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Discussion Starter #1
I have been messing around for a while now trying to get the sound card and meter calibrated. However I seem to be getting no where.

First dumb question of probably many,

How do I know if the computer is even seeing my meter?

Im using a DFI lanparty board with the karajan module that came with it. I can get sound out to my amp, but plugging and unpluging the meter seems to have no effect. When i go to measure i dont get any trace either. Could it be that it doesnt support in and out at the same time?

Any help on how to get going in the most basic of instructions would be greatly appreciated.
 

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I have been messing around for a while now trying to get the sound card and meter calibrated
Calibrating the soundcard is the first hurdle (and doesn't use the SPL meter).

Have you successfully calibrated the soundcard and then saved and stored that calibration file in REW and then taken a measurement of the looped back cable from line-out to line-in (that you used to accomplish the calibration) and gotten a flat result?

brucek
 

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First dumb question of probably many,

How do I know if the computer is even seeing my meter?
You remind me of the first time I tried to use REW :bigsmile: I had similar questions. I can at least tell you how to check ifthe line out of the SPL meter is working. It's easy. Connect the SPL meter to an audio input on your receiver and talk. It should act like a mic, then you know it is working.
Im using a DFI lanparty board with the karajan module that came with it. I can get sound out to my amp, but plugging and unpluging the meter seems to have no effect. When i go to measure i dont get any trace either. Could it be that it doesnt support in and out at the same time?
Again I had similar problems. If you're using RS meter, note that it has a mono input, and if your soundcard has a stereo input, it won't work until you connect a stereo jack to your computer and receive only mono to the RS meter (one of both inputs shoud be working). This is of course to be after soundcard calibration step. Iam also assuming you computer soundcard has line out and line in.
Any help on how to get going in the most basic of instructions would be greatly appreciated.
Hope this helps a bit :)
 

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Discussion Starter #5
Thanks chaps,

so the first step is to forget the spl meter and calibrate the sound card. :scratch:

I tried pluggining into the aux input on the amp. it does indeed work like a mic, if i fail to get the sub set up at least i can do some singing along to the music, that way we will both be out of tune.
 

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Discussion Starter #7 (Edited)
I have been reading for a while, the more i read the more confused i get. In fact i am having trouble getting my head around connecting it all up.

I have two cables each has a 3.5mm jack on one end and a pair of phono connectors on the other end (male, red and white)

The sound card has line in and a line out

I plug one of the cables into the line out using the 3.5mm jack. The other end of the cable, i plug the red bit into the red bit of the aux channel. I can now play a test tone from the computer through the amp and out of the speakers. I have a white plug spare.

The second cable, the 3.5mm plug goes into the line in on the soundcard. At the other end of that cable the red and white ends, i plug the red bit into the spl meter.

To create the loop that is required i took the white end of one cable and connected it to the white end of the other cable. This gives me horrendous feedback.

so starting again,

What i have done in REW so far, with a single cable running from the line out to the amp, red connector into aux, white connector not hanging free. No spl connected

I open it up
I select settings, i dont change anything
I press check levels
adjusting the volume on the amp does nothing, using the sweep i can up and down the reading on the screen, i set it to approx 75 on the screen spl meter. (sweep level 19)
click finish

at this point i go a bit pear shaped.
 

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I plug one of the cables into the line out using the 3.5mm jack. The other end of the cable, i plug the red bit into the red bit of the aux channel. I can now play a test tone from the computer through the amp and out of the speakers. I have a white plug spare.

The second cable, the 3.5mm plug goes into the line in on the soundcard. At the other end of that cable the red and white ends, i plug the red bit into the spl meter.
Great, and that's exactly how you will hook it up when you actually start to do measurements. But that only comes after you've calibrated the soundcard - which you haven't done yet.

So, disconnect all that and do the soundcard calibration first.

This involves connecting the 3.5mm plugs to the line-in and line-out. Then you will have the red and white ends dangling there. Connect the red ends together, so that now you have a loop on the right channel from line-out to line-in. You will never use the white ends. Leave it dangle forever.

Press the Measure button on the Settings page under the soundcard tab and follow the bouncing ball until that's done and save the file in REW with an appropriate name. Do not have the Use Left Channel calibrate as reference checked. Leave it unchecked forever. Do not have any meter calibration file loaded yet.

You should get a graph that looks like this if it's a crummy card: The better the card, the better it will look..



