Aerius in combination with active crossover

[djuke]

Hi all, my name is Menno from The Netherlands. For a hobby, I am designing and building audio related components for about two decades. In the past, some conventional loudspeakers, more recently audio electronics (DAC, preamplifier, mosfet amplifier, etc).

For a long time I wanted to try electrostats and last week finally bought a pair of Aerius. The sound is great, panels were replaced about 5 years ago. In my feeling the woofer is slightly more present than mids and high, so maybe some reduction of the panel efficiency is already happening. In due time a panel replacement or refurbishment might be needed, but what I would like to do first is similar to what I did on my DIY conventional loudspeakers. For it, I have designed a custom 2x2-channel Mosfet amplifier with an active crossover, so each input is splitted in low/high at the crossover and then amplified independently and connected to the woofer and midrange/tweeter independently. Only the midrange/tweeter combination has a small passive crossover.

I understand the passive crossover in the Aerius is set at 500 Hz, so this is probably also a good frequency for the active crossover. Then I want to bypass the passive crossover since that is not needed. Anybody having experience with similar setups?

 

[djuke]

For a couple of months, I still really enjoyed listening to the Aerius. Some reduction in the panels (compared to the woofer) was present though. I tried the shower trick, which gave noticeable increase in panel gain, but still some unbalance remained. I used my custom made 4-channel power amplifier to bi-amp the Aerius. By increasing the gain for the panel channels the balance was restored, but in the long run I was still considering to refurbish the panels though.

Then, I came across a second-hand pair of SL3s for a really affordable price. Having obtained some experience now where to pay attention to, I bought them after a listening test. These SL3s were in perfect shape with no noticeable unbalance, either left/right or low/mid/high. So I am very happy with the deal and still enjoy every minute listening to them (btw, the Aerius are now in use for the rear channels). At home, I had a look at the panel serial numbers, to get some idea about the production year, because they seemed newer than the speakers. The numbers are SS3GJ4##. I could not figure out the production year from the serial number PDF. Can someone help with that?