notboating Posted September 8, 2014 Share Posted September 8, 2014 I recently acquired a pair of 1982 La Scalas. They have the AL-3 crossover networks that I replaced the caps in using a Bob Crites kit. I'd like to test the network to make sure that I did everything correctly. On a side note, while listening today, after about 10 minutes a strange hum began and as soon as I heard it i got up and went to the stereo (12 feet from me) to turn it off and when I got there it had peaked and then just stopped. I couldn't tell if it was from 1 or both speakers. No smoke or odor, nothing that I could easily pinpoint. At the time I was listening to a TV concert. TV signal to McIntosh C-28 pre-amp sent to a pair of Dynaco Mk III's then to the La Scalas. New to forum, ther is a lot of la scala information here and a few searches yielded a ton of results but nothing I thought was in the right direction. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Daan Posted September 8, 2014 Share Posted September 8, 2014 Time to check things from the beginning; search for loose cables, or other visible damage in your install. I highly doubt this could occour from changing caps.... Quote Link to comment Share on other sites More sharing options...
Deang Posted September 8, 2014 Share Posted September 8, 2014 Yes it can. Quote Link to comment Share on other sites More sharing options...
notboating Posted September 8, 2014 Author Share Posted September 8, 2014 I'll start looking at connections. Everything was pretty firmly attached when dissembling and reassembling. Can I put a meter on the caps to check them? DeanG is there something you recommend? Quote Link to comment Share on other sites More sharing options...
Deang Posted September 8, 2014 Share Posted September 8, 2014 It went away, right. Over the years, I've had two customers tell me that when they fired their systems up after installing the crossovers that a "howling sound" followed, which then dissipated. You can use a meter to check for cold solder joints - put the leads on the joints and then tap or wiggle the leads - if the number jump - you have a bad joint. As for the noise - I have no idea. I was just glad it went away. : ) Quote Link to comment Share on other sites More sharing options...
notboating Posted September 8, 2014 Author Share Posted September 8, 2014 Yes it went away. It was a lower frequency, started low, increased linearly to a peak and then quit. did not get loud or painful. If I find a bad solder joint how to I check the cap to see if it is good or if it needs replaced. Replaced 7 caps in each XO. Quote Link to comment Share on other sites More sharing options...
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