Review : Klein + Hummel O500C digital active studio monitors

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My new speakers arrived about 2 months ago and I thought that maybe there is some interest in first impressions.
It took me about 9 months and the lecture of lots of technical papers about speakers, speaker design and room acoustics, one book and more than one
speaker review until the decision for the bumblebees (Hummel in German) were made. You may ask why consider room acoustics when buying speakers. The answer is simple :
speakers and the room interact. Everything that the room adds (resonances, reflections, reverberation) is not present on the sound carrier and
therefore not desired. Within the critical distance we have resonance and, depending on placement, reflection effects, outside that distance additionally reverberation effects.
Consequently, a good speaker should interact as little as possible with its environment, so some knowledge of how this interaction looks like seems
useful. Important parameters in this context are directivity, critical distance, and off-axis response.

First some facts :
- 920 Watt amplification per channel
- drivers are from PHL, ATC and Seas, X-overed at 520 and 2,800 Hz with about 100 db/octave
- 3 pre-set FIR-filters to choose from (LLL : all way linear-phase, MMM : all ways minimum-phase, MLL : bass minimum-phase, mid and high linear-phase)
- IIR-based room-EQ
- 10-band IIR-based EQ with different EQ-shapes and Q's to choose from
- 65 kg each, 75x40x46 cm (h, w, d), comes with a 36-button remote control and 64 pages manual, price about 8,800 EUR (about 7,600 USD) per unit.
Response is flat (Â±1.5 dB) from 30 Hz to 20 kHz, drivers are perfectly time-aligned (step- and impulse response).
The speakers are connected (balanced analog input) to one of the tape output of my integrated amp by microphone cable + Neutrik connectors. They are
interconnected via their MIDI-interface as to have master-and-slave configuration. The room-EQ is set to -4dB for the bass because of placement
on the floor, all other settings are at flat.
The overall sound is neutral, very clear and very clean even at highest sound levels, and highest means 130 dB at 1 m.
What strikes immediately is the very deep, powerful and clean bass, even with bass-EQ set to -4 dB. Setting bass-EQ to zero gives more bass
(obviously) but then it sounds a bit blown-up.
Deep bass notes like from pipe organ are perfectly sustained without any wow. On some records I can now hear some rumbling noise that I never heard before. Set the lower cutoff frequency higher and the rumbling disappears.
Some piano recordings sound as if the piano has been covered with blankets, one waits that the sonic curtain is pulled away, really not nice. Obviously these speakers not only show every detail present on the recording but also every flaw.
What is further striking that one can listen at highest levels without feeling the desire to lower the volume, on the contrary, adding some more dB is no problem at all.
What still amazes me is the absolute clarity of the sound, no signs of muddying up even on highly charged symphony orchestral works.
The speakers are spaced some 2 meters apart with a leather armchair placed inbetween and about 70 and 50 cm from side wall and system rack. Distance
to rear wall is about 20 cm. 2 meters is a bit on the short side and with the current placement of system and furniture an equilateral triangle is not possible. Distance of listening place from speakers is about 2.5 m. The "sweet spot" sits two persons.
The position of musicians is well defined, the soundstage has depth. The room is acoustically unsymmetric and first reflections are not treated so I think that some improvement might be possible.
The FIR-filters : I compared the LLL (80 ms group delay) and MMM (15 ms group delay). The differences are subtle, the MMM gave the impression of being somewhat clearer, brighter, the imaging a bit more focused. Positions of musicians changed a bit in depth. CD used was "Sanctuary 1" by Windham
Hill.
A further quite interesting parameter that can be adjusted is the lower cutoff frequency. It can be set to 30, 40, 50, 60, 70 or 80 Hz. A shift
from 30 to 40 already has audible effects when playing tracks with deep bass, no matter if classical or rock music. The bass loses a bit of its "body", becomes a bit thinny. This effect is obviously more pronounced when setting the cutoff to higher values.
This exercise clearly shows the effects of the low-frequency extension of speakers. 10 Hz more or less makes an audible difference. 50 Hz speakers
seem acceptable unless you hear what you are missing.
The sound of studio monitors is often said to be uninvolving, sterile etc. This may be true for those who are used to the sound of hifi speakers. For me the good old goosebump-tracks still work.

Klaus

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Topic - Review : Klein + Hummel O500C digital active studio monitors - Klaus 02:18:46 03/25/02 (1)

Re: Review : Klein + Hummel O500C digital active studio monitors - Rex Mills 09:23:47 03/25/02 (0)

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