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Digidesign RM2 Powered Studio Monitor - ProSoundNetwork.com

Digidesign RM2 Powered Studio Monitor

Digidesign has been expanding its product base for several years, including the introduction of the ICON digital desk and subsequently the highly acclaimed VENUE digital live board.
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Fast Facts
(click thumbnail)
Applications
Studio, post, broadcast

Key Features
Transmission-Line design, bi-amped active amplification, digital crossover, DSP HF and LF controls, Bass Port Emulation, 6.7-inch woofer, 1-inch tweeter, analog and digital inputs

Price
$3,498 per pair

Contact
Digidesign | 650-731-6399
www.digidesign.com

PRODUCT POINTS

Plus

  • Digital Crossover
  • PMC build quality
  • Very good sound
  • Analog and digital connections

Minus

  • Price
  • No 192 kHz input compatibility
  • Not much low bass

The Score
Digi’s PMC commissioned, premium-priced powered speakers enter a competetive field of good value/performance monitorsDigidesign has been expanding its product base for several years, including the introduction of the ICON digital desk and subsequently the highly acclaimed VENUE digital live board. The company also purchased M-Audio, the bang-for-the-buck audio manufacturer. Now Digi has turned its attention to the powered studio monitor market niche.

Introduced in April at NAB 2007, the Digidesign RM1 and RM2 are powered speakers coming courtesy of British-based PMC, manufacturer of audiophile and pro speakers. The RM2 tested here is Digi’s flagship model and comes in at $3,498 per pair retail.

Features

The Digidesign RM2 speaker is a transmission line-speaker equipped with a 6.7-inch woofer, 1-inch soft dome tweeter, 150 watts of bi-amped Class D power, a digital crossover and on-board DSP. The speakers measure 11.5-inches tall by 11-inches deep by just over 7.5-inches wide, and weigh 14 pounds each. The very well braced cabinet is gray colored and is an attractive desktop or stand monitor.

The front panel houses a Digidesign-monikered perforated screen, which covers the exit of the transmission line channel. (Smoother midrange is a reported advantage of a transmission line design’s internal baffle design).

In back are controls for high-frequency (-4 dB to + 3 dB) and low-frequency settings (-4 dB to + 3 dB), gain trim (0 dB to -8 dB), and a bass-port emulation switch using digital EQ to enhance the mid-bass frequencies to emulate the tonal characteristics of a ported bass-reflex speaker. Connection options include XLR analog, AES-3 digital input and a RJ-45 phone-type connector for optional digital and pass-through for use in digital-input mode only.

The RM2 specifications include 40 Hz - 25 kHz frequency response (no tolerance given), 113 dB peak SPL and 3 kHz crossover frequency. Power is 100 watts for the woofer, 50 watts for the tweeter at 1-percent distortion.

Unlike analog active speakers, the Digidesign/PMC speaker converts the analog to digital to enable high frequency and low frequency control, as well as the crossover, bass-port emulation and speaker gain. The digital signal is converted back to analog before the final amplifier stage. Digital conversion allows for more efficient processing for EQ, gain and other DSP. Also, a well-designed digital active crossover can produce seamless crossover performance — without the artifacts of passive crossover networks.

(Many speakers companies convert analog to digital in their active speaker systems, and I can attest that many sound very good. But I have talked to high-end engineers who say that multiple stages of digital conversion within a speaker could have a subtle, perhaps audibly degrading effect that could offset the excellent crossover performance capable in a digital design. Food for thought.)

If you drive the RM2s with an analog mixer, preamp, etc., the analog is converted to digital via the internal A/D, which operates at 24 bit, 96 kHz. A digital input signal — up to 96 kHz — from your digital mixer, workstation, etc., is passed through without any resampling. The speaker accepts digital sample rates of 44.1, 48, 88.2 and 96 kHz for direct digital playback.

Bench TestBENCH MEASUREMENT DATA

Frequency Response:
On-axis 75 Hz to 20 kHz +/- 3.0 dB
Bass Limit:
72 dB SPL @ 50 Hz @ 2 meters (<10% Distortion)

Control Action:
HF +3 Actual Response +2.9 dB > 2 kHz
HF +2 Actual Response +1.9 dB
HF +1 Actual Response +0.9 dB
HF -1 Actual Response - 0.6 dB
HF -2 Actual Response -2.1 dB
HF -3 Actual Response - 2.5 dB
HF -4 Actual Response - 4.0 dB

LF +3 Actual Response +2.0 dB < 1 kHz
LF +2 Actual Response +.1.2 dB
LF +1 Actual Response + 0.5 dB
LF - 1 Actual Response - 0.8 dB
LF - 2 Actual Response - 1.6 dB
LF - 3 Actual Response - 2.4 dB
LF - 4 Actual Response - 3.6 dB


Note:The Bass Limit of the speaker is the Sound Pressure generated at 2 meters. The figure of merit 10-percent distortion is used because operating characteristics of drivers (using DLC Design DUMAX) shows that when a speaker has reached the end of its linear operating range (BL product has fallen to 70-percent of the rest position value or the suspension compliance has stiffened by a factor of 4) the unit will still sound clean, but distortion increases exponentially with further drive. With powered speakers amplifier output or limiting may also limit sound pressure capability.

BENCH MEASUREMENT DATA

Basic measurements here have been taken at a full two meters in a large room on a six-foot stand. Using time windows then gives equivalent anechoic results above 200 Hz including front panel reflections, cabinet diffraction and true acoustical summation of all drivers and passive radiating elements. Control action was measured using a closefield microphone on the tweeter and the woofer separately.

(click thumbnail)Frequency response shows a slight trough just above 100 Hz and a moderate degree of roughness above 3 kHz.

