Guru Loudspeakers » The QM60 http://guruproaudio.com Here's where you find pretty much all you need to known about the famous Guru QM10 and QM60 loudspeakers. Wed, 18 Jan 2012 14:39:29 +0000 en hourly 1 http://wordpress.org/?v=3.2.1 Introducing the QM60 http://guruproaudio.com/2008/11/qm60/ http://guruproaudio.com/2008/11/qm60/#comments Wed, 12 Nov 2008 16:23:55 +0000 admin http://guruproaudio.com/?p=188


“My ambition has never been to make loudspeakers that “create sound” for people chasing spectacular experiences. My ambition has only been to recreate the music caught on the recordings. I’m driven by my own curiosity towards these originals. I have found however, that in the long run, no coloring can compete with creating an opening to the true happening of the past, even in the aspect of being spectacular. It simply does not get more spectacular than opening up an uncolored window to the world of the recording.”
Ingvar Öhman, Head of R&D


The QM60 tweeter is a marvel in driver design. Its intrinsic high efficiency together with a crossover design that takes into account not only the shaping of the frequency response, but also the optimization of the impedance feeding the driver, minimizes the power compression as well as the distortion. On top of that, the speaker can handle many times the input power in the high frequency range, than speakers with normal 1” tweeters can.

The QM60 was originally designed as a laboratory instrument for a project researching the properties of human hearing. Reproducing the acoustic signals used for this project required a neutral wide-band speaker with accurate reproduction of timbre, taking into account and compensating for the inherent colourations in the stereo system itself, generated in the process of phantom projection. It also required a very low distortion as well as a capability to reproduce wave shapes with a very high accuracy. Although this speaker may seem over qualified for hifi-use, the very same properties that enables them to reproduce artificial test signals in the four domains timbre, dynamic, time and space, are to a high degree beneficial when reproducing signals as complex as music. The difficulties in reproducing music should never be underestimated. The nuances are not no be ignored no matter how small and delicate they are.

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The low and mid frequencies are handled by a single mid/bass driver. A single driver handling frequencies from below 20 Hz and up to over 7 kHz puts very high demands on such a device. Having to combine flawless mid range clarity also when complex music signals are handled simultaneously with long stroke action in the low frequency range makes such a driver even more difficult to design. Consequently many unusual properties and design features have been incorporated into this unit. The crossover design offers similar benefits as the filter for the tweeter, together with an intrinsic efficiency designed to increase with frequency in order to keep the heating of the voice coil to a minimum helps achieving this class leading driver design.

By using titanium in the bobbin, the heat distribution is controlled and the eddy-losses in the low frequency range are eliminated. Other extraordinary features are the use of aluminum core copper wire for the voice coil, double vented dust cap cavity and a distortion controlled undercut pole piece to linearize the force factor. A short circuit ring is implemeted in the magnet system to linearize both dynamic force factor and the position dependent inductance. The membrane is acting as a true bend wave transducer in the mid band, and the dust cap (made out of SPN) forms a midrange dome above that. The rubber surround is non-aging.

Technical Specifications

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