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-   -   Instrument volume control vs mix channel gain (https://www.propellerheads.se/forum/showthread.php?t=184976)

ianfoster 2013-06-16 19:58

Instrument volume control vs mix channel gain
 
Hi all,

I've had a trawl through existing posts and I can't seem to find anything that answers this (hopefully) simple question.

I'm very new to mixing, and I'm struggling to understand the difference between the master volume control on an instrument, and the gain control on the mix channel for that device. What level should you aim to set the instrument volume at, and how should the gain be positioned? Should I aim to get the instrument volume as loud as possible (without clipping) with the gain set to 0, or is there a better approach?

Thanks for any help you can give - sorry if this is a dumb question :)

Ian

selig 2013-06-16 21:52

Quote:

Originally Posted by ianfoster (Post 1339056)
Hi all,

I've had a trawl through existing posts and I can't seem to find anything that answers this (hopefully) simple question.

I'm very new to mixing, and I'm struggling to understand the difference between the master volume control on an instrument, and the gain control on the mix channel for that device. What level should you aim to set the instrument volume at, and how should the gain be positioned? Should I aim to get the instrument volume as loud as possible (without clipping) with the gain set to 0, or is there a better approach?

Thanks for any help you can give - sorry if this is a dumb question :)

Ian

Here's my approach, which folks around here are probably getting tired of hearing by now!

I try to aim for a peak level of -12 dBFS for everything coming into the SSL mixer.

For audio tracks I follow the 'best practices' laid out by the Props in the user guide, suggesting to record all audio tracks with peaks @ -12 dBFS. This is where the input meters turn from green to yellow, making it easy to see if you've peaked over this reference level.

Most FSB patches, especially all of the newer patches, are also programmed to peak at the same reference level, -12 dBFS.

That's the 'best practices' as far as I'm concerned - read on for why this is suggested.

Advantages:

•Having all channels in the mixer peak at -12 dBFS or so allows you to combine many tracks in the mixer (as it typical) without major concerns of clipping the outputs.

•All dynamics devices used in the SSL Channel or Inserts will behave similarly, allowing you to save your favorite presets and have them work pretty much as expected on ANY channel you use them on in the future.

•Audio Tracks/Channels: recording at these levels ensures your microphone preamps are in their preferred range. Running them hot to get close to clipping typically runs them above the range they were designed for (even vintage preamps), since even analog recorders/mixer provide headroom above the nominal level (preferred level for that device). Since a digital system doesn't have any headroom above 0 dBFS, you must account for that when recording - this reference level of peaking @ -12 dBFS typically provides a similar amount of headroom, allowing the analog sections (preamps etc) to operate at their nominal levels.

•Instrument Tracks/Channels: most of the same concepts apply, mainly about leaving headroom for the main mixer. But consistency is the key here, and by treating audio and instrument tracks exactly alike with regards to levels, you have one less thing to worry about! I often tweak the master volume of an instrument after making a new patch or making changes to a preset, with the goal of hitting peaks of -12 dBFS.

Tips:
•Setting recorded audio levels to peak at -12 dBFS is easy because the audio input uses a peak reading meter. But what about Instruments? The SSL Channel meters read VU so you can't see an accurate peak level. One approach is to bypass EVERYTHING in the channel AND the mix bus, then set the Big Meter to read Peak or (my personal favorite) VU + Peak. But you MUST bypass everything in the Mix Channel and Master Section for this to read accurately. Another suggestion is to use something with a peak hold display, like the Flower Audio Loudness Meter or even the Selig Leveler.
•Whenever adding processing like EQ/compression/distortion/saturation, try to A/B your "before and after" levels to be sure you're not adding (or subtracting) gain. Some devices make this difficult, like the Saturation Knob for example, because it doesn't have 'makeup gain' on the output (and the output level is typically hotter than the input).
IN these cases I've added a line mixer after a device like this, to bring the final level back down to your reference level before it hits the SSL mixer inputs. Doing an A/B comparison with the levels matched is also a good idea to be sure you're not fooled by simply adding gain, which tends to always sound better even though it's not any better 'sounding'. Make sense? :-)

ianfoster 2013-06-16 22:41

Thanks Giles - this is very helpful :)

I'm still a little confused regarding the process required to get a particular instrument (say Thor) to peak at -12dBFS. Would your approach be to leave the input gain on the mix channel at 0dB, and only tweak the output volume of the Thor? You said that most of the factory patches are configured to already peak at -12dBFS - this would imply that the volume of the patch, and the input gain should just be left as they are (default). I suspect I'm missing an important point in your response!

So essentially I'm trying to answer the question - do I need to change the instrument volume, or the input gain (or even both) to get to the reference level?

Thanks again - appreciate you taking the time to help out.

Ian

selig 2013-06-17 02:20

Quote:

Originally Posted by ianfoster (Post 1339153)
Thanks Giles - this is very helpful :)

I'm still a little confused regarding the process required to get a particular instrument (say Thor) to peak at -12dBFS. Would your approach be to leave the input gain on the mix channel at 0dB, and only tweak the output volume of the Thor? You said that most of the factory patches are configured to already peak at -12dBFS - this would imply that the volume of the patch, and the input gain should just be left as they are (default). I suspect I'm missing an important point in your response!

So essentially I'm trying to answer the question - do I need to change the instrument volume, or the input gain (or even both) to get to the reference level?

Thanks again - appreciate you taking the time to help out.

Ian

I would adjust with the instrument's master volume, because if for some reason you re-use the patch it will already be saved at the correct level. :-)

colcifer 2013-06-17 04:00

What does VU+Peak do that makes it your favorite?

selig 2013-06-17 04:36

Quote:

Originally Posted by colcifer (Post 1339297)
What does VU+Peak do that makes it your favorite?

It shows the "crest factor" (the difference between the peak and average level), which is a basic measure of loudness (remembering that loudness is subjective). :-)

ianfoster 2013-06-17 05:53

Quote:

Originally Posted by selig (Post 1339262)
I would adjust with the instrument's master volume, because if for some reason you re-use the patch it will already be saved at the correct level. :-)

So effectively there's no reason to ever change the input gain value for instrument channels?

Ian

colcifer 2013-06-17 06:24

Quote:

Originally Posted by selig (Post 1339303)
It shows the "crest factor" (the difference between the peak and average level), which is a basic measure of loudness (remembering that loudness is subjective). :-)

Good to know!

selig 2013-06-17 17:26

Quote:

Originally Posted by ianfoster (Post 1339320)
So effectively there's no reason to ever change the input gain value for instrument channels?

Ian

I've heard from some folks that they have built combinators where the last device doesn't have a volume control (Saturation Knob is one example). They have preferred to use the Input Gain knob to trim levels instead of adding a line mixer. But my reasoning still stands: if you use that Combinator again you'll have to trim it's gain in the SSL again - why not do it once and be done? Also, the level of the patch will depend on how many notes you're playing and the settings of the patch - change these and the level will change. So you need to keep an eye on these things, and for some the Input Gain is more accessible, for others the Instrument Volume is more accessible. Sonically it really doesn't matter, so that's why I mention workflow as the decision maker in this case.

History:
The original SSLs had an Input Trim because the signal was coming from tape in those days, and that was the ONLY place you could trim it's level (besides inserting a rack device and using that for gain - but you had a limited number of rack devices…). So it was used more in those cases, but the audio rules still applied. In other words, if you adjusted the gain on the input and you had already set a compressor for that channel, you'd need to check the compressor settings to adjust for the new input level. :-)

ianfoster 2013-06-17 20:09

That's very good to know.

Thanks again

Ian


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