jfmacken Posted January 11, 2005 Share Posted January 11, 2005 In order to attenuate the K55V driver you must drop it down one tap as well as install a resistor upon the drivers terminals. My question is: would a 15 ohm 10 watt resistor be suitable for this? I can not find a 16 ohm 10 watt resistor! Also, would backing off the K-77 two taps (to 1) shift the frequency response to the point of needing a new cap or resistor? Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 11, 2005 Share Posted January 11, 2005 The difference between 15 and 16 is, basically nothing. So you're okay. My recall is that the cap for the tweeter is between the "output" of the autotransformer and the tweeter. Therefore dropping the output level by going down a tap will not effect the crossover point of the tweeter. Gil Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 11, 2005 Share Posted January 11, 2005 The K55 driver is actualy more like 13 Ohms than 16 Ohms, so a 15 Ohm resistor would actually be better. You could also put a 100 Ohm 10 W resistor from tap #5 to #0. This will do the same thing. Moving the tweeter tap reduces the SOURCE impedance. Only changing the LOAD impedance will cause the crossover to shift. Depending on what you are trying to do, moving BOTH tweeter and squawker taps down one would be a good idea. It will keep thing in proportion. Al K. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted January 11, 2005 Share Posted January 11, 2005 Gil, We both said exactly the same thing in different ways at the same time! Neat! Al K. Quote Link to comment Share on other sites More sharing options...
WMcD Posted January 11, 2005 Share Posted January 11, 2005 I was wondering if Al and I have any disagreement here. Particularly regarding the tweeter issue. Nope, not at all. Technically, you have to look at the ALL the impedances in the loop. The amp is presenting a very low impedance, typically well below 1 ohm even without the autotransformer. But let's call it that. At the crossover frequency point, the cap and the tweeter have equal impedance of about 10 ohms, for a total of 20 ohms. That is their contribution to the loop. We'll say there is another 1 ohm from the driving impedance. Making it 21 ohms. Using a lower tap on the autotransformer to the circuit is going to just lower the effective input impedance of the loop to, for purposes of discussion, 0.5 ohms. So now the overall loop impedance is 19.5 rather than 20. That is, again, nothing. Gil Quote Link to comment Share on other sites More sharing options...
Hardhead Posted January 12, 2005 Share Posted January 12, 2005 Al-- Are you saying that I could attenuate an overly hot tweeter connected to one of the Type "B" networks you designed for the Cornwall/Heresy by simply moving the tweeter connection to the autoformer down one tap, and I wouldn't be shifting the crossover point of the tweeter or changing the overall impedance of the crossover? In other words, would the only thing that would change be the level of the tweeter? If the above isn't correct, what would I need to add/change in order to keep everything except the tweeter output level the same? I'm satisfied with the squawker and woofer output, but the K-77-M tweeters are too loud by about 3 dB. Thanks in advance for your help. Quote Link to comment Share on other sites More sharing options...
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