Hi, @bruce19 I started modifying speakers when I was a store manager at CMC Stereo. I visited the audiophile shops in the St. Louis area regularly. We had a retail store called SpeakerCraft that custom built speakers. In 1980, I took a job as General Manager at SpeakerCraft, we had a division called Marcof Electronics, we built Moving Coil head amps, cables, modified cartridges, tables and built several Amps and Preamps..
It was there that I established a fairly in depth knowledge of Speaker Design. I had a good enough foundation that over the years, I was able to expand my knowledge to a complete understanding of speaker design. The owner there had and still has a full knowledge, but when I left, I just hadn’t absorbed it all yet. I have done hundreds of repairs and builds in the past years, even here on Audiogon, I have done several modifications, a couple of repairs and a couple of designs for members. In my Listening room, I currently have an MTM with 6.8 inch woofers and a dome tweeter, I have a 3 way with a paper cone 10 inch woofer an aluminum 5 inch mid and a ribbon tweeter, I have a pair with the top end Heil AMT with a 12 inch woofer and I am currently enjoying a 15 inch woofer and 1 inch dome in a 2 way. These speakers are 86 db 4 ohm, 87 db 8 ohm, 94db 8 ohm and 95 db 5 ohm. So, that’s the best I can answer, what kind of speakers I build... As far as professionally building. My 15 inch 2 way turned out so radically good and most audiophiles would not believe a 15 and dome to be able to sound as it does, that I truly explored going into manufacturing. I bought domains, registered a name, but no shows, my industry contacts are as old or older than I am or worst... Dead. So, recently I bailed on that Idea.