On the S&M CD, in the intros to One and Nothing else Matters, and also in the interlude during MOP (the background guitar, not the solo one) the guitar has a "bright, hollow ringing" noise. It's hard to put in words but just listen to it and you'll know what I'm describing. What hardware do I need to duplicate that sound (obviously not perfectly, but just generally). Are they using a flanger? I'm not too familiar with guitar effects yet.