KLS 3--Radical re-design

[Guy Pettigrew]

You may remember a thread about upgrading the crossover components in my KLS 3s after Peter Comeau had replaced my piezo tweeters with SEAS millennium ones.

After the rebuild a friend of mine who has been designing and building 'speakers on an amateur basis for 40 or so years suggested trying out some modifications to the crossover circuit. Despite being a bit unsure I made some tentative changes. Seemed reasonable, as the crossover could easily be put back to its original spec. And if you never try, you never know! The result was the bass and mid sections of the crossover remained the same, but the tweeter section was reduced to just one 4.7uF capacitor in series with the drive unit.

And this is how it remained for a couple of years, other than rebuilding the mid range enclosure to ensure it was airtight.

Last Friday things changed hugely. My mate had persuaded me to become a bit more adventurous and had offered to come round to guide me in trying other ways of configuring the 'speakers.

We spent several hours trying all sorts of things. He had the easy job of making the suggestions. I had the hot and sweaty job (it was nearly 30C that day!) of crawling around behind the 'speakers to put components in and out of the circuit. Fortunately all the crossover components are on a board on the back of the cabinets.

The end result was almost entirely different from where we started. The tweeter still has the 4.7uF capacitor in series, but that's where the similarity ends.

Are you sitting down? The bass and mid drivers are now wired in series with no crossover components at all! This has significantly improved the bass control, the imaging, punch and timing of the KLS 3s.

It may be because the amps, WAD 300B PSEs, like the higher impedance presented to them. Or it may not! All I know is it sounds much, much better.

Guy