STV_Keith Posted June 24, 2003 Share Posted June 24, 2003 Hello. I have a pair of CF-4's I bought new back in 1996. An outstanding speaker, I've never had to touch them and they sound great. Until recently, I had always powered them off my Yamaha DSP-A1000 with only 80w/channel. I have recently purchased a Yamaha M-65 (which runs the highs) and a Yamaha MX-800 (which runs the lows). They are bi-amped - a nice feature with these speakers. Both amps are rated for 170w/channel with 2.7db headroom at 8ohms. First, in bi-amp wiring, are the high freq and low freq inputs 4ohm or 8ohm? Second, what kind of power should this setup take? The old specs said 300w continuous, so I'm assuming 300w total, or 150 on the high and 150 on the low. Is that correct. Also, where can I go to get a replacement K-30-KN woofer driver...I seem to have hurt one last night. It's rattling and buzzy now when playing. Thanks! Quote Link to comment Share on other sites More sharing options...
djk Posted June 25, 2003 Share Posted June 25, 2003 Unless you have removed the internal passive crossover and are using an electronic crossover, you are not bi-amping. People using two amps connected to the bi-wire terminals on their speakers are duo-amping. Alternately referred to as: fool's bi-amping. The speaker is under no more strain duo-amping than it was with one of the same amplifiers in uno-amp mode. Most modern speakers cannot be bi-amped properly without a lot of time and trouble. It takes someone with a lot of test equipment to do the job right. Call Klipsch about your damaged woofer, maybe they can re-cone it. Quote Link to comment Share on other sites More sharing options...
STV_Keith Posted June 25, 2003 Author Share Posted June 25, 2003 All of the internals are stock, so I must be duo-amping. Seems to work great in this capacity, other than the blown woofer. In duo-amp mode, is each input 8ohm or 4ohm? Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted June 25, 2003 Share Posted June 25, 2003 I would suggest borrowing a multi-meter and get an actual reading, other than just a published specification. Those are high quality Yamaha amps that you are using but 340W (170W + 170W) or more on peaks and dynamics to each speaker is a little overkill especially with an efficient speaker like Klipsch. I bet it sounds nice and clear though. Ease up on the volume control some or get some Klipsch Heritage speakers your ears will give out before the speakers do. Quote Link to comment Share on other sites More sharing options...
STV_Keith Posted June 25, 2003 Author Share Posted June 25, 2003 They are both rated at 170w RMS, with a dynamic of 255w for the M-65 and 270w for the MX-800. I know that's up there, but I don't have the gains up too much. I think having more power and turning the gains down sounds quite good on these things. I did run a meter on the inputs, but the readings were way out there...not sure what was going on. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted June 25, 2003 Share Posted June 25, 2003 djk BZZZZZZT! Incorrect answer. The CF4 crossover is on two boards, a high pass and a low pass. They are electrically separate. In stock configuration, the only connection between them is the external jumpers. (I took mine out of the cabinet and looked at them.) If you run two amps, you are in fact bi-amping the speakers. STV_Keith, Simply putting a meter on the binding posts and reading the DC resistance won't tell you a heck of a lot about the impedence characteristics of the speakers. You might try emailing Trey Cannon or one of the other Klipsch BBS hobbits, call tech support, or email customer service. I'm thinking you might have a hard time finding someone who knows what the individual impedence characteristics of the CF4 high and low sections might be. As to power, I seem to recall the speaker was rated for a max peak input of 1,000 watts (short term). In any case, I don't think you've got so much power you're going to hurt them. I'd be more worried about driving the M65 into clipping by trying to "see how loud they'll play..." and pushing some clipped signals into the horn, which might very well fry the tweeter. Quote Link to comment Share on other sites More sharing options...
JohnA Posted June 25, 2003 Share Posted June 25, 2003 Realistically, one 170 wpc amp is MORE than enough for a pair of CF-4s. Can you actually stay in the room with them when pushing one of those amps? If I were you, I'd run one amp, ebay the other and try bi-wiring. The speakers are properly set up for bi-wiring. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted June 25, 2003 Share Posted June 25, 2003 oh, forgot... regarding the buzzing woofer, it might be something as simple as a wire inside is close to or sitting on the backside of the woofer cone, and vibrating when playing. Pop the woofer that making the noise and check to see if there's anything inside that might be bumping against it. Be careful when removing / reinserting the woofers. It is extremely easy to strip out the screwhole and get all flummoxed up. Not that *I* ever did that, of course... Quote Link to comment Share on other sites More sharing options...
STV_Keith Posted June 25, 2003 Author Share Posted June 25, 2003 I originally wanted to run them off a single Yamaha MX-1000, but I've been unable to locate one. Those are rated at 270w/channel. The CF-4's were rated for 300w RMS/1200w peak, so I though this would be a good combination. I know my current hookup exceeds that, but it works well. Yes, I can be in the room with them, but they are very bright. The Yamaha's have level knobs from -infinity back to 0. I run the highs at around -8 to -10, and the lows around -6. Plenty of volume there...especially since this setup is just in my bedroom. Quote Link to comment Share on other sites More sharing options...
