Low Latency! -- RME Multiface Review
by Hans Van Even- 29 May 2002 -

(With thanks to Matthias Carstens for the technical
information & Michael Stowe for additional editing)

For our review, we will focus on the new Multiface with Hammerfall DSP PCI card in SONAR 2, and we will especially concentrate on the latency performance of this card. The Multiface/Hammerfall DSP PCI pack is a professional audio solution for DAW users (PC and MAC) that lets you transfer audio to your computer from almost every possible external source (such as ADAT Optical, Analog, S/PDIF) and up to 24 bits/96 khz. Here are some important technical specs (for a complete list, please visit the RME website) :

Multiface & Hammerfall DSP PCI Card Specs

Digital :

•  Internal sample rates: 32 / 44.1 / 48 / 88.2 / 96 kHz
• Supported sample rats through word clock: 27 kHz - 103 kHz
• Internal resolution: 24 Bit
• Clocks: ADAT Sync In, word clock I/O
• Formats: SPDIF (Consumer and Professional), ADAT optical

Analog :

• Stereo Monitor Output (can also be used as 24bits/96Khz DA headphone out)
• Dynamic range: 108 dB (RMS unweighted, unmuted), 112 dBA
• THD+N: -100 dB / 0.001%
• Frequency response DA, -0.1 dB: 20 Hz - 20.8 kHz (sf 44,1 kHz)
• Frequency response DA, -0.5 dB: 10 Hz - 44 kHz (sf 96 kHz)
• Sample rates playback: 32 / 44.1 / 48 / 64 / 88.2 / 96 kHz and variable (word clock)

AD:

• Resolution AD: 24 Bit
• Signal to Noise ratio: 101 dB RMS unweighted, 106 dBA
• THD: < -107 dB, < 0.00045 %
• THD+N: < -96 dB, < 0.0016 %
• Crosstalk: > 120 dB
• Input Line: 1/4" TRS jack, servo balanced
• Input sensitivity through jumper: Lo Gain, +4 dBu, -10 dBV
  

DA:

• Resolution DA: 24 Bit
• Signal to Noise ratio: 108 dB RMS unweighted, 111 dBA (unmuted)
• THD: < - 98 dB, < 0.0013 %
• THD+N: < -91 dB, < 0.002 %
• Crosstalk: > 100 dB
• Maximum output level DA: +19 dBu
• Output Line: 1/4" TRS jack, servo balanced
• Output level through jumper: Hi Gain, +4 dBu, -10 dBV

What's in the BOX?

We received two nearly identical futuristic boxes: one with the Multiface Breakout box and the other with the Hammerfall DSP card. One of the most impressive aspects is this card's modular design. Let's say you have a laptop and would like to use Multiface on it as well. With the purchase of a CardBus card, you can use the same Multiface breakout box; the breakout box will fit both the CardBus and PCI card. Cool! The box also comes with

• An IEEE 1394 cable (firewire cable) for connection between the Multiface and PCI card
• Internal cable (note that there's only a power supply needed when you use the CardBus card (for use in laptop)--the Multiface breakout box gets its power from the PCI card through the IEEE 1394 cable)
• Quick start guide
•  DIGICheck
• Meterbridge
• Owner's manual

Our Test Setup

ASUS A7M266* (bios 1006, onboard audio disabled, USB enabled)
Athlon XP 1700+
512 DDR Samsung
GeForce MX200 32Mb
Yamaha 20X/10X Burner
Teac 50X CD Rom
Hammerfall DSP PCI Card
Multiface break out box
WindowsXP Pro ACPI disabled
Cakewalk SONAR 2

* Performance may even be better using the latest Asus A7N266-C or MSI K7N420 Pro motherboards. Unfortunately we hadn't these motherboards available when doing our tests.

Installing

Installing RME hardware and drivers has always been very easy, and the DSP PCI card + Multiface is no exception. Just install the PCI card, start Windows, wait for Windows to ask for drivers for your new audio device, point to your drivers and install :)

To WDM or not to WDM?

When SONAR users buy a new soundcard, they usually ask, "Do we need WDM drivers?" While WDM surely has its place as a standard driver model for Windows 2000/XP, MME drivers have been on the market for a long time, and Cakewalk has allowed very low latencies with this driver protocol since Cakewalk Pro Audio 9. RME has made some special MME drivers that can compete with WDM drivers (or ASIO for the Cubase and Logic Audio users) when used in SONAR. I'm not going to start a WDM vs. MME vs. ASIO driver debate here, but I want to show you some numbers from using the Multiface's MME drivers in SONAR. I think the numbers speak for themselves.

We did some tests to measure the real latency of Input Monitoring using the Multiface HDSP card. You can do the same test with your own card by following the next tip from Scott Reams.

This test measures the exact latency between the AD inputs, software (+ effects when present) and DA outputs.

To start, we selected a 1.5 ms latency from the Hammerfall DSP dialog box and 1.5 ms effective latency (using 2 buffers) in the SONAR audio options. It's important to note that effective latency in SONAR does not give you the exact latency for Input Monitoring or MIDI latency for softsynths. You will have to add the latency of the AD/DA convertors and the buffers used in the software, which is one of the main reasons we did this test.

