richieb Posted February 14, 2016 Share Posted February 14, 2016 So I have a pair of nicely designed amps with 4, 8, 16 Ohm speaker connections. I know I will probably be told to try all three for best results but with stock K33 woofs and K55 mids which rating should be followed. Xovers are ALK extreme slopes. I have followed this scenario with my 16ohm ZU's using the 16 taps and indeed they sound better. Technically what is the KHorn recommendation? Quote Link to comment Share on other sites More sharing options...
Coytee Posted February 14, 2016 Share Posted February 14, 2016 I always used 8 but that's out of habit if nothing else. (certainly no specific technical knowledge on my part) Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 14, 2016 Share Posted February 14, 2016 In order to avoid having to re-EQ your Khorns, the lowest output impedance tap setting should be used. However, I see a lot of people using their amps for EQing (albeit without much control over what's happening other than pushing the bass performance up and down). A plot of the Khorn's input impedance from Richard Heyser's Khorn review of 1986. Your amp should have lower output impedance than the minimum input impedance of the Khorns in order to avoid the re-EQing issue: Quote Link to comment Share on other sites More sharing options...
richieb Posted February 15, 2016 Author Share Posted February 15, 2016 Thanks Chris The EQ thing is way beyond me and any/all equipment required. I appreciated the graph but i have no way interpret it. I'm gonna give the 4 Ohm setting a try. Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 17, 2016 Share Posted February 17, 2016 As the electrical input impedance of the loudspeaker (varying with frequency) begins to drift toward the value of the output impedance of the amplifier (usually constant), the amplifier begins to "couple" to the loudspeaker crossover (or in the case of direct-coupled drivers--the driver itself). This means that the amplifier begins to act in a nonlinear fashion, and its output no longer linearly changes with its input voltage signal. This means that the amplifier starts to drive the loudspeaker at those low-input-impedance frequencies (as shown in the plot above--the bass bin frequencies) more, thus unbalancing the equalization of the loudspeaker. One way to handle it is to re-EQ the amplifier and loudspeaker together so that the output is flat with frequency. However, as the crossover network and the long loudspeaker cables begin to heat under load, the resistive portion of the impedance begins to grow (Ohmic heating), thus reducing the output of the loudspeaker again at those low impedance frequencies (i.e., the bass below ~400 Hz). Another way to handle it is to simply reduce the output impedance of the amplifier by using the lowest impedance tap of the output transformer so that the amplifier's output impedance remains at least 10 times lower than the loudspeaker's input impedance at all frequencies. Then the loudspeaker-amplifier can be re-EQed, and it will remain stable under high load conditions--it's stable with load and temperature. Chris Quote Link to comment Share on other sites More sharing options...
mark1101 Posted February 17, 2016 Share Posted February 17, 2016 ALK ESNs are swamped (designed) to produce a virtually constant 6-8 ohm impedance to the amplifier (which comes from the impedance of the woofer). You should use the 8 ohm tap when using ALK ESNs. You can go read how to use these type of networks here. www.alkeng.com Quote Link to comment Share on other sites More sharing options...
garyrc Posted February 17, 2016 Share Posted February 17, 2016 So I have a pair of nicely designed amps with 4, 8, 16 Ohm speaker connections. I know I will probably be told to try all three for best results but with stock K33 woofs and K55 mids which rating should be followed. Xovers are ALK extreme slopes. I have followed this scenario with my 16ohm ZU's using the 16 taps and indeed they sound better. Technically what is the KHorn recommendation? Ask ALK? Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 17, 2016 Share Posted February 17, 2016 https://community.klipsch.com/index.php?/topic/32872-new-extreme-slope-crossover-requiring-no-zobel/ I'd use the 4-ohm tap since he's claiming 6 Ohm across the loudspeaker--not 8. In any case, you should hear little or no difference at all with the 4 or 8 ohm taps on your amplifier(s). Chris Quote Link to comment Share on other sites More sharing options...
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