M-Audio Revolution 7.1 Audio Card Review

This spring M-Audio launched a new interesting audio solution - Revolution 7.1 sound card. M-Audio products are known as inexpensive quality semiprofessional solutions. The revolution means that this card is not professional but positioned mostly as a card for home theaters, playing music and games. It's for those who cares about sound.

The card was launched right after the successful advent of the Terratec 6fire. Such cards could be very popular a couple of years ago. But today Creative is always a step ahead of other players on this market. It's very difficult to compete today because the top Audigy2 possesses high-quality sound ( thanks to the expensive high-quality Crystal DACs) and unattainable gaming capabilities (EAX3.0, and EAX4.0 expected soon).

But if this is a real revolution will be clear in the end of the article. For testing this kind of cards we developed a special benchmark suite RightMark 3DSound which makes easier testing 3D sound quality and CPU load in different modes of operation of sound cards. The DSP installed doesn't support DirectSound in hardware, and all 3D functions are supported on the drivers level (based on Sensaura).

The box contents

• PCI sound card;
• CD with drivers;
• CD with software;
• CD with Tony Hawk's pro skater 3 game;
• User Guide.

The thin brochure with the user guide written in English has all necessary information on installation and utilization of the sound card. One of the CDs contains demo versions of Ableton Live 2.0.1 and Propellerheads Reason 2.0 sequencers with a suite of loops, as well as the ArKaos VJlite 2.2.2 and WinDVD4.

Appearance & Connectors

Hardware capabilities

Digital controller	Envy24HT (24-bit, 192 kHz; interfaces: 5 I2S/AC-link output, 2 I2S/AC-link input)
Converters	6-channel ADC AKM AK4355 24-bit 192 kHz (THD+N -90 dB, DR 106 dB) stereoDAC AKM AK4381 24-bit 192 kHz (THD+N -94 dB, DR 108 dB) 24-bit 96 kHz stereoADC AKM AK5380 (THD+N -94 dB, DR 105 dB)

Software capabilities

Gaming capabilities	support of DirectSound, DirectSound3D, EAX2 based on the Sensaura algorithms
Others	SRS Circle Surround II, Dialog Clarity, TruBass
Bass Management	Crossover cutoff frequency (40, 60, 80, 90, 100, 120 Hz)

Control panel

The control panel consists of a single window with 5 tabs. The upper part of the window shows configurations of the speakers. Beside 5 configurations in the Current Set there are also 2.1, 4.0, and 4.1 schemes available. You can save a certain configuration under its own name and then load it without making new settings. It's funny that the same Set Selection option also offers various presets called real acoustic models. They are 50 models in all from such companies as Altec Lansing, Creative, Harman Kardon, Logitech, Klipsch etc. The models have different specific parameters. Below you can find the Master Volume and Mute buttons.

The first Speaker Setup tab shows individual parameters of a channel selected. The left side highlights satellites adjusted. You can adjust a volume level for each channel, speakers' sizes, the LF filter cutoff frequency and latency (from 0 to 30 feet), and tick off Solo and Mute. The Test will send a sinusoidal signal into the channel selected. 

The subwoofer settings also include LFE signal level adjustment and phase inversion enabling. The Speaker Bass Management supports Bass Boost LFE signal reproduction by satellites. 

The Mixer shows indicators and volume level controls of outputs used in the speaker set configuration. You can adjust volume levels of channels, enable mute and solo functions. Also note that the channels unused are not available. For example, in case of the 5.1 configuration there is nothing in the place of back surround channels controls. 

The Surround Sound tab has the option of enabling Sensaura algorithms. It's the advantage that rebooting in not needed after switching to the Sensaura/Game Mode: the panel reappears in a second the new mode enabled. It's also pleasant that with the Sensaura supported sound applications like Winamp working in the MME do not reproduce sound. 

The SRS Circle Surround option offers three algorithms of distribution of the stereo/mono signal into six or more speakers and two additional controls of the central satellite's level and the overall LF level. 

The Input/Other tab incorporates the indicator and control of the input signal level. A clip indicator is also provided. On the right you can see sampling rates and ASIO buffer sizes available. 

The last tab, About, indicates the drivers version. At the time of testing we used v5.10.00.0036. 

Tests in RMAA 5.1

The card was compared to the reference one Lynx Two (117 dB SNR). A short low-noise microphone cable, Proel, with gold-plated connectors was used to connect the cards. The input sensitivity of the Lynx Two is standard: -10 dB V. The output signal amplitude is low, that is why the recorded signal was normalized up to the required level. 

