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New member Username: ConfuseddavePost Number: 1 Registered: Jul-04 | Hey there; I have a Denon AVR-1802, I'm currently using as a 3 speaker setup mainly for music; a pair of TDL Nucleus 2's and a Gale Centre 10. My speakers are biwirable, and I've heard this can improve sound quality, and my Amp has twin outputs; so I'm thinking of trying and seeing the improvement. The only thing is I'm paranoid of blowing up my system (I'm a student and can't afford to replace it!) So my query is this; what does biwiring do to the Impedance of the speakers? The TDL's are rated at 6-8ohms; my amp reckons A or B at 6-16ohms per channel and A+B at 12-16ohms per channel. Would biwiring the speakers give me 4 speakers at, like, 2ohms each, or do they stay at 6-8? If they split, is it even, or does the woofer have a different impedence to the tweeter? Would you recommend bi-wiring on both channels, just one channel, or not bothering? Cheers for your thoughts. |
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Silver Member Username: SoccerPost Number: 236 Registered: Apr-04 | Those impedance limitations on your amp are telling you not to bother biwiring, 'cause the design is not made for real biwiring, but rather adding 2 more speakers in series to the system. Don't even try it. |
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Silver Member Username: KeggerMICHIGAN Post Number: 889 Registered: Dec-03 | dave the impedance will stay the same so their is no fear of blowing your system. the way impedance works on speakers is each individual driver "woofer/midrange/tweeter" has it's own impedance. so say your speakers are rated at 8 ohms. now when you play bass it goes to the woofer which is 8ohms and when the music/amplification sends out treble it goes to the tweeter which is 8 ohms and so on. so when a speaker is rated at 8 ohms that means when a given frequency is played it's load to the amp is 8ohms. you only change the impedance when more than 1 driver plays the same frequencies. take a 3way speaker, it has a crossover in it which sends the bass to the woofer the midrange to the mid and the treble to the tweeter. all biwiring is doing is 1 pair of wires is going to the woofer crossover and the other one goes to the mid/tweeter crossover.in a 2 way it's woofer and tweeter. now after all that it doesn't mean that biwiring will definatly give you a benefit in sound. it may so go ahead and try if you like. |
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Silver Member Username: SoccerPost Number: 244 Registered: Apr-04 | Warn us when you blow teh amp |
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Silver Member Username: KeggerMICHIGAN Post Number: 906 Registered: Dec-03 | joao ferreira why do you say that? |
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Silver Member Username: SoccerPost Number: 251 Registered: Apr-04 | Because they must have a reason to limit the impedance to 12-16 ohms per channel when using A + B lh and rh channels. When using either A OR B lh and rh channels, the minimum is 6-8 ohms. Funny, that's half the impedance of 12-18. To me, lh channels of A and B drivers are in series, when current is sensed on both drivers, same for rh channels. A real biwiring capability has ALWAYS biamping capabilities, meaning FOUR drivers are always available, to be used or not. |
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Silver Member Username: SoccerPost Number: 252 Registered: Apr-04 | I may be wrong, but I wouldn't bet the amp on it. |
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Silver Member Username: KeggerMICHIGAN Post Number: 910 Registered: Dec-03 | joao ferreira i think you got it wrong. in theory both sets aren't driven at the same time. you will only have an 8ohm load on either channel at 1 time. say a 20hz signal is played it will only go through the woofer "8ohm load to the amp on 1 channel" say a 20k signal is played it will only go through the tweeter "8ohm load to the amp on 1 channel" in theory that should be how it works. but even if speakers didn't work like that "which they do" if you had 4 speakers at 6 ohms that would still be 12 a side if it's in series anyway. so i don't see the problem. |
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Silver Member Username: KeggerMICHIGAN Post Number: 911 Registered: Dec-03 | but you are right to question it. and to be for sure he should probably contact the manufacturer to see how the reciever is wired. and get their awnser.to be positive. |
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Silver Member Username: SoccerPost Number: 254 Registered: Apr-04 | Keeger, Dave wrote specifically 12-16 ohm PER channel when driving the 4 outputs... But yes, he should contact the Manufacturer Enjoy |
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Silver Member Username: KeggerMICHIGAN Post Number: 916 Registered: Dec-03 | how the heck could you have 12-16 per channel and be in series. that would be 24-36 total on each side. that would also mean his speakers have to be 12-16 ohms each? they probably mean you add the 2 speakers per "side" together to get 12-16. as in 4 speakers would be 16ohms a side "if they were all 8 ohm speakers" but like i said your not really using a+b because you are biwiring. you well get the frequencies below the crossover point on 1. and above the crossover point on the other. technicaly you are using a or b because neither will have 2 drivers at the same frequency. |
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Silver Member Username: KeggerMICHIGAN Post Number: 917 Registered: Dec-03 | woops! "that would be 24-36 total on each side" should have been 24-32 total on each side |
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ssphoto Unregistered guest | Boooom!!! |
