paully Posted July 5, 2007 Share Posted July 5, 2007 I got to say that for a company that prides itself on the fact thatits speakers are so effecient, the fact that they won't publish animpedance curve on any of the speakers is a bit disheartening. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted July 5, 2007 Share Posted July 5, 2007 The answer is that the impedance varies with frequency. Here is a link that has what you are looking for......graph of impedance on one of the Klipsch Heritage networks. You need to look at the "Universal upgrade". Scroll down and you will see a graph of impedance vs. frequency. Everything you heard at my house (except the heresys) was using ALK engineered networks that had a constant impedance across the whole fequency band. I believe in the 6 Ohm range. http://www.alkeng.com/ Quote Link to comment Share on other sites More sharing options...
paully Posted July 5, 2007 Author Share Posted July 5, 2007 I understand that impedance varies, that was why I was curious about the minimal impedance which matters more from a low powered amp perspective than nominal. Interesting site, I will look through to see what they have for Chorus II crossover, if anything. Quote Link to comment Share on other sites More sharing options...
paully Posted July 5, 2007 Author Share Posted July 5, 2007 Now that you mention it though, I didn't realize that impedance could be made to work so directly as a function of a crossover network. That is interesting, there is still a lot to this I don't understand. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted July 5, 2007 Share Posted July 5, 2007 Al's networks are popular with tube guys since they do present a constant impedance. You can also see the accuracy of response of his filters. Klipsch's approach has been to add EQ or balancing to their networks to shoot for the flatest response out the horn. Impedance varies as you now know. Al's networks have no EQ. Quote Link to comment Share on other sites More sharing options...
pauln Posted July 5, 2007 Share Posted July 5, 2007 Keep in mind that impedance matching is only important when the most power needs to be delivered. With music, this is in the range of 125Hz to 500Hz, centered about 250Hz. In this range the La Scalas (and most other Klipsch) are about 8 ohm and this is why they are rated nominally 8 ohm overall. 250Hz is about middle C, 125-500Hz is the range an octave below and above middle C... Variation in speaker impedance can cause a frequency response variation, more so with amps whose output impedance is high (tube amps), and more so with direct radiators than compression horns; which is why some tube amp users sometimes prefer a flatter speaker impedance curve or use horn loaded speakers. The mechanical loading nature of compression driver horns almost completely compensates potential frequency response variation potentially otherwise due to variations in speaker impedance. The tube and horn combo often will provide a very flat frequency response in spite of an elevated and or varying impedance curve in the mids and high end. Flat speaker impedance has additional advantages for tube amps with output transformers in helping stabilize the load line slope of the output tubes. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted July 5, 2007 Share Posted July 5, 2007 If you heard the stock Klipsch networks at my house instead of what I had in those speakers.....I do not believe you would have the impression you have now. Remember this. This is why I kept mentioning the networks during your visit. When you finally score your trophies you may be surprised about the results until you play with the networks. The heresys you heard were recapped stock networks and are up to spec. The rest were all ALK networks. Remember how I told you how much I paid for the speakers....then how much for the networks? There is an important reason for that. Edit: Ha...just realized Pauln is not Paully. Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 5, 2007 Share Posted July 5, 2007 http://forums.klipsch.com/forums/permalink/243775/243775/ShowThread.aspx#243775 Here you can see the curve of the industrial lascala. It is different from the home version in that it uses a slightly different woofer. I have not seen any for the Chorus II. Gil Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 5, 2007 Share Posted July 5, 2007 I've not seen any impedance respones for the Chorus II published. The guys at Klipsch are pretty cool about sharing that info though (at least on discontinued models)...you should give Klipsch a call: 1-800-KLIPSCH I'm in process of expanding my acoustical measurement rig and the next thing on my list is to obtain the means to measure impedance. I own Chorus II's and would have no problem sharing the measurements once obtained. My goal was to have it done before the end of summer. Keep in mind that impedance matching is only important when the most power needs to be delivered..... Flat speaker impedance has additional advantages for tube amps with output transformers in helping stabilize the load line slope of the output tubes. I don't think I would word it that way... A varying load impedance can change the frequency response of the amplifier. Basically, the amplifier gets a boost wherever the speaker has a rise in impedance. You could lay an impedance response on top of a frequency response to get an idea of the most dramatic worst case possibility for change. (talk about ugly). The magnitude of the change is going to depend on the output impedance of the amp....higher is worse. The damping factor is directly related to output impedance, so you can get an idea through that spec too. The reason we associate low output impedane with "stabilization" is because the impedance of the speaker also changes with the music you pump through it...so with a low output impedance amplifier, it's like you've got a kid wiggling an EQ knob. The other advantage of using a low impedance to drive a high impedance is that the wire connecting the two doesn't affect the frequency response. As you move the two closer, the characteristic impedance of the wire starts to matter more... Anyways, the impedance of the speaker is going to tell you the maximum output impedance of the amplifier before wierd stuff starts happening. And I agree, it should be something advertised on the website. Quote Link to comment Share on other sites More sharing options...
