Review- Audioease Altiverb 6XL

	Pros: Best impulse library ANYWHERE, more impulses added every month, lots of tweaking options, low on CPU
	Cons: External impulses need scanned first, could use more gear, not cheap
	Summary: If you have to pick one convolution reverb, and you want the best, look no further. You won't find this selection of impulses anywhere else, period. The cost, though high, will be well justified.

I’m a reverb junkie. There’s no way around it. Maybe it’s the 80’s childhood. But I do love my ‘verbs. So when I got the chance to review what is widely known to be one of the best convolution reverbs around, there wasn’t a second thought. You’ll quickly find that this reputation is well deserved.

Can I Run It?

Altiverb is available for virtually any system or configuration you may have. On Mac, there is VST, RTAS, Audio Unit, MAS, and Audio Suite, with the addition of TDM in the XL version(TDM is Mac only). On Windows, you'll find VST, RTAS, and Audio Suite versions.

Altiverb comes in true stereo, with options for every configuration you may need such as mono to mono, mono to stereo, and stereo to stereo. If you go the XL route, you also get any configuration up to 5.1 surround. Sample rates up to 96kHz are available in the regular version, and up to 384kHz in the XL version.

Altiverb gives you a choice of iLok dongle authorization or Pace challenge/response. Installation is pretty simple, running two installers(one for the plug-in, and one for the library). Authorization works the same as any other Pace protected plug-in. I didn't notice any issues during installation, and the library was found right away when loading for the first time. The library installer is current as of the time you downloaded it, and new impulses that are added regularly can be added manually.

Taming The Altiverb Beast

Loading impulses can be done using the browser window(with a choice of two font sizes). You'll find all spaces organized by type, such as "Churches", "Operas and Theaters", and "Scoring Stages". You'll find a large selection of impulses, including several different impulses per space with different stage positions, listening angles, etc. We'll cover the impulses themselves shortly.

You can also load presets from a dropdown menu. While loading impulses in the browser gives you a new space, presets give you a new space along with the recall of all other settings throughout Altiverb. Things such as your Early Reflection and Equalizer settings are saved in a preset.

Going beyond presets, you can also save Automation Presets. You assign the current settings in Altiverb to any of the 40 preset buttons for instant recall without browsing or using menus. This is cool because it allows you to change the environment instantly, which is very helpful in creative sound editing and post production.

You can adjust the length(Time) of your reverb, which basically changes the length of the tail. Or you can adjust the Size of your space, which changes room modes and the width of the reflections to simulate a different sized room than the impulse was designed for. I did find it odd that the Reverb Time knob uses circular mouse control(drag in a circle to change) while the rest of the interface uses linear mouse control(drag straight up and down). Not a huge deal, just strange.

In this section, you can also switch to a Reverse reverb sound for the sake of special effects or rhythmic enhancements. It basically turns the impulse backwards so it builds up instead of dying down, commonly referred to as "Inverse" reverb.

In the lower section, Altiverb provides full control over the sound of your impulse. First, you can adjust the Damping(absorption) of the low, medium, and high frequencies independently. You can shave off some of the lower frequency reflections to avoid too much muddy buildup, for instance. You can also change the crossover frequencies for these bands to any frequency you desire.

You can individually adjust the levels of the Direct sound, Early Reflections, as well as the Tail. For the Early Reflections and Tail, you can set a pre-delay amount. For Early Reflections, this works as with a normal reverb's pre-delay by putting time between the Direct sound and first reflections. With the Tail, you can actually "detach" the late reflections from the early reflections to create a soft slap-back sound(pretty subtle, but effective).

On the Direct sound, you can adjust the color of the sound. With most reverbs, if you eliminate all early and late reflections, you're left with the unaltered original sound. But what if you want that sound to still take on the coloring of the environment, such as from the microphone, the air, and speaker? Altiverb lets you apply this coloration to the direct sound so you still have some character from the room, even if you don't have any reflections. Very subtle, but another one of the cool ways Altiverb lets you adjust the sound, and something that is quite unique in the convolution world.

You will find a four band equalizer on board with Altiverb. The two middle bands are fully parametric, with the two outer bands being shelving filters. These outer bands also apparently have provisions in place to avoid any possible phasing artifacts that may occur normally. I haven't seen any obvious signs of phasing, so I'm taking their word for it that it's working as it's supposed to. Overall, the EQ sounds good and lets you further tune the sound(wet signal) to your liking.

  Finally, Altiverb contains a 3D positioner. This lets you move the audio source around in the space to a certain extent. You can also adjust stereo sides separately or together in the 3D field as well. This feature is not available on most external impulses as the feature requires extra information about the placement of the source recording(which all the Altiverb impulses obviously include). Also, this is NOT meant to replace your normal host panning and positioning. It's much more subtle than that. So it's best for creating more space and spread for the sources being fed to Altiverb.

In addition to the impulse Browser, there are two additional top views. First is the Waterfall view. This is a handy view that gives you a 3D look at the reverb so you can see both timing and frequency information that is updated in real time as you tweak. You can zoom, rotate, drag, or set the view to auto-focus on whichever part of the impulse is being changed at the time.