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New member Username: Nobig423Post Number: 3 Registered: Apr-04 | I believe Dave is asking about bi-wiring, not bi-amping. In bi-wiring, both sets of wires would originate from the A speaker outputs of the Denon. They would separately terminate at the speaker on the tweeter and woofer posts respectively. If you mean bi-amping, that is a completely different matter. |
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Gold Member Username: KeggerMICHIGAN Post Number: 1188 Registered: Dec-03 | regardless of how you do it the impedance will stay the same. anyone who disagrees should read up on how speakers work. as i said earlier if you don't send more than 1 driver the same frequency the impedance will not change. thats what xovers are for! thats what they do. whether you biwire or not. |
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Anonymous | Bi Wiring is probably not worth the effort anyway. If you have passive crossovers what possible good can it do (apart from do away with the crappy bit of steel connecting the terminals) You can get the same results by running a decent piece of wire between the binding posts. Bi wiring is just a cheap imatation of bi amping. Don't bother it's not worth the effort! |
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Silver Member Username: Rick_bNew york Usa Post Number: 392 Registered: Dec-03 | Kegger is right. There will be no change in impedance. Bi-wiring can give improved sound quality for the cost of a second set of cables. Bi-wired arrangements work to keep the heavy LF return earth currents away from the HF section of the crossover reducing or eliminating modulation distortion. |
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Silver Member Username: SoccerPost Number: 261 Registered: Apr-04 | Ok, let's if I get myself through. I think when the manufacturer says minimum imp. must be 12-16 ohm when using BOTH sets, they're saying the amp will put A-LEFT and B-Left in parallel, as well as the right side, meaning to get an overall (seen by the amp) imp. of 6-8 ohm, the speakers should be 12-16 ohm (12||12=6 and 16||16=8). There's no high's or low freqs. issued here, that division will be made on the speakers's xovers. Therefore, when using only one set, the imp should be 6-8 ohms. Simple as that. As someone said early, it's biwiring issue, not a biamping one. Of course all this depends on the amp's output design, but it's much cheaper to build amps like this than to prepare them to biamping, which is what Keeger is thinking about. Sorry if I can't be here as often as I wanted. Enjoy |
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Silver Member Username: SoccerPost Number: 262 Registered: Apr-04 | Also when the manufacturer of the speakers say they're biwirable, they mean they can be biamped (or biwired, IF your amp's up to it, which is not)However, there could be some aftermarket impedance matching circuits. I still think if you biwire them like that, your amp will run much much hotter and blow sooner or later, or at least enter protection mode. And note, some designs don't allow protection mode to be reseted, and then the manufacturer (or a suitable technician) would have to replace the thermistors and realign the current bias of the output devices's prestage drivers. |
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Gold Member Username: KeggerMICHIGAN Post Number: 1220 Registered: Dec-03 | joao ferreira your still missing the point. if he takes the biwire jumpers off the speakers and uses both sets of outputs "biamping" the impedance will not change. because one set of amps has a speaker on it from the mid on up. and the other will have one on the bass speaker. so neither one is playing the same frequencies as the other. so their will not be 2 drivers sharing frequencies so they will not be in paralell to drop the impedance. that is the low of speakers and how their impedance work in a xover. if their were no xovers and the speakers played the same frequencies then wherever the same frequencies were played by both drivers then the drivers would be in paralell and the impedance would drop! that is how speakers work. if it wasn't then anytime you had a 2way speaker with (2) 8 ohm drivers you would have a 4 ohm speaker. but you don't (2) 8 ohm drivers with a proper parralell xover seperating the frequencies will give you an 8 ohm speaker! because neither driver is playing the same frequencies. so the amp only sees 1 driver accross the whole spectrum of frequencies. |
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Silver Member Username: SoccerPost Number: 265 Registered: Apr-04 | Listen, Keeger, you're forgetting one thing: it doesn't really matter if an audio signal is going to the tweeter or the woofer or both. Why? Because impedance is the resistance the coil presents to the amp when this one applies an AC signal, right? Now, you remove the signal and you won't have an impedance seen by the amp, but rather a flat resistance. Therefore, no matter where the signal goes, the amp will always see a resistance and, if an Ac signal is applied, also an impedance value. Let's suppose he does that, but leaving audio signal off. What will happen is, supposing the tweeter is 8 ohm and also the woofer, the amp will see at least a flat resistance of 4 ohm. When you apply the audio signal, that resistance will work on the impedance value as well, not to mention there's NO WAY you'll ever gonna have a note that doesn't cover both range, due to harmonics, which may be lower in volume, but ARE THERE!!! On the other end I don't know any kind of music that in any given moment doesn't have both ranges covered. Audio frequency does not exist ONLY at the moment it's played or HEARD! I think you know what harmonics are? Plus, if he plugs the amp your way, even without audio signal it will stat heating, maybe not overheating. And when he start playing the music, the impedance, lowered by the resistance, will vary and then blow the amp. Do you know what an 8 ohm impedance is? It's the AC resistance to the signal at a frequency of 1014 Hz Wiring like that will lower the imp to 4 Ohm at 1014 Hz. Not to mention bass lