Heil AMT tweeter on top. It took a lot of effort to get them into the Seventies Stereo World Headquarters building. So far, I know that all 4 woofers were replaced with genuine ESS parts a few years ago, that the midrange drivers need refoaming, and on firing one up, there is only sound coming from the woofers. I will open them up soon...could be connection problems, could be crossovers. I love a challenge and after my last ESS experience, I can't wait to hear these.