Loopback issue - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 17 Old 07-08-16, 10:40 AM Thread Starter
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Matthijs
 
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Loopback issue

Hi, My name is Matthijs, im from the Netherlands and am also trying to get this working but whitout succes so far.
I get stuck on the loopback part, im using an mk3 motu as interface but the results from the soundcard doesnt seem to be right and i realy dont understand why that is.
i watched diffrent tutorials tried diffrent versions.

Some things are realy confusing to me, maybe its becouse im dutch and im not interpreting it the right way but could you confirm if the following is correct ?

- before doing the test you need to select the output and input and so on at the soundcard settings.

My speakers are on outputs 5/6
My measurement mic is on analog 1
my loopback is on 2/2


For measuring the soundcard you need to create a loopback for example output 2 and input 2. (correct?)
Does this mean that for the input device you first select the loopback input and after the callibration the mic input ?

My input channel i set to "Right" which should act as channel 2 (the loopback input) (where do i select the output for the loopback ? or is this automatic?)

After setting it up like this im getting some results that dont look the same as other examples.



If someone could help me with this i would be realy happy )

* side note , an update for a youtube tutorial would be realy nice as there are only tutorials for the older versions which have allot of diffrent functions, i think thats a bit confusing to
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post #2 of 17 Old 07-08-16, 11:43 AM
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Re: Loopback issue

Quote:
matthijs87 wrote: View Post
For measuring the soundcard you need to create a loopback for example output 2 and input 2. (correct?)
Yes

Quote:
Does this mean that for the input device you first select the loopback input and after the callibration the mic input ?
Yes, if they are on different inputs, but it is usually best to use the same input for both as otherwise you are not calibrating the input you are using. Just switch the connections after you are done with the loopback measurement.

Quote:
where do i select the output for the loopback ? or is this automatic?
The same output is used for any measurement, whether it is a loopback depends on how things have been connected.

Quote:
After setting it up like this im getting some results that dont look the same as other examples.
The graph scale is very large so hard to tell too much, but you might be suffering the effects of some monitoring being active.
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post #3 of 17 Old 07-08-16, 04:03 PM Thread Starter
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Matthijs
 
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Re: Loopback issue

Thank you for the fast reply ! , I will take a look at it as soon as im back at my studio.

I got two questions left and the first is about the graph, becouse i thought that the graph should be like one thin line overall , at least thats what im seeing in all the other examples on google and in the help menu. is this not the case then ? (in mine picture its not)

Do you mean with the loopback that it wont work properly if you make the callibration on diffrent out/in puts ?
(i thought it just gets information about the delay in your soundcard in general to generate and use in a file)
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post #4 of 17 Old 07-09-16, 06:53 AM
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Re: Loopback issue

The loopback measurement is to correct the soundcard's response, not its delay. The response can differ a little between channels, so it is best to make the loopback measurement on the same channel that will be used for the acoustic measurements. The loopback measurement also helps detect whether there is any monitoring or feedback active. The noisy looking plot you posted could be due to monitoring being active.
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post #5 of 17 Old 07-11-16, 11:37 AM Thread Starter
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Re: Loopback issue

Thank you , i checked for monitoring being active, (check images) my output was on monitor so i can controll the output, i did a new test after putting it off but it still gives some weird results.
Attached Thumbnails
Loopback issue-outputs.png  

Loopback issue-voorbeeld1motu.png  

Loopback issue-soundcard-measurement3.jpg  

Loopback issue-soundcard-measurement2.jpg  

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post #6 of 17 Old 07-11-16, 12:54 PM
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Re: Loopback issue

Looks like a measurement of an unconnected input. What connections do you have now? Need one of the selected outputs to be connected to the input you have selected for measurement.
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post #7 of 17 Old 07-12-16, 04:13 AM Thread Starter
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Matthijs
 
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Re: Loopback issue

Im using 1/2 for my speakers now. I took the cables out as you suggested and used output 2 and connected it with 2 from my input. For the measurement you have to set the in and out at the same level so i did, I had to put the input on its loudest and had to set the sweeplevel till -17 for it to match up.



I used channel 2 becouse i can controll the trimlevel of the input that way on the soundcard , 1, 2 ,3 and 4 are with a physical knob , the rest are split up in line ins and outs. Would it make any diffrence if i used only line ins and outs ? Every in and out is mono on its own right, so it shouldnt matter to much is what i thought.
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post #8 of 17 Old 07-12-16, 05:28 AM Thread Starter
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Re: Loopback issue

yay Turned out it did make a diffrence . Im using 5/5 now (both line ins and outs). Now the readings are good (Y) So why does this make a diffrence ?
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post #9 of 17 Old 07-12-16, 06:13 AM Thread Starter
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Re: Loopback issue

Wow, next question, i got a lot to learn i guess. When i put the monitoring off my controll of the volume also seems to been gone. I have set the volume level on very low in the soundcards mixer as well as in windows, but when i tested the levels in REW it went Full volume , what am i doing wrong here ? i can controll it if i put the monitoring back on but thats not how it should be right ?
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post #10 of 17 Old 07-12-16, 04:33 PM
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Re: Loopback issue

It depends on your drivers, ASIO drivers bypass Windows volume controls. You can control the sweep level from REW but your soundcard's mixer panel must have level controls besides those used for monitoring?
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