X-Fi and the Elite Pro: SoundBlaster's Return to Greatness
by Derek Wilson on August 30, 2005 11:59 AM EST- Posted in
- Smartphones
- Mobile
New Features, Possibilities, and Modes
The main new audio processing features of the X-Fi line are the 24-bit Crystallizer and CMSS-3D. These features, as well as the onboard RAM and the three modes of operation (gaming, entertainment, and creation) will be explored in this section. We know what each of these features is and the basic principles on which they operate. While we could make a much more thorough analysis of the quality of these features, if we had some actual math to go on, it is understandable that Creative would want to protect their investment by keeping the intimate details of the architecture private. What we do know should be enough to go on for now.The 24-bit Crystallizer
The 24-bit Crystallizer takes 16-bit audio and tries to add dynamic range to the audio signal. If we were to convert our 16-bit audio stream to 24-bits, we could essentially do so by adding 8 zeros to the least significant end of each sample. It becomes clear that the highest value that a sample can take on is much less than the highest value possible with 24-bit audio. Likewise, on the low end, the audio stream isn't capable of representing values between zero and 256. The basis of the 24-bit Crystallizer is to fill in these least significant bits with meaningful data and thus, expand the dynamic range of the audio. What, exactly, is meaningful data in the least significant bits? We're glad that you asked.Audio engineers are big fans of compression. Applying compression to a sound decreases the dynamic range of a sound in order to preserve the loudest and quietest parts without clipping or burying the subtleties in noise. This is very necessary to make good use of 16-bit audio, as things like whispering over a snare hit are not easily representable otherwise. Knowing the basic manner in which audio engineers go about applying effects to sounds, Creative can try to reverse-engineer the process to add more data where it seems necessary.
Details on the technique are fuzzy at best, but we do have some information. The algorithm doesn't simply expand the audio signal; it looks for recognizable patterns in frequency and time and applies algorithms that fill in the data where necessary. For instance, the X-Fi hardware is able to detect something like a kick drum hit and use the sound and proportionally weighted, transient, low-frequency data to boost the impact of the event.
The algorithms focus on the energy flux in different frequency bands in order to localize the impact of the effect. This means that things like snare and symbol hits, the plucking of strings on an acoustic guitar, the slapping of a string on a bass, and gunshots in games should all become more distinct. Each sound will be enhanced according to its energy flux, frequency, and waveform. Creative states that this can even help clean up the high end on MP3 encoded files. What this doesn't enhance quite as well are quiet subtleties in the audio signal.
CMSS-3D
For 5.1 sources played on headphones with CMSS-3D, Creative uses HRTF (Head Related Transfer Functions) to virtualize the position of each audio channel around the listener. This technique is augmented with simulated environmental reflections, which attempt to improve the externalization of sound to the listener. These environmental effects are more subtle than the Dolby Headphone effects and are meant to convey a listening environment that matches the recording rather than one that fits the room in which the listener is sitting.When enabled for 3D virtualization with two speakers, the methods used are similar to that of the headphone implementation. Rather than adding environmental reflections, this CMSS-3D mode includes a cross-talk canceller to make sure that signals from one speaker are not destructively combined with signals from the other at the listening sweet spot. Unfortunately, there is still a sweet spot for listening to audio in this mode, but settings like speaker angle are easily adjustable.
Probably the best use for CMSS-3D has nothing to do with two speaker setups. Getting the most out of a 7.1 channel audio setup is much easier with CMSS-3D. We still don't recommend using CMSS-3D for stereo sources, but for listening to 5.1 audio, CMSS-3D will do a good job of fitting the 5.1 sound to 8 channels. For creating a multi-channel environment with a two-channel source (if we absolutely must), our favorite solution is still Sonic Focus' implementation on Intel hardware. It's a shame that they won't open up their software for other hardware.
64MB onboard RAM
The top two models in the X-Fi series feature 64MB of SDRAM on the sound card itself. This feature is called X-RAM, but that isn't a technical term. X-RAM is a marketing name given to maintain the X- moniker of the card itself. This RAM is supposedly included to enhance the performance of games. Until games are written to take advantage of this feature, we will have to simply accept the possibility for performance improvement.Creative has shown us some numbers that they have run using UT2K4 and a special patch that allows for playing over 100 voices at a time (currently only 30 are supported in the game), as well as uploading uncompressed sound files to the onboard memory. The numbers show a pretty big performance improvement when X-RAM is enabled in this case. Unfortunately, we don't know how real world this test is. Without having the patch to test ourselves, we can't really know what's going on. If we are more than tripling the number of concurrent voices, we would hope to see some sort of quality improvement as well. A performance improvement for a feature that isn't necessary is a useless test.