Front output

Mode of operation: 16 bit 44 kHz 
 

Frequency response (40 Hz to 15 kHz), dB:	+0.13, -0.06	Very good
Noise level, dB (A):	-92.2	Very good
Dynamic range, dB (A):	92.6	Very good
THD, %:	0.0007	Excellent
Intermodulation distortions, %:	0.0068	Excellent
Channel crosstalk, dB:	-93.9	Excellent

General performance: Very good

The detailed results for the front output for 16 bits 44 kHz are here. 

THD level at 44 kHz is very low



The diagram of IMD (SMPTE) at 44 kHz demonstrates no artifacts from oversampling

General performance: Excellent

The detailed results for the front output for 16 bits 48 kHz are here. 

Mode of operation: 24 bits 96 kHz 
 

Frequency response (40 Hz to 15 kHz), dB:	+0.06, -0.05	Excellent
Noise level, dB (A):	-101.1	Excellent
Dynamic range, dB (A):	100.9	Excellent
THD, %:	0.0009	Excellent
Intermodulation distortions, %:	0.0038	Excellent
Channel crosstalk, dB:	-97.1	Excellent

General performance: Excellent

The detailed results for the front output for 24 bits 96 kHz are here. 

Line-in

Mode of operation: 16 bits 44 kHz 
 

Frequency response (40 Hz to 15 kHz), dB:	+0.03, -0.19	Very good
Noise level, dB (A):	-79.0	Average
Dynamic range, dB (A):	78.8	Average
THD, %:	0.0028	Excellent
Intermodulation distortions, %:	0.042	Good
Channel crosstalk, dB:	-78.5	Very good

General performance: Good
 

The detailed results for the front output for 16 bits 44 kHz are here. 

Mode of operation: 16 bits 48 kHz 
 

Frequency response (40 Hz to 15 kHz), dB:	+0.03, -0.19	Very good
Noise level, dB (A):	-79.0	Average
Dynamic range, dB (A):	79.0	Average
THD, %:	0.0026	Excellent
Intermodulation distortions, %:	0.042	Good
Channel crosstalk, dB:	-78.0	Very good

General performance: Good

The detailed results for the front output for 16 bits 48 kHz are here. 

Test	Reference 1644	M-Audio Revolution synchro by S/PDIF	M-Audio Revolution synchro by 44100
Frequency response (40 Hz to 15 kHz), dB:	+0.00, -0.00	+0.00, -0.00	+0.00, -0.00
Noise level, dB (A):	-97.8	-94.7	-96.9
Dynamic range, dB (A):	97.7	94.7	96.4
THD, %:	0.0003	0.0007	0.0003
Intermodulation distortions, %:	0.0037	0.0052	0.0043
Channel crosstalk, dB:	-99.3	-96.3	-99.2

IMD (SMPTE) spectrograms of the digital-out:
the same jitter, not that bad

The detailed results for the front output for 16 bits 44 kHz are here. 

Tests in RightMark 3DSound

DirectSound diagnostics

Device: M-Audio Revolution (revo.sys) 

Features:
DirectSound 3D Hardware present 
DirectSound 2D Hardware present 
EAX 1 present 
EAX 2 present 
Device has no EAX3 support 

Rates:
dwMinSecondarySampleRate 100 
dwMaxSecondarySampleRate 48000 

Free buffers stats:
dwFreeHw3DAllBuffers 32 
dwFreeHw3DStaticBuffers 32 
dwFreeHw3DStreamingBuffers 32 
dwFreeHwMixingAllBuffers 32 
dwFreeHwMixingStaticBuffers 32 
dwFreeHwMixingStreamingBuffers 32 

Max buffers stats:
dwMaxHwMixingAllBuffers 33 
dwMaxHwMixingStaticBuffers 33 
dwMaxHwMixingStreamingBuffers 33 
dwMaxHw3DAllBuffers 33 
dwMaxHw3DStaticBuffers 33 
dwMaxHw3DStreamingBuffers 33 

CPU load

Windows XP SP1, DirectX8.1, Athlon 2100+, KT333, DDR333. 
 

	M-Audio Revolution 7.1	Audigy2
DirectSound 3D  16 buffers	10/1.2	1.7/0.3
DirectSound 3D + EAX2  16 buffers	12/1.2	2.1/0.3
DirectSound 3D  32 buffers	12/1.4	3.6/0.7
DirectSound 3D + EAX2  32 buffers	21/1.3	4.0/0.7

CPU load (%) for different modes of operation and a different number of DirectSound buffer. The average value and dispersion go after the slash (mean of distribution and standard deviation) for the 2-minute test and with accidental releases of the system discounted (swap etc.). 

Cubase SX

The M-audio Revolution 7.1, like other Envy24HT based cards, perfectly work in Cubase SX without any problems. 

In the ASIO Buffer Size menu you can select a buffer size to optimize latency depending on the number of tracks, VST instruments, effects and sampling rates. 

