ESL High Voltage Supply Mod

moray james · « **on:** 5 Jul 2005, 02:14 am »

The following is a simple and cost effective modification for any ESL speaker which has insulated stators be they wire or perferated metal/plastic. The mod envolves inserting a large value choke in series with the high voltage supply just ahead of the panel connection. The choke should be a wide bandwidth one with low internal capacitance. DCR and voltage rateing are not really an issue here. A multi chamber choke (6) will work best as will a series of small chokes physically separated and wired in series. A value of 10 Henry's is excellent.
What the choke does? Well the choke damps the diaphragm. This is how this works. The stator dielectric (insulation) acts like a capacitor and stores charge. This dielectric stored charge can then AC modulate the charged diaphragm. When the diaphragm is modulated by the stator dielectric the choke damps this AC component.
The end result will be a significant improvement to the speakers bass/mid response. Everything will be cleaner and clearer. The speaker will sound more dynamic. This is not one of those "I think I may hear a difference mods" this is very easy to hear. I cannot imagine anybody hearing this mod and wanting to remove it after.
What this mod really suggests is that ESL's should be built with non insulated stators.
For those more interested in argueing about how things cannot work rather than trying to see how they work for themselves you can look into the discussion at DIYAUDIO. While I can give you no assurance that this theory is accurate I can tell you that the results are impressive. Best regards Moray James.

woodsyi · « **Reply #1 on:** 6 Jul 2005, 02:52 pm »

Hello,

I am totally new at this ESL and I just backed into a pair of Soundlab A5 (slightly smaller than A3. I had the transformers sent to Soundlab and they upgraded the power supply (switching power) and the torroids were already upgraded a few years ago. Would these speakers benefit from chokes? I don't know if these are insulated or not. Thanks for the ESL infos.

moray james · « **Reply #2 on:** 6 Jul 2005, 07:40 pm »

The Sound Labs are insulated stator designs and so would benefit from this simple modification. I would recommend that you find some small one Henry chokes and build up a composite ten Henry choke. If you build just one to try it out then you can charge both speakers from the one modified supply to see how you like things. If you use a low quality choke with high internal capacitance you will not be able to hear what this modification can really do. So rather than waste your time build a good choke or buy a good multi chamber choke and enjoy. Best regards Moray James.

woodsyi · « **Reply #3 on:** 6 Jul 2005, 08:06 pm »

Would 6 Hammond 156R open chokes in series (9 Henrys) do? How far apart should these be physically? Would closed chokes of same value be better than open ones?

moray james · « **Reply #4 on:** 6 Jul 2005, 10:41 pm »

The Hammond 156R chokes should make a good quality composite choke. I would set them up with minimum space on a board with each choke set at 90 degrees to the next to minimize any field coupleing. Please let us know what you hear and enjoy. Best regards Moray James.