505 ESL Panels

DIY anyway you like

Yes, we’ve made some more changes to the 505 panels. After gaining a lot of experience with the 505 panels and listening to suggestions from end users we have made further changes to the 505 panels. The gap between the diaphragm and the stator has been increased by 50% allowing the panel to deliver lower frequencies. The EHT supply has increased output to accommodate this change and to maintain the same sensitivity (more or less). This allows the panel to take advantage of the revised transformer with a low frequency response down to 150Hz, this makes matching the panel with a bass driver / sub-woofer easier.

Due to customer requests we have discontinued the direct plug in banana sockets and 12v connector that were mounted on the board, instead we have installed screw terminals. This makes internal connections easier and less costly for the constructor. Output to the panel is via a header plug and socket.

The rear connections on the earlier panels were a bit flimsy but were the only connectors that would go through 2 layers of stators. So, we’ve changed the stators to accommodate terminals with 2 pins to make them more sturdy and now have a solder through link to connect the front stator to the rear screw connector. The panels carry their own surface mount filter resistors, this has 3 benefits. First there are no wires leading to the front of the panel making for a neater installation, Second, due to the resistors now being on the panel there are only 3 wires leading to it. Third, we have installed more sturdy screw connectors for the wires so there is no soldering to be done at the panel end.

As we had to re-design the stators while we were at it we added a second internal charge rail, this is what transfers the bias voltage to the diaphragm. While one charge rail works very well we now had the ability to create another rail on the opposite side of the panel, this ensures charge gets on the diaphragm evenly.

As well as the change to rear connections we have provided connections at the top of the panel that require a short link to the next panel when stacking. Again, these links are only necessary on the rear of the panel.

The power supply board was also redesigned to accommodate a PCB mount transformer with a 30% thicker core. This allows the transformer to go to lower frequencies before saturation sets in.

Some rearrangement of the circuitry gave us sufficient room to provide a space for an on board inductor so those that are using a passive crossover can choose either a first order or second order filter and mount the inductor on the board instead of off the board in a less convenient position.

The same improved electronics remain and provide room for a high quality on board crossover capacitor and an adjustable bias voltage for the panel. This features a 25 turn trimpot so the voltage applied to the panel can be very finely adjusted. Protection for the panel from over-driving or accidental spikes is provided by a series arrangement of VDR’s (Voltage Dependent Resistors) across the panel. These are essentially out of circuit until they conduct and have no effect on the sound but will shunt the signal when the cut off threshold is reached.

Rob from Australia has had good success using an SB Acoustics Satori bass driver and a single 505 panel, follow this link to see what he has achieved.

The panel is supplied ready built with assembled and tested electronics, you only have to connect the panel to the power supply and provide music. You do have to solder the connecting wires to the plug that plugs onto the power supply board as we can’t predict how long you want to make them, however, this is an easy task.

What does it cost?

What do you get? 

2 x ready built and tested ESL panels

2x power supplies

2x step-up transformers with a first order filter to prevent bass being applied to the panels

2 x regulated 12vdc multi region mains adaptors.

The transformer and power supply are ready assembled and tested. This is truly a connect it up, provide power and play some music system!!

For those that are after something a little different we can supply ready made 505 panels without the power supplies to enable stacking of multiple panels without the additional cost of multiple unnecessary power supplies. See below for suggested applications.


For those that are after something a little different we can supply ready made 505 panels without the power supplies to enable stacking of multiple panels without the additional cost of unnecessary power supplies.

Typical applications are for rear or side home theatre effects, centre channels for home theatre, 1 or 2 panels can be placed horizontally to suit the size of the screen. Addition to a large flat screen TV  (this gets you away from the typically poor sound quality most TV’s have).

 A single ready to use 505 Mini ESL Panel without a power supply?   What does it cost?