Make a list of loudspeaker manufacturers, and chances are Denon won’t be near the top, if they make the list at all. But besides their more recent lifestyle speakers the brand has had a number of models in the range over the years, though few (if any) actually manufactured by them. The subject of this review is no exception. The Denon SB-M5K bookshelf speakers were manufactured in the late 1990s by Mission, sold to partner Denon UD-M5 stereo receiver or the UD-M7 component stereo system.
The K in the model denotes the UK manufacturing, produced in Huntingdon. The non K models, and the M50s, were made in Malaysia. The Malaysian model uses an emulsified silk dome tweeter, where the UK model uses an open mesh silk dome tweeter that I believe was manufactured by Audax. I believe the bass driver is a variant (possible direct rebadge) of the Audax HP100GO. Regardless of its origin it is a 110 mm (4 inch) driver with a polymer basket, glass-fibre cone and rubber surround.
The M5Ks are unusual in that they are oriented with the tweeter at the bottom and the midbass driver above. This makes them a true bookshelf design, as the alignment of the drivers will generally result in a more appropriate tweeter height when the speakers are on a bookshelf. The grilles will flip to orient the badge correctly if you want to stand them in a more traditional orientation with the tweeter above the bass driver, but this also cites the cable terminals at the top of the rear baffle, and at a slight downward angle. I see no reason not to use them as intended, as even on a pair of stands the imaging doesn’t suffer from the downward tweeter. The drivers are so close together anyway.
On the rear are a single pair of 4 mm terminals with tri-wing nuts which are nice and easy to grip. They’ll accept 4 mm banana plugs, stripped wire or spades, and have raised polarity markings. The rear panel is some kind of composite plastic, as is the front baffle, at least on the UK model. The Malaysian model has an MDF baffle in the same simulated wood vinyl wrap as the rest of the cabinet. The plastic baffle is preferable as it flush-mounts the drivers, which ought to give a welcome performance advantage in terms of phasing and time alignment. I was also impressed by how dead the cabinets are, the usual knuckle thump test produces very little resonance to speak of. The thin walls do resonate playing music though, more on that later.
The speakers are front ported, and unfussy about room placement. The grilles are removable, but their mesh fabric cover is so thin there is no audible difference with the grilles in place. Incidentally the grilles of the UK model are a much nicer fit to the baffle, and have longer mounting posts. They’re a simple plastic frame design with subtle Denon (or Mission) branding.
These speakers, and their mission equivalent, were targeted toward mini component and budget hi-fi systems. The Denon versions were to be used with the UD-M5, a stereo receiver that put out 30W per channel into a 6 ohm load at a highly audible 10% THD (total harmonic distortion). That’s not a lot of power, especially given a speaker of only 86dB efficiency.
Having a lower impedance helps though as it loads the amp and draws more current, which helps give a bit of low end grunt to a design that would otherwise sound all of the 20 watts or so it is actually capable of at a reasonable level of distortion. The speakers specify an amplifier power between 20 and 75W. I wouldn’t be surprised if many of the tweeters in these speakers succumbed to clipping, a distortion that is caused when the amp can’t produce enough power and the peaks of the waveform are flattened. Clipping damages tweeters, and conveniently the protection circuit of the Denon receiver doesn’t implement any kind of clipping detection. So if it was played at or near its maximum volume, especially with a loud track, it would be quite capable of killing the matching speakers simply because it wasn’t man enough to provide the amount of power they really needed.
Naturally I forewent the original system and connected them straight to the Hypex Nilai500s. Capable of 525W into 4Ω, 260W into 8Ω and somewhere around 320W into a 6Ω load, the Nilai500s could without doubt tear the cones from the baskets and vaporise the crossovers without much encouragement. Any amplifier of high quality can safely be used with any speaker within reason, providing the speaker falls within the amplifier’s minimum impedance specification. Damage is more likely to occur driving a power-hungry speaker with an underpowered amp than the reverse, though it is possible to damage a low-power speaker with a high-power amp. Generally you’ll hear the point of damage approaching before any irreparable destruction occurs. I get a lot of people asking if an amp of x wattage can be used with speakers of x wattage, and the answer is generally yes.
My first impression of the SB-M5K was a speaker that sounded as small as it is, albeit with solid imaging. This was at relatively low volume where the low end suffered and the mids were quite pronounced, though imaging was solid. Crank them though and things improve dramatically.
The forward midrange remains. I’m not sure if they’re purposely tuned in this way or if it’s down to the small cabinet, or resonance in the cabinet. But with a bit of power behind them, the low end improves significantly and the top end opens out nicely too. They’re never going to produce ground-shaking bass, and there are numerous other bookshelf speakers of a similar size or only slightly bigger that will offer up more bass and. Smoother, flatter response than these. But they’re sure-footed and articulate, and great fun when things get loud.
I’m not generally a fan of a subwoofer in a stereo system. Though frequencies below a certain point aren’t directional, meaning you’re supposed to be unable to tell where they originate from, I find that I can easily hear an imbalance unless the sub is perfectly centred which isn’t always possible. The added grunt from a sub would I’m sure help the SC-M5Ks along nicely though. The effect would obviously enhance the low end, but would probably also further smooth out the midband. Even without a sub, however, they’re great little speakers for a small room or small system.
I did try them with the Denon UD-M5 CD receiver. The sound was decent as you’d expect from an intentional pairing, and had most of the characteristics described above. The amp of the Denon however doesn’t have enough power to bring the best out of the speakers. If you have one of these systems in its original configuration, and are looking to upgrade, you could do a lot worse than the speakers you already have so my suggestion would be to start with a better amp. I tried a Sony TA-FE370, an early 2000s unit with about 60W per channel into a 6 ohm load. This seems to be a sweet spot, and sound much like the Hypex amps did, though a bit more laid back and lacking the sheer brute force of the bigger amps.
Denon sold a lot of these systems and they’re at the age now where the receiver units are starting to fail. Many are being sold off with the matching speakers and sometimes the cassette deck, a nifty half-sized tray loader with Dolby B and C, auto reverse and a few other nice features. The Missions (same speaker, different name) weren’t expensive in their day either, and there are plenty of them about. Guide price of the Denon or Mission speakers on their own is around £15 for a used pair with minor cosmetic flaws, to £40-60 for a mint pair in the box. If you buy them with the system, you’ll usually pay less. I bought the broken CD receiver, cassette deck and working speakers mint in the boxes for £20. You’ll pay more if the system has been refurbished, but there are still bargains out there to be had.