Home Theater Forum and Systems banner

1 - 17 of 17 Posts

·
Registered
Joined
·
3,069 Posts
Discussion Starter #1
Hi there,

Can anyone give me a step by step guide in setting up the levels for REW before doing measurements. I have read the REW online help over and over again but no matter what I do I can never get the levels correct. I am using a Turtle ARM external sound card in vista. I can calibrate the soundcard no problem although I have to much around with the soundcard's volume settings a bit but I do get that done.

I then go to check levels for the subwoofer and they are really low and even with the input volume on max and the onkyo on -15db it is still reading -30db which is too low.

I would appreciate some guidance please so if someone could break it down in simplist terms that would be great.

cheers

graham
 

·
Registered
Joined
·
7,514 Posts
Can you first tell us the type of cable and adapters you used to run the soundcard calibration and the Check Levels routine?

brucek
 

·
Registered
Joined
·
3,069 Posts
Discussion Starter #4
Brucek,

Here are the pictures I promised. The first one is the 3.5mm lead I used to calibrate the soundcard and the second one is of the 3.5mm lead in the line in and line out for soundcard calibration. The third picture is the 1 rca to 2 rca leads I am using. I have two of these. One is in the line in and goes and I use the red of the two rca to go into the spl meter and the other identical lead I have goes in the line out and I connect both rca's into the left and right channel input on the onkyo amp to give me left and right output.

Let me know if I have the wrong leads and whether or not this would actually work.

cheers

Graham
 

Attachments

·
Registered
Joined
·
7,514 Posts
It's a bit difficult to see the 3.5mm ends in the pictures, bit I trust they're stereo.

Personally I would use the same cables you're using to run REW for running the soundcard calibration routine. Just short the right (red) channels with an in-line connector for the soundcard cal. This stops the left channel from supplying any noise or crosstalk into the right channel when you use the single stereo cable for the soundcard cal routine.

If you are able to establish correct levels during the soundcard cal routine, then the only reason you wouldn't be able to enjoy the same levels when setting up the Check Levels routine, would be that the meter was malfunctioning.

Once the soundcard cal routine is complete and the file saved, connect the SPL meter and receiver and run Check Levels. The volume on your receiver is adjusted to be 75dBSPL at the listening position. The SPL meter should output plenty of level for the adjustment of the REW input volume. I have the same soundcard,and I have to have the input volume very low to not overdrive the input.

The levels are all adjusted using the Vista Device mixers. Be sure the line-in is disabled in Playback and enabled in Recording.

Once that's complete, run Calibrate SPL routine and then Measure...

brucek
 

·
Registered
Joined
·
3,069 Posts
Discussion Starter #6
Brucek,

Can you run REW measures without it blasting the house down.

The single black lead which I use to do the soundcard cal has the 3.5mm on both ends.

cheers

Graham
 

·
Elite Shackster
Joined
·
7,142 Posts
To calibrate the sound card you simply connect the line out to line in. The proper instructions stipulate you should only calibrate the right channel, as the spl meter is mono and you only use the one channel (right) when measuring. I didnt bother with this and my sound card works fine.

One its calibrated, and yours looks like its calibrated correctly, you need a 3.5 mm to phono (RCA) for the spl meter, using only the right channel (red connection). This goes from the spl meter to the line in of the sound card. Then you need a 3.5mm to phono lead to go from the sound card to your amp. You can connect only the right channel and put your amp in direct mode, but if your having issues you might want to follow the instructions exactly, split the right channel and connect that to your left and right inputs on the amp. IMO, using only the right channel and putting the amp in direct mode amounts to the same thing. I actually used 3.5mm to L/R in nd everything was fine, I dont seem to find REW as problematic s some.

If thats how your connecting, then all is well. Basically, right phono out of the spl meter to 3.5mm sound card line in. Then line out of the sound card to L/R in on the amp, or just R in if you wish, with the amp in direct mode.
 

·
Registered
Joined
·
7,514 Posts
Can you run REW measures without it blasting the house down.
I don't understand the question.

The single black lead which I use to do the soundcard cal has the 3.5mm on both ends.
The question was whether all the 3.5mm plugs were stereo or mono?

brucek
 

·
Elite Shackster
Joined
·
7,142 Posts
Brucek,

Can you run REW measures without it blasting the house down.

cheers

Graham
Yes, I run them when the kids are in bed. 0-200hz sweeps at 75db are not very loud at all.
I don't understand the question.


The question was whether all the 3.5mm plugs were stereo or mono?

brucek
Thats a good point, if its a mono cable then the L&R channels will be mixed together into a mono signal by the cable?
 