We really need to spend more time with games that currently support X-Fi to see if we can find a case where the extra RAM affects performance. Our best guess is that we won't see real impact from this feature until developers realize that they can target the Creative solution to deliver a higher quality audio experience. Playing audio with higher sample rates, adding voices, using uncompressed audio to save CPU overhead, and freeing system RAM for other uses should be quite attractive to audio designers.
3 Modes of Operation
The final major feature is the inclusion of three distinct modes of operation. This feature is necessary because of the complexity and flexibility of the Audio Ring architecture. Tradeoffs are necessary for every type of audio application, but a configuration that can switch between modes depending on the task at hand could be a major development in the "one size fits all" audio department. These are the features of the different modes.| Gaming | Entertainment | Creation | |
| Video Game Frame-Rate: | YES | NO | NO |
| Hardware 3D Audio Processing: | YES | NO | OPTIONAL |
| Environmental Effects: | YES | OPTIONAL | OPTIONAL |
| High-Resolution Audio Playback: | NO | YES | YES |
| Audio Enhancement Processing: | NO | YES | OPTIONAL |
| 2-Channel to Multi-Channel Up-Mix: | OPTIONAL | YES | NO |
| Multi-Channel Audio Recording: | NO | NO | YES |
| Hardware MIDI Playback: | NO | OPTIONAL | YES |
| Hardware Effects: | YES | YES | OPTIONAL |
| Sample-Synchronized Record and Playback: | NO | NO | YES |
| Low Audio-Streaming Latency: | NO | NO | YES |
| Bit-Accurate Audio Capable: | NO | OPTIONAL | YES |
Professional recording requires low latency, especially when using ASIO drivers. Therefore, it makes sense that Creative would implement a mode targeted at getting audio in and out of the Audio Ring as fast as possible. Effects possible in Creation mode are limited to those that can be performed very quickly, and audio comes through the chain as unmessed as possible. Less than 2ms latencies are possible in this mode. Again, our only complaint with the Elite Pro as a professional solution is its lack of balanced I/O.
Entertainment mode focuses on the music and movie experience. Options for enhancing both stereo and surround sources are pushed to the foreground and features like the 24-bit Crystallizer and CMSS-3D will likely be heavily used in this mode.
Gaming mode is optimized for creating a multitude of hardware accelerated voices and processing them to create the best real-time 3D that audio developers can throw at it. With up to 127 3D + EAX voices, extremely complex effects are possible. Under this mode, X-RAM can be used to assist in the storage and playback of audio files.
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SDA - Wednesday, August 31, 2005 - link
>>For listening, I generally stick with my Sony MDR-7509 headset. I also have the Sennheiser HD580 that I use to audition sound hardware. The reason I stick with the Sony gear for general listening is due to my environment. I can turn everything off when I need to do a noise test or listen closely to something, but the lab with all the computers and workstations running is not a quiet environment. I realize that open air headests will reproduce (especially) the low end in a more appropraite manner, so I do listen with them, but I know the sound a little better on the MDR-7509s as I've been using them for a long time. >>Are either of those headphones being amplified? If not, you are probably putting unfair stress on the sound card's line out, and should at least compare with and without an amp (lots of sound devices sound great if not under undue stress). Also, consider getting monitor speakers to test surround sound output.. old Minimus-7s will do if you're on that tight of a budget (no bass whatsoever, but surprisingly neutral midrange and treble for small bucks and a small room), otherwise look around.
>>I am planning on picking up the HD650 as I've heard great things about them. >>
Enh, they're not different enough from the HD580 to warrant buying if you're looking for sound test gear. Get something with a different flavor first (Grado SR-225 or Alessandro MS-2 for high-current low-impedance rock phones, AKG K501 for analytical ridiculously inefficient mid-impedance phones), and get a reasonably good amplifier (no need for audiophile BS, just something with enough balls to run a K501).
>>Doing something like a double blind subjective study on audio is difficult. People that don't know how to listen won't be any help because even if they hear a difference they won't know how to describe it very well. People who do know what they are talking about are hard to come by in volume. Don't get me wrong, we'd love to do something like this. But we just don't have any idea how to work out the logistics. Suggestions are welcome. >>
Find three different people who know what they're talking about and aren't slaves to the placebo effect. Have them test the gear in a double-blind setting.
More specific advice... look for musicians. Especially look for musicians for testing songs heavy on specific instruments: someone who plays, say, the violin will know exactly what a violin will sound.
>>Also, I appreciate the suggestion to avoid general statements about the goodness of something. It is a good suggestion even in cases where we know everything about everything in detail. There are always surprises and erring on the side of caution is the best way to go. We will be more careful in the future. >>
And, fwiw, I appreciate the maturity and responsibility one gets from AT editors. (Yes, I can give compliments too!)
DerekWilson - Wednesday, August 31, 2005 - link
I am not sure if I want to go with active amplification. I understand that stressing the opamps on the card towards the top end of their range could adversly affect their linearity. But my impression is that spending this much money on an audio card means a listener should not have to invest in an amp to get the best quality sound. We want talk about the audio as it will be heard by our readers.Do you have a different opinion on the subject?
