Match Volume vs. Max Volume

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bakersfieldaccordion
Posts: 3
Joined: Sat Feb 20, 2010 2:23 pm

Match Volume vs. Max Volume

Post by bakersfieldaccordion »

Greetings,
First, I've learned a lot just from browsing the posts, but I'm stymied by the recording levels reported by the Max Volume vs. Match Volume routines. I'm using max volume, as suggested, to be sure that my initial recording (stereo input from a Roland FR-7 digital accordion into a Presonus firebox, then to Goldwave) is below the clipping level. One of my recent recordings showed that both tracks were below zero as displayed with the Max Volume routine.

However, when I run Match Volume on the same file, the levels are -21.50 and -23.58 db for the treble and bass channels, respectively. This is fine, but the peak levels are in the red, +2.98db and +.84 db. I initially had assumed this meant there was clipping, but based on the Max Volume report, there should be none. In fact, most if not all of my recordings have peaks in the red when I run Match Volume, but are below zero decibels on the Max Volume program.

So, what is the meaning of the red values in the Match Volume routine? Should I be concerned about them, particularly when the Max volume shows no clipping?

Second, I suspect there is a recommended order of processes to use when editing the raw file. These are the operations I use most often: Volume Increase for one of the channels (checking to see that I am below clipping level), Compress Peaks, Max Volume (usually 90%), and sometimes Match Volume at -18db (with the option of avoiding clipping). My guess is the order I've listed them makes sense, but I'd appreciate suggestions. And, if after Maxing Volume it is still at a level lower than -18db, it seems that the only way to increase the volume without clipping might be to compress first, but I'm not certain about any of this.

Thanks,

Richard
mathyou9
Posts: 70
Joined: Mon Nov 10, 2008 7:36 pm

Re: Match Volume vs. Max Volume

Post by mathyou9 »

Match volume changes the overall average volume of the entire file. Although the peak is right at 0 dB, the average volume (across the entire wave) for each channel is -21.50 and -23.58 dB.

When you first open Match Volume, by default, it wants to change the average volume to -18dB. So what the red numbers are telling you is that to increase the overall average volume of the file from -22-ish dB to -18dB, it will require the waveform to be clipped (that is, the peaks in the wave will be increased from 0 dB to the value of the numbers displayed in red; +2.98dB and +.84 dB.)

Here's a simple analogy of the analysis that Match Volume performs. You have a bunch of numbers: 2, 4, 3, 6, 7, 2, 1, 4, 6, 7, 3, 57, 3, 2, 5. Obviously, your numbers "peak" at 57 (the 0-dB mark, if you will) but the average value is 7.47 (or the -21.5 and -23.58 dB levels of the two channels.)

---

If -18 dB is what you, indeed, want, you will need to apply some compression ("reduce peaks" would work) and then run Match Volume. On the other hand, if all you want is to keep the full dynamic range of the waveform, don't run Match Volume at all; Max Volume is what you want.

Now if you had two files; one that averaged -12 db and another at -25 dB; and you planned burning them to a CD (or for a playlist), then you'd want to use Match Volume and make them the same (otherwise, the end listener would have to change the volume knob substantially between tracks.) This is what Match Volume is good for. Otherwise, for single files, changing the final average level with Match Volume is entirely [and arbitrarily] up to you to decide. If clipping is required, change your final desired level or apply compression before Match Volume.

[edited to add stuff]
bakersfieldaccordion
Posts: 3
Joined: Sat Feb 20, 2010 2:23 pm

Re: Match Volume vs. Max Volume

Post by bakersfieldaccordion »

Great--once you told me that the default, upon opening Match Volume, is the final peaks under -18db, it all made perfect sense--and should have been perfectly obvious to me.
Thanks for your help--mystery solved!
So here's another question--bear with me while I better understand the process. My bass channel often sounds better at about 2 db below that of the treble channel. Is there any compelling reason to try to equalize the volume of both channels? If so, how can I do so while also maintaining the relative volume levels of treble vs. bass? E.g., it looks like MaxMatch maximizes the volume of both channels while staying below clipping levels, but I'm assuming that would just raise the volume of the bass channel, defeating my attempt to reduce the influence of the bass. Using the equalizer can reduce the bass, but at least to my ears with a sacrifice in fidelity.
Thanks in advance,
Richard
mathyou9
Posts: 70
Joined: Mon Nov 10, 2008 7:36 pm

Re: Match Volume vs. Max Volume

Post by mathyou9 »

There aren't any "bass" or "treble" channels. The green channel on top is what you hear in your LEFT speaker and the red channel on bottom is what you hear in your RIGHT speaker. The bass and treble levels will pretty much be equal in both channels.
bakersfieldaccordion
Posts: 3
Joined: Sat Feb 20, 2010 2:23 pm

Re: Match Volume vs. Max Volume

Post by bakersfieldaccordion »

Well, I guess I didn't make my situation clear enough. I understand there are left and right channels. However, my instrument plays in stereo, with the bass predominantly feeding to one channel and the treble into the other (the degree of stereo separation is adjustable). This is similar to what you would get if you recorded a string bass on one channel and a piano on the other--or more accurately, if one mic was positioned next to the bass and the other next to the piano. The outcome is a preponderance of bass on one channel and treble on the other.
But in the meantime, I think I've solved the issue by selecting the "treble" channel (my terminology) and using the compress peaks routine a couple of times before using the match volume on both channels. At least, for now, that seems to allow me to increase the volume to -18db without clipping in either channel.
Richard
mathyou9
Posts: 70
Joined: Mon Nov 10, 2008 7:36 pm

Re: Match Volume vs. Max Volume

Post by mathyou9 »

Ahh, I see what you're saying.

My guess is that your "unbalanced" sound stems from the human ear not "picking up" the frequencies in the sound spectrum equally. That is, a 20Hz signal at -18dB won't be perceived nearly as loud as a 500Hz signal at -18dB. Lowering the volume of the 500Hz signal (or raising the volume of the 20Hz signal) solves the problem (which is basically what you've done in applying compression to your treble-rich channel.)
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