From Brian Willoughby Sent Thu, Dec 27th 2018, 00:13
This is a tough question to answer, partly because I think there are two = aspects to the answer. 1) Avoid distortion from clipping; maximize signal-to-noise. 2) Postpone adjustments for loudness until the final mixing stage. = There=E2=80=99s a difference between optimizing per-channel S/N and = adjusting the loudness for a good mix. Don=E2=80=99t confuse the two by = trying to handle them at the same time with a single control. On the first topic, I would hope that every synth/drum machine would = have been designed so that it will not clip its own mixing stages. = However, we cannot rely on this because many audio circuits over the = years, even from well-respected brands, have included design mistakes = that are less than optimal. Therefore, it seems that you will have to = determine whether each of your synths/drum machines clip internally when = the master volume is at maximum, and if so then you=E2=80=99ll have to = discover the amount that the volume needs to be reduced until there is = no distortion (unless, of course, this distortion is part of the sound = that you=E2=80=99re trying to record). Part two is whether your =E2=80=9Cmixer" input can handle the maximum = volume of each synth/drum machine. In my experience with the MOTU 896HD, = the input levels can only be boosted, not attenuated, so there were many = recording situations where I needed to reduce the output level on the = sending device because it was otherwise too strong for the 896HD to = handle. Analog mixers tend to have switchable pads, and my Metric Halo = Labs interfaces have programmable Trim that can reduce excessive input = levels. If you don=E2=80=99t have this option, and if any of your = synths/drum machines are =E2=80=9Ctoo hot,=E2=80=9D then you=E2=80=99ll = need to reduce the master volume. Personally, even when I have the option for Padding Line level inputs, I = rarely boost a device=E2=80=99s output level if it means that the mixer = will need to be Padded. Those pad resistors can add a little noise, so = it=E2=80=99s better to reduce the send level so that the Pad can be = disengaged. The result will be cleaner. Of course, it=E2=80=99s = generally true that more signal level on a cable is better for S/N, but = once you=E2=80=99ve reached the limits of a +4 dBu Line Level input = (which is about +26 dBu!), then you already have more than enough S/N. = Boosting above this, to the point where you need Pad resistors, is not = going to improve anything at all. Finally, you don=E2=80=99t want to sacrifice the signal-to-noise = performance of an individual channel by turning it down to adjust its = loudness to match anything else. Psychoacoustics research tells us that = there is a difference between the level of signal as measured by = voltages and meters versus the loudness perceived by the human hearing = system. Since noise gets worse as you turn things down, I recommend = avoiding the temptation to match loudness between synths/drum machines, = and just maximize the channel S/N. Once you have a mixer full of = channels that have minimal noise, you can mix based on loudness and = retain the option of making some devices louder than others during part = of a song, while other devices might be louder in other parts of the = song. Looking at the above from a different point of view: If you=E2=80=99ve = already maximized S/N for every channel, then you no longer have the = option of turning anything up. Thus, balancing loudness means turning = some things down, which just makes the noise worse. Loudness adjustments = should be a creative step, possibly automated, and certainly dynamically = changing during the progression of a piece of music. Another issue to keep in mind here is that the presets on any synth or = drum machine will vary drastically from one selection to another. If you = try to adjust levels to match loudness across devices, that balance will = be lost as soon as you select a different sound or a different bank of = sounds on any one or more synths/drum machines. Instead, if you adjust = for maximum signal-to-noise, as described above, then your mixing = process will be most successful at matching (or mismatching!) loudness, = as appropriate for the art. Bottom line: These questions are all part of the general topic of = =E2=80=9Cgain staging=E2=80=9D - which is very important in a recording = studio. There=E2=80=99s a lot to learn. I recommend Bob Katz=E2=80=99 = =E2=80=9CMastering Audio: the art and the science=E2=80=9D as one = starting point. It won=E2=80=99t cover all aspects of recording studio = gain staging, but it certainly covers all of the technical basics that = you=E2=80=99ll need. If anything, Bob=E2=80=99s book is probably more = appropriate for your situation, where you have a digital MOTU interface. Brian Willoughby On Dec 26, 2018, at 3:22 PM, Boniforti Flavio <xxxxxxxxx.x@xxxxx.xxx> = wrote: > Hi all. > I've now almost finished wiring all my devices' audio outputs to my = "mixer". It's made of: > 1x MOTU 828 MK3 Hybrid > 2x MOTU 8pre >=20 > Now I'd like to know how to best "calibrate" the volumes, so that I = don't have instruments which are "too loud" compared to others. What's = the recommended/best procedure to achieve this? >=20 > My first point is: I would set the master volumes *on* the synths/drum = machines at maximum. Is this already a wrong starting point? :-/ >=20 > Thanks for your hints and suggestions! > F.