And thanks for the suggestions on speakers and other headsets.
SDA - Wednesday, August 31, 2005 - link
>>I am not sure if I want to go with active amplification. I understand that stressing the opamps on the card towards the top end of their range could adversly affect their linearity. But my impression is that spending this much money on an audio card means a listener should not have to invest in an amp to get the best quality sound. We want talk about the audio as it will be heard by our readers.Do you have a different opinion on the subject? >>
The amplifiers on sound card line-outs are rarely equipped to drive headphones, especially not extremely power-hungry one. While I agree there is value in an ampless test, I also feel that an amplifier would be a good idea for pure line-out performance. A lot of us don't put any real strain on the line-outs, after all, and I'd like to see how evening the playing field a little helps various cards.
At any rate, spending this much money on (insert piece of equipment here) never entitles a listener to avoiding another link in the chain entirely. Not that headphone amps are a necessity, but hooking a $200 headphone to a line-out of a $400 sound card is a little silly and probably wouldn't yield sound as good as a lower-tier sound card and a cheap headphone amp (the things don't need to be pricey, just gutsy enough to power any normal dynamic headphone with ease).
Xentropy - Wednesday, August 31, 2005 - link
Sorry this is a bit off-topic, but you seem to know what you're talking about, and everywhere else I've asked I've gotten audiophile answers (e.g. buy this or that $2000 piece of equipment), so......What reasonably priced headphone amp(s) can you recommend for use between a soundcard and a set of HD570's?
SDA - Thursday, September 1, 2005 - link
The PPA and M^3 are reasonably priced, at least from a DIY perspective. At a lower price point, PIMETAs are fine.If I were you, though, I would upgrade that HD570 first-- driver upgrade (meaning speakers or headphones) is generally much more noticeable than amp or source upgrade. If you like a bass-n-treble signature, try the HD590; if you like something bassy and trebley but with midrange in the bargain, try a Grado or Alessandro. A very simple amp / 'CMoy' (buy on Head-Fi or somewhere, they're overpriced on eBay) with a decent op-amp (OPA2134PA is fine) covers a surprisingly large amount of the gap between no amp and top-end amp-- the biggest thing is taking undue stress off of the sound card's line out.
Or, you know, buy a $3000 amplifier, and line it with sound-improving rainbow foil (hur hur hur).
mindless1 - Friday, September 2, 2005 - link
Personally I found an unbuffered design like a CMOY to be a more similar to a soundcard's line-out than to a Pimeta, PPA or M3... they're all fairly harsh with terrible channel separation.SDA - Friday, September 2, 2005 - link
What op-amp? An unbuffered design is bound to be heavily opamp-dependent.. I've heard some that I'd prefer a Sony D-33's headphone out to, and I've heard others that are 80% of a META42. A great op-amp might be terrible in an unbuffered design for current output reasons.mindless1 - Friday, September 2, 2005 - link
Just about any mid-grade or better? I find some of my favorites, like AD8610, AD843, and OPA637, all sound far better unbuffered than jellybeans like TL072 or old standards like JRC4556/8, BUT *almost* anything buffered beats them. Higher current chps like LM6171 give more current but still lack quality sound. I "almost" find completely dreadful, entirely unmusical general purpose opamps sound as good buffered as the average "good" opamps in an unbuffered configuration... and it doesn't even take much of a buffer to make that difference.This is of course keeping in mind the current limitations, they don't even sound very good at low output. IMO, a CMOY type design is only useful for higher Z cans that need a bit of a volume boost. Then again, vast difference in price too, some people have enough spare parts to crank out a CMOY on protoboard plus $10. CMOY is like a gateway drug, it only teased me onto harder habits.
SDA - Friday, September 2, 2005 - link
Wow... well, I guess our ears just disagree there, especially since the AD8610 is my favorite for unbuffered. I still prefer buffered, of course, I've just always felt that an unbuffered AD8610/20 or similar CMoy-type amp covers a good chunk of the gap. Well, each to their own, I suppose, and AT editors should be looking for something higher-end anyway.mindless1 - Thursday, September 1, 2005 - link
Well, LOL."Audiophile" <> reasonably priced... never has and never will.
However, a ballpark $200 headamp might be a "PPA v2" custom-built with AD843 opamps rolled in. Thee are a few lists of trade builders for PPA2 or other customizable amps that you can DIY, actually tailor to your cans, or to your tastes, there is a vast gulf between gamer pseudo-audiophiles that buy Creative Labs cards with digital tricks and those who simply want cleanest analog possible and bit-perfect digi out. Wheverver you fit into the grand scheme, may dictate the optimal amp for you.
Then you'll want another amp, and more cans, and another sound card, and a DAC, and... Sorry about your wallet. ;-)