Bonzo Posted October 8, 2005 Share Posted October 8, 2005 I just picked up a nice pair of Forte' I's in walnut oil. They are clearly marked as 4 ohm on the crossover plate. My last pair of Forte's were 8 ohm and the Klipsch specs say they are 8 ohm. Is this perhaps an early pair or late pair or??? I guess the crossovers would be a little different but what about the drivers? I haven't pulled the drivers out of the cabinet yet. I generally like to leave them alone unless they need fixing. Any help would be appreciated. Mark Quote Link to comment Share on other sites More sharing options...
Rivendell61 Posted October 8, 2005 Share Posted October 8, 2005 Mark, I've got the 8 Ohm version.... In fact, Trey responded to this question explaining that they are all the same. Fortes were labelled 4, 6, or 8 Ohm--depending on how Klipsch was describing the spec: 4 Ohm is minimum 6 Ohm is average 8 Ohm is 'nominal' Mark Quote Link to comment Share on other sites More sharing options...
Bonzo Posted October 8, 2005 Author Share Posted October 8, 2005 From one "hair lip dog" to another, thanks. It is still a little confusing to me why they would label the same model speakers with different nominal impedence. I don't know of any other manufacturer that does that. It could certainly cause some confusing when matching amps for multiple speakers especially when using the A and B speaker outs. Impedence curves become pretty important even though most modern amps can handle it. Some manufactueres caution against multiple speakers rated at less than 8 ohms, could void the warranty if something happens. Maybe I am over thinking this? Quote Link to comment Share on other sites More sharing options...
Number 9 Posted October 8, 2005 Share Posted October 8, 2005 Look for the Stereo Review 1986 Forte review scanned here recently. The speakers have a WILD impededance swing. ALK has made that comment a few times before too. They drop to as low as 3.7 Ohms at one point, and hit a peak around 130. Thank god they are effecient, but certainly not an easy load for an amplifier. Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 8, 2005 Share Posted October 8, 2005 I wonder how the chorus II's and cornwalls compare in regards to the impedance... is there an easy way to measure this? (I have access to some cool labs in school with all sorts of fancy equipment). Quote Link to comment Share on other sites More sharing options...
Rivendell61 Posted October 8, 2005 Share Posted October 8, 2005 The Hirsch SR 1986 review has them going from 4 Ohm min (I've seen the 3.7 quoted before--not sure if it might be from another source?) at 150HZ, up to max of 130. His review of the Chorus in Feb. 1988 (which would be a 'One') gives it a 4 Ohm min at 140Hz, and a max of 70. He says overall an 8 Ohm rating is reasonable. For the Cornwall II, look at this great site: http://www.belgaudio.com/kcmap.htm A web site devoted to the Cornwall II. Scroll down to bottom of linked page and click on 'Impedance frequency response'. At bottom of that page he gives a simple impedance plot--and says 5 ohm is min, at both 20 and 100Hz. [Edit--looking at the plot it seems more like a peak at 20Hz.....] Mark Quote Link to comment Share on other sites More sharing options...
j-malotky Posted October 8, 2005 Share Posted October 8, 2005 Guys You have to remember one thing. In the old days before high powered amps were built with dampening factors of 200 or more, you use to have to set your amp taps to the lowest ohm setting that your speakers would draw to keep the amp from overheating. Im sure this is why they put 4 ohms on some of the speakers as this would be the best setting to use on a tap block. There is no good way to measure ohm draw, as it is dependent on the frequency of the sound wave. If you are in the crossover range, your signal will be going to two of the drivers. Also depending on the combination of sounds at one time, and what that draw is at that one moment in time.... etc.... etc. That is why they put on an average of the driver components. Example, the K33 woofer has a 4 ohm draw. The K55 has a 16 ohm draw. Average is 8 and why the label reads 8 on most heritage speakers. But because the K33 is 4 ohms, I set my vintage McIntosh amps to the 4 ohm tap to get the most out of my system. JM Quote Link to comment Share on other sites More sharing options...
Number 9 Posted October 8, 2005 Share Posted October 8, 2005 Such a wild swing in impedance seems like poor design to me. Please correct me if I am wrong. Makes it a more difficult load for an amp to manage and will result in wide variation in sonic performance from one amp to another. Most speakers today are being designed to have a much more benign load. Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted October 9, 2005 Share Posted October 9, 2005 it seems Klipsch ignore a lot of factors like this , to get the Highest Eff. rating .. this hold s true, think, for drivers, crossovers as well it's a big reason a lot of the drivers run full range on the top, like the mid horns throw a cheap woofer in the mix .... and you've got a impedance dip Quote Link to comment Share on other sites More sharing options...
DrWho Posted October 9, 2005 Share Posted October 9, 2005 Correcting for an impedance swing is a "fix" that most people won't be able to tell the difference when purchasing the speakers. BTW, it is easy for an amp to drive a 100 ohm load...it's the smaller loads that give amps a hard time. The smallest impedance you can get is zero which would be shorting out the cable...the reason it is hard on the amp is because there is a lot of current flowing which causes it to overheat (if overheating wasn't a problem then the amp could drive a short all day long). At 100 ohms there is way way less current flowing into the device. If you think about it, a really high impedance indicates that the driver is extremely efficient because it takes very little current to produce the force needed for the same SPL's. There are fancy crossovers out there that can make the amplifier see a constant 8 ohm load through every frequency while also maintaining the correct balance between drivers....but these things cost money and would increase the overhead of the speaker (which means they cost more to us). If you honestly want to have your speakers sounding as good as possible, then that means you should be willing to spend more money on them....so instead of klipsch spending the money, why not mod them yourself and tailor the finer tweaks to your own situation. This approach makes the speaker cheaper for those that won't notice the small performance increase, and makes the speaker something great to mod with (because it's not good enough to where we can't hear performance increases and the tweaker inside each one of us is going to enjoy it more). Quote Link to comment Share on other sites More sharing options...
Number 9 Posted October 9, 2005 Share Posted October 9, 2005 DrWho... I think that is what ALK has been doing with his xover networks (redoing for a flatter impedance curve). However, I don't think an ALK for the Forte would be something he would find worthwhile doing ... even with the venerable Cornwall, there was limited demand. I wish I had bookmarked the quote last night, but I came across an article on speakers where the writer was suggesting that a very wide swing in impedance can, with some amps, make speakers sound a little brittle. I wonder if that is why some find Forte bright? I've never felt that to be the case (I use McIntosh), but perhaps with some amps, that may explain what is going on. Quote Link to comment Share on other sites More sharing options...
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