Deang Posted January 28, 2017 Share Posted January 28, 2017 Nice work Carl! Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 On 1/28/2017 at 3:45 PM, Deang said: Nice work Carl! Thanks Dean. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 Question for the masses. As these were my first build, I sent them to Bob to run on his analyzer to be sure I wired them correctly. Somehow or another I got them right. He was also curious as to how these caps tested (which metered excellent by the way). When he ran them he noticed a 4-5 dB hump centered around 400 Hz. Any ideas? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 This is a typical response from an AA. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 This is mine. Both crossovers I built look the same. Quote Link to comment Share on other sites More sharing options...
mboxler Posted February 2, 2017 Share Posted February 2, 2017 If you reused the T3A autoformer, I believe it is set for -6db. The stock AA uses tap 4 of a T2A, I think, which is only down 3db. Maybe it is more of a dip then a bump??? Quote Link to comment Share on other sites More sharing options...
Deang Posted February 2, 2017 Share Posted February 2, 2017 What mboxler said - it's the T3A providing more reduction in squawker output than the AA T2A. Look carefully, it's a dip. Quote Link to comment Share on other sites More sharing options...
BEC Posted February 2, 2017 Share Posted February 2, 2017 Dean, look at the blue line. Yes it is attenuated more than the AA as we expected. What we did not expect is that before we see that additional attenuation, it went 5 or so db high at first right at 400hz. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 The extra attenuation might not be bad at the levels my brother listens to but the boost before the drop might be bad. Quote Link to comment Share on other sites More sharing options...
mboxler Posted February 2, 2017 Share Posted February 2, 2017 Probably a dumb thought, but can a metal-cased capacitor be placed that close to an inductor? I think it's okay for other capacitor types. It's almost as if the capacitor value is higher at lower frequencies. Quote Link to comment Share on other sites More sharing options...
BEC Posted February 2, 2017 Share Posted February 2, 2017 If that were a problem, we would see that as a change in the value of the inductor. We do not see that as we have a perfect tweeter curve. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 1 minute ago, BEC said: If that were a problem, we would see that as a change in the value of the inductor. We do not see that as we have a perfect tweeter curve. So the woofer and tweeter are perfect. If I understand correctly, they're exactly the same as an AA. The only thing different in the mid circuit is the different value of the autoformer and cap. There has to be some weird interaction between the two hasn't there? It has to be that or I've done something weird with component orientation. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 16 minutes ago, mboxler said: Probably a dumb thought No dumb thoughts. It has to be something. Quote Link to comment Share on other sites More sharing options...
BEC Posted February 2, 2017 Share Posted February 2, 2017 Question to myself. Could I be seeing something similar to what I saw on a crossover that Dean built some time ago? Quote Link to comment Share on other sites More sharing options...
BEC Posted February 2, 2017 Share Posted February 2, 2017 18 minutes ago, BEC said: Question to myself. Could I be seeing something similar to what I saw on a crossover that Dean built some time ago? Answer: No, that is not it. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 Just now, BEC said: Answer: No, that is not it. Well I'm glad we cleared that up Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 OK, Bob, you know for a fact that I know nothing about crossovers. When you change a tap on an autoformer (and cap) to attenuate a driver does the frequency plot stay relatively flat compared to stock (other than lower)? Quote Link to comment Share on other sites More sharing options...
BEC Posted February 2, 2017 Share Posted February 2, 2017 Yes, as long as the change is not by a large amount (like the case I was asking myself about earlier) depending on the type of crossover. This is complicated and one needs to read the thread (that I can't find right now). I hope that is adequately confusing. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 6 minutes ago, BEC said: Yes, as long as the change is not by a large amount (like the case I was asking myself about earlier) depending on the type of crossover. This is complicated and one needs to read the thread (that I can't find right now). I hope that is adequately confusing. OK, wracking my brain here. What would occur if I didn't get a good clean solder joint on one of the autoformer leads? There was a coating on them I had to scrape off in order to solder but what if I didn't make a good connection on one of the 3? I guess I would have had to make the same mistake on both of them though as the graphs are identical. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 2, 2017 Author Share Posted February 2, 2017 Autoformer leads mixed up? Quote Link to comment Share on other sites More sharing options...
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