Report back when you get that far. (I want to see your graph). There's a little floppy icon in the lower left corner of the graph for saving.

brucek
 

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Discussion Starter #9
Thanks for that,

I have done what you said and managed to get a graph. I find a lot of the technical aspects a bit over my head and the help files are so detailed i can get a little lost. If i stick to, red plug to red socket we will get there.

adjusting the volume, as i cant hear anything i adjusted the sweep level until the spl figure on the screen was 75, then i adjusted the input level until the bar was at 18, this brought the spl figure on the screen up to about 78, however the input lervel is very low, if i drop it any more it will be doing nothing. Thescreen shot shows what is there



the graph i managed to make:jump:

 

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I have done what you said and managed to get a graph.
Yep, and you're almost there, but I need to point out some problems you have. :)

It would be best to select your card type in the Settings Input and Output Device pull downs, and also select the line-out (speakers) and line-in pull downs.
You'll see what I mean in the third picture below called (Windows Playback and Record Mixers interaction with REW).
See where I have the RealTek Audio card selected? Try and select that instead of default.

Your volume control Playback mixer is not correct. You want to Mute Line-in in Playback and enable it in Record. To select the Record mixer, pull down Options (on the Volume Playback Mixer you have shown in your pics) and select Properties and Recording Mixer.
My pics show what should and should not be muted.
Basically in playback you want Volume and Wave only, and in Record you want line-in enabled.
If line-in is enabled in playback, you get feedback.
I also show the interaction of the volume sliders and the controls in REW as a reference for you.

OK, when performing the soundcard cal you don't use the REW SPL meter as you have indicated. You don't use it at all in the routine. How would REW have any idea of an SPL level. It can't until its calibrated to the real world (later). That's what the VU meters are for.
Set a -12dB sweep level for the output with the Wave and Output about where I show them to be and then adjust the input level until the VU meter is around -12dB on the input.

So, clear your file from the REW window and give it another try...



Playback Mixer
Windows MIXER Playback.jpg



Record Mixer
Windows MIXER Record.jpg



Windows Playback and Record Mixers interaction with REW
Windows MIXER plus REW Mixer control interaction.jpg



REW controls interaction with VU meters
Check Levels soundcard calibrate.jpg

Hopefully this makes sense............


brucek
 

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sorry to hijack this thread. I have related question. On my volume controle window< I dont have an option for line in. Only volume, wave, sw synth, cd player and imput monitor. Should I just assume it is muted. Also on your recording options window you posted. You have the line in muted, but then you have an arrow pointing towards the input volume. Should line in on recording control be muted or not?
Thanks
 

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On my volume controle window< I dont have an option for line in.
You have an option to select what shows on the mixers..

Also on your recording options window you posted. You have the line in muted
No, look again, it's selected, not muted.

sorry to hijack this thread
Yeah, best to leave this thread to "blasted". Start a new thread for questions...

brucek
 

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Discussion Starter #13
Excellent pictures, thanks, I didnt even know about the recording parts.

however i have found that i am unable to tick the box for line in on the recoding window and the advanced features seem locked. I have checked with the realtek site and it may be that i need a different driver. Im downloading it to see if it opens up the line in part. All other widnows will replicate the settings you have shown. I will update as i go on.

Thanks

Blasted
 

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Discussion Starter #14
Hello again,

I have just handed in the last of my course work and the exams are all done, so i have had chance to re vist where i left off.

I did exactly as you said but I dont seem to be able to raise the input volume any where near your levels. I had reinstalled the driver and it allowed to select the line in channel on the recorder, which is a start.

what shall i do?



thanks.
 

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Discussion Starter #16
hi brucek,

i upped the output volume to 1.000. It had no effect on the right channel, which stayed low.



To me, that doesnt look like what i think it should look like.
 

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Yeah, you're not measuring anything.

All the software looks setup correct.

I can't imagine what you're doing wrong except that one of your 3.5mm splitter adapters or the cable looping back between them has some problem.

I take it you're still attempting to get a soundcard cal file - correct?

brucek
 

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Discussion Starter #18 (Edited)
Im still stuck at stage one yes,

I cant help but feel that the sound module that i am using on the board is not helping my cause. I used to have a sound card but not long back there was a thunder storm and i suspect lightening hit one of the phone lines which caused my pci modem to go bang, i actually saw it flash. From that point on i dont think any of the pci slots have worked, my grapics pci express do work though. Im tempted to get an external usb soundcard.


EDIT just found that by wiggling the jack in the back of the computer i can affect one of the readings for the loop back, i shall have to check further.
 

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Blasted,

I don't know if this might help but I'll say again to make sure you're not using a mono jack into a stereo output...
 

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Discussion Starter #20 (Edited)
Im pretty sure they are both stereo, but I shall check none the less.

Thanks people and please bear with me, i can be a home theatre shack sucess story:nerd:
 
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