What to look for when choosing speakers for Audio Mastering

PMC speakers


Starting a blog is a lot of work and discipline. It obviously takes time to build a “fan base” or simply to have few followers. I have the chance to have Fred, a guy from France that always had plenty of questions for me, since our first chat about a year ago.

It’s always rewarding to have a participating audience, as this audience will naturally tell you what information is missing out there. So here again, I’ll take the time to answer Fred’s question.

Fred’s Question: 

After reading your article, I was wondering what do you suggest about speakers for mastering?

It’s a complicated question to answer, so I’m not surprised there aren’t many blog discussing that. We need to keep in mind that the monitoring must be flawless for mastering (as opposed to mixing), as its the final step prior to distribution, and therefore there is no safety net if something goes wrong.

The short answer:

Personally, I like to upgrade speakers often as my budget goes up. Here are the basic rules and guidelines I follow:

  • Don’t be frugal; that’s the most important piece in your studio.
  •  Stay away from “Studio Monitors” you find in music store, especially the affordable active 2-way. No KRKs, Yamahas, Presonus, M-Audio, etc.
  • Choose 3 way over 2 way. That’s not an absolute rule, but unless you go very high end, but there aren’t so much drivers that can cover half of the audible range without having a weak spot.
  • If you can build it yourself, do so ! You will get the best “bang for the buck”. There are plenty of very good design available online.

And Yes… that was the short answer.

The more complete answer is:

Guidelines are a good reference point to start with, but I wouldn’t personally pick my speakers only based on price and the number of drivers… I think you shouldn’t either. If you want to make a living from Mastering, you’ll have to be more critical about your monitoring and need to know what to listen for. Mastering is about as high end as an application can be for a speaker. It was therefore critical to come up with a well detailed guide:

To start with the beginning, here are the basic criteria I look for in a pair of speaker dedicated to mastering:


Frequency response is good place to start with, because it’s the easiest to understand. Also, the frequency response curve is one of the few technical chart that we can usually put our hands on. Even then, very few of the fabricant put them out there. The response curves are often generated by Audiophile magazines when they review it. This is the measured frequency response of the DIY speaker I’m currently using for mastering:

Flat Frequency Response

  • A flat frequency response – That’s the basic criterion to get in the game. Most HiFi speakers are far from being flat; Most of them will have incredible dip and peaks and that’s not workable for mastering. Eventually you will end up knowing your speakers, but if everything you do feels counter intuitive (e.i. It feels better with more 2kHz, but you know your speaker has a dip there, so you keep it low…), you will never able to get creative at mastering. Fortunately, that criterion is the easiest one to satisfy. If you decide to design it yourself, there plenty of flat drivers on the market and response curves are available everywhere.

venting options

  • An extended low end response – Okay, you’re speaker is flat, but how low does it get ? The term “F3″ is used to define the lowest frequency that is within 3dB from the baseline of the frequency response. There are three basic families of enclosures: Sealed, ported and transmission line. Sealed will have a tight response but little to no bass extension. Ported (or vented) will have a decent bass extension, but it will slow down the transient response. If the port is tuned too low, the transient response will be too smooth to be accurate. If it’s tune too high, it will not be able to reproduce lows, but it might also sound boomy as the bass extension will create a peak instead of a smooth extension. The best of all is clearly transmission line. The transmission line design allows the woofer to go as low as it can while retaining a very precise transient response and improving the efficiency. The harmonic distortion is also kept at its minimum using this design. Unfortunately, transmission line speakers are not popular on the market as a) they cost more money to build b) they require larger cabinets. An example of commercial speakers that uses the transmission line principle will be the PMC. The following picture shows how a transmission line design look like in the inside:

transmission line


extended high frequency response

An extended high end response – Indeed a spectrum has two opposite ends. The low end of obvious to most people, but the high end of the spectrum is also important. There is way more information above 16 kHz that people think. If there is a sound that is aggressive there, you want to be able to hear it and cut it out. That’s also where all the harmonics from all the distortion get up to, sometimes you need to add some sparkle, sometimes you want to clean it out. Please note that on most affordable “Studio Monitor”, you can’t hear anything above 16 kHz. On my speakers I can actually hear in the 21 kHz range. That indeed suppose your ears still can hear well these frequencies at all. Most people to hear much above 18 kHz, and with age this number constantly goes down.


Okay, but that’s just the basic!

Having a flat and extended response is basic criterion to get into the game, but it’s not merely sufficient to make world class masters!