STV_Keith Posted June 25, 2003 Author Share Posted June 25, 2003 Thanks Ray...I did pull it out last night. Nothing loose. Pushing on the cone, I can't feel anything rub (like a voice coil binding). The woofer is a K-30-KN, retail of $199.82. OUCH! For now, I have just removed that one speaker and turned the gain up on the amp for the lows in that cabinet. At normal levels, almost can't tell it's gone. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted June 25, 2003 Share Posted June 25, 2003 oh, forgot again... John, the CF4 can suck an *ENORMOUS* amount of current out of an amp at low frequencies / high outputs. I was using an ADCOM GFA-555 (200 watt amp) for awhile on mine, and if I played something with train wrecks or explosions or cannons or other big boomy bass thingies in it, I'd light up the clipping indicators pretty consistently. For awhile I tried using two GFA-555s bridged in mono mode (600 watts), but it sounded sooooooooo bad (hard tinny thin bright etched piercingly shrill) that I never turned 'em up loud enough to find out if 600 watts was adequate. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted June 25, 2003 Share Posted June 25, 2003 then again, I'm the guy who melted the voice coil in a subwoofer rated at 75 watts by driving it with a 600 watt amp while listening to American Beauty playing in the den and cleaning the boat out in the driveway... Quote Link to comment Share on other sites More sharing options...
djk Posted June 26, 2003 Share Posted June 26, 2003 "BZZZZZZT! Incorrect answer." Hey Ray, you don't even have a clue as to what we are talking about. "If you run two amps, you are in fact bi-amping the speakers." When a child points at a dog and calls it a cat, and all the other children in his class at school start pointing at dogs and calling them cats, does that make the dog a cat? The fact is that after 50 years of using a frequency dividing network ahead of multiple amplifiers and defining that as 'bi-amping' a few people have hooked up multiple amplifiers without the frequency dividing network ahead of them. They just use a 'Y' cord to feed all the amplifiers. People that have done it the old-fashioned way call the new-fashioned way 'Fools Bi-amping", because the people that do it this way are fooling themselves if they think they are getting the benefits of bi-amping the old-fashioned way. Sorry if any of you fall into that group. ". I know my current hookup exceeds that, but it works well." It does not exceed 300W, in fools bi-amping the power does not add. It doesn't add in real bi-amping either, the voltages add, and power is the square of the voltage divided by the load impedance. Quote Link to comment Share on other sites More sharing options...
STV_Keith Posted June 26, 2003 Author Share Posted June 26, 2003 So are you saying that this setup is not pushing 170w to each cabinets hi freq and 170w to each cabinets low freq? I don't understand that, please explain. If I turn the low amp off or turn that channel down, that cabinet loses all sound. It would seem to me that if they are independent enough that turning off one amp stops all sound from the drivers which they are connected, and the other amp and drivers can be running independently, then how can you not have the sum of the power going to the cabinet? OK, I'm lost. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted June 27, 2003 Share Posted June 27, 2003 djk, Okay, I don't follow. If you take an active crossover, split the preamp output signal into two parts, one high frequency and one low frequency, feed those two signals into two different amps, and tie the output of one amp directly to the woofer and the other directly to the tweeter with no passive crossover components in place, you are certainly bi-amping the speaker. I agree with you completely on that. I don't follow why you consider the setup under discussion here (feed preamp signal into two separate amps, by using Y connector or whatever, then feed output of amp one to woofer crossover and other amp to tweeter crossover, where woofer crossover and tweeter crossover are electrically isolated) to not be a form of biamping. Certainly it is a less *EFFICIENT* form of biamping than active biamping, as the two passive crossovers are now dumping a lot (like, half) of the power being applied to them in the form of heat. However, you are still gaining most of the benefits of biamping. For example, if the signal has strong bass content, and you clip the amp driving the woofer, the tweeter amp remains unaffected. Also, if the tweeter and woofer have wildly different impedence characteristics (and with the horn loaded tweeter and the direct radiating woofer, I'd bet this is the case with the CF4), you have the ability to mate the best matching amp to each driver, using something that can dump a lot of current into the woofers, while selecting a (possibly) different amp that won't be bothered by the higher, and more varying, impdence of the tweeter. Also, the power outputs of the two amps would seem to be additive. If I have a 150 watt amp driving the bass, and a 150 watt amp driving the tweeter, and turn up the volume so each amp is outputting 150 watts, each component of the passive crossover (the high pass section and the low pass section) is fed 150 watts. We are dissipating (either as heat or sound) a total of 300 watts. If I replace those two amps with one 150 watt amp, and reinsert the straps between the binding posts, the crossovers are now dissipating a total of 150 watts. ? Ray Quote Link to comment Share on other sites More sharing options...
