In a word "NO"!

Do yourself a favor and do a search for self mastering on this forum. It has been covered so many times here it should probably be a sticky.

In essence, attempting to master your own mixes (the processing portion, anyway) is little more than second-guessing what you've done already.

But if you need to produce a production master (which really is the basis of mastering in general) you can buy a copy of CD Architect and have at it. Just make sure you're happy with the mixes.

thanks for the advices and ideas.

well, hello again!

:) i knew it. cuz i actually tried to master 2 of my songs by myself in the past and it didn't make any sense listening to my own voice :oops:

I guess i'll have to try everything you guys are teaching me.

Again, many thanks to you guys.

Daniel

I master my own mixes, and I'm proud of it! Sure, it's not as good as a pro ME, but when I say master, I try to only do subtle tweaks. For example, I raise the volume with a soft clipper. Not to get as loud as pro stuff, but to get at least a little more volume out of a mix where the soft clip isn't noticable, and dynamics aren't compromised. I also tend to add a tiny bit of master reverb for a little wider stereo. Maybe a tiny bit of high frequency harmonic enhancement to give a little sparkle.

I only do these things because they're rather difficult to do within a mix. At least for my unprofessional ears, the mastering stage is the best place to do them. You shouldn't do anything with master EQ. If you have to EQ something, you should fix whatever it is in the mix, and leave your master EQ flat. MEs use EQ as a way of remixing problems they hear in the mix.

Avoid compression. If you do use a bit of master compression, play it safe and use high thresholds, low ratios and slow attack and release times (40+ ms attack, 300+ release). If your music has lots of bass peaks, you might need faster release so volume gets back to unity before the next bass peak. At least that's what I read somewhere.

So, if you're short on cash and absoutely have to do it yourself, always play it safe with very subtle tweaks, and you'll regret it less down the road. It's 100% possible for a pure mix to sound very professional without mastering, so don't think mastering will magically make things sound better. If you're looking for volume, you'll have better quality music if you leave it quiet with more dynamics and tell your listeners to use their volume knob. But I'm just a mastering hobbiest - what do I know?

wow..thanks for the very useful info of yours, headchem!

headchem, many thanks to you for your awesome info.

well, it seems like you're a talented mastering hobbiest :), i've learned a lot from your info. I am going to try it this weekend.

About my music style, i'm a pop vocalist. I record everything into the computer as dry signals. The reason i think i need the mastering process it's because i want my vocals to sound as good as possible. I don't have a lot of good hardware equipments so, i basically rely on softwares for recording and editing.

If you have time, teach me more. I'm willing to learn :)

Once again, many thanks go to you, headchem.

Daniel

Everything I know I learned from Google, and from people in these forums (who often told me to google things...) So, I think the best way to get a little more info is to google some of the key terms like "master compression," "stereo field," "frequency balance in music," or maybe even "pop vocal mastering" to see if there are any sites dedicated to your exact subject. There are tons of great sites that can explain these topics for beginners. Once you have a basic idea of what's going on, then you'll have some more specific questions, which is what you'll use these forums for.

Of course, you'll have to practice a ton, too, but for now take the phrases that interest you most in these forums, and google them. Happy researching!

Auto Mastering

I do my own mastering, and I used to suck at it, but then I realized that whenever I used anything that wasn't a Waves plugin, the master started tu suck. This is because less is actually more when it comes to auto mastering. I use slight multiband compression with Waves C4, Mastering EQ, Steinberg's Loudness Maximizer and a PAZ meter to measure RMS levels, that's my mastering chain and works beautifully for me i totally recomend it

cool! you guys are really helpful.

i can't thank you guys enough :)

cool! i'm learning a lot of stuff now.

have u guys ever tried mastering your mixes using AKAI QUADCOMP?
What about some PSP plugins?

I think you're right on with the "less is more" approach, assuming you have a solid mix.

As always, remember I'm no pro, but I've read enough on these forums to know that the pros would advise against using multi-band compression. I've always read that multi-band compression is usually used to correct severe problems in the mix. If you have a solid mix, single-band compression is generally recommended only to tame some occasional peaks (or even most bass drum, and snare hits) in order to get a few more decibles of final volume. Multi-band compression tends to take the dynamic life out of your various frequencies.

