As Staffay says it can be difficult to comment without the original mix though we can make some comments that relate it to comparable commercial music. Additionally it can be difficult to judge mastering based on mp3s due to the additional compression. It can help a lot if you can post a wave file - doesn't need to be the entire track, often 1 - 1.5 minutes of 16 bit is enough to get an overall impression.
Anyway I'll download the mp3 and format shift it to a wave and give it a listen asap but will probably be sometime tomorrow (just finishing off and then up-loading a mastering session for some UK label). Whilst I'm doing that a bit more info:
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An all in one like Ozone could probably get you most of the way to a mastered end product good enough for commercial release. The two main things to watch out for imo are: 1-presets, only use them as a starting and not an end point. They're not specific to your audio and so you shouldn't think that they're ideal for it. They can be a good place to start at least until you get some experience. 2- over doing it, any processing that you do should be careful and improve things. We often get things sent here that have been over/poorly processed and when we ask why the reply is, 'but it's part of my daw so I kinda always use it'. All processing distorts the original in the sense that it changes what was originally recorded so it needs to be done with care.
Personally, and perhaps I would say this as it's my work, an all-in-one plug like Ozone is fine but can't replace a good ME who knows how to use their particular hardware/software. We use very specific items for specific instances and we have to get to know them well. I might use 1 or more specific EQs on a track both for technical reasons and also because a particular EQ will give me a coloration that the others might not. AFAIK although all-in-ones have improved a lot over the last few years they still can't do that. But I would say that as I'd find it hard to believe that something that costs a few hundred bucks for lots of processors could match say my hardware EQ that costs over 6000
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On a good mix the processing shouldn't make radical changes; a bad mix needs this and excellent mix might not need any processing at all. Generally the processing used in Mastering is: EQ> wide band compression> limiting (plus dithering if you see that as processing). Of those EQ is the most important and most used ime. At the mastering stage you should be after fine tuning, or as my daughter calls it, 'sprinkling on the fairy dust', a mix to get the best out of it and removing anything that shouldn't be there. So on a good mix you often are talking about cutting or adding less than 3dB to any particular frequency range/band; compression ratios are often less than 2:1 - very often 1.3:1; limiting is often done not in a single process but sequentially moving the level up gradually.
This might sound counter-intuitive but processing is actually not the main part of an MEs job. By far the two biggest bits are quality control and sequencing IME. Ozone can be good enough for the processing but afaik you'd still need to look elsewhere for the other aspects of mastering. Nonetheless there's no harm in using it, learning about and getting experience in how to audio process masters
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Dithering - is a process used for bit depth reduction when we convert from say a 24 bit to a 16 bit file. Most MEs work in 24 bit but the red book standard for audio CD requires 16 bit digital audio. To go from 24 to 16 you could either hard truncate ie cut out 8 bits of data, or you can dither and noise shape.
If you just truncate the bit depth from 24 to 16 then you will have quantisation error. In some cases this may not be too noticeable but in the majority it will be.
The issues with changing bit depth from 24 to 16 is that you both remove audio data and you increase the amount of distortion in the audio due to quantisation error. In the former you can never get back the data that is removed so dithering 24 to 16 and back to 24 will not give you back the original data - you will get a 16 bit depth file plus 8 bits. In the latter there are different ways of dealing with the distortion - and this essentially is dithering. Dithering involves masking the quantisation error by putting low level noise over it. There are different ways to dither - how and where you apply the noise, and the type of noise you apply. So when you dither though you are 1 reducing the bit depth, 2 inducing quantisation error, 3 masking that by inserting low level noise. Hence, if you have to dither do it as little as possible and so if you intend to get your audio mastered leave the dithering to the ME. If you're doing the mastering yourself then place the dither at the end of the processing chain as the very last process when the wave is rendered to 16.
I don't have, and never have had, Izotope but I think it has an option to use the Powr noise shaping algo. That's a v good one, we have it as an option in sadie as well though tbh I tend to use tpdf routinely.
Multiband dynamicsI very rarely use MBC in mastering - possibly about 2-5% of all the mastering that comes in needs it and it's always for a very specific purpose and even then I only use it if the client can't remix the audio instead. Where it can sometimes be used is for deliberately adding different compression levels to different frequency bands - say where you want a tight rythmic bass that needs the release to follow the tempo but also need to clamp down on high frequency transients with very short attack and release. In your case though as you've got the original audio stems I'd suggest that you stick to wide band compression and leave the MBC alone as much as possible - ie if you needed to do the preceding example compress the bass stem separate to the drums.
The main reasons why I suggest you avoid an MBC as far as possible are: 1- they're pretty complicated and it is very easy to get things wrong and ruin a mix; 2 - they can mess up the stereo field and placement of instruments a lot if used incorrectly and 'unglue' a track; they can add some quite nasty artifacts and pre-ring; there's v little you can do with an MBC that you can't do on the stems with a wide band.
ExcitersPersonally I don't use them. Most, not all, add some form of distortion to the audio - usually phase related - as a means to increase the perceived level of a given eq region. (I don't know what process Ozone uses.) Depending on the region used you get an increase in air/sparkle/warmth etc. Ozone's is a 'harmonic exciter' so I guess that it aims to affect the perceived level of 2nd or 3rd level harmonics. IMHO much of this can be better achieved by good eq'ing at mixing and mastering.
Multi-band stereo imagingNew one on me tbh. I guess what it is supposed to do is allow you to reposition particular frequency bands in the stereo field/depth. So you could for instance bring up and forward a vocal whilst leaving the bass alone in the field. If I need to do something like this (apart from asking for a re-mix) then I'd look at other ways to do this: M/S matrix to an eq to only adjust mid or side etc; mono collapse and process a bass; some careful reverb, etc.
TBH it is rare for an ME to make any significant alteration to the stereo field of a track. Stereo field and placement is very much an aesthetic production decision and usually what an ME has to do is maintain the integrity of that despite any processing that they've done. Sort of imagine the situation if I re-mastered 'Dark side of the moon' to collapse the field and move instruments about - probably not a very good idea
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