Then there is the Waveform view. This only shows the time perspective, but lets you see every channel in the impulse(such as left and right, or more in surround impulses) and how it's effected by the controls in real time.

Altiverb also provides "test" sounds so you can hear the reverb without playing audio through it, and these sounds can be set to automatically play on every parameter change.

If you want more information about each impulse, Altiverb gives you plenty. You'll find images of the space or gear, as well as engine statistics like CPU usage, latency, and more, a diagram of speaker placement and distances inside the space, and even information about the equipment used to record the impulses and historical information about the venues. There's even a button that is supposed to open up Google Earth to show you exactly where the venue is located. This button didn't seem to work for me in any host though.

To top it all off, most of the factory impulses of real spaces include a Quicktime movie of the space. You can expand this movie(and all of the panels of information mentioned here) and even use your mouse to rotate around and zoom in and out of the space in real time. Pretty virtual-reality-futuristic kind of stuff here! And all right inside the Altiverb interface! However, this feature seemed to not work in many hosts.

The control over the sound in Altiverb is excellent, and really lets you create a space of your own in ways that most convolution reverbs don't do. Some of this is a result of the extra information contained in the Altiverb impulses. But needless to say, you can probably get the sound you are wanting very easily. Plenty there to mess with.

But enough about controlling the impulses. This control is all a waste if the impulses themselves aren't very good. So how do they measure up?

Factory Impulse Library

There is a common idea thrown around, and it's mostly true. This idea says that a convolution reverb is only as good as the impulses you throw at it. But I'll put your mind at ease right away and throw it all out there: Altiverb's library rocks…..a lot. So please forgive me as I give you the textual tour around the library, as it will likely resemble an advertisement! It's really that cool.

Audio Ease has more experience in the impulse response field than probably almost any modern audio company. They claim three years more experience than anyone else in the field, but that's kind of tough to prove. But they know their stuff. And it shows.

In case you haven't heard already, the Altiverb factory library is widely known as the best impulse library around. So let's cover in detail some of the large variety you will find inside.

You'll find everything from real indoor and outdoor spaces, to high end gear, to post production and sound effect impulses. And for each space, there is anywhere from a few impulses to a couple dozen. These may be different listening positions within a room or concert hall, or it may be different presets from a hardware unit. But almost every impulse "location" contains multiple impulses.

In my opinion, the most special part of this library is the variety of indoor venues that have been captured. Ever wanted to sing at the Sydney Opera House? Altiverb is one of the only, if not THE only library, that gives you this space. How about the Vienna Konzerthaus or the LA Philharmonic? Both there, along with a couple dozen other large concert houses around the world. There are medium sized locations all the way up to the grandest of concert stages, opera houses, and theaters. And all in outstanding quality and with multiple impulses to place you at almost any distance from the stage you want(or on the stage, or in the choir loft, or the balcony, etc.).

In addition to traditional concert houses, you'll find a variety of unique locations such as castles, caves, and even tombs. You'll find impulses from a 2 million gallon underground water storage tank, an ancient Indian tomb, to the limestone walls of Howes Cavern in Albany, New York. Grand and majestic locations, to creepy and historical, you'll find it.

Wanna be a stadium rock star? You'll be happy to know of the selection of both outdoor AND indoor stadium impulses available. Fancy a visit to the club? Altiverb has impulses of some of those, too.

Grand churches and cathedrals are every impulse fanatic's dream. Altiverb has some of the most magnificent places in the world. From St. Joseph's church in the Netherlands to the Notre Dame Cathedral itself, it's there, as well as over a dozen more.

Famous recording studios have been captured, such as the Sound On Sound studios in New York. Westlake Studios, Cello Studios, Allaire studios, and more are represented here. Some you've heard of, and some you haven't, and multiple rooms and positions in many of them. You'll even find IR's of the authentic plate reverbs and echo chambers from some of these studios.

Orchestral composers will appreciate the selection of scoring stages included. You'll find the 20th Century Fox stage, the Todd AO scoring stage, Paramount Stage M, and more.

There are many hardware reverb units included, ranging from famous Lexicon units like the 480L and 224 XL, to a Fender reverb, EMT Plate reverbs, etc. Even some boom box and intercom speakers are included, as well as some not-so-high quality units that have been captured in all of their not-so-high quality. Add some spring reverb units and guitar spring verbs, and there is a decent collection.

I do wish there could have been more gear though. The philosophy that Audio Ease has taken is that people have more access to these hardware units, while almost nobody has access to the other types of spaces included in Altiverb. So more time is focused on the real spaces. This makes sense, but gear junkies who can't have the gear they want, wouldn't mind having it virtually, right?

For the post-production enthusiasts, you'll find a unique and interesting selection of ambiences. From the cockpit of a Boeing 747(or maybe a mig, or a Lockheed and more, you choose!) to the interior of a variety of European cars, to bathrooms and kitchens and more. Impulses from large forests to the inside of a classroom and even an old brothel. Greenhouses, home studios, office spaces, workout gyms, fire department rooms, train cabins, public streets, and the list goes on and on. The sheer number of different types of spaces is huge, and very useful.