At least, that's what I think a pro would say... To the pros: If I'm off here, help this topic not turn into amateurs advising amateurs! :-)

There's nothing wrong at all with using a multiband compressor, if you know what you're doing, and WHEN to use it.

Unfortunately, it's so often misused (esp in final mastering) that it's gotten a bad name. In the right hands, and at the right point in the process, it'll do ya fine. Just don't think it's going to fix a bad mix.

Very often, a multiband limiter is more what's needed, and depending on the project, a fast attack/quick release is called for, at least when taming spikes and peaks. If it's robbing you of punch and clarity, then something's wrong.

In a word "NO"!

Beat me to it there, Thomas!

It's true, even if your budget means you gotta work with someone who ain't exactly a pro, like just another engineer with some experience...go to their place with yr mix and watch what they do, ask for less or more and learn what u can. I understand yr doing a demo but it will haunt u forever (demos always do) and another experienced set of ears is probably more important than any piece of gear/plug-in out there.

If you simply must DIY, I'd avoid multiband plugs and keep it light. Most stuff induces listening fatigue after a while at anything over -10dB RMS for sustained periods, like, too loud. I dont see any reason not to experiment with compressing the mix a little, it's very much part of the process. Initially, try a ratio of 1/1.5 (ie very little) and a threshold somewhere in the minus teens, as headchem says keep att. & rel. slow. You only want a few dB's of gain reduction at first, then it's up to your ears.

It's a can o' worms tho, ordinary humans like us need ME's!
Good luck,
A.

The one thing that you cannot get by doing it yourself is another pair of trained ears. If you go to a "real" mastering engineer, some one like Brad Blackwood, Bob Katz or Glenn Meadows you are not only getting a pro but you are getting someone with a lot of experience doing mastering and they know what can and cannot be done with your material and have the experience to do it quickly and, need I say it, professionally. If you go to the "local Joe's recording mixing and mastering CD duplication emporium" then you may not get any better results than you could do yourself. Just because someone hangs our a sign saying "mastering done here" does not mean that person knows what they are doing or can help you achieve what you are looking for.

Just MTCW

a lot of good ideas adn advices!!!!!!

ahhh....i feel like i'm a caveman lost in NYC :)

so many good ideas and advices. I think my learning of self-mastering has a little progress.

I took headchem's advices seriously and it works! after spending more than 10 hours to record and master 4 songs, i compared mine to those sung by pro singers, i actually sound great :). My demo songs were received by an entertainment production. Yay, i did it!

Again, thank you all of you for the valuable info.

Audio Mastering

Are you sure you even need to master your audio?

(Thanks for not pimping or advertising. MODERATOR)

Thanks,
Jason

I have heard mastering make an improvement in so many programs, even those that the artist thought were digitally perfect, that I really believe it will make a difference in all projects. Really!

Accepting the reasons to use a pro when the project demands, there ARE reasons that in the proper acoustic environment with good monitoring YOU CAN DO BETTER THAN A PRO.

If you were to mixdown and send it to the pro ME he starts with your mix and proceds from there.

If you can put the right mastering chain together in your studio, understand your gain structure and push your mix toward what you want as a final product , doing it yourself is not as hit and miss as some would like you to believe.

YOU can still adjust the mix going into the mastering chain. The mastering engineer has no such option unless they call you and try to get you to adjust your mix with cryptic instructions (which IMHO is an excercise in futility) compared to adjusting the mix you are actively listening to.

To much cymbals YOU can turn them down or EQ the tracks they are coming from --- or even EQ the tracks differently during certian parts of the song where they are sounding harsh. The ME can only try to EQ the entire mix. Get it? If they try to roll off the cymbals then everything else gets rolled off.

I tend to come back and do the mastering when the mix is not so fresh in my head.

Within the next month I will have the oportunity to master an album that was done in my buddies studio and then we will take the same album to Rodny Mills and attend his mastering session.

I can not wait.

Peace
Phil

Uh...
Phil -
I think what you're referring to is doing a good mix in the first place.

