequencies (for electronic measurements?).
ms is the default unit. Unfortunately you cannot save this as setting for opening SysTune.


Here are the measurment I've been doing and their related changes

the measurment is on a driver which frequency is set between 513hz to 1450hz. The filter is a digital filter with 96db slope at cut of.
I've set the sampling on systune to 48k and the buffer on the asio either at 64 or 8192. Then i've raised the sampling to 88.2k with 128 buffer or 8192.

with sampling at 48k and buffer 64, the delay is 6750m and is the same with buffer set at 8192.

when the sampling is raised to 88.2k the dely is 6495m in both 128k or 8192k buffer

If I perform the same measurment on a bass (frequency from 16hz to 530hz), the delay is 7508m for 48k sampling and either 64 or 8192 buffer and is for 88.2k sampling either 7259m with 128 buffer or 7652m with 8192 buffer.

There differences i try to understand.
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PostPosted: Sun May 20, 2012 8:20 pm Reply with quote
Nicola
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Waldemar wrote:
Nicola, the email address was cut while submit. It is WRichert@afmg.eu


Dear Waldemar, what files would be usefull for you and how shall i produce them ?
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PostPosted: Tue May 22, 2012 7:54 am Reply with quote
Waldemar
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Joined: 05 Dec 2005
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Nicola,
those long delays are due to the filter mostly?
We would suggest the compensation of the internal delay by the means of shortcut the output to the input, like Charlie mentioned. If you use the output to out1 and out2 you can use the shortcut from out2 directly without a "Y" cable.
The difference for different sample rates is probably also due to the filter.
If you switch off the filter for testing, what is about the delays then?
If you have an impulse response in systune, click on "Stop Measurement" and Save to Audio File / Impulse Response in the File menu.

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