Look here!

My old "DELTA" dipole speakers are open baffles. The woofer systems covers the range up to 250 Hz and each use 8 Peerless 8" drivers.

The bass eq for the baffles

The mid on the picture is the ATC 3" dome, but these have since been substituted by the Focal 6W "Utopia" midrange drivers. 

The top range - from about 3.200 Hz - is a Hiquphone (in the picture). This driver has been replaced with the Monacor DT 252. I plan to find a better driver, and plan to buy the new Scan Speak Ring Radiator, when it becomes available. Air Motion Transformers have also been considered.

I've bought a set of the Greek Dynasonic PL-160 magnetostatics. They call it a ribbon but actually the diaphragm is a 12 um foil with an alu voice coil. This is placed in a quite powerfull neodym magnetic field.

Measurements shows a small peak around 2 kHz with a 100 dB/1W sens. XO should not be placed below 2kHz as it drops like a stone beneath this frequency. From 3 to 8 kHz it is ruler flat with a sensitivity around 97 dB at one meter/1 Watt (into 5 ohms with the two coils in parallel). A small drop and some irregularities can be detected around 8-12 kHz after witch the PL-160 comes back to level around the 97 dB.

Measured at 30 degrees the average sensitivity drops to around 95 dB/1 W.

Soundquality is what you would expect from a typically high end magnetostatic/ribbon. A lot of air and resolution in the higher octaves and really a sense of rightness and being there. At the same time the reproduction is less physically - read "heavy". There is a sense of lightness around the reproduction much different from what you typically get from a good dome.

Gated on axis (level not calibrated).

A passive XO should have been the way to use them, but right now I'm trying out digital X-overs and plan to cut very steep with 48 dB/oct at 200 and 2.000 Hz.

The gated frequency plot on the right is made with the PL-160 as comparison. As it can be seen the sensitivity is higher than the PL-160 which I know is around 98 dB at 2.500 Hz.

This project is a small full-range speaker implementing the new Danish Reen Ribbon (magnetostatic) for the range above 2 kHz. This unit is a prototype and the finished product should have been released in the beginning of 2003, but I do not think it will ever be realised. A pity, as this is a really fine unit.

The little Focal 5V-4211 is working in a 4 liter cabinet tapering to a small damped slot on the back.

Click for larger pictures

4 mm thick cork covers the front and top, with cut outs for the units.