If you mix the album right, the mastering engineer won't have to call you to adjust things.

I never call a client and say "could you turn down the cymbals?" I can do that in my rig.

The only time I ever really call to get a remix is:
The mix is over compressed and they want it even louder
or
They forgot to mute a channel and I hear something in the mix that doesn't belong (talking, errant drums or guitar noodling, etc.)

If you mix and master on the same monitoring chain, you will have problems...

Cucco wrote: Uh...
Phil -
I think what you're referring to is doing a good mix in the first place.

If you mix and master on the same monitoring chain, you will have problems...

This statement must assume that every monitoring chain is out of wack.

Perhaps some of us studio guys have a little better monitoring chain and rooms than more than a few of these guys calling themselves mastering engineers have?

Otherwise please explain how some ME's have said that some mixes they master need nothing, just their ears to verify such a fact. If all mixes mastered on the same monitoring chain had problems this would be impossible.

Cucco wrote: Uh...
Phil -
I think what you're referring to is doing a good mix in the first place.

If you mix and master on the same monitoring chain, you will have problems...

This statement must assume that every monitoring chain is out of wack.

Perhaps some of us studio guys have a little better monitoring chain and rooms than more than a few of these guys calling themselves mastering engineers have?

Otherwise please explain how some ME's have said that some mixes they master need nothing, just their ears to verify such a fact. If all mixes mastered on the same monitoring chain had problems this would be impossible.

philsaudio wrote: [quote=Cucco]Uh...
Phil -
I think what you're referring to is doing a good mix in the first place.

If you mix and master on the same monitoring chain, you will have problems...

This statement must assume that every monitoring chain is out of wack.

Perhaps some of us studio guys have a little better monitoring chain and rooms than more than a few of these guys calling themselves mastering engineers have?

Otherwise please explain how some ME's have said that some mixes they master need nothing, just their ears to verify such a fact. If all mixes mastered on the same monitoring chain had problems this would be impossible.

Most recording studios around this general area have a pair of Mackie speakers, no room acoustics to speak of, unless you consider the old overstuffed couch their parents let them have an acoustical device. If you are mixing and mastering on the SAME speakers in the SAME room then if there are problems you will NEVER hear them. I get mixes in all the time that have a lot of bass noises in them and the reason they are there is because the mixing engineer did not have speakers that reproduced the bottom octave of music or more probably because he or she was sitting in a null spot for bass. I also get mixes in that are way to bright and all I can think is that the tweeters on the mix down speaker are either blown or they are turned way down. Just because you have good speakers and a good room does not automatically mean that the room and speaker interface is good or that you are hearing everything you should. I hired an acoustical engineer and he brought out a lot of equipment to "ring" out our two rooms and boy did he find problems. We have all top quality equipment and speakers but the room and the speakers have to work together. After a couple of weeks and some serious MONEY the rooms sounded REALLY GREAT where before they just sounded good.

Another pair of trained ears in an acoustically designed space is always better for the mastering phase IMHO.

Best of luck doing your own mastering and if it works for you and you can keep your client happy and returning then more power to you.

philsaudio wrote:
This statement must assume that every monitoring chain is out of wack.

Damn straight!

Every monitoring chain IS out of whack! However, when you take 2 out of whack monitoring chains that are out of whack in different ways, you negate problems.

I would also suppose that many "supposed" mastering houses don't have jack for monitoring systems and I know this because I've seen it. (The other local mastering house here where I live uses Alesis monitors in a warehouse (literally) with cracked Waves plug-ins).

That's why one should actually SHOP their mastering services to find a balance in price and quality that meets their needs and expectations.

philsaudio wrote: To much cymbals YOU can turn them down or EQ the tracks they are coming from --- or even EQ the tracks differently during certian parts of the song where they are sounding harsh. The ME can only try to EQ the entire mix. Get it? If they try to roll off the cymbals then everything else gets rolled off.

First of all, strange to see such an old topic come back up! Oh, I remember when I was a young whipper-snapper questioning the value of mastering... Stirring up trouble in the mastering forums...