(click thumbnail)The Bass Simulator action begins at 300 Hz and simply increases response by approximately 3dB below that frequency.Operating control action was, generally speaking, fairly close to specified making the controls useful in real conditions. Frequency response shows a slight trough just above 100 Hz and a moderate degree of roughness above 3 kHz. The Bass Emulator action begins at 300 Hz and simply increases response by approximately 3 dB below that frequency. The system response becomes much less smooth as the microphone is moved father off axis. Users will most likely want to use this system in the direct field.

— Tom NousaineThose working with 176 kHz or 192 kHz sample rates can’t listen to a direct digital input — the speakers simply mute with those frequencies. Since Digi HD systems are 192 kHz capable, I’m surprised the RM series doesn’t accept the higher rates. If you want to listen to 192 kHz audio through the RM2, you have to do it via the analog input (where the ADC will convert the audio to 96 kHz.), or sample rate convert via your workstation software or outboard converter.

In Use

I connected the RM2 to three different analog systems and compared it to my reference closefield systems. Comparison speakers included the very accurate Lipinski Sound L-505 and the Legacy Studio. Both systems are passive two-way designs. Amps included the Pass X350.5 with 350 watt Class A-Class A/B MOSFET output; and the Bryston 14B SST with 600 watt bipolar output; and a Class D switching amp from Audio Control. I did not have any active speakers on hand to compare the RM2.

I also connected the speakers to my Apple G5 workstation via Lynx’s excellent L22 digital PCI card and played mixes and master material from 44.1 kHz to — oops! — 192 kHz.

I set up the speakers on custom Apollo speaker stands in front of a Trident 8T mixer and connected them to the Legacy Coda stereo monitor preamp via Alpha-Core silver balanced XLR cables. The speakers were placed about 3.5 feet from the work position, angled in. Sources included CD, DVD-A acoustic guitar mixes, several prerecorded jazz and classical SACDs/DVD-As and an analog European techno pop dance mix I remastered a couple of years ago. The sources included Esoteric DV-50 universal player, Apple G5 workstation with a Benchmark DAC-1.

The first thing I noticed in listening to the RM2s was the crossover accuracy: phase coherent, smooth and no artifacts in the 3 kHz region where the ear is very sensitive. Martin acoustic guitar recordings sounded similar on the Lipinski’s with that strummed crispness and warm bass, but I noticed that the subtle room reverb decay of treble string plucks was not quite as apparent as on the Lipinski’s, an excellent-measuring, phase coherent passive speaker. I must mention the passive Lipinski’s cost nearly the same as the active Digi speakers alone, and the Pass and Bryston amps costs are well in excess of $6,000. But I really want to know if I am missing anything, so I referenced with the best I have.

On vocal mixes, the RM2’s tweeter is very smooth and uncolored and is not overly sibilant on female voices. On well-recorded transients imaging is excellent with wide dispersion and depth, letting you know precisely where you put the sound in your mix. Off-Axis dispersion was pretty good (although PAR bench tester Tom Nousaine’s measurements showed a few irregularities when measuring off-axis).

The RM2 does not have much low bass output (see measurement) below 75 Hz. Most of the audible bass is in the 100 Hz and higher with a bit of emphasis above 100 Hz. Playing bass drums, bass guitars and other music, 50 Hz and below was mostly absent. Turning on the bass port emulation only enhanced the mid-bass emphasis already exhibited. Most small speakers do not have appreciable low bass reproduction, but this one rolls off pretty fast.

(Digidesign’s Sales and Marketing department responds: “In fairness, it’s really a matter of physics that a 6.7-inch cone can only naturally produces frequencies down to a certain point. Most speakers manufacturers chose to counter this by deploying common tricks to artificially re-introduce a low end, such as porting and the use of passive radiators. We chose to avoid that and go for a true reference, rather than an artificially created low end.” — Ed.)

If you are working with sounds that have sub-50 Hz bass, use a subwoofer. Digi does not yet have a model to mate with the RM1 or RM2, but I am sure one is forthcoming. By the way, the Lipinski LS-505s also are low-bass deficient; they must be used with a subwoofer for sub-70 Hz bass to be audible in any real way.

Digi boasts low listener fatigue at higher volumes with the fairly powerful Class D amps. In my tests, they were practically fatigue free to moderate levels of 90 - 94 dB or so, but when pushed harder with pop music containing midrange/low-treble energy they definitely weren’t as easy on the ear as the Lipinski’s plus high-end outboard amps. I was not audibly clipping the speakers, but I could feel a bit of high-level ear grit with the RM2s. after 30 minutes-plus monitoring.

Ultimately, I used the RM2 extensively via the direct digital connection using the G5/Lynx card — a routing method that will likely be very popular for this speaker. The speaker sounded very good with the gain controlled from Peak 5. Of course, as previously mentioned I could not play my 192 kHz recordings through the RM2s — unless I sample rate converted; I just stuck to 96 kHz or lower sample rates for monitoring during the test sessions.

Summary

So, what are we to think about Digidesign getting in cahoots with PMC and moving into a niche with numerous players? Overall, I think the RM2 is a very good powered speaker with fairly accurate tonal reproduction, excellent imaging and a nice, basic feature set.

However, the speaker is not cheap at $3,500 per pair. There are a number of good sounding, full-feature, comparable-sized driver monitors for less money. But if the Digi RM2s are on your short list for new speakers, regardless of the price, my nitpicks are its lack of 192 kHz digital input compatibility and the low-bass shy response curve. The latter is rectified by a sub; the former needs to be addressed by the designers — guess that would be the Digidesig-ners.