Klein + Hummel O 300 D 3-Way Active Studio Monitors


Klein + Hummel have been making speakers in Germany for about 60 years. They have a solid reputation for making high quality products and the subject of this review supports and continues to bolster that reputation.

I’ve had some opportunities over the past few years to work in rooms that had excellent monitors (Genelec 1032AM, Tannoy Eclipse, Dynaudio AIR 15, and so on) but this is my first experience with the Klein + Hummel product line. When I’ve worked with really great monitors, it’s always been on the clock so I’ve never had the time to fool around using a signal generator or pulling out a huge variety of program material to test them with. The reality is that speakers in this price range have always been a bit beyond my budget, so the chance to get to own them for even a super short time makes me feel pretty lucky.

The O 300 D is a relatively compact 3-way studio monitor — only 10" x 15" x 11.5" and weighing 32 pounds. The 8" polypropylene woofer takes up most of the real estate on the face with a 3" fabric dome midrange speaker and a 1" fabric dome titanium tweeter nestled into the remaining space. The red K + H logo badge lights up when the main power is switched on and acts as an overload light and flashes with any clipping.

Splitting the frequency range across three drivers makes less work for each one thereby freeing each one to only do what it is best at. The low-end driver has no reason to generate mids, for example, so there will be less resonances, harmonics, and standing waves in the cabinet, permitting better accuracy, or so the theory goes. The cabinet uses a new material called Low Resonance Integral Molding (LRIM) that has been shaped into “waveguides” for both the midrange unit and the tweeter to help control dispersion, and allowing the drivers to be mounted in the correct vertical plane for accurate time alignment. The tweeter waveguide disperses wider horizontally rather than vertically to minimize the high frequency reflections from the surface of the console and creates a larger sweet spot.

Each of the drivers is powered by a separate MOSFET amp (with 150 watts for the woofer, and 65 watts each for the mid and tweeter) with built-in protection limiters. The peak SPL from one meter is quoted as 112.8dB with 3% THD, or at 95dB with less than 5% distortion for all frequencies above 100Hz. The overall frequency response is stated as 40Hz to 20kHz, and by all accounts extremely flat. The points where the frequencies cross over for each are set at 650Hz and 3.3kHz in 24dB/octave slopes with a subsonic filter that rolls off 6dB/octave below 30Hz. With a signal generator issuing a –10dB sine wave, I got to a lovely 28Hz before hearing the roll off and then it rolled off quickly.

The O 300 D has an analog input via a transformer balanced line level into an XLR connector (no TRS input), and digital signals can be connected using the same XLR as the analog in for AES/EBU or via BNC connector in either unbalanced AES3id or S/PDIF. The D/A is a 24-bit converter that takes up to 96kHz sampling rate.

Like many active speakers these days, there is a full range of room correction EQ features. These are really small, screwdriver-adjustable pots. I tried to get my fingernail in one of them, but they are too recessed. These controls will help compensate for near-wall placement, or corner-near-ceiling placement, or in the middle of the room with 3dB attenuated increments to the low’s output — plus a broad midrange (50Hz to 1kHz) control to attenuate 0 to 6dB, and finally a high frequency level control that goes from a +1dB to –2dB around 2kHz and up.

One interesting thing on the rear panel is a 7-pin XLR connector that is used to bypass all the crossover, EQ, and protection circuitry so that a K+H controller (the Pro C28) can take care of all those controls digitally. This unit provides much more sophisticated control over all the input signal handling, digital conversion, etcetera. The Pro C28 runs about $5,000 — we didn’t get one to play with for this review.

After putting the speakers through a recommended burn-in period (pink noise @ 85dB for 72 hours), I collected a large collection of mixes from many disparate sessions — from Reason-y blip-hop to string quartets, tweaked out post-rock to Meters-esque funk, willowy folk bliss to angry chaotic skronk — and prepared for my initial day with the monitors.

From the very first note of the very first track, I had to scrape my jaw off the floor. These monitors blew me away immediately. They sound huge for such compact boxes. Every track I played was instantly stripped of its hazy outer layers — every track suddenly became much, much more that it was — either in a really good way or in a flaw-ridden, embarrassing way.

The bass came alive with a tight and natural clarity that was not exaggerated in any way. I guess it feels and sounds “right” or truthful. Wide and clear mids — beautiful full-range mids — and at the same time with some of my mixes: horrendous! . . . but vivid and 3 dimensional. The highs are seamlessly integrated and are not hyped at all. The entire spectrum is ultimately represented and absolutely pleasant to listen to.

Every sound issued from the K + H O 300 D’s took on a new life or afforded me a new perspective on that sound. You have to hear them for yourself. They are by far the best near-field monitors I’ve had the pleasure to use.

It’s depressing to have to go back to my normal monitors. It always is depressing to get used to something great and then have to give it back. I wish I could afford these things, then I wouldn’t have to give them back, but they go for about the same that I paid for my last car. The price is prohibitive. I understand the old adage, “You get what you pay for” but it’s still just unfair.