Whenever a major corporation acquires a music software company, there's always some uncertainty about what the future holds. When EM reviewed Acid Pro

Whenever a major corporation acquires a music software company, there's always some uncertainty about what the future holds. When EM reviewed Acid Pro 4.0 in its June 2003 issue (available online at, the program was still under the aegis of Sonic Foundry. Today, however, Acid is a Sony product. It is a special pleasure to report that Sony has taken Acid's development seriously. Acid Pro 5 boasts several vital new features that should keep it competitive in the hurly-burly of desktop music production.

For starters, Acid can now function as either a ReWire host or a ReWire client, which allows it to integrate fairly seamlessly with a number of important DAW programs on the PC. Acid can now quantize MIDI and audio to grooves in a flexible and intuitive fashion. The Track view has been cleaned up by the addition of folder tracks (see Fig. 1), and the new Media Manager database utility will be a godsend to any Acid user who has a large loop library.

Acid is primarily a multitrack production tool, and therefore it makes no attempt to compete with the real-time interactive capabilities of programs such as Ableton Live. It has some important features, though, such as support for video and surround mixing, that Live lacks. In this review, I'll focus on the new features in Acid Pro 5. But first I'll start with a quick survey of the program's basic functionality.

The Acid Base

Acid's raison d'etre is to allow audio loops to be time-stretched and pitch-shifted seamlessly. Throw a bunch of loops into the program, paint them into the tracks where you want them to play, and you can achieve a professional-sounding mix with the greatest of ease, provided you have the right loops on your hard drive. If Acid doesn't change the tempo of a beat or other audio clip with the kind of transparency or precision that you need, you can open the Track Properties window and drag the slice points around on the waveform, auditioning the results at the current tempo of the project until it sounds good.

The track-editing commands are comprehensive. When dragging-and-dropping audio clips, you have the option of making them snap to a grid. Tempo changes can be programmed, and you can pitch-shift different instances of a sample separately in order to follow a chord progression. Five types of timeline markers are supported. As an alternative to using track automation, you can fade in at the beginning of an audio clip and fade out at the end.

Track parameters can be automated with graphic point-and-click envelopes (though not by recording control moves in real time with the mouse). The same technique applies to plug-in effects' parameters, if the plug-in allows it. A built-in suite of effects gives you plenty of control over sonic details, and Acid's VST support opens up a world of other options. I tried Antares Filter and iZotope Trash — two of my favorite plug-ins — and got good results. My computer had two freeze problems, however, when opening the Edit window for Filter. Sony reports that it has duplicated the problem — which is intermittent — and is working with Antares on a fix. I also had two crashes while Acid was running as a ReWire slave under Cubase SX 3. Sony has not seen any other reports of that problem, but the company indicates that version 5a, which should be available for download by the time you read this review, contains several ReWire fixes.

Although most programs that host plug-ins have a CPU usage meter, Acid is not one of them. Nor will Acid freeze tracks that use synth or FX plug-ins in order to free up CPU horsepower — another feature found in most DAW software. It is true that you can render a track and then unload the plug-in, but that takes several extra steps. What's more, Acid will destroy any automation envelopes when an effect is unloaded, which will be a big headache if you should need to reedit the effect automation later.

Acid's Chopper window provides a quick way to make new beats out of old ones or do buzzing 64th-note fills. Regions within a loop can be selected and inserted in the track using key commands, a much faster method than dragging segments around in the track window itself. Using the Chopper is definitely fun!

MIDI Miasma

Starting with version 4, Acid added MIDI tracks, which can be used with either external hardware synths or VSTi soft synths. Though they are functional and are certainly an important addition to the program, Acid's MIDI implementation is inferior to what you'll find even in an entry-level sequencer. The conceptual logjam, which Sony has failed to come to grips with in the version 5 release, arises from the fact that Acid allows you to assign only one media clip to any given track. Although that might make sense for audio tracks (albeit Acid is the only program that I know of with this limitation), it doesn't make any sense for MIDI tracks.

Several undesirable results stem from that design choice. For instance, the piano-roll editor window doesn't scroll during song playback, and its time ruler always starts with bar 1, beat 1, no matter where in the song the MIDI clip is positioned. What's worse, while you can record a new MIDI phrase just the way you would in a real MIDI sequencer, once the phrase has been recorded, you can't overdub or punch-in on it. Flubbed notes can be fixed in the piano-roll or event-list window, but if you need to erase a particular lick within a MIDI track and rerecord it, your new recording will go onto a different track. Copying and pasting will then be required to get the two MIDI licks into the same track.

In version 5, MIDI Control Change contours can be edited graphically in the piano-roll window using a familiar controller strip. Unfortunately, the selection and eraser tools don't work in the strip: whenever the mouse cursor is over the strip, it turns into the paintbrush tool. As a result, if you should want to overdub a MIDI part that includes Control Change or Pitch Bend data, cutting-and-pasting can't be used to get the data into a single track, because those data types can't be selected for copying. They can be selected for deleting in the event list, but the Copy command doesn't work there.

