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Denon UD-M30. enlarge.
Denon UD-M30 enlarge.
The UD-M30 is a small all-in-one remote-controlled Hi-Fi receiver.
It has a CD player, FM stereo and AM tuners, connections for two external sources or recorders, and a 16 watts-per-channel (actual measured at 0.1% THD into 8Ω) power amplifier in its tiny box. To use with AirPlay for remote playing iPods etc. use an AirPort Express.
It also has a stereo preamp output to connect to a much larger power amp, or crossovers and power amplifiers for a multi-amplified system, or direct connection to powered monitors.
Another use of the stereo preamp output is for connection of self-powered stereo subwoofers, driving the main speakers from the UD-M30's own amplifier. In other words, for a very simply high-performance system, drive the main speakers full-range, and set the subwoofers to cross-in at the speaker's natural cutoff point.
The preamp output also may be switched to mono if you have only one subwoofer.
Great precise all-range volume control
Remote controlled, also has a switched 120 V power outlet to control a power amp or other audio products from the UD-M30's remote.
Clean Hi-Fi audio performance.
Extremely useful stereo preamp output makes adding subwoofers or more powerful amplifiers a breeze.
Plenty of power to drive large loudspeakers. Sounds great driving my B&W 801 to loud enough levels.
Solid metal construction.
Vacuum fluorescent display not legible from above, also difficult to read in daytime because the transparent cover is half-silvered to make it look silver when off.
FM tuner goes in 100 kHz steps and uses a European 75Ω connector, not an F connector. That's OK, as the included FM antenna is a piece of wire with a clip on the end to engage the connectors center terminal.
Nearly impossible to get the clock to display. It always turns off by default, and if you figure how to get it to display overnight with the UD-M30 off, the receiver still consumes almost as much power as if it were on!
No clock backup. The clock keeps time based on the power line frequency, so if you unplug it and plug it back in, it still reads the time at which you unplugged it — and blinks asking you to reset it! Good news is that there's no internal battery to need future replacement.
Volume reads in arbitrary units instead of decibels.
6.2s power-on delay.
Too many buttons on the remote.
No external processor loop and no separate power amp input (there are to in/outs for tape recorders and a preamp output.)
No MUTE button
No balance control
Denon RC-877 remote for UD-M30.
Measured Power Consumption
Standby: 2.1w ($4.60/yr at 25¢/kwh)
Standby with Clock on: 13.5 W.
Power On, no output: 14.9 W on FM, 16 W with CD selected, 18.5w with CD playing.
With 1 watt-per-channel output (2 W total): 28.2 W playing from AUX in, 32.4 W from CD.
With 10 watt-per-channel output (20 W total): 57.6 W playing from AUX in.
With 16 watt-per-channel output (32 W total): 68.7 W playing from AUX in.
When playing CDs, it's silent mechanically. You can't hear the disc spinning.
The 120BV switched outlet turns on at once, but waits 25 seconds to turn off after the receiver is turned off.
The system is quiet enough to hear noise potting up and down in Peter Gabriel's New Blood. In fact, the Denon UD-M30 is so clean that as I auditioned it on my B&W 801, for the first time I heard noise on the left at the end of track 5 and thought for sure it had to be some low-level DAC nonlinearity in the CD player. Nope, listened on other reference equipment, that noise is simply part of the recording. Aha!
The headphone jack seems almost direct-connected to the speaker outputs. This is great for low-sensitivity 600 Ω headphones, but with high-sensitivity headphones you may hear a little but of hum with no music playing.
Audio measurements made with a Rohde & Schwarz UPL.
Most frequency response measurements are made with an expanded scale that shows even the slightest response variations, be sure to note that these are plotted at ±1 dB full scale.
Unless otherwise noted, measured with 200mV input at unity gain (VOLUME 26) from LINE 1 (AUX) in to PREAMP OUT.
The gain (volume) control is one of the best things about the UD-M30. It has perfect tracking and covers a huge 77.13 dB range with 2 dB per step precision from +16 to -24 dB, and 3 dB per step from -24 to -62 dB.
Maximum gain is 15.73 dB which is a linear voltage gain of 6.1165.
Maximum Input Level
3.21 V at 0.1% THD.
At VOLUME 22, this gives 1.27 V out at 0.1% THD.
At VOLUME 26, this gives 3.122 V out at 0.2% THD.
At VOLUME 16 (-20 dB), this gives 0.327 V output.
Maximum Output Level
At VOLUME 26 or MAX: 1.41 V at 0.1% THD.
VOLUME 00: -111 dBV, A weighted.
VOLUME 01: -92 dBV, A weighted.
VOLUME 26: -91 dBV, A weighted.
VOLUME MAX: -89 dBV, A weighted.
Source Direct Mode
This is what Denon calls playing it without the tone controls or bass-boost active.
Preamplifier frequency response.
Preamplifier volume control channel to channel tracking.
Preamplifier harmonic distortion components.
Preamplifier THD versus level (input = output) at 1 kHz.
Preamplifier THD versus frequency, 200mV.
Preamplifier tone control response, composite plot of changing either Bass or Treble, one at a time.
SDB, Super Dynamic Bass, does nothing at the highest gains of VOLUME = 33 or MAX.
At lower settings, it boosts the bass around 100 Hz.
Nothing about it is dynamic; the amount of boost simply varies with the setting of the volume control.
While this seems like a bad, boomy idea, it actually sounds swell for its intended purpose both with full-size B&W 801 or small Monitor Audio Silver S2 speakers.
Preamplifier SDB response, VOLUME = 31 or 32.
Preamplifier SDB response, VOLUME = 29 or 30.
