A long time ago, about ten years, I was in a small recording studio that had a speaker that looked like my 604's but was much bigger, it sounded fairly harsh as I recall and was used as a near field monitor in large cabinets, as I remember they were about 5.5L X 3.5W X 2.75D and hanging from the ceiling directly in front of a mastering board that had hundreds of knobs and switches. This small studio on lake ontario did record some well known acts as I recall, one that I remembered was a band called "Bush" that had some success. So my question is did Altec or another company make an 18 inch coax that looked very similar to 604's?
