REVIEW: Serato Pitch ‘N Time DJ Expansion Pack


Link: Serato  |  Price: $29 via Serato Store

Serato Pitch 'N Time DJ Review

Pitch ‘N Time DJ: KEY WHAT?

Though it generally affects sound quality, key lock – also referred to as “master tempo” – is an indispensable tool for DJs who care about harmonic mixing. Knowing the root key of a track and locking it down allows you to achieve perfect blends between tunes that might have sounded off key when beatmatched, and it also covers subtle manual tempo corrections. It originated on early CD players, briefly touched the turntable world and blossomed when digital DJ software became commonplace. Let’s take a look at the status quo.

HOW TRADITIONAL KEY LOCK WORKS

In very simple terms, a digital audio stream consists of small bits of sound. When you change the tempo with key lock disabled, those pieces are sped up or slowed down accordingly and their key changes naturally. With key lock enabled, those pieces are locked down to their original speed (and thus the original key). When you increase the tempo, they move closer together and overlapping parts are left out. When you decrease the tempo, they move apart, creating blank spaces which the algorithm then tries to fill in.

This is why speeding up a track with key lock on generally works better than slowing it down – but the process always affects sound quality. On older CDJ units, especially the Technics SL-DZ1200, the results were awful. Vinyl users had it even worse – though some turntables (like the Numark TTX (review) and the Stanton STR8-150) actually had key lock built in, its low quality effectively made it a useless feature.

AIN’T NO SCHOOL LIKE THE OLD SCHOOL

If both sound quality and harmonic blends are important to you, the traditional approach is best: leave key lock disabled and stick to the 6%/3% rule. First, you need to figure out the original key of each track. You can do that by ear using a synthesizer for reference, or with digital tracks, using a tool like MixedInKey which gets it right most of the time (not always though – just like with BPM detection, it’s best to trust your ears). When mixing, a 6% pitch change will shift a track’s root key by a semitone. When the pitch is below 3%, you stick with the original key and when the pitch is above 3% you go with the next/previous semitone, depending on whether you pitch up or down.

It’s the only way to preserve sound quality and mix harmonically, for the most part at least – but it requires a significant amount of practice and is naturally limited by the original tempo of the songs. This is why 12″ versions of tunes have such long intros and the main part usually only comes in after 32 bars. Of course the idea is primarily to give you enough time to beatmatch if you’re doing it manually, but it also allows you to mix over a break without having to worry about melodies clashing.

Serato Pitch 'N Time Dj Review

ELASTIQUE HARMONY

When Traktor Scratch was released and subsequently received an update which included zplane’s Elastique Pro time stretching algorithm, the situation improved significantly. Taking advantage of working on a software level allowed NI to achieve a quality way beyond any DSP built into hardware units at that time. What makes key lock in Traktor special is the fact that in addition to being able to lock down the root key, you can also shift it independent of the track’s tempo in cent steps (that’s 1/100th of a semitone). This opens up a lot of creative possibilities – the most obvious is blending tracks that would’ve sounded off key together even with key lock activated. While this only sounds acceptable within the range of +/- 1 semitone close to the original tempo, it still helps a lot. In addition to that, knowing you can go as far as an entire octave (+/- 12 semitones) allows you to pull off some cool tonal buildups.

If you’re a Traktor user, try this: set a short loop, activate a subtle delay and/or reverb, then gradually increase the wet level while you “pitchbend” the track (works nicely with big rotary encoders and 25 cent steps) to the root key of whatever you’re mixing in and then drop it right on top. Or map a couple of buttons to set the track’s key to specific values and combine that with hotcue drumming to play melodies – this is one of the things I implemented in my performance mapping for the Electrix Tweaker. Pretty cool, but the bottom line is: it could definitely sound better than it does.

WHAT ABOUT SERATO?

Serato Scratch Live users have always had a tough time with key lock. This is the reason why it took me so long to take the software seriously. After making the jump from analog into digital DJing, I naturally stuck with the product that offered me the most creative possibilities: Traktor. Knowing Serato’s portfolio, however, always left some room for speculation. Having made an excellent time stretching plugin for Pro Tools, they clearly aren’t strangers to high quality in that department. “So when’s Pitch ‘N Time coming to the DJ world?” has been a regular question on the Serato forums for years – but even with the release of Serato DJ, nothing changed. In my NS7II review, I speculated that they could very well release an FX Pack dedicated to harmonic mixing, the lack of which was one of my few gripes with the software – and imagine my surprise when just a few weeks later, that very thing happened.

CHANGE MY PITCH UP

The expansion, named “Pitch ‘N Time” after its Pro Tools counterpart, can be purchased directly from within Serato DJ for 29 USD. Like the other expansion packs, it doesn’t require an additional download and unlocks the functionality immediately. Once activated, it replaces the original key lock, but it can be disabled in the setup menu if you want to do a side-by-side comparison between both modes… which is what we’ll do now, throwing Traktor’s Elastique Pro into the mix for good measure.

