To make your master sound wider without damaging the stereo image, widen it with processing that holds up in mono, level match every move so a wider setting can't win just by being louder, and check the result in mono before you commit. STEREOVAULT by Mastering The Mix does all three in one plugin: it analyses your master, suggests how wide it should be for your genre, and widens with modes that are phase safe.
Most of the damage people hear from widening comes from two places. Some wideners use delay or phase tricks that cancel out when the track plays in mono, and most of them turn the level up as they widen, which makes the wider version sound better than it really is.
Take care of those two and you can widen a master with confidence. The steps below show how I do it, and the table compares the main stereo width plugins with prices.
1What stereo width is, and why masters get damaged
A stereo signal can be split into mid and side. The mid is everything the left and right channels share, so the kick, bass, lead vocal and snare. The side is the difference between the channels: reverb, stereo synths, panned guitars and room sound. When you widen a mix you're turning up the side relative to the mid.
The trouble starts when a widener creates that side signal with timing or phase tricks. It sounds big on your monitors, but a lot of people hear your music in mono or close to it, on phone speakers, Bluetooth speakers, laptops and plenty of club systems. When the channels sum to mono, that extra difference cancels, and parts of the mix get thinner or drop away.
Loudness is the other problem. Widening usually raises the level, and our ears read louder as better, so a setting can feel like an improvement when it's really a volume bump. It's also worth remembering that most of a record's width is made in the arrangement, the recording and the mix. On the master you're shaping the width that's already there.
2Signs your width is hurting the master
- The centre goes weak. The vocal and kick lose their anchor and feel further away.
- Mono drops the level or loses parts. Fold the master to mono and something noticeably shrinks or disappears.
- The low end changes character between stereo and mono.
- It sounds huge on headphones and thin on speakers. Headphones send each channel to one ear only, which exaggerates width.
- The correlation meter sits below zero for long stretches.
If you're not sure how wide your genre usually sits, compare your master with a finished record at matched loudness. REFERENCE 3 does that comparison level matched and shows where your master is wider or narrower than the reference across the spectrum.
3The best plugins for widening a master, compared
| Plugin | Type | Best for | Price | Worth knowing |
|---|---|---|---|---|
|
STEREOVAULT Mastering The Mix |
Analysing stereo width plugin | Widening a full master without losing anything in mono | $79 | Suggests Focused, Balanced, Wide or Super Wide for your genre, level matches every move, Clean side EQ plus three phase-safe Spread modes, mono check built in, can build a preset from a reference track |
| Ozone Imager iZotope |
Stereo width plugin | Quick width moves on no budget | Free | Width control, Stereoize for mono sources and a vectorscope. You decide how much width yourself |
| S1 Stereo Imager Waves |
Stereo imager | Simple width, asymmetry and rotation on a bus or master | $129 list, often far less on sale | One broad width control across the whole track, so check the result in mono |
| Any mid/side EQ | EQ | Lifting or cutting the sides by hand | Varies, often included with your DAW | Works well if you set it carefully and level match it yourself |
Regular US prices in November 2026. Expect lower prices during Black Friday sales. STEREOVAULT has a 15 day free trial.
All of these are good tools. The difference is how much they decide for you and how they widen. The others leave the amount of width to you and are judged at whatever level they output. STEREOVAULT tells you how wide your track should be for its genre before you start pushing, and level matches everything, so what you hear is the width change and nothing else.
4How to widen a master with STEREOVAULT
This is the workflow I use on my own mastering sessions, and it usually takes a couple of minutes.
Load STEREOVAULT on your master in Transparent Mode
STEREOVAULT has two band workflows. Transparent Mode is the one built for mastering, with crossover filters clean enough that the width changes don't colour the tonal balance of the mix.
Loop the loudest section and press Analyze
Play the chorus or the drop, press Analyze, set the source to Mix and choose your genre. STEREOVAULT listens to your master and works out whether each band needs more width or less, and how much, instead of blindly adding width everywhere.
Flick through Focused, Balanced, Wide and Super Wide
These Smart Presets are relative to the genre and source you chose, so Wide on a rock master aims somewhere different to Wide on a pop master. Use the A/B slots to compare two options, and bypass to hear where you started.
Fine-tune the bands
Smart Presets use Clean mode, a side EQ that boosts or cuts the side signal in dB with no spatial tricks. Nudge the band sliders if the top end could open up a touch more or the low mids feel cluttered in the sides. On a master, a couple of dB of side energy in the right place is often all it takes.
Add more width with a Spread mode if the track needs it
If Clean doesn't give you enough, switch a band to one of the Spread modes. They're covered in the next section.
