Welcome to the Audio Page of Geert Meddens!

last update: 28-sep-2019 .

The Contrapunt is a DIY dipole subwoofer for the Quad ESL-63. It has a remarkable natural bass. For years I have been building enclosures for bass, without realizing that I it is possible to drop the idea of an enclosure. This different approach to bass reproduction has several specific advantages. There are less standing waves generated in the listening room, because the bass produced by a dipole is directional. It goes deep, because the resonance frequency of the woofer is not shifted upwards by the enclosure.
Two 12" woofers are used for a frequency range from 26Hz to 110Hz, within 3dB.   The subwoofer can be combined with all kind of speakers but it is optimized for use with the Quad ESL-63. Despite the dipole principle, the sub woofer can deliver a powerful extended bass in a living room of 60 m2.

The large speaker is a Eddie Verkroost project from 1980, with four 15"woofers per channel in a 2 meter (40") cabinet. Best loudspeaker I have ever heard.

The ESL-63 page gives information about this legendary loudspeaker. There is a collection of pictures of the different parts of the interior. Graphs of the very low distortion, frequency characteristic (sine wave) and impedance can be found here.

On the miscellaneous page are among other things links to other dipole subwoofers. The  design from John Forasiepi uses four NHT1259's in a compact configuration with a dipole  direction pattern.  And a link to a page with the names of the people I went to school with.

Programming the low cost CY7C68013A development board: as a cheap USBi interface to be used with Sigmastudio

List of some music

The current presentation of waterfalls is not optimal. Scale could be 60dB instead of 30 dB and the z-axis cycles instead of fixed time. The interesting thing of a cycle-normalized waterfall is, that for any given frequency, the tweeters response time is the same IN CYCLES. It sws more details. Two examples are shown, one with TC 120Tdx placed on a baffle with FronTex. The second graph is a set with the Scan Speak revelator 2905/9900.

Maintenance manuals not on the page: Marantz 43,53,63 SE, Marantz PM-16, Philips MFB 545 motional feedback monitor, Philips MFB 544, Quad 44, Quad 34, linn sondek lp12 valhalla circuit diagram scheme.

Philips 8 channel mixer LBB 1149 service manual

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