itsmyforte Posted June 27, 2003 Share Posted June 27, 2003 Ray, your explaination in the last post is correct. djk, english please, your confusing me. Quote Link to comment Share on other sites More sharing options...
djk Posted June 28, 2003 Share Posted June 28, 2003 Artificial Intelligence: Someone with a BS, MS, & PHD and still doesn't get it. "Ray, your explaination in the last post is correct." I hope you guys don't teach somewhere. "the two passive crossovers are now dumping a lot (like, half) of the power being applied to them in the form of heat" Bilge! ideal capacitors and inductors do not absorb ANY power, NO heat is generated. Where do people get these weird ideas? http://www.pesupport.com/cgi-bin/config.pl?read=125252 PWK liked using autoformers to avoid the use of a resistve pad. "Also, the power outputs of the two amps would seem to be additive. If I have a 150 watt amp driving the bass, and a 150 watt amp driving the tweeter, and turn up the volume so each amp is outputting 150 watts, each component of the passive crossover (the high pass section and the low pass section) is fed 150 watts. We are dissipating (either as heat or sound) a total of 300 watts" So, if I have no load on the amplifier how much power is is dissipating? Nothing? By having your dividing networks after the amplifier all you are doing is removing the load above or below the crossover point. If the amplifiers in quesion had regulated supplies then the sum of power of the two amps in 'fools bi-amping' would be identical to the one amp. The trap that catches most people is that music has more than one frequency at the same time. Imagine two notes played at the same time 'gasp'. 100hz and 1Khz mixed at equal levels at full output of a 200W/8R amplifier. This requires a 40V amplifier to produce two 20V tones at the same time. If I use a 'Y cord to connect two identical amplifiers together each will be reproducing this 20V + 20V signal right at the 40V clip level of the 200W/8R amplifier. If I hook an 8R resistor to each amplifier, each amplifier will be delivering 200W/8R. If I hook up two 8R with a 500hz crossover between them then each resistor only sees 20V with the amp clipping at 40V. If I hook one 8R and its high-pass (or low-pass) to one amplifier and the other half to the second amplifier then each 8R still only sees 20V with both amplifiers driven at 40V with the 100hz + 1Khz composite signal. If I put the crossover ahead of the amplifier then the gain may be increased until each amplifier puts out 40V on each tone. Power is proportional to the square of the voltage. I have doubled the voltage swing, thus I have quadrupled the power. "If you use an electronic crossover and bi-amp a speaker like a Klipsch Cornwall with a 50W amp on the bass and a 10W amp on the mid and hf it will play as loud as a 400W amp through the passive crossover.If you 'bi-amp' your Newform speakers with a 250W amp on the bass and a 160W amp on the hf without an elecronic crossover it will play as loud as the 160W amp would play running both.The 4:1 benefit for bi-amping is only there when the spectrum is divided ahead of the power amps and when the division point is near the mid point of the spectral distribution of energy.On a voltage basis the division occurs around 250hz.This must be weighted by the peak to average ratio so that the equal energy point for above and below the crossover is about 500hz.This is also affected by the slope of the crossover.For the example of the Klipsch Cornwall it has a 600hz crossover point.If the drivers were the same efficency then 50W + 50W would = 200W through the passive crossover.In reality the HF is 10dB more efficent than the LF so we only need 50W + 5W to = 200W.If the HF remains undistorted it will mask distortion from the LF amp driven slightly into clipping.This means that if we use a 10W HF amp with a 50W LF amp it would take 400W to play the same level undistorted through the passive crossover.If you 'bi-amp' your Newform speakers without an electronic crossover each amp will be receiving full range signal and will clip at the same point it did with only one amp hooked up to the speakers.It does sound different to do this, but make no mistake, you will not be getting the benefits of dividing the signal ahead of the amplifiers." http://www.audioasylum.com/audio/general/messages/164118.html Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted July 1, 2003 Share Posted July 1, 2003 *BUMP* Just wanted to knudge this back up the ladder. I'm still thinking about djk's last response, and I haven't figured out, uh, anything? yet... Anyone else have any thoughts on this? Quote Link to comment Share on other sites More sharing options...
itsmyforte Posted July 9, 2003 Share Posted July 9, 2003 its simple one amp feeds highs to the mid-tweet, and the other amp feeds the woofer. That is bi-amping. it doesn't matter if they have passive or active xovers. passive xovers eat power, unless there is no resistance in the networks. Quote Link to comment Share on other sites More sharing options...
djk Posted July 10, 2003 Share Posted July 10, 2003 "its simple one amp feeds highs to the mid-tweet, and the other amp feeds the woofer. That is bi-amping. it doesn't matter if they have passive or active xovers. passive xovers eat power, unless there is no resistance in the networks." If you don't understand the issues it might be best to keep quiet, otherwise you risk looking like the ID10T that you seem to be. I wish everyone had an oscilloscope and an electronic crossover so they could see and hear the difference. I've been doing this so long (30+ years) I sometimes forget there was a point in time that I didn't get it either. Quote Link to comment Share on other sites More sharing options...
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