The mastering process is a lot about shaping dynamics, through compression, limiting and enveloping. That’s what makes all the difference between a world class and a demo mastering. To come back to the KRK RP-10-3 example, I had a relatively flat frequency response throughout the spectrum, so I was able to produce masters that sounded well balanced everywhere. BUT, the impact of the transient, the details, the musicality of my masters were suffering when listened to elsewhere, mainly because the transient response of my speakers wasn’t accurate. . In other way, what I was hearing wasn’t the truth.


The waterfall plot you see above comes from the measurement of the RS-100, a 4 inch woofer. You could generate the same plot if you were to measure your speaker response as well. These plots are usually hard to find otherwise, although they tell a lot about a speaker. (That’s actually why the fabricant doesn’t publish it!!)

The perfect theoretical speaker would have only slim layer at 0.0 ms and then absolutely no ripples afterwards. Beside plasma speakers (which are expensive and dangerous – Ozone generation + high voltage), no technology is actually able to reproduce something near that. That said, tweeters can get very close to it. Here is an example of a tweeter that stops on a dime, Hiquphon OW4:


This tweeter is very popular among DIY audiophiles as it creates an amazing sense of realism. At that point, you don’t hear the tweeter anymore, but you hear the original sound. You can actually listen to a piano recording, close your eyes and actually BELIEVE the piano is in the same room as you. Most of us will never experience this with any speakers, but these are pretty rare and incredibly expensive.

Woofers aren’t even close to have such responses. Generally speaking, the bigger the woofer is, the slower it is to respond and longer will be the ripple effect after. The reason is quite simple, heavier the membrane is, the harder it is to control it. That comes back to why I recommend 3 ways over 2 ways…

The first reason is that you will need a large woofer to get the low end we discussed about. Unless you have a tweeter that gets incredibly low, your woofer will have to take care of most of the mid. If the woofer is large (8 or 10 inches for example), it will have a hard time reproducing the mid and high mid accurately. The second reason will be discussed in the next session (Harmonic Distortion).

In a 3-way configuration, you will have the option to place either a smaller woofer (that can move more quickly) or even better a 3″ dome midrange. The 3″ dome midranges tend to be incredibly clean on the distortion and they respond on a dime, such as a tweeter. Not surprisingly, they tend to be much more expensive as well. Still a small woofer will do a very good job. Plus, the transition from the tweeter to the midrange to the lower woofer will sound more transparent as their transient response will gradually degrade from the top to the bottom, instead of a very obvious contrast.



harmonic distortion


Harmonic Distortion is a good example of something that matters much more in a mastering than in a mixing context. Affordable “studio monitors”  are terrible in that area.

All drivers have harmonic distortion, but only expensive well designed and built one have low distortion profiles. Generally speaking, the distortion increases with gain and decreases with frequency. That’s why cheap mini speakers distort a lot in the bass when they are pushed to far.

What is distortion exactly ?

No driver is perfect. Instead of reproducing the exact pure sound, it will also generate what we called harmonics. For example, if you play a pure sine wave at 1 kHz, the woofer will indeed reproduce the 1 kHz, but it will also generate a more quiet 2 kHz tone, as well as an even more quiet 3 kHz one, an again quieter 4 kHz and so on. They are respectively called the 2nd, 3rd, 4th order.

Generally speaking, higher is the order, the quieter it gets, but it isn’t an absolute truth. The 3rd order distortion might be louder than the 2nd order for a certain frequency, It’s common practice to measure up to the 5 first order, but the order above that are usually too quiet compared to the 2nd and the 3rd and are therefore neglected.

The lower the distortion profiles are, the more expensive are the drivers.

Why should I worry about distortion ?

Lack of resolution

Distortion will have the effect of hiding details. In some ways, the definition or the lack of is usually caused by the distortion content of a speaker. Imagine this: Instead of having the pure sound, you have a constant noise playing in the background. That’s why some speaker will sound “cleaner” than others.

Ear Fatigue

Another very important consideration is the following: If you work all day long on your speakers, your ears will get tired very quickly. This is due to the harmonics that are adding up on top of each other and creates a fake high frequency content. That high frequency content has a lot of energy and sounds very aggressive. This can actually hurt your ears more than you would think.

Fuzzy Low End

If it wasn’t clear already, the lower you want to get in frequency, the bigger the woofer has to be. At least 8″ woofer is recommended to get a good low end. That said, it is true that some 6-1/2″ woofers can get pretty low too. The main problem with using undersized woofers is that it will introduce more harmonic distortion (more about this subject later on) in the low end. One way to bypass this problem is to work with a dual woofer system. Dual woofer implies that each of them will work less intensively to reach the same level, which with reduce their individual harmonic distortion by much.


My current setup uses two 6-1/2 to take care of the low end, and gets down to 40 Hz with a rather clean distortion profile. In that case, the quality of the woofer plays for a lot. Still, I can’t expect these to go any lower than that.



Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>