last update: 05-feb-2006.

The Contrapunt is a DIY dipole subwoofer. 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 project from 1980, with four 15"woofers per channel in a 2 meter (40") cabinet.

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. 

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 shows 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.

Last project, 2001, was the transcription of the first LP from New York Rock & Roll Ensemble to CD. Also eight miles high by the Golden Earring. First the LP was recorded 24bit/96kHz, restored, and then written to CD.