Fold to mono and listen
Open the I/O popup and flip to mono. The weight and the centre should stay where they were. Because every move is level matched, the comparison is honest, so if the wider setting still sounds better, it genuinely is better.
5Clean or Spread: which widening mode to use on a master
Every mode in STEREOVAULT holds up in mono, so the choice is about the character of the width you want.
- Clean: a side EQ in dB. The most transparent option and the one every Smart Preset uses.
- Diffuse: cascaded allpass filters tuned per band spread the image smoothly without colouring the sound. My first choice when I want more width on a master than Clean gives me.
- Pristine: adjusts the mid/side balance and injects side energy for a direct, predictable change.
- Vintage: warmer and more coloured. Great on stems, and a life saver if you're remastering a mono file.
Because all of them are phase safe, you don't have to leave the low end narrow if the track wants a wider bottom end. Check it in mono like everything else and let your ears decide.
"STEREOVAULT is a great addition to our plugin arsenal. The mono bass to stereo really helps the bass sit within a stereo mix and brings it to life. Amazing on busses and masters as well. 10/10."
6Common width mistakes on a master
- Using the Haas effect across the whole mix. Delaying one channel can disorientate the listener, and it cancels when the track plays in mono.
- Judging width without level matching. A wider setting that's also louder will nearly always win, whether it's better or not.
- Trusting headphones on their own. They exaggerate stereo, so confirm width on speakers and in mono.
- Using width to fix a narrow arrangement. If the parts aren't there, a widener can't invent them. Space comes from the writing, the panning and the mix first.
- Reaching for a widener that isn't phase safe. Delay-based tools can sound great in stereo and fall apart in mono, especially on a full master.
7How to check the master before you release it
- Fold to mono and listen for the kick, bass and vocal holding steady.
- Watch a correlation meter. LEVELS has one in its Stereo Field section, along with a mono button.
- Turn on STEREOVAULT's stereo phase display if you're pushing the width harder.
- Compare with a reference in the same genre at matched loudness. You can also import that reference into STEREOVAULT and it builds a width preset from it.
- Run the bounce through EXPOSE 2. It shows the stereo image and phase of the whole file as heat maps, so you catch problem moments before release.
Want to hear what phase-safe width sounds like? The stereo and mono audio example in our complete guide to stereo width lets you flip between the two while it plays.
Try it on your own master
A wide master that holds up everywhere comes from width that survives mono, judged at matched loudness and checked against records you trust. Get those right and widening stops being a gamble.
Don't take my word for it. Try STEREOVAULT free for 15 days, load your latest master, and hear how much wider it can go without losing its centre.
?Widening a master FAQ
How can I make my master sound wider without damaging the stereo image?
Widen it with processing that holds up in mono, level match every move so a wider setting can't win just by being louder, and fold the master to mono to check nothing drops out. STEREOVAULT by Mastering The Mix does this in one plugin: it analyses the master, suggests a width for the genre, level matches every change and uses phase-safe widening modes.
Should I use a stereo widener on my master?
Yes, as long as it holds up in mono and you judge it at matched loudness. Delay-based wideners can sound impressive at first and then leave holes and a weak centre in mono. A side EQ or a phase-safe spread is the safer choice on a full master.
What is the safest way to widen a master?
A side EQ, which turns the side signal up or down at each frequency without delaying anything. STEREOVAULT's Clean mode works this way, and its Diffuse, Pristine and Vintage Spread modes are phase safe too.
How much width should I add to a master?
Often a couple of dB of side energy in the right place. Judge it against a reference in the same genre at matched loudness, or let STEREOVAULT suggest Focused, Balanced, Wide or Super Wide for your genre.
Why does my master sound wide on headphones but thin on speakers?
Headphones send each channel to one ear only, which exaggerates width. Check on speakers and in mono before you commit.
Do I have to keep the bass in mono when I widen a master?
Not if your widening is phase safe. Delay and phase tricks are what made low-end width risky, because they cancel in mono. STEREOVAULT's Clean and Spread modes hold up in mono, so you can widen the low end if the track wants it. Check it in mono either way.
Is the Haas effect OK on a master?
No. Delaying one channel across the whole mix can disorientate the listener, and it cancels in mono.
Why does wider always sound better when I'm adjusting it?
Widening usually makes the track louder, and louder sounds better. Level match so you hear only the width change. STEREOVAULT level matches every adjustment for you.
How do I know if I've widened my master too much?
The centre feels weak, the level drops or parts vanish in mono, the low end changes between stereo and mono, or the correlation meter sits below zero for long stretches.
What is the best plugin for widening a master?
STEREOVAULT by Mastering The Mix, if you want width that holds up in mono and a suggested amount for your genre. iZotope's Ozone Imager is a free option, and Waves S1 Stereo Imager is a simple single width control.