I’ve put together a 140 BPM loop (16-bit 44.1 kHz WAV) which I’m going to play back at normal speed once, then (about half a minute in) gradually pitch down 25% and then up 25%, resulting in 105 and 175 BPM respectively. For the record, I’m running Serato DJ 1.6.1 and Traktor Scratch Pro 2.6.8.

VERDICT

Pitch ‘N Time DJ is clearly superior to Serato DJ’s original key lock and even outperforms Traktor’s Elastique Pro. It doesn’t put too much strain on the CPU either, which is really impressive considering the quality it delivers. The audio examples tell the whole story from a user’s point of view, but it’s interesting to know the technological approach behind it. Pitch ‘N Time DJ works in a different way than I described above in that it doesn’t copy any of the original signal into the output – it’s a sophisticated combination of analysis and re-synthesis, which leaves room for imagination in regard to its future development.

So, is it worth buying and are 29 USD a justified price tag? That’s something you’ll have to figure out for yourself. I’ll definitely stick with it until something better comes along, though I still miss the tempo-independent key adjustment in Traktor. It’s safe to assume Serato aren’t done developing Pitch ‘N Time DJ though, and seeing as NI haven’t made any major updates to Traktor in a long time, perhaps we’ll see something cool from them this year. In any case, for the time being, Pitch ‘N Time DJ definitely is the highest quality time stretching solution you can get in a DVS.

PRO

Superior sound quality
Low CPU load

CONTRA

No tempo-independent key adjustment (yet?)

  • Gábor

    “When you increase the tempo, they move closer together and overlapping parts are left out. When you decrease the tempo, they move apart, creating blank spaces which the algorithm then tries to fill in.”

    This is called “time-domain” time stretching, but it’s used in older gear only or where CPU power is very limited.

    Modern, “frequency-domain” time stretching works like this (in very simple terms):

    The algorithm disassembles a chunk of audio to an array of sine waves. One sine wave represents a few nearby frequencies. The algorithm changes the sine wave phases according to the tempo, and then assembles them back together.

    It handles transients separately, keeping them intact, and changes audio between transients only.

    • http://www.arkaei.com/ arkaei

      I should have clarified that I was talking about traditional key lock (edited – thanks!). Pitch’n Time DJ uses a different approach altogether, which I mentioned at the end of the review.

      • Gábor

        Frequency-domain methods are quite “traditional” too. Both Élastique and Pitch’n’Time are such solutions.

        • http://www.arkaei.com/ arkaei

          Thanks for helping me out. Learning as I go :)

          • Wolfwristman

            Gabor is the master, having written the key lock functionality in DJ Player himself from scratch, no generic library code here!

  • Gábor

    One thing i don’t understand, let’s discuss:

    I read some time-stretching comparisons and reviews here and there. They almost always test audio quality with extreme tempo changes, like going down to 30% or 50%.

    Sure, this method reveals some “internals” of a time-stretching solution, but i think it’s not representative for “audio quality”. Time-stretching should mostly work within the range of plus-minus 10%, maybe 20%…

    In other words: just because a time-stretching solution sounds nicer with extreme tempo changes, it doesn’t mean it’s superior in the “normal” range.

    • http://www.arkaei.com/ arkaei

      I agree – if you stay within one genre, you rarely go further than +/- 4% anyway. But if you want to slap a hiphop acapella over a big beat tune, you’re going to reach the 25% mark easily. In general, this opens up some creative buildup and breakdown techniques (like drastically slowing down D’n’B to mix in some midtempo breaks). This is why I recorded progressive changes instead of 3 static speed settings.

      Personally, I enjoy messing with harmonies, so I’d really love P’n’T to be updated with a functionality similar to Traktor’s. Playing melodies on hotcues is fun as hell, so is changing the key mid-tune – but it doesn’t sound good enough yet. Of course there’s a limit to how far it can be pushed, but I hope developers don’t stop challenging it.

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  • Frank

    You listed “Low CPU load” I question this as looking on the Serato forums alot of people are having major latancey and audio drop outs when using Pitch and Time on DVS with lowest buffer settings

    • http://www.arkaei.com/ arkaei

      I looked at the difference in CPU load between running the original SDJ key lock and Pitch ‘n Time – didn’t notice much of a difference at 96 samples (default Rane Sixty-Four setting) and had no problems with the NS7// either.

      Generally, I’m having a hard time reproducing anyone’s problems because my laptops (custom-built Schenker/XMG twins) are the computer equivalent of a honey badger: http://www.youtube.com/watch?v=4r7wHMg5Yjg

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