While using Native Instruments Absynth 2 as a plug-in synth in Acid, I found that Absynth played the correct patch when I loaded the file but sometimes subsequently switched back to patch 1. That happened several times.

Managing Media

Acid's new Media Manager will be a terrific boon for those people who have a collection of loop libraries on their hard drive (see Fig. 2). Media Manager creates a searchable database of all the loops in whichever folders you choose. Initially, the database will show only the information in the file name and any tags that the library developer thought to include in the file header, which means, for instance, that you could see a list of dozens of files all named “drums02.” You would then have to scroll over to the column containing the full directory path information to figure out what you're hearing.

You can add existing tags or your own comments to any item, which will then be included in the search process. Compilation and searching of the database are fast, and you can organize the database window to show the items with which you are most concerned. Note that the Media Manager is in addition to, and not a substitute for, a conventional browser. That is good, because you can still use the browser to find files that are on uncataloged CDs, for example. (Sony claims that all new Acid libraries are now catalogued.)


The new Groove Pool in Acid 5 offers a quick way to realign audio to fit any rhythmic feel (see Fig. 3). Just drag-and-drop a groove from the Groove Pool window onto a track, and notes within the audio file will shift forward or backward as needed to match the groove. Grooves can be extracted from any existing loop and can be added to the Pool, provided that stretch markers already have been placed in the loop file. (If stretch markers haven't been placed, you can do that yourself.) You can also move groove markers to different spots to create your own grooves.

It's normal for sampled loops to have slightly different placements of different beats, and Acid gives you a quick way to line up the beats so that they lock together. Grooves can be applied to different portions of a single sample, and grooves can be applied to MIDI data in exactly the same way.

In my experiments, applying grooves to audio clips didn't always sound good. Even when a beat is playing back at its original sampled tempo, laying a new groove on it sometimes produces audible time-stretch artifacts. It's best to use grooves selectively; for instance, in a beat with an 8th-note feel and just a few 16th notes, I added the “16th Note Swing” groove only to the spots where there were 16th notes. That changed the feel of the 16ths without blurring the other drum hits. You can find an example of this editing technique on the EM Web site (see Web Clip 1).

More New Stuff

Among my favorite new features in Acid are folder tracks. After creating a folder track, you can tuck any number of other tracks into it and open or close the folder. That eliminates a lot of clutter in the Track window. If your project uses a dozen different drum loops, for instance, you can put them in a folder track, name it Drum Loops, and close the folder so that the dozen tracks are displayed as only a single narrow strip. Folder tracks can be muted or soloed but have no other track parameters. (A global output-level fader for each folder track would be a nice addition to the program.)

Speaking of track muting, I'm still waiting for another problem in Acid to be fixed: the Track Mute buttons override the track's volume fader, but a track's output can be sent to a bus either prefader or postfader. If a prefader send is being used as a track output, the Mute button doesn't shut off the sound of the track. (Sony claims that design choice was intentional, and it is not viewed as an oversight in need of fixing.)

Multimedia developers will be pleased that Acid lets them add interactivity to a presentation streamed over the Internet. At a particular spot in the music, for instance, you can open up a new Web page. Text (even closed-captioning) can be added, as well as clickable links. And speaking of media, Acid will now perform disc-at-once CD burning.

You can extensively customize Acid's keyboard command set to match the way you like to work. The toolbar at the top of the Main window can also be customized. Most of the other enhancements in version 5 are minor: a metronome for playback and recording, the ability to reverse playback of a given audio clip without stopping the transport, support for VSTi soft synths that require multiple mixer channels, and mixer routing from one effects bus to another, rather than from only each bus to the master bus. There's also support for Macromedia Flash SWF file import, the ability to adjust the levels of several clips within a track with a single mouse move, and more. The metronome lacks precount for recording, but at least you can control its loudness. I tested the VSTi support by instantiating Native Instruments Battery 2, whose 16 stereo outputs make it a real mixer hog, and Acid had no trouble coping.

The Acid Test

The new features in Acid Pro 5 make the program a pleasure to work with. ReWire support largely overcomes the significant limitations of Acid's MIDI tracks, at least for anyone who owns a ReWire-capable sequencer. ReWire also makes it easy to use Acid in tandem with Reason for deep-groove productions. The Groove Pool and Media Manager are excellent additions, and the folder tracks, while a seemingly humble detail, eliminate screen clutter, which makes a big difference in handling the workflow. My biggest reservation about Acid is that it won't freeze CPU-hogging tracks. Overall, I'd put Acid in the “good but not great” category. It isn't the lightning bolt that it was six years ago, but it's still a respectable piece of software and will continue to have a worthy place in many desktop music environments.

Jim Aikin writes, plays, and teaches in Northern California. His latest book is Chords & Harmony, an introduction to music theory. For more information, visit him online


Acid Pro 5

loop sequencer
$399 retail; $299.96 direct download


PROS: Video and surround-mixing support. New database and groove-editing functions. ReWire (host and client).

CONS: MIDI track handling has not been improved. No CPU usage meter. No track freeze.


Sony Media Software