You'll find plenty of non-traditional ambiences as well. Impulses from the striking of large metal storage tanks with mallets, to the inside of a Bosendorfer piano, and a variety of other resonant spaces. They sampled impulses from the inside of trash cans, cups, tin cans, vacuum cleaner tubes, washing machines, and even the inside of a djembe!

The quality of literally every impulse in the Altiverb library is as high as you could possibly expect. The techniques used are as good as it gets, and the experience behind the recordings make for a truly special collection that is second to none. While I can't judge exactly how every single space SHOULD sound, I do know that they sound fantastic. There isn't a library out there with the things that Altiverb includes, and the library sets Altiverb apart from other convolution reverbs.

I've tried to give you an idea of what to expect in Altiverb's factory library. I definitely haven't covered it all, but you can probably tell by now that the library is vast. There are hundreds upon hundreds and even thousands of different impulses included. But it doesn't stop there. Audio Ease adds to the library every single month. And these are all in the same high quality as the rest, and the spaces are just as unique and grand. Many users are submitting impulses of their own frequently as well.

Altiverb will also load all your external, third party impulses. Just add them to your Altiverb impulse directory. Unfortunately, there is no way to load impulses directly in Altiverb without letting it rescan your directory. And you can only select a single directory, so you have to have your impulses all in one place. Keep in mind that one or two features in Altiverb, such as the 3D positioning, won't work with most external libraries. But everything else will work fine.

Altiverb also includes a utility that lets you create your own impulses in the Altiverb format. This is a great addition so you can sample your own gear and share it with the world. But oddly enough, this tool is only available on the Mac OSX platform. PC users will have to resort to recording an impulse using a sine sweep and sending it to Audio Ease to process. I'm a PC user, so I could not test the utility.

People buy Altiverb for it's library, and it's likely the reason it will stand out for you as well. I really had a hard time finding a bad sounding impulse in the library. The care that went into creating each and every one is more than apparent. These impulses weren't just created in an hour with a mic and a laptop. Environments were analyzed, and the highest quality equipment was used to create every impulse. Some of the impulses, I don't even know how they accomplished getting them. But they did, and when you first run through the library, you're bound to smile.

Altiverb Performance

Convolution is notoriously a CPU intensive process. Fortunately, Altiverb is rather light on your processor.

Running on a last-gen 1.83gHz Core2Duo laptop, I was able to attain anywhere between 3% and 8% of a single core, depending on the impulse. Longer impulses would run at the higher end of the CPU usage numbers. The typical reverb would sit in the 4-5% range. Definitely nothing to sweat over for a reverb, and even surpassing many algorithmic reverb performance numbers.

Also, when tweaking some parameters, such as the 3D positioner, there would be a temporary jump in CPU. But nothing huge(maybe a few %), and it would drop down when you stopped tweaking.

I did find Altiverb to be heavy on the RAM usage. Just inserting Altiverb into a track would add around 140MB of RAM usage for the default preset, with smaller spaces taking a bit less and the larger spaces taking as much as 200MB of RAM. Now, this is for the first instance. Adding a second instance created only around an additional 20MB of RAM usage, with the longer presets making the total use for the second instance around 100MB or less.

I believe the first instance high numbers are due to Altiverb loading it's cache file, which each further instance then draws from. Also, these numbers vary based on if you have a mono or stereo impulse loaded. Mono files take around 20-40MB less than the similar stereo impulse. I did not test any surround impulses, though I'm guessing they would raise these numbers a bit.

These numbers aren't terribly different than I would expect, but they did strike me as being slightly on the high side. If you consider the quality of these impulses though, it does make the RAM usage a very minor issue.

Altiverb is not zero latency unfortunately. In fact, on a native system, Altiverb runs at around 11ms of latency(512 samples) with 44.1kHz sample rate. Though this is not necessarily ideal, it's still workable in most cases. There is zero latency when using the TDM version in 44.1 or 48kHz though. I really would have liked to see a zero latency option for all versions.

The interface in Altiverb does rely on Quicktime for the virtual reality tours. Most of the time, this caused no issues. In fact, the CPU didn't seem to jump as a result of the interface at any time. There were a few instances where a slight GUI lag would appear for a brief moment.

Overall, Altiverb performs well for a convolution reverb. I didn't find myself doing any extra freezes or bounces to make room for more Altiverb goodness. There always seemed to be room for it, which is good because I found myself using it as the final reverb on a large amount of tracks.

You Get What You Pay For

Altiverb is thought by many to be the king of the convolution reverb world. Audio Ease has been at this game for a long time. But with this status comes a high price tag. At the time of this writing, Altiverb is the most expensive convolution reverb on the market. So is it really worth it?

Absolutely. There are definitely cheaper options in the plug-in market. But there isn't anything that comes close to what the library in Altiverb brings you. And let's face it, that's a big part of what you are paying for. It sounds fantastic, and it offers spaces that no other library includes. When you add the detailed control over the sound that Altiverb offers, you are left with a plug-in at the top of the game. If you need a convolution reverb, and you want the best, Altiverb is it. Though not perfect, I'm certain that you will find Altiverb to be THE convolution plug-in you reach for most often.