euphemismos
New Member
Greetings everyone. I'm a longtime reader, but just posting today for the first time. I recently acquired a pair of HPM-60's. According to the date codes, one is from 1978 and the other is from 1979 (which would make them the later, "Mark II" versions). The mid range and tweeter have white trim resembling the HPM-100's. Both seem to be working fine as far as I can tell. However, although they look identical at first glance, it turns out there are some differences between them. I find it curious and I'm wondering how significant this may be. The numbers on the components are different on each speaker and magnet sizes appear slightly different. The super tweeters look identical from the front, but are different on the back (and one is flush mounted while the other is sunken). Also, the crossovers look mostly the same, but have 2 components that are different. On top of all that, one has a grill with a painted wooden frame while the other is hard black plastic. I must admit, it's been a bit of a let down because now it seems that I have a mismatched pair. Date codes (YD & ZK) are stamped on the back, but the YD/1978 also has the serial number stamped, whereas on the ZK/1979 the serial number is printed on a plastic sticker (it also has a "U" on the end). It's surprising to me that Pioneer made so many changes in the span of less than a year, and I'm hoping that some of you may have some thoughts or insights regarding these differences.
