Wait a minute! A catch 22 with hardware leveling amp?

[RawDepth]

Since I've started using a hardware summing amp with my DAW, I've noticed a marked improvement in my final mixes. I have fairly decent A/D-D/A converters, (RME,) so it's been working well for me. In fact, I've also started using more hardware gear such as effects and compressors. I'm having a blast over here with my new toys. Well, that is, until it comes time to make it loud...

The main reason I keep my recording levels down (around -18dBfs) is to not overdrive the hardware portion of my recording chain, especially at the A/D converters. Even when I create an effects loop, I make certain that the returning signal (to the DAW) is still at roughly -18.

Now let's assume that I am happy with the final mix and want to burn it to a CD. But wait! The artist wants it louder. How do I send the two-track out to a hardware leveling amp, (to raise the level,) if I must adhere to proper recording levels at the returning A/D converter? Won't the raised level cause distortion by over-driving the analog portion of my converters?

 

[Track Rat]

How are you summing? Are you sending individual tracks out on individual lines to be summed in the analog domain? If so does the summing network have inserts anywhere? You could put a limiter there to even out dynamic range and raise the overall level in a two track editor inside the DAW after the fact.

 

[Massive Master]

Now let's assume that I am happy with the final mix and want to burn it to a CD. But wait! The artist wants it louder. How do I send the two-track out to a hardware leveling amp, (to raise the level,) if I must adhere to proper recording levels at the returning A/D converter? Won't the raised level cause distortion by over-driving the analog portion of my converters?

You use a set of converters calibrated for that particular task (or you slap a digital limiter on the mix).

 

[RawDepth]

How are you summing? Are you sending individual tracks out on individual lines to be summed in the analog domain?

Yes, 16 tracks out of the DAW. I use the TLAudio Ebony A4 summer. I aslo have a smaller summer with 12 additional channels in case I need more, but it is mono.

If so does the summing network have inserts anywhere?

Yes, it has inserts on the 2-bus prior to the output (headed back to the DAW,) but I have not yet used them for anything. I was considering buying an outboard leveling amp just for that spot, hence this line of questioning.

You could put a limiter there to even out dynamic range and raise the overall level in a two track editor inside the DAW after the fact.

That is basically what I do now. I do software limiting/leveling as well as raising the level there. I'll buy a leveler and give it a try, thanks.

 

[RawDepth]

You use a set of converters calibrated for that particular task (or you slap a digital limiter on the mix).

Hmm, interesting. I've calibrated my meters on the Central Station for the playback, but I'm not sure how to calibrate my input converters. Could you be more specific or perhaps point me to an article for reading?

 

[Massive Master]

I'd go as far as to say the vast majority of typical converters out there have a fixed calibration point (1.23v = -[X]dBFS -- And it's usually something goofy in the middle of where they should be, IMO). *If* you have a set that can be calibrated to a specific operating level, it's as simple as equating 0dBVU (1.23v) to whatever digital reference you want (within whatever the available parameters are).

 

[PRHunt]

The manual for your interface should specify what voltage corresponds to 0dB FS. For my Audiofire, for example, it is +18dBu.

If you can't calibrate the input on the converter, you could simply insert an appropriate pad ahead of the converter.

I would think that, for the final master export, you can nudge up closer to 0dB FS. If the converter is anywhere near decent, you should be able to nudge full scale input without degradation. The converter will either not clip or it will clip. It doesn't saturate or harmonically distort like analogue gear. If your peaks remain below 0dB FS, you won't clip.

 

[RawDepth]

I did a little digging and don't see any mention of calibration or adjustments other than switching input sensitivity between +4dBu and -10dBv.

The manual for the Interface states the following...

Input level for 0 dBFS @ +4 dBu: +12 dBu
Input level for 0 dBFS @ -10 dBV: +2 dBV

I suppose I can push it a bit harder than I have been in the past. I've usually kept it at or below -18 dBFS on the recorded tracks.

EDIT:
The manual for the Summing Amp says the following...

The meters are calibrated to indicate 0VU when a signal level of +4dBu is generated at the main outputs. A pair of red Peak LEDs operate on the stereo buss as a conventional warning that clipping is about to occur. The LEDs illuminate at a threshold of +21dBu, when there is less than 5dB of headroom remaining on the main outputs. Normal operation would be to set the stereo buss fader levels so that occasional illumination of the Peak LEDs occurs on loud transients.

Now I know. Thanks for the help, everyone.