We used to upgrade speakers all the time at our shop. Both consumer and professional speakers. We would add a super tweeter to Bozaks 305's 4000's, 4005 and a short line array of super tweeters, to 310B and 410's. JBL, we would re-cone the woofers and up date the midrange horn or tweeter horn diaphragm. We would pull out the old bullet nosed ring radiators and install the latest models available. We might have to rebuild a crossover too. Altecs might need the 803B woofers replaced with better performing 416 models. 806 drivers with 802. If they kept blowing diaphragms we would go with the heavier tweeter diaphragms which rolled off starting around 12 KHz and add either MR 902 16 HF tweeters or the Altec UHF 950 ring radiator made for the Japanese market. EV was always an issue, because the T-35 and T-350 were so fragile. Klipsch had the same issues. later on we would use some of Klipsch more advanced tweeters to replace the old T35/350 tweeters in EV speakers. Georgians, Model 6 and Patricians. Mac ML and XR series were a challenge at first, but Mac came up with new tweeters from Phillips. Roger designed a crossover up grade for some ML models and XR models so Morell drivers could be used. Making a ML1 as strong as or stronger than a ML 2 down to 50 Hz. XR-7 that have been up graded are so much better. Contact Audio Classics for ML &. XR series upgrades. Altec 604's could be improved by re-coning and adding the latest most advanced diaphragms. Some times cross overs need to be rebuilt and supplemented. I loved the idea of a Paragon, but the original bullet tweeter was an instant turn off. I always wanted to hear one with the last of the most advanced ring radiator as a replacement. We used to combine Altec with the big drivers and the heavier diaphragms with JBL ring radiators, what an improvement. We would install Emilar drivers on Altec sectorial horns for the same reasons. I would like to hear some Corn walls and Corner horns with Bob Crites up dated tweeters and crossovers, too. Consumer brands like Boston, RTR, AR, KLH, Epicure, Celestion, Snell, Jensen, B & O, etc, we just had to hope they had a solution, maybe a new driver or an improved crossover etc. Bose was the most frustrating because their speakers were always perfect. Give me a break! Frazier was easy to work with. We never sold paneled speakers that often. 3 or 4 pair maybe a half dozen KLH model 9's were it. We would go to shows and listen to Magnapan, Acoustat, and Appogee, etc and we passed. our competition passed also. I re-coned a lot of Cerwin Vega. and replaced a lot of Heil accordian diaphragms, but never made any upgrades. Some times we would change a Klipsch consumer woofer for the professional model which would take more power. JBL was always upgrading their products as did Altec. It was a continual race and keeping up with model changes and which replacement parts could be used for best performance was a continual struggle some times. We didn't bother with Japanese speakers that much. Yamaha NS series was pretty well liked, Marntz were less well accepted. I liked some Tannoy, but they were to Pricey for are market. The competition sold B&W successfully. I never had to repair one. We fixed everything else they sold one time or another. There are so many brands that came along in the consumer market that I never saw because by the 80's. I was totally involved in the professional business and only rarely had to deal with consumer stuff. Then just before I retired I got involved with HT, Loved M&K speakers. I owned a set in fact. Never had a driver fail and we sold the stuff by the tons it seemed. I am glad they are back in business even if they moved over seas to Denmark.
