Every song ever recorded, in surround sound?

You're probably yet to hear the most disruptive music software in the world. So I'll tell you about it here.

I recently had the pleasure of hearing Penteo 4, which takes any stereo audio track and converts it into full glorious surround sound.

Penteo 4 isn't the first plugin to convert stereo to surround, but it sounds like the best. I heard it in front of speakers the size of a bus at British Grove Studios in May, where I heard a whole range of stereo music and broadcast material being processed live. Unlike similar plugins, the sound was full, had clearly defined channels, and seemed to compliment the original mixer's intentions.

How the original stereo source is split between each surround speaker

Here's Penteo for beginners.

You start with two channels, left and right. (Told you this was for beginners.)

First, everything that is panned dead centre (and therefore common to both channels) is output through the front centre surround speaker. This will tend to be lead vocals, kick drum and other weighty bass sounds.

The remarkable thing about Penteo separating channels like this is that it is TOTALLY ISOLATED from the others. You can mute this channel in the full mix, and hear nothing at all from the vocal and kick in the other speakers, save for perhaps some reverb in these rear.

Anything that is panned hard left or hard right, or unique to either channel (like stereo reverb which will behave slightly differently on each channel, and therefore not be considered the 'centre' channel) is sent straight back to the rear speakers.

A lot of fun effects are revealed in this zone, and there's an incredible sense of space that manages out translate trait from an original stereo mix with no effort.

The rest of the stereo field seems to be balanced between the front left and right speakers, though it may be shared with the rear too. Now that I think about it, this could be the smartest part of huge whole Penteo system, because it's working with a whole field of audio and dealing with it flawlessly.

As for the bass, it sounds like it's filtered off below a certain point and sent straight to the sub. To be honest, I didn't ask. But I didn't notice anything unusual - the bass was at full volume all day and not one person complained.

Testing Music at the Live Penteo 4 event 

Nigel Heath from Hackenbacker, whose work you have heard on the Harry Potter films and Downton Abbey, demoed the plugin on a solid range of music and film trailers. He showed how it effectively takes the stereo signal, chops it up into millions of slices, then wraps it round the full surround field without any phasing or old-fashioned trickery.

The first lesson is that decades of stereo music could be revitalised and sold all over again by being up-mixed to surround sound in the time it takes to load a plugin. Seriously, you could load it up and the output would sound ready to go, and if you want to tweak the levels to taste, you've got six faders to play with. I've noticed people pull the rear surrounds down to tame the reverb a little, but the integrity of the original mix is fine - good music seems to work from the get-go.

The musical highlight for me was a track by Nine Inch Nails, with its bold compression and hard panning. There's roaring vocals in the front centre, a firm rhythm section wrapping the front left and right, and all sorts of percussion and electronic effects dancing in the rear speakers.

Another song I loved was Bohemian Rhapsody which revealed a reverb in surround rear that I had never consciously noticed in the stereo mix. It was like seeing Queen perform live, with the band in front and the sound of the room all around.

For me, the best thing about Penteo is that it gives you a chance to hear all your favourite music for the first time again. I could spend all day going back to personal classics from my music collection and hear it with fresh ears in a new light.

Penteo 4 on Film Trailers and Vintage Analogue Equipment

Film trailers and TV shows worked wonderfully too; the idea is that some suppliers are struck with a stereo music track, along with the usual fleet of surround effects. Normally, the post-production mixer would up-mix the stereo track into surround with a few age-old techniques, to meet cinema broadcast requirements.

The problem is, these techniques require adding new reverbs and delays to simulate the rear surround sound - and you can bet your last few quid that a composer or mixer is going to spot the difference on their perfectly crafted score and dislike it.

Not so with Penteo, which doesn't add extra reverbs and other trickery to simulate surround sound. This is perfect for certain composers, according to Nigel, who work exclusively with boutique analog mixing desks. Naturally, a desk from the 1970s is unable to mix to surround, no matter how attractive its analogue tones sound. Penteo lets composers can make music on any vintage equipment they like and be happy with the resulting surround version.

Live Mixing with Penteo

Finally, Black Sabbath and Judas Priest producer Tom Allom (he's now at Penteo) put this very theory into action by running classic analogue audio through the Penteo system, and mixed the entire output into surround with a simple stereo desk and vintage outboard equipment. It was remarkable.

This is the real wonder of Penteo; a whole canon of music can be brought into the 21st century, and users can use simple stereo mixing tools to accurately position these tracks in surround.

There was one side effect, where a slightly off-centre pan pot on the mixing desk meant the centre vocal wasn't fully isolated in the front centre channel, and instead leaked out into the front left speaker. This is the fault of the desk, and revealed Penteo as a useful diagnostic tool for engineers who maintain vintage analogue equipment. In this case, you could use Penteo to ’tune’ a pot to find the dead centre. It seems British Grove Studio missed this while maintaining the desk, and it took Penteo to reveal the error.

What doesn't work on Penteo 4?

Don't think that Penteo is a solution that suits every stereo source. True, it often seems like a magic box, but some music just doesn't work to my taste. 

One orchestral live stereo recording from the 1950s had no clear centre front output, because the wide stereo field left everything flung to the far left and right. In some cases this would be an impressive effect, but unlike other songs where you feel like an observer to the concert, it sounded like I was invading the musicians pit with them sat all around me. Fun on paper, but in practice, it lacked definition.

Most modern pop mixing would work fine, but here's one that doesn't: acoustic guitars panned hard to the left and right. It's a classic stereo mixing trick that sounds great, but Penteo sends this straight to the rear speakers. Not bad, but they'd sit more comfortably in the front left and right space. There's a simple solution if you're the original mixer; bring the acoustic guitars in toward the centre just a little bit, and bam, the band is back in front of you.

My Conclusion of Penteo 4

Ultimately, I'm very impressed. It's the most exciting plugin release since Steven Slate convinced the world that plugins really can simulate analogue summing. Best of all is the potential for decades of music to be revitalised and generate new money for rightsholders, and that's a good thing for the wider music community indeed.

Penteo 4

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