How much voltage does the 001 deliver at full coded sample?

[where02190]

Monitor outs and outs 1/2 are balanced +4dvu. Outs 3-8 are unbalanced -10dbu.
Hope this is helpful.

[apetrocelli]

also, is there different level on different outputs? Thanks in advance. I swear I went thru the manual but couldn't find it, and I read a couple of things about headroom here but I didn't understand them. I guess it delivers a nominal level just like any analog gear, isn't that so?

Regards, Andrés

[apetrocelli]

thanks. Do you know if those levels refer to a full coded sample ( 0 dbFS), or do they refer to some lower level (headroom)?

BTW: it's +4 dBu and -10dbV, right?

Andrés

[Matt Zeiner]

quite right, Andres...+4dbu = 0dbfs. Also -10dbv = 0dbfs.

[apetrocelli]

Hey Matt, thanks for the reply. But I was reading a little more on the subject and I found this thread, where Brent says that at 0 dBFS the Digi 001 delivers +18 dBu, meaning that +4 dBu is at -14 dBFS. So it seems that it has +14 dB of headroom before you run out of bits.
I guess my misunderstanding comes from the fact that digital is not as analog, meaning that you don't need a nominal level because you can go as far as you want without clipping. In analog you have to trade between a good signal to noise ratio on one side, and the possibiliy of distortion on the other.

BTW, Brent also talks in that thread about using a voltmeter to measure output, and he explains that you have to "terminate properly" the balanced output to measure it. What does it mean (I thought you didn't need a load on this device)?
Can anybody give a practical guide on how to do it?
Say you have a voltmeter that reads alternate current (like most of us have).
Then I assume you need a 3 conductor cable for each Digi balanced output(stereo cable since the digi uses stereo cables for balancing the outputs, but please correct me if I am wrong). So you have tip, ring and sleeve on one side, and positive and negative on the meter side. What do you connect to what? Also, is it necessary to build the adapter with the resistor, or can you do it without it (if so, is it 600 Ohms?)? I know that given a balanced output, you have to multiply the voltage reading by 2, right?

Regards, Andrés

[CCash]

Andre,

You are right on track. "dBFS" refers to Digital Full-Scale. NOT VU! What Matt referred to is an analog standard, where a nominal operating level of +4dBu should equal 0VU on an analog-style meter with equipment running at +4 nominal. Likewise, -10dBV equipment would equal 0VU on an analog piece of gear or input rated for -10dBV nominal.

The outputs of 1 and 2 on the digi001 are rated at +4 nominal. Run those outputs into mixing console inputs rated for +4 and you might see zero on an analog type meter. On a digital meter, you'd see about -14dBFS. And if you ran outs 3-8 into a -10 input you'd also expect to see about zero analog, or -14dBFS.

So, you are correct, the headroom of the digi001 is a measly +14dB. Actually, I've measured it, and it's really about 13 and a half.

I would guess that most people here don't have voltmeters and other test equipment... you're actually getting deeper than most people do on the subject. You can expect someone to jump on this thread and say "just make music dude."

When people talk about terminating, they usually mean a 600 Ohm load. I don't feel qualified to give you instructions on using a voltmeter, but...

Here's a simpler way to find out about the operating levels of the digi001:
Run the RTAS Signal Generator plug-in on a MONO track, set to a mono out... say digi001 output one. Turn your monitors down. Set the Signal Generator to generate a sign wave at 1000Hz at 0dBFS. This is full-scale... the max your system can output.

Plug the output of channel one on the digi001 into a +4 nominal input on a mixer or other equipment with meters, using a balanced cable. Now see what the mixer's meters read. If they have an analog-type scale, you'll probably see about +14. If so, then turn the signal generator down to -14 and hopefully you'll get zero on the console.

With the -10 outs, use an unbalanced cable into a -10 input on the mixer and you should get the same sort of results.

I have the digi001 outs going into channels on my mixer that have gain control (they are really mic pres). I have set each channel so that -20dBFS on the signal generator = zero on my mixer's meters. This way, when the ProTools reaches full-code (0dBFS), my mixer shows +20. The reason I did this is because my mixer has about 20dB of headroom. When I get a red meter in ProTools, I also see a red clip light on my mixer. It's all relative.

Does this help clear things up?

[apetrocelli]

thank you CCash, It really helps. As you can seeI'm trying to get deep on it, just for the sake of it.

I'm gonna try to use a mixer to do your check. I wanted to use a voltmeter, just to make an absolute calibration cause I want to calibrate the mixer too. I have to get deeper into the termination thing, since I supposed that you didn't need a 600 Ohms load on these device (I thought that was necessary for older gear).

Your peak alignment scheme is good, I really like it. I Have a big VU meter on a tape deck, I'll use that along with my PPM meters in the mixer.

I will start checking the -unbalanced outs, since I don't have a cable for balanced connection that has TRS on one side (Digi) and XLR on the other (mixer). I think I'll make one, but I'll need the specs. on each device way of balancing. Do you know which one of T,R and S in the Digi is Hot, Cold and Ground? Maybe there is a standard that I ignore. The Yamaha MX console is T=Hot,R=Cold,S=Gnd.

Thanks again, Regards Andrés

[CCash]

Originally posted by apetrocelli:
Do you know which one of T,R and S in the Digi is Hot, Cold and Ground? Maybe there is a standard that I ignore. The Yamaha MX console is T=Hot,R=Cold,S=Gnd.

<font size="2" face="Verdana, Arial">Yes, this is standard, with XLR pin 2 being hot, 3 cold, and 1 shield/ground.