Subjective tests

Music

The Event 20/20bas active monitors were used in the comparison tests. The Creative Audigy2 as a direct competitor in this price range was used as a reference card. 

Actually, we expected that the Audigy2 would sound better because its Audigy2 DACs have better specs. But the Revolution 7.1 showed a little advantage! Its sound was a bit more detailed and richer. However, you will hardly notice any difference on the acoustic systems up to $500. Secondly, with the SSRC plugin used in the Audigy2 the difference is vanishingly small, and it disappears at all if you listen the other card in 30 seconds. 

Tests in movies

The next two tests were carried out on the Logitech Z-680. But this is only a 5.1 acoustic system, and given the analog connection, the front satellites reproduced the signal of the back surround speakers, and the active stereo speakers Microlab SOLO-1 was used in front. 

Before estimating the sound let me remind you something from the Creative Inspire 6.1 6700 Review. 

As to audio tracks in movies in cinemas and on DVD, 5.1 means that soundtracks are recorded in the format that consists of five main channels: left, center, right, left surround and right surround, plus a low-frequency effects bass channel (LFE). The suffix of ".1" indicates that the additional bass channel contains low frequencies from the main channels.

Some soundtracks use the 5.1 format called Dolby Digital Surround EX which is currently entering the sphere of home theaters with DVD media. This format has the third surround channel encoded into the left and right surround channels of the 5.1 track with the matrix algorithm, and it can be decoded or left as is depending on whether the equipment used is compatible with this standard. Since additional information is stored in the left and right surround channels, the sound track in the Dolby Digital Surround EX format still represents the 5.1 format.

Obviously, a 5.1 track can be successfully played by the 5.1 acoustic system. It also can be played by 6.1 or 7.1 speaker sets. Two surround channels in a 5.1 track are distributed between 3 or 4 surround speakers. It can be done with a Dolby Digital EX decoder, THX Surround EX or other suitable equipment.

Thus, a format describing a sound track (5.1, 6.1, 7.1) does not mean that it can be played only by a respective speaker set. It's also possible to play stereo content on a multi-channel acoustic set using a matrix decoder such as Dolby Pro Logic II. A source format and a speaker set operate independently, and a decoder is to manage them.

There is actually one thing you should understand from the above abstract - the DolbyDigital Surround EX has 5+1 discrete channels, and data for additional channels are decoded with a matrix algorithm into left and right surround channels. 

But these two additional channels do not contribute much into the overall picture. In DVD movies recorded in the Dolby Digital/Dolby Digital Surround EX format the rear channels can be heard only in the scenes rich in effects. One more mono channel decoded in two rear channels in not noticeable at all... This technology is well suited for cinema halls. But a user sitting in front of a PC monitor doesn't need a 7.1 system at all. It looks like one more marketing step, the attempt to attract users' attention to new capabilities of sound cards. 

In movies the Audigy 2 and M-Audio Revolution 7.1 play equally. But there is one interesting thing. The Audigy 2 has its own decoder, and the Audigy2 could have an advantage if its decoder performed better than the one used in the WinDVD. However, the decoder in the WinDVD Platinum 4.51 plays much better. 

Tests in games

The listening tests were carried out in Unreal Tournament 2003 and Soldier of Fortune II. To estimate the relative sound quality we used the Audigy 2 card again. We listened to the same game episodes switching the cards as fast as possible. 

The sound coming from the M-Audio Revolution 7.1 i inferior to the Audigy 2: it's less clear and detailed. We actually expected that from the Sensaura. Sensaura never won against Creative starting yet from the Live! and EAX2.0. 

The Revolution's strong point is not games at all. And realization of the Sensaura algorithms in this card should be regarded as a bonus. Nevertheless, you can play games with this card, - the sound is not that bad (for a card with the Sensaura). 

Sound in headphones

With the Senheiser HD600 headphones the card produces a clear signal without distortions even at the maximum volume level. In games with the Sensaura support we didn't have to turn up the volume over 30% in spite of the drop in the volume level. 

Conclusion

The card plays pretty well, and it's easy to handle it. Although the realization of the 24bit/96kHz mode is not of high quality and it is the most difficult mode for many cards, the 16bit/44kHz mode sounds excellently. The comparison with the Audigy2 was one of the most important tests. The Creative's solution is a bit inferior in music, but when coupled with the SSRC, it almost catches up with the Revolution. But remember, that you can notice the difference only on high-quality speakers. In games Creative's cards maintain its leading position because competitors have nothing to beat them with (the Sensaura technology is obsolete and doesn't suit anymore for cards with so good sound). 

Highs

• high-quality converters;
• excellent sound in music;
• no distortions at 16 bits 44 kHz;
• Sensaura algorithms supported;
• ASIO supported;

Lows

• no MIDI interface;
• 3D sound is inferior to the Creative Audigy2;
• no digital-in.