paully Posted July 20, 2007 Share Posted July 20, 2007 Sorry for all of the questions (I am new to Klipsch, I know). But I am going to be building my amplifier in the next few days and I need to know if I should build it using the 8 ohm or 4 ohm tap. It saves hassles later. I did a search and there was some response to the effect that one probably should use the 4 ohm tap. Just wanted to see if anyone else concurred. Quote Link to comment Share on other sites More sharing options...
leok Posted July 20, 2007 Share Posted July 20, 2007 4 Ohm (2 Ohm if you can). Chorus-II doesn't need much Voltage, but the impedance swings are better controlled with lower impedance amp outputs. Both of my tube amps are set for 4 Ohm (and I still prefer the ss Crown or pwm on the Chorus-IIs because they ignore the high impedance peak in the midrange). Bear in mind: my amps have no feedback so output impedance is higher than that of feedback amps. If your amp is a feedback type I'd still go for 4Ohm out, but would expect reasonable handling of the mid high impedance peak .. better than the no feedback types. Leo Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 20, 2007 Share Posted July 20, 2007 I agree - go with the 4ohm tap. Quote Link to comment Share on other sites More sharing options...
paully Posted July 20, 2007 Author Share Posted July 20, 2007 No negative feedback. But I will put it on the 4 ohm tap and see how it goes. Quote Link to comment Share on other sites More sharing options...
Deang Posted July 20, 2007 Share Posted July 20, 2007 You will want to try it both ways. Also, with a zero feedback design, you might also want try a swamping resistor on the amp's outputs. Quote Link to comment Share on other sites More sharing options...
leok Posted July 21, 2007 Share Posted July 21, 2007 Dean, Good point. I found another way to limit impedance excursions and damp parasitic oscillation also: place a damping resistor on the input side of the output transformer. Not as easy as the output method, but I found more effective. I can look up the value if anyone's interested. That approach is on my SET amps. I'm in process of revising the pp amps and may install it there too. In any event, good point, I had forgotten that I also find damping resistance of some kind a plus when dealing with large speaker impedance variations. Leo Quote Link to comment Share on other sites More sharing options...
paully Posted July 21, 2007 Author Share Posted July 21, 2007 Not sure how I would even go about that or what values I would use. Quote Link to comment Share on other sites More sharing options...
leok Posted July 21, 2007 Share Posted July 21, 2007 On my pp amps I've had a 29 Ohm 2W resistor across the speaker terminals (in parallel with the speaker). Those amps have only the one 4 Ohm output. It's probably a good idea to try adding a damping resistor there first. If you like the general affect you can try resistance (several 10s of KOhms if I remember correctly) on the transformer primary. I'll look up my notes and post some sample values. Leo Quote Link to comment Share on other sites More sharing options...
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