Hammerfall DSP Settings

SONAR Audio Options

We tested the Input Monitoring (IM) of the Multiface device with the above settings at 3 different sample rates: 44.1 Khz, 48 Khz and 96 Khz. In some cases editing the Aud.ini file in SONAR can give better IM latency; this is also the case for other soundcards. (Only for advanced users: go to C:\Program Files\Cakewalk\SONAR 2 and open Aud.ini file in Windows Notepad. Here you can alter the "WaveInBuffers=8" parameter, trying out other settings like 6 or 4 or even higher). We also indicated until wich CPU load the latency settings were useful (before crackles appear). Note that we could push the system pretty hard and didn't have any dropouts or crashes at all. Also be aware these tests may vary, depending on which mainboard and CPU you are using.

E.L. = Effective Latency in SONAR's Audio Options
I.M. = Input Monitoring Latency (that is, when using effects in SONAR2 on a live input)
MAX CPU I.M. = Maximum effective CPU load shown in SONAR2's CPU meter (before crackles/tunnel sound apear)

Sample Rate	E.L.	I.M.	MAX CPU I.M.
44.1Khz	1.5ms	4.3ms*	40-45%
"	1.5ms	5.7ms**	40-45%
"	2.9ms	7.3ms**	70-75%
"	4.4ms	10ms**	75-80%
96Khz	1ms	3.6ms	20%
"	2ms	5.3ms	45%
"	3ms	9.7ms	60-65%

* with "WaveInBuffers=4" in Aud.ini
** with "WaveInBuffers=6" in Aud.ini

With the latest CPUs available, IM is becoming an increasingly important tool for a DAW, and IM will be even more useful in the coming years as CPU power increases. During our tests we didn't encounter any stability problems at all. The Multiface was exceptionally stable with the latest drivers available from the http://www.rme-audio.com/ website.

Note for people using softsynths :

We didn't have the time and the tools to test MIDI > softsynth > DA latency for this review. The results should be even better than the current IM results we have here. Performance is somewhat equal when using softsynths and the noted Effective Latency settings in SONAR.

Note : When using MME drivers, Hammerfall DSP can use automatic monitor solutions, one controlled by the recording state (mode mix/replace) or one controlled by the software itself (ZLM* for use with Samplitude/Sequoia/SAW Studio).

*ZLM is a special function for tape machine style monitoring when doing punch-ins and outs.

Total Mix

One of the tools that make Multiface so flexible is Totalmix, a 720- channel digital realtime mixer that operates at 40-bits internal resolution and uses 0% CPU, because it's completely stored in hardware. Totalmix is completely configurable and can become a very complex mixer. You can even save your mixer settings; eight preset buttons are available for quick access of your favorite mixer setups. You can also use up to three Hammerfall DSP cards and any combination of three Multiface or Digiface boxes. Here are some situations where Totalmix can become very useful :

• setting up delay-free submixes (headphone mixes)
• unlimited routing of inputs and outputs (free utilisation, patchbay function)
• distributing signals to several outputs at a time
• simultaneous playback of different programs over only one stereo channel
• mixing of the input signal to the playback signal (complete ASIO Direct Monitoring)
• integration of external devices (effects etc). in real-time
• mixdown of three ADAT inputs to one (realizing two additional inputs)

MIDI I/O

Multiface comes with a build in Midi I/O interface (two on Digiface) that makes it the perfect addition for use with a midi sequencer. The advantage of having a midi interface onboard, eliminates the hassles often encountered when using external USB midi interfaces. A smart led indicator displays if data is send over the midi port. We found this onboard midi interface to be very stable.

HDSP Meterbridge and DIGICheck

As a nice addition to the package, RME developed an utility for testing, measuring and analysing digital audio streams.

• Level Meter. High precision 24-bit resolution, 2/8/26 channels. Application examples: Peak level measurement, RMS level measurement, over-detection, phase correlation measurement, dynamic range and signal-to-noise ratios, RMS-to-peak difference (loudness), long-term peak measurement, input check.
• Bit Statistics. Shows the true resolution of audio signals as well as errors and DC offset.
• Performance Test. Measures overall system performance (computer + HDSP).
• Memory Test. Tests the Hammerfall hardware and the entire audio data path in the PC.

To celebrate 5 years of existance, RME made a nice addition to DIGICheck called Totalyser. A professional Spectral Analyser (Peak/RMS detection for up to
2 x 26 + 28 channels), Goniometer and Phase Correlation meter ! This tool replaces analysing gear costing a lot of money (Klark Teknik, ...), and guess what, RME give's it away for free to users of the Hammerfall, Hammerfall DSP and Digi96/Digi32 cards.

Final Words

We give this product 5 stars out of 5. RME has proven once again they can make outstanding audio cards for a reasonable price. If you're looking for a great-sounding, stable, low-latency audio card with great convertors and a lot of options compatible with 24 bits/96 Khz format, we highly recommend the RME Multiface. For more questions and support, RME has created its own newsgroup, which you can acces here: RME Newsgroup. RME staff and users are both very active and responsive on this newsgroup, so you will always find answers to your questions.