·
Registered
Joined
·
3,069 Posts
Discussion Starter #10
Brucek,

So if I connect the two blue leads to the line in and line out as normal. and join the two spare rca ends together with the rca adapters (see link below) to do the sound card cal and then take out once that is done. So that means blue lead that goes from the line out to the onkyo I connect the black end into one of the inputs on the onkyo and the other blue lead goes from the line in and connect the black rca end into the spl meter. Does it matter which input on the av amp (black/red) or do I still connect both rca's into the onkyo.

I just want to be sure.

cheers
Graham
 

·
Registered
Joined
·
7,514 Posts
So if I connect the two blue leads
I don't understand what blue leads are.

Let's start over.

The adapter cables you're using must be 3.5mm stereo plugs that split the right and left channels of the stereo jacks.

The left channel is never used, only the right channel.

The soundcard cal routine requires the right channel line-out to be connected to the right channel line-in.Once completed, and the cal file is saved, the connection is removed.

To use the calibrated right channel for Measurements, connect the right channel line-in to an SPL meter. Connect the right channel line-out to your receiver. If you want both channels of your receiver active, split the signal with a Y-adapter at the receivers input.

Set your receiver to stereo only. No soundfields or effects allowed. Set the crossover you normally use.

Run Check Levels routine.

Run Calibrate SPL routine.

Measure.

brucek
 

·
Registered
Joined
·
3,069 Posts
Discussion Starter #12
Brucek

The blue leads are the 3.5mm to two rca's. I have two of these. I think I have it now. I connect the first blue lead 3.5mm single jack (pic attached) to the line in. Then I use the other blue lead to connect the 3.5mm single jack into the line out of the sound card.

To do the soundcard cal I attach the rca adapter plug to join the two red rca's of each cable. Measure to get the cal on the soundcard. Then disconnect the adapter plug and insert the red rca (the single jack end that goes to the line in of the soundcard) into the spl meter and the other red rca into the av amp.

Instead of using a y adapter can I not just connect both the left and right output of the rca into the amp. Is that not the same thing.

The strange this is when I use the single lead which has a 3.5mm jack on each end I don't have a problem doing the soundcard cal. I will do one now and attach a picture to show you.

Am I getting there?

cheers

Graham
 

·
Registered
Joined
·
3,069 Posts
Discussion Starter #13
Brucek,

Here is my soundcard cal measuresd using the black lead with the 3.5mm jack on each end.

Does this look right. I used the left input channel in REW and adjusted the volume controls on the Turtle soundcard control panel as follows:

On the mixer panel:
Line in - Muted
Microphone - Muted
Master - half way between half and three quarters
Record settings:
Pan L/R - almost all the way to the right
input volume - half way between a quarter and half

Speakers panel
Master - half way between half and three quarters
Volume on the front - max

Do these settings look ok? Do I have the C weighed spl meter clicked on or off for soundcard measuring or does it not matter. Mine was clicked on.

cheers

Graham
 

Attachments

·
Registered
Joined
·
3,069 Posts
Discussion Starter #14
hi guys,

I have managed to get the sub levels done ok and produced a graph but can't do the speaker levels. I cannot get them high enough. I have all soundcard volumes on max and the onkyo's volume on -3db with the channel levels on +12.

Help!

cheers

Graham
 

·
Elite Shackster
Joined
·
7,142 Posts
Are you talking about measuring the speakers alone by themselves. If so then you might have the spl meter in 'c' weighted mode when its not supposed to. It will also be dependant on which noise tone you use as well.

You need to clarify the issue a little more. The speaker levels should be correct because Audyssey takes care of them. Have you checked to see what the amp has set the speakers to?
 

·
Registered
Joined
·
3,069 Posts
Discussion Starter #16
Dan,

What are the correct settings for the spl meter when you want to run REW on your speakers and not your sub. I will be moving my speakers tonight but found last night that I could get the levels ok but when I did a measure it looked low on the REW graph.

Also I can do the sub ok but when you do the sub and speakers together do you simply hook the speakers back up and run another measure with the sub and speakers connected on the same level set up you had for the sub and run a measure to give you what the sub and speakers are doing together.

I hope that makes some sort of sense.


cheers

Graham
 

·
Registered
Joined
·
7,514 Posts
When you measure mains speakers, use the correct pink noise test signal for mains in the Levels pulldown on the Settings panel when you run Check Levels. When you measure subs, again use the correct pink noise signal for subs when you run Check Levels.

Measuring sub + mains should be done (with the sub pink noise used in the Check Levels) and measure from 0-200Hz. This will be suffice to observe the crossover region levels and effects.

Measuring mains only should be done (with mains pink noise used in the Check Levels) and measure from 200Hz-20000KHz.

brucek
 
1 - 17 of 17 Posts
Top