Phil touched on a good point that was emphasized to me long ago, when I was less receptive: a good mix is more valuable than a good master. I'm a hobbiest at best, so when I'm talking mastering I really mean me and my buddies switch songs. We usually have at least 3 different mixing friends take a listen. Our "mastering" of each others' work has evolved into each other re-mixing a track on our separate set-ups and rooms, getting back together, and compromising on the changes.

With the right compression on the individual tracks, we rarely find a need for any master compression. With the right EQ and mixing on the tracks, we rarely find any need for master EQ. With the right oratory skills to the bands we're tracking, we rarely find a need to crank up the volume until all dynamics are lost...

In short, we mix our tracks until there's nothing left to master. I'm sure Bob Ludwig could do something magical to them, but for the amateur, there's no better system considering it's freeeeee!

headchem wrote: [quote=philsaudio]To much cymbals YOU can turn them down or EQ the tracks they are coming from --- or even EQ the tracks differently during certian parts of the song where they are sounding harsh. The ME can only try to EQ the entire mix. Get it? If they try to roll off the cymbals then everything else gets rolled off.

Phil touched on a good point that was emphasized to me long ago, when I was less receptive: a good mix is more valuable than a good master. I'm a hobbiest at best, so when I'm talking mastering I really mean me and my buddies switch songs. We usually have at least 3 different mixing friends take a listen. Our "mastering" of each others' work has evolved into each other re-mixing a track on our separate set-ups and rooms, getting back together, and compromising on the changes.

In short, we mix our tracks until there's nothing left to master. I'm sure Bob Ludwig could do something magical to them, but for the amateur, there's no better system considering it's freeeeee!

This is exactly what we are doing here in Atlanta. Listening in three different studios and now we have our masterpiece and we are bringing it to Rodny Mills who maybe ain't Bob Ludwig, but he was inducted into the Georgia Music Hall of Fame and the main talent and I were there when it happened.

Soon we will find out Rodny's opinion of how good we are and more importentaly I will be able to hear it all in his room while he does it and then we can all take it back to our studios.

For non masterpiece work, I think we do pretty well.

BTW I have my studio calibrated to Bob Katz's K system, my room nodes are understood and out of the way and the room is pretty damn flat. I have years of listening experience in it and understand how many of the recordings discussed in magazines like tape-op and recording sound in it.

Mastering is just another set of calibrated ears to me and sometimes we have plenty of them on hand here in our basement studios.

peace
Phil

IF YOU HAVE TO MASTER YOURSELF WAVES AND MCDSP PLUGINS ARE THE ONLY WAY TO GO

song4gabriel wrote: IF YOU HAVE TO MASTER YOURSELF WAVES AND MCDSP PLUGINS ARE THE ONLY WAY TO GO

Thanks for sharing your opinion. And why are these plugs the only way to go?

philsaudio wrote: [quote=Cucco]Uh...
Phil -
I think what you're referring to is doing a good mix in the first place.

If you mix and master on the same monitoring chain, you will have problems...

This statement must assume that every monitoring chain is out of wack.

Perhaps some of us studio guys have a little better monitoring chain and rooms than more than a few of these guys calling themselves mastering engineers have?

Otherwise please explain how some ME's have said that some mixes they master need nothing, just their ears to verify such a fact. If all mixes mastered on the same monitoring chain had problems this would be impossible.

I would not send it to any "Mastering Engineer" unless the guy had major credits/and or his work sounded great. There are too many guys with gear in a room, calling themselves mastering houses.

When I set up my indie label, I learned the hard way on this one. I let a high volume guy master some stuff for me. They had just moved into a state of the art room, with the best of the best. But he handed off my work to a kid with no ears. We went through no less than 6 attempts. This kid could not hear the distortion he was inflicting by smashing it. I told them eventually to notch it is a couple of places and leave the compression alone, I wanted dynamics anyway.

So, then I learned to do the sit in thing.

DIY Mastering Workflow.

Mastering for masterpieces is one thing but what about all those CD's that we make that are never intended for wide distribution? Like the Jam CD's I produce from my bi-weekly semi-open-house jam here in my studio. Players get a copy of the session next time they come over.

In most cases these CD's will only be interesting to the people who play on them or those who were at the party. I make like ten of them and as soon as I finish I delete all the tracks so I CANT go back and spend more time on them. Surely no one would recommend spending money on a legit mastering job for this kind of work. But do I want them to be the quietest CD's in the jukebox? No I don't, but it does not have to be the loudest either.

So I master them myself and there is nothing evil about that.

But what workflow I use is important to me and perhaps others. After one of my jams I have a 25 track DAW project that is 2-5 hours long with some non-playing time in there.

My goal is to have a 74-minute CD with the best performances right before I delete the project. My secondary goal is to be done in less than five hours. I delete the project for my own sanity cause once it is deleted the work is over. I do not name songs or take copious notes. The names of who was playing that night are the only information I want to remember, not even who played what and especially not when.

To do this I "finalizing" I set up a plug-in chain on the mix bus. It is Waves L3 multiband dithered at 16 bit feeding Tape-It set to 16-bit record. I know the levels to use to get a nice crest and a quality sound without a lot of distortion. The finals are at a competitive level with other fine sounding recordings but they are not smashed.

Once I find the right beginning and end places to mixdown a "song" I give it a name and start tape-it. I hit play and mix with the mouse while the tune plays. When the tune is done I have a file with the song.

I put the mixed down song back into the project and keep it right under the tracks so I can see what is complete. I make another copy and put that in a row at the front of the project so I can see how much elapsed time of mixdown I have completed.

Once I get to 74 minutes I put the files into a burning program and make a CD and delete the project.

For masterpieces we follow the more traditional method.

peace
Phil

sheet wrote: [quote=philsaudio][quote=Cucco]Uh...
Phil -
I think what you're referring to is doing a good mix in the first place.

If you mix and master on the same monitoring chain, you will have problems...

This statement must assume that every monitoring chain is out of wack.

Perhaps some of us studio guys have a little better monitoring chain and rooms than more than a few of these guys calling themselves mastering engineers have?

Otherwise please explain how some ME's have said that some mixes they master need nothing, just their ears to verify such a fact. If all mixes mastered on the same monitoring chain had problems this would be impossible.

I would not send it to any "Mastering Engineer" unless the guy had major credits/and or his work sounded great. There are too many guys with gear in a room, calling themselves mastering houses.

When I set up my indie label, I learned the hard way on this one. I let a high volume guy master some stuff for me. They had just moved into a state of the art room, with the best of the best. But he handed off my work to a kid with no ears. We went through no less than 6 attempts. This kid could not hear the distortion he was inflicting by smashing it. I told them eventually to notch it is a couple of places and leave the compression alone, I wanted dynamics anyway.

So, then I learned to do the sit in thing.

I don't thing that a bad experience with one mastering engineer should sour your feelings toward ALL mastering engineers. If you were paying for a top mastering engineer and he gave the project to a subordinate without telling you then I think you were dealing with someone who was less than honest. If you did not want to pay his prices and he agreed to do the mastering for less than his published rates and turned it over to a subordinate then I think he should at least have told you that he was doing it. There are a lot of people on this web board who do a lot of mastering and probably don't have MAJOR CREDITS but they are also not charging MAJOR bucks for their services. I think it boils down to "you gets what you are paying (or not paying) for. I have a couple of MAJOR CREDITS in mastering for classical artist but most of the pop stuff we work on is for local bands so I have very few MAJOR acts to hang my hat on but still to a professional level job with every mastering that comes though the door. I think a lot of professional mastering engineers on this web board can do a really good job with your material and not have to have you spend your life savings getting your stuff mastered. If in doubt how good someone is ask others who have used him or her and send them a track to have mastered so you can hear how they approach the material. Mast good mastering engineers will do a 1/2 track master for no charge.

Best of luck on finding someone who you can trust and whose work you like.

Sure, if you guys are doing your own projects, indies, etc that don't have a shot at distribution, then sure, you have no choice but to master.

