The following is a guest post from Francis at Echoplex Mastering. Echoplex offer professional mastering services at reasonable prices. Find out more at the link.     Recently I’ve been asked a lot about stem mastering. There seems to be some misinformation floating around over when and why people use it and as well as what it actually is so I thought I’d take the opportunity to break down this subject into the three main FAQs I get then we’ll talk about some of the details.   What is Stem Mastering?   Stem mastering is the treatment of multiple stems, consisting of grouped channels from the mix session, and comes just before the traditional mastering stage.   When is it needed?   There are two main scenarios where stem mastering might be needed. The first scenario is when there is an issue with the mix. Perhaps you think the bass is interfering with the mids too much, or maybe the vocals need to be a little bit louder. I would always recommend that these kind of problems get fixed at the mix stage as making any sorts of adjustments will always leave the door open for compensatory adjustments elsewhere, but sometimes it’s simply not possible for the mix engineer to spend any more time on the project, or if you’re self mixing then you might just want an extra pair of ears on the project.   The second scenario is that there aren’t any problems with the mix but it may be desirable to feed the stems through the equipment that the mastering engineer has.   What happens in a stem mastering session?   Most engineers will have their own work flow during the actual stem mastering session so giving specifics here is tricky but, broadly speaking, the mastering engineer will take the stems you have provided and process them using the tools at their disposal. Once they and/or the client are satisfied that any issues have been removed and/or the track has been improved then the traditional mastering stage will begin.   So, it all sounds pretty nice, doesn’t it? Like a no-catch “Mastering v2.0” guaranteed to make your tracks better! Well, yes and no… There is no doubting that stem mastering has some pretty cool benefits but much like anything else to do with making music there are some pitfalls that should be considered. If there’s a problem and no chance to fix in the mix then yes there’ll be a reasonable chance it can be wholly or partially solved, but if you’re already happy with the mix? Stem mastering doesn’t always mean a better master as there’s no guarantee of an improvement over a traditional master. In fact, if you’re having stem master purely for the thrill of pushing your mix through some fancy gear then it can be the reminder that expensive gear doesn’t always make a better track! Stem mastering is more expensive than a regular master due to the amount of work and time needed. There are also limits on how many stems you can submit and every engineer will have their own upper limit on how many stems they will accept before they start to view it as a mixing session.   If you have a lot of stems you’ll either be turned away in the direction of a mixing engineer or the price will raise considerably! Also, bear in mind the strength of adjustments and type of processing that mastering engineers will be doing for a stem master. Unless there’s a very specific issue that needs addressing it’s rare to find a good ME that will be approaching a stem master with the intention of make drastic changes. It’s hard wired in ME’s brains to polish and strengthen what is already there so if you’re after drastic changes then stem mastering may not be appropriate.   Having said that, if you’re aware that the changes you have mind might go beyond what a ME might be willing to ordinarily do then talk to them and be upfront, some mastering engineers might love the opportunity to get involved in more of a production/mix role. Finally, and as with all other mastering situations, clear and forthright communications with your engineer is a must… You can never be too detailed!   In the right cases, stem mastering can be brilliant, but in the overwhelming majority of cases regular “final mixes” mastering will be the top option so don’t feel like you’re settling for 2nd best if you’re having a regular master. If you’re in any doubt as to what might be right for you and your music then talk with your engineer who will be more than happy to give you all the advice you’ll need.