Preamplifier SDB response, VOLUME = 25, 26, 27 or 28.
Preamplifier SDB response, VOLUME = 01 through 24.
It seems like a regular class AB output stage. Speaker ground is ground.
The power amplifier has no direct input, so all these measurements are made via the LINE 1 (AUX) preamplifier input.
All measured into 8Ω resistive load at 1 Watt (2.828 VRMS) and 1 kHz unless otherwise noted.
15.8 W at 0.1% THD at 1 kHz, VOLUME 26 with 1.035 V input at LINE 1 (AUX).
From LINE 1 (AUX) in to speaker output into 8Ω:
VOLUME 20, 1.005 V in gives 0.98 W out.
VOLUME 26: 0.260 V in gives 1.00 W out.
There is no significant output noise, at least as heard through speakers at close range.
From LINE 1 (AUX) in to speaker outputs loaded by 8 Ω:
-69 dBV A-weighted, -64 dBV unweighted, at VOLUME MAX.
-71 dBV A-weighted, -66.5 dBV unweighted, with VOLUME 01 to VOLUME 26. Referred to 1 W output at 8Ω, this is an 80 db A (75.5 dB unweighted) signal-to-noise ratio.
-89.4 dBV A-weighted, -81 dBV unweighted, at VOLUME 00.
Damping Factor at 8 Ω
I measured a damping factor of 60, but that was through some sloppy wiring. The actual damping factor at the output terminals will be even better.
System Frequency Response
System frequency response.
System infrasonic frequency response.
System harmonic distortion components.
System THD versus frequency, 100 mW into 8Ω.
System THD versus frequency, 1W into 8Ω.
System THD versus frequency, 10W into 8Ω.
PREAMP OUT Output Voltage at 0 dBFS at 1 kHz
19.87 mV at VOLUME 10.
300 mV at VOLUME 20.
1.162 V at VOLUME 26.
1.455 V at VOLUME 27 at 0.17% THD.
1.82 V at VOLUME 28 at 0.3% THD.
2.29 V at VOLUME 29 at 0.24% THD.
2.87 V at VOLUME 30 at 0.18% THD.
3.52 V at VOLUME 31 at 3.9% THD.
Power Amplifier output levels into 8 Ω from a CD at 0 dBFS
VOLUME 01: 16 µW.
VOLUME 10: 6.1 mW at 0.07% THD.
VOLUME 19: 0.888 W at 0.02% THD.
VOLUME 20: 1.39 W at 0.018% THD.
VOLUME 21: 2.18 W.
VOLUME 22: 3.42 W.
VOLUME 23: 5.37 W at 0.02% THD.
VOLUME 24: 8.4 W at 0.02% THD.
VOLUME 25: 13.2 W at 0.022% THD.
VOLUME 26: 18.7 W at 5.5% THD.
CD Player Frequency Response
Measured playing track 11 of the CBS CD-1 test disk.
CD player frequency response at preamplifier output.
CD player frequency response at power amplifier output.
As we saw above, the preamp's frequency response is down a dB at 20 kHz.
However, the CD Player's response at the preamp's output is flat at 20 kHz.
The system's response from the LINE 1 (AUX) input to the power amp's output is also flat.
The power amp must have a 1 dB boost at 20 kHz when fed internally, and the CD player must skip whatever part of the preamp is losing 1 dB at 20 kHz. Otherwise, the 1 dB droop in the preamp's response from the line input is compensated by the power amp's 1 dB boost.
No big deal, but it is obvious at the expanded scales at which I plot these.
Set the Clock
With the power off, tap MENU/SET (or press Display on remote). This shows the clock.
Hold MENU on the unit until the hours blink. Now the the unit's + and - buttons will set the hours.
Tap MENU again and the minutes blink. Set them the same way.
Tap MENU a third time to mark the seconds, or to escape early, turn on the power.
The display usually does what it wants to.
To show the clock:
With power ON: press MENU + + on the unit, or press DISPLAY on the remote.
With power off: press MENU on the unit, or press DISPLAY on the remote. Tap again to cancel.
The little speaker-wire sockets on the rear can swallow 14-gauge tinned leads — barely. They can't handle 12 AWG.
Digital TOSLINK output
The only thing I heard coming out of it is the direct output from the CD transport. The volume control has no effect.
I heard nothing with other inputs.
The BAND button swaps between AM and FM. FM is STEREO with weak stations muted. If you want FM MONO and/or to hear weak stations, that is the third selection as you keep pressing the BAND button. In other words, be sure to skip the FM MONO "band" if you want to hear FM in stereo.
You can tune either all channels, or just the preset channels. To swap between these modes, Hold the + and STOP/BAND buttons at the same time.
Set Radio Presets
The radio presets are direct-access from the remote.
To select presets from the front panel, select the preset tuning mode by holding + and STOP/BAND for a moment.
Each preset may be either AM or FM, no problem.
To program radio presets:
1.) Tune your station.
2.) Press ENTER on the remote.
3.) On the remote, press the number of the preset in which you want to store this station.
4.) Press ENTER on the remote.
To program alphanumeric names for each, you have to do a lot of fiddling with EDIT and ENTER and < and >, again all on the remote. I gave up.
To clear an aphpanumeirc name, select the station, press EDIT and then CLEAR on the remote.
You can just press PLAY to turn on the receiver and play the CD.
The remote allows full control, programming and direct calling of track numbers.
The front-panel only offers play, pause, stop and track skip. Oddly, you can't move forward inside a track from the front panel by holding the < and > buttons, all they do is skip tracks.
This is a handy little desktop or remote-controlled receiver that is perfect for driving great speakers for a small but very good Hi-Fi system.
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08 May 2017; November, December 2013