Deang Posted July 6, 2007 Share Posted July 6, 2007 The mechanical loading nature of compression driver horns almost completely compensates potential frequency response variation potentially otherwise due to variations in speaker impedance. The tube and horn combo often will provide a very flat frequency response in spite of an elevated and or varying impedance curve in the mids and high end. Neither of these things is true, in fact, the exact opposite occurs. The following is from an old Stereo Review test report for the Chorus. "The speaker's impedance varied widely, from a minimum of 4 ohms at 140 Hz to a maximum of 70 ohms at 2100 Hz. There were smaller peaks of 40 ohms at 26 Hz and 28 ohms at 75 Hz, and there was a dip to 5 ohms at 52 Hz. By conventional rating methods, it is a 4-ohm speaker, although its impedance is well above that value over most of the audio range. In view of this, its 8-ohm rating seems reasonable." Quote Link to comment Share on other sites More sharing options...
mas Posted July 6, 2007 Share Posted July 6, 2007 The mechanical loading nature of compression driver horns almost completely compensates potential frequency response variation potentially otherwise due to variations in speaker impedance. The tube and horn combo often will provide a very flat frequency response in spite of an elevated and or varying impedance curve in the mids and high end. Neither of these things is true, in fact, the exact opposite occurs. The following is from an old Stereo Review test report for the Chorus. "The speaker's impedance varied widely, from a minimum of 4 ohms at 140 Hz to a maximum of 70 ohms at 2100 Hz. There were smaller peaks of 40 ohms at 26 Hz and 28 ohms at 75 Hz, and there was a dip to 5 ohms at 52 Hz. By conventional rating methods, it is a 4-ohm speaker, although its impedance is well above that value over most of the audio range. In view of this, its 8-ohm rating seems reasonable." And that conclusive observation of a "widely" varying impedance response pertains to, and effectively rebuts the assertion that "the mechanical loading nature of compression driver horns almost completely compensates potential frequency response variation" how? The impedance my vary "widely", but it provides no necessary relationship to the frequency response within the context of the quoted statement. [] And with that wry observation I will now run away, as I have little interest in, or knowledge of, the Chorus. [] But then, I am still pondering just what the original question regarding the efficiency of a speaker has to due with the nominal impedance, assuming a relatively benign load of between ~4-16 ohms... Should I feel disheartened? Quote Link to comment Share on other sites More sharing options...
paully Posted July 6, 2007 Author Share Posted July 6, 2007 When running a speaker with 2-9 watts, both effeciency and sensitivity matter a great deal. Having a speaker around 96db or above and an impedance curve that doesn't actually dip much below 6 ohms, most certainly not below 4, is key. Wanting to know what the minimum impedance of a speaker I have never heard seemed reasonable to me, if not even being able to see the impedance curve itself. Quote Link to comment Share on other sites More sharing options...
DrWho Posted July 6, 2007 Share Posted July 6, 2007 I can't think of anyone that has good results running a Chorus II with under 10 watts, but I suppose some of them are gonna prove me wrong since I'm posting this... Nevertheless, I would go for over 100W (mostly for the damping factor that comes with it). Quote Link to comment Share on other sites More sharing options...
paully Posted July 6, 2007 Author Share Posted July 6, 2007 Not me! Heading the opposite direction. The La Scalas would be optimal for SET from what I understand, and I might get a pair, but I think that if 2 watts was able to comfortably run the Heresys, Cornwalls, La Scalas, and Khorns that I heard it is a fair chance that 8.5 watts will run the Chorus. I guess we will just have to see! No insult intended, but I do hope you are wrong... If not I can always dump them for what I bought them for and get a pair of La Scalas, they are just in such high demand that they are hard to come by around here. Quote Link to comment Share on other sites More sharing options...
paully Posted July 6, 2007 Author Share Posted July 6, 2007 I hear you. It seems that the Chorus speakers are one of the least modified of the group. I imagine that is because they are newer and had a shorter run. More gets done to a pair of speakers that have a run of 30 years compared to 6-8. Quote Link to comment Share on other sites More sharing options...
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