Alexander Posted October 29, 2018 Share Posted October 29, 2018 I have a pair of woofers that are the same part number and are sounding fine. I measured them both and while the dcr is the same (5.8xohm) I got 1.57 vs 3.0x mH 50hz-1khz. I realize that the DATS software has questinable accuracy but the differance in the values is repeatable. Would this not be a concern? Can't do anything about it right now but maybe I should look for alternative(s) in the future? Quote Link to comment Share on other sites More sharing options...
Panelhead Posted October 29, 2018 Share Posted October 29, 2018 That is large. The same Dcr indicates the winding matches. There may be a difference in the magnet structure. Quote Link to comment Share on other sites More sharing options...
Wirrunna Posted October 29, 2018 Share Posted October 29, 2018 Alexander, you have found yet another variable in the interaction between speakers and passive crossovers that certainly raises concerns but may or may not be audible. Do the cross over networks have Zobel Impedance Equalization Circuits? I suspect that the Zobel is sometimes deliberately left out as the speaker sounds better without it or else it is just to save a few dollars.. Here is a link explaining Zobel networks - http://audiojudgement.com/impedance-equalization-circuit-zobel-network/ and here is an online calculator http://diyaudioprojects.com/Technical/Speaker-Zobel/ Quote Link to comment Share on other sites More sharing options...
Alexander Posted October 29, 2018 Author Share Posted October 29, 2018 24 minutes ago, Wirrunna said: Alexander, you have found yet another variable in the interaction between speakers and passive crossovers that certainly raises concerns but may or may not be audible. Do the cross over networks have Zobel Impedance Equalization Circuits? I suspect that the Zobel is sometimes deliberately left out as the speaker sounds better without it or else it is just to save a few dollars.. Here is a link explaining Zobel networks - http://audiojudgement.com/impedance-equalization-circuit-zobel-network/ and here is an online calculator http://diyaudioprojects.com/Technical/Speaker-Zobel/ These are Klipsch items and there isn't any Zobel circuit in the oem xover. Not sure how one would "add" this to an existing (Klipsch) xover , without effect it in some way. Quote Link to comment Share on other sites More sharing options...
Wirrunna Posted October 29, 2018 Share Posted October 29, 2018 Well, you could add the Zobel directly across the speaker terminals with alligator clips and listen and measure to see if there was any difference. ALK ES designs take into account the woofer inductance - https://community.klipsch.com/index.php?/topic/32872-new-extreme-slope-crossover-requiring-no-zobel/ Quote Link to comment Share on other sites More sharing options...
pzannucci Posted October 30, 2018 Share Posted October 30, 2018 12 hours ago, Alexander said: These are Klipsch items and there isn't any Zobel circuit in the oem xover. Not sure how one would "add" this to an existing (Klipsch) xover , without effect it in some way. The zobel network will modify the impedance of the driver / zobel pairing. This will have an interaction on the crossover point and slope since it will remove the rising impedance that occurs in the circuit. It may help to reduce a deviation that is occurring between the two speakers but that deviation may not be that noticeable with the current system. You may need to modify the crossover to compensate for the change also. Quote Link to comment Share on other sites More sharing options...
Wirrunna Posted October 30, 2018 Share Posted October 30, 2018 8 hours ago, pzannucci said: The zobel network will modify the impedance of the driver / zobel pairing. This will have an interaction on the crossover point and slope since it will remove the rising impedance that occurs in the circuit. It may help to reduce a deviation that is occurring between the two speakers but that deviation may not be that noticeable with the current system. You may need to modify the crossover to compensate for the change also. Agreed, and I like ALK's comment - " The significance of the impedance matching really relates to the performance of more complex filters. A simple 6 dB / octive filter can operate into anyhting. It's all over the place anyhow! A more complex filter, even a 12 dB / octave, starts require a good terminaiton to act as it should. " This is from a post in the thread I linked to above. So, if the woofer crossover is a simple 6 db (a single inductor in series) then don't worry about the impedance variation Quote Link to comment Share on other sites More sharing options...
WMcD Posted October 31, 2018 Share Posted October 31, 2018 Are these Klipsch woofers?? Maybe one was reconed in any case. WMcD 1 Quote Link to comment Share on other sites More sharing options...
Alexander Posted October 31, 2018 Author Share Posted October 31, 2018 9 hours ago, WMcD said: Are these Klipsch woofers?? Maybe one was reconed in any case. WMcD possible, these are a neighbors t-400's that I was re capping and thought I would messure the drivers while I had them out. Quote Link to comment Share on other sites More sharing options...
Alexander Posted October 31, 2018 Author Share Posted October 31, 2018 On 10/30/2018 at 7:13 AM, pzannucci said: The zobel network will modify the impedance of the driver / zobel pairing. This will have an interaction on the crossover point and slope since it will remove the rising impedance that occurs in the circuit. It may help to reduce a deviation that is occurring between the two speakers but that deviation may not be that noticeable with the current system. You may need to modify the crossover to compensate for the change also. Quote Agreed, and I like ALK's comment - " The significance of the impedance matching really relates to the performance of more complex filters. A simple 6 dB / octive filter can operate into anything. It's all over the place anyhow! A more complex filter, even a 12 dB / octave, starts require a good terminaiton to act as it should. " This is from a post in the thread I linked to above. So, if the woofer crossover is a simple 6 db (a single inductor in series) then don't worry about the impedance variation this xo has an inductor in series and cap in parallel across the driver so I believe that should be a 12db / octive, The owner of these t-400's probably won't want to do anything more than the re-cap. Just wanting to learn more about these things. Thanks you gents for your replies. Quote Link to comment Share on other sites More sharing options...
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