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Infinity Quantum Line Source

Four Way Loudspeaker System (1977)

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Infinity Quantum Line Source


From top to bottom, from highs to lows, the Quantum Line Source represents a radical departure in speaker design - an important new direction for Infinity and for the industry.

The Samarium Cobalt EMIT (Electromagnetic Induction Tweeter) is utilized in a multiple configuration 125 centimetres high forming a true line source; producing a deep fan shaped wavefront of high frequency energy; and resulting in excellent horizontal dispersion to all points where listeners might reasonably sit or stand to listen.

Another line source, in the midrange, is made up of six high definition ventilated 3.8 centimetre dome drivers. This unusually
treated grouping has been designed with careful attention to phase and acceleration capability.

The phase coherent midbass coupler, which is transmission line loaded, handles the frequency range in which half of all musical fundamentals lie (200 to 600 Hz), and we have provided a driver that can speak with absolute authority there.

The bass driver is the revolutionary Infinity Watkins Dual Drive Woofer. This brilliantly conceived, patented woofer with two voice coils exhibits an impedance curve that is virtually flat. It reproduces bass frequencies with unmatched accuracy, power, and lifelike presence - in the Quantum Line Source, to 18 Hz.

The Quantum Line Source, has, in fact, opened up all frequencies to previously unheard of levels of power, cleanliness, and three dimensional depth.

This is very probably the most musically accurate speaker ever made.


Type: 4 way, 10 driver loudspeaker system

Frequency Response: 18Hz to 32kHz

Recommended Amplifier: 100 to 500W

Crossover Frequency: 200, 600, 4000Hz

Bass: 1 x 300mm dual voice coil

Midbass: 1 x 100mm coupler

Midrange: 6 x 38mm ventilated dome

Tweeter: 2 x EMIT

Dimensions: 1680 x 460 x 380mm

Weight: 86kg

Year: 1977


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Reviewed Aug 28th, 2017 by howardhudson

These speakers WILL test your amplifier's current capacity and power supply rails. I run mine in a biamplified setup, and there really is no upper limit to the power you can throw at them.
The bass from these speakers is unstoppable, and the dispersion and staging from the EMIT tweeters is simply amazing. They also have an uncanny ability to reveal details at both high and low volume listening.
If you have a chance to listen to these speakers, plan to spend some time A/Bing amplifiers to find the right match for your speakers. With some good iron in the amplifiers, these speakers truly sing. If you throw an inadequate amp at them, the sound will likely be thin, and unimpressive. Take your time, try different designs and manufacturers, and be amazed.
Hat tip to Arne Nudell for an amazing loudspeaker design and to Infinity for putting it all together.

Reviewed Apr 25th, 2016 by baggman

All drivers are still available. Still sounds great.



re: Quantum Line Source


re: Quantum Line Source

I just bought a pair of QLS-1's. would you be willing to share your Docs?


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