Check out the Roger Nichols plugs. They are very good. Also the new Waves limiters sound great.

you know, I've never really been given a good definition of mastering. to me, if it sounds good, it is good. I understand you should mix on nice studio monitors and make sure the mix sounds good, but the rest seems to go along with mixing, in terms of an album. you are just mixing an album after you mix the individual songs. maximizing, mixdown compression, punch and sparkle eq, and dithering should just be part of the "mixing of the album." seems to me people put this huge ambiguous misunderstood word of mastering to mean a relatively simple process. Use common sense, and think, why should I pay for some guy to sit and master this for me? what can he do that I can't? They don't have magic ears or some special filter on their eyes that tells them "this is a good track." so instead of putting the responsibility of your beloved creation in the hands of someone who probably does not care about your life long ambitions or the true essence of your music, buy some genuine wal-mart confidence, and work it.

GarydaBeauford wrote: you know, I've never really been given a good definition of mastering. to me, if it sounds good, it is good. I understand you should mix on nice studio monitors and make sure the mix sounds good, but the rest seems to go along with mixing, in terms of an album. you are just mixing an album after you mix the individual songs. maximizing, mix down compression, punch and sparkle eq, and dithering should just be part of the "mixing of the album." seems to me people put this huge ambiguous misunderstood word of mastering to mean a relatively simple process. Use common sense, and think, why should I pay for some guy to sit and master this for me? what can he do that I can't? They don't have magic ears or some special filter on their eyes that tells them "this is a good track." so instead of putting the responsibility of your beloved creation in the hands of someone who probably does not care about your life long ambitions or the true essence of your music, buy some genuine wal-mart confidence, and work it.

You should do some reading on this web forum.

A good mastering engineer can take an OK sounding album and make it sound GREAT! They have the tools, the experience and skills and the monitoring setup to do what is needed to the album. If you don't believe it then send your tracks to a professional and I can almost guarantee that they will come back sound better then when you finished mixing them....

If you think you can do it by yourself in mixing then do it.

Thomas W. Bethel wrote: [quote=GarydaBeauford]you know, I've never really been given a good definition of mastering. to me, if it sounds good, it is good. I understand you should mix on nice studio monitors and make sure the mix sounds good, but the rest seems to go along with mixing, in terms of an album. you are just mixing an album after you mix the individual songs. maximizing, mix down compression, punch and sparkle eq, and dithering should just be part of the "mixing of the album." seems to me people put this huge ambiguous misunderstood word of mastering to mean a relatively simple process. Use common sense, and think, why should I pay for some guy to sit and master this for me? what can he do that I can't? They don't have magic ears or some special filter on their eyes that tells them "this is a good track." so instead of putting the responsibility of your beloved creation in the hands of someone who probably does not care about your life long ambitions or the true essence of your music, buy some genuine wal-mart confidence, and work it.

You should do some reading on this web forum.
A good mastering engineer can take an OK sounding album and make it sound GREAT! They have the tools, the experience and skills and the monitoring setup to do what is needed to the album. If you don't believe it then send your tracks to a professional and I can almost guarantee that they will come back sound better then when you finished mixing them....
If you think you can do it by yourself in mixing then do it.
This is a classic exchange and is probably repeated in dozens of similar threads on this forum and thousands over the web.

One of the big keys to the disconnect is the point that Gary makes in his first sentence and the Tom doesn't really address - In the digital age the distinction between mixing and mastering has been blurred if not completely obliterated. (Yes, I am overlooking some of the technical chores of preparing a CD for duplication and focusing exclusively on audio processing.) Tom's point (They have the tools, the experience and skills and the monitoring setup...) applies right down the recording chain to the mixing engineers, musicians, to the guys serving coffee in the studio. So it doesn't really tell us why we need a mastering engineer if everyone's DAW has the tools to do the job (inferior though those tools may be).

However, Tom is clearly right in terms of the big picture. The practice of sending disks off to mastering engineers persists twenty years after vinyl records have (all but) gone. Why? I think that Gary inadvertently hits it with his questions. He has all the marks of someone who has fallen in love with his tracks and doesn't want someone else to touch them. No, there is nothing magic about an MEs ears. They are simply different than those of the musician and the mixing engineer. Maybe it is a good thing to have someone who has not sat through twelve takes, listened to a song a hundred times, comped a vocal syllable by syllable adjust the final mix. It may be true that the technical distinction between mixing and mastering is blurred, but the psychological distinction is still there. My guess is that this is the real reason that sending disks to mastering houses is still standard practice.

BobRogers wrote: [quote=Thomas W. Bethel][quote=GarydaBeauford]you know, I've never really been given a good definition of mastering. to me, if it sounds good, it is good. I understand you should mix on nice studio monitors and make sure the mix sounds good, but the rest seems to go along with mixing, in terms of an album. you are just mixing an album after you mix the individual songs. maximizing, mix down compression, punch and sparkle eq, and dithering should just be part of the "mixing of the album." seems to me people put this huge ambiguous misunderstood word of mastering to mean a relatively simple process. Use common sense, and think, why should I pay for some guy to sit and master this for me? what can he do that I can't? They don't have magic ears or some special filter on their eyes that tells them "this is a good track." so instead of putting the responsibility of your beloved creation in the hands of someone who probably does not care about your life long ambitions or the true essence of your music, buy some genuine wal-mart confidence, and work it.

You should do some reading on this web forum.
A good mastering engineer can take an OK sounding album and make it sound GREAT! They have the tools, the experience and skills and the monitoring setup to do what is needed to the album. If you don't believe it then send your tracks to a professional and I can almost guarantee that they will come back sound better then when you finished mixing them....
If you think you can do it by yourself in mixing then do it.
This is a classic exchange and is probably repeated in dozens of similar threads on this forum and thousands over the web.

One of the big keys to the disconnect is the point that Gary makes in his first sentence and the Tom doesn't really address - In the digital age the distinction between mixing and mastering has been blurred if not completely obliterated. (Yes, I am overlooking some of the technical chores of preparing a CD for duplication and focusing exclusively on audio processing.) Tom's point (They have the tools, the experience and skills and the monitoring setup...) applies right down the recording chain to the mixing engineers, musicians, to the guys serving coffee in the studio. So it doesn't really tell us why we need a mastering engineer if everyone's DAW has the tools to do the job (inferior though those tools may be).

However, Tom is clearly right in terms of the big picture. The practice of sending disks off to mastering engineers persists twenty years after vinyl records have (all but) gone. Why? I think that Gary inadvertently hits it with his questions. He has all the marks of someone who has fallen in love with his tracks and doesn't want someone else to touch them. No, there is nothing magic about an MEs ears. They are simply different than those of the musician and the mixing engineer. Maybe it is a good thing to have someone who has not sat through twelve takes, listened to a song a hundred times, comped a vocal syllable by syllable adjust the final mix. It may be true that the technical distinction between mixing and mastering is blurred, but the psychological distinction is still there. My guess is that this is the real reason that sending disks to mastering houses is still standard practice.

Nice summation BobRogers!

I cannot tell you the number of people who come here for mastering that have never really heard their tracks until they come and listen to them on wide range speakers in an acoustically designed room. There are all kinds of noises that are present and some low frequency material that their 8 inch monitor speakers will not reproduce.

They also have a lot of problems on their tracks they they never noticed like missing starts and ends of tracks that were clipped off in production along the way (they hear them in their minds but they are simply not there) or they don't hear the out of sync vocal parts because as you pointed out they have heard them literally hundreds of times and have forgotten what they were suppose to sound like.

As a mastering engineer I don't have any attachment to the recording or mixing. All I am hearing is what I hear over my monitoring system I am starting with a clean slate. I don't know that the lead singer had a cold that went on for weeks or that the drummer was going though a very messy divorce and was not at a lot of the sessions and did most of the percussion at odd times or that the lead guitar player cut his fingers at work and was playing a lot with an injured finger. All I hear is the results of the recording and mixing and that is the way it should be. I should bring fresh ears and a open mind to the mastering process. I follow the mentoring I received early on in my career "DO NO HARM to the music or the artist's vision, instead try and make what is presented to you better and use all of your skills to make the music come alive." I can smash with the best of them but I don't automatically do it just because I can. I am a professional and have the knowledge and ears to do what needs to be done to make the music sound better. That is what professional mastering is all about

I am here to help not to hinder the artist's artistic vision and anyone that has used our services can attest that we go the extra mile on every project that we do.