Creating test tone / reference CD??

formerlyfzfile

New member
I am in the process of creating a test tone and reference cd.

I am referencing the ideas of Hugh Robjohns in his Sound On Sound article from Sept '03.

For creating calibration signals I am using Sound Forge 6.0.

My sound cards are a Delta 44 and Gadget Labs 496.

I am using a Tascam M30 mixing board which has unbalanced connections.

I generally track and mix through this board (to the computer at home and to a VS880 "on location").

My monitors are Event 20/20 passives (if thats relavant).

The test CD will be played through an external CD player hooked directly to the mixer.

I want to have as complete a test CD as possible.
I just want to make sure I understand the levels involved.

O.K. so......

My 1st question is what do I need to set the test tone levels to???
The article mentions a GLITS signal set to -18dBfs.
Is the Sound Forge meter in decibles equal to dBfs's???
i.e. do I set the level of the tones to -18?????

By default the stock SF test tones (both FM / Sine / and DTFMS??) are at -12dB.

My next question is, when I run the CD, if the reference CD levels were burned correctly then my VU meters should be at 0 for these test tones, yes????

And finally should I be setting up for -10dB, 0dB, or +4dB test tones with my M30.

I think its -10 on this older board, but I do not have the manual.

Thanks for all your help in advance.

-mike
 
You are getting a bunch of stuff mixed up. -10 and +4 operating levels dont really have anything to do with the test tone or recording levels on disc. If you want a test tone at 0db then print it there (or more realistically -.5 so it doesn't distort). If your CD player is set for -10 and the mixer inputs were +4 then you would have some problems but you wouldn't really create a skewed CD to make up for that.

The main thing is to have a constant tone and it almost doesn't matter what level it is because you would generally use it to calibrate the output of the mixer and the inputs of the recorder. Whether or not you apply some gain on the channel input is irrelevant. Remember though that your soundcard will distort way before the board does so you may want 0db on the soundcard or recorder inputs to be +8 (or whatever is the highest point on your mixer you are likely to use).

You would probably want to add some sweeping sine waves at different frequencies so you can check your monitoring environments for problem areas in the freq range.
 
Hmmmm...??

I guess I am getting some things messed up.

Here's the thing that I have observed with my set up.

Using a 440hz tone played from within Sound Forge......

My Delta 44 outputs are set to -10 and I was fairly certain the board is -10.

But I have to set the tone at -6dB on the SF meters in order for me to get my boards input meters to read 0dB with the faders at the nominal 7.

Does that mean the board is a +4 device????

Am I confusing things even more?????

I guess if I know my CD player is a -10 device I would be set.

Also, when I do a 20hz - 24Khz sweep tone at -6dB and the input faders at 7...... the VU meters start to creep up at around 3K and reach up to +3dB in the left channel and +1.5dB in the right.... peaking at around 12K.

Is this normal for channels to respond differently to different frequencies????

What will this mean practically?

Does this indicate that my channels have a certain Chinese condenser type character to them? ...... cuz they certainly sound better than my V93 did.... lol.


-mike
 
VU and peak meters on a console are not calbrated to the same scale as meters in s/w or digital devices.

0 VU on a board will correspond to about -15dBFS on a digital recorder's meter (assuming uniform gain structure).....


And yes - if you sweep a tone, you will see slight variations in level on the meters at different frequencies.
 
Danke.

I sent th tones through each set of 2 channels.

They are all close except 7 which starts to peak a little sooner in the sweep.

It get REALLY tiring listening to sine waves.

-mike
 
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