Pio Posted April 11, 2016 Share Posted April 11, 2016 (edited) hello, i am in the process of reduce the la scala mid horn level by 3db, as i read in other post i need a 15-20 ohms 10 watt resistor for retain the 13 uf cap value, now my question, are these adequate? https://www.parts-express.com/dayton-audio-dnr-16-16-ohm-10w-precision-audio-grade-resistor--004-16 or maybe this? http://www.mouser.com/ProductDetail/Xicon/280-CR15-16-RC/?qs=X6lXmupekPJ9RPx3p5JZmQ== i have here some Xicon of the same series, but 3.9 ohms and these reads 7.8 μH each one. this is too much? as i read needs to be non-inductive, but if not, how much inductance is the limit permissible? sorry about my poor english. best regards. Pio Edited April 11, 2016 by yo0 Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 11, 2016 Share Posted April 11, 2016 (edited) I believe the resistors you mention are good for the application. It appears you might use a few of the last mentioned one in series to get the correct resistance value; is that your thought? It is good. I read about "non-inductive" also but it is certainly mis-understood by most. It seems that you have measured values of a few (7.8) μH or micro-Henrys. That is far to small to have any effect at audio frequencies. At radio frequencies of millions of cycles it would be significant. If my math is correct there is a reactance of 0.49 ohms at 10,000 cycles. The voice coil of the driver and the autotransformer certainly contribute a lot more than that to the overall scheme of things. Klipsch used similar wire wound in their advanced crossovers. So don't worry, IMHO. WMcD Edited April 11, 2016 by WMcD Quote Link to comment Share on other sites More sharing options...
Pio Posted April 11, 2016 Author Share Posted April 11, 2016 (edited) I believe the resistors you mention are good for the application. It appears you might use a few of the last mentioned one in series to get the correct resistance value; is that correct? I read about "non-inductive" also but it is certainly mis-understood by most. It seems that you have measured values of a few (7.8) μH or micro-Henrys. That is far to small to have any effect at audio frequencies. If my math is correct there is a reactance of 0.49 ohms at 10,000 cycles. The voice coil of the driver and the autotransformer certainly contribute a lot more than that to the overall scheme of things. Klipsch used similar wire wound in their advanced crossovers. So don't worry, IMHO. WMcD yes, saddly the 3.9 ohms ones i mentioned are part of an array (dummy load), i think i go for the mouser ones, 15 watts instead dayton 10 watts, and as bonus Mouser ones are cheaper. thank you for your valuable comments best regards Pio Edited April 11, 2016 by yo0 Quote Link to comment Share on other sites More sharing options...
Matthews Posted April 12, 2016 Share Posted April 12, 2016 I don't know if it would be of any help? The Crites crossovers I have are equipped with an alternative -3dB lead. It is a simple as switching between the stock option and the -3dB wire. I know nothing about the values and such of resistors. I just know the alternate wire works well if I want to tame the mid horn a bit. The only thing I could offer is to snap a few photos of the crossover I have, if you like? Matt ♪ ♫ ♪ 1 Quote Link to comment Share on other sites More sharing options...
Pio Posted April 12, 2016 Author Share Posted April 12, 2016 (edited) I don't know if it would be of any help? The Crites crossovers I have are equipped with an alternative -3dB lead. It is a simple as switching between the stock option and the -3dB wire. I know nothing about the values and such of resistors. I just know the alternate wire works well if I want to tame the mid horn a bit. The only thing I could offer is to snap a few photos of the crossover I have, if you like? Matt ♪ ♫ ♪ thank you very much, i will like to see your crossovers, maybe there is another trick i dont know, but afaik if just move the tap the capacitor needs to be changed to another value to mantain the crossover frequency, for example to 6.5 uF, and with the resistor in parallel to the drive the original 13 uF capacitor can be mantained, so a resistor is cheaper than a capacitor. best regards Pio Edited April 12, 2016 by yo0 Quote Link to comment Share on other sites More sharing options...
Matthews Posted April 12, 2016 Share Posted April 12, 2016 thank you very much, i will like to see your crossovers, maybe there is another trick i dont know, The alternate -3dB lead I am talking about is at the top middle of the photo. The two red leads with black tape holding them together. Matt ♪ ♫ ♪ Perhaps some other can chime in... ? Quote Link to comment Share on other sites More sharing options...
Pio Posted April 12, 2016 Author Share Posted April 12, 2016 ah! ok are the Crites type A convertibles, very good! best regards and thank you very much! Pio Quote Link to comment Share on other sites More sharing options...
pzannucci Posted April 12, 2016 Share Posted April 12, 2016 (edited) The problem is when you change 3db on your auto-former, I believe you usually approx. double the impedance. To be able to use the same caps in the crossover, you have to add resistance across the line to bring the impedance back to an appropriate level for the capacitors to work correctly. The cheaper non-inductive resistors are usually OK across the line. If you are in line with the driver (like an lpad), the Mills wirewound are very good. Edited April 12, 2016 by pzannucci Quote Link to comment Share on other sites More sharing options...
djk Posted April 12, 2016 Share Posted April 12, 2016 The inductance of a suitable resistance for this application is trivial, don't even be concerned about it, Quote Link to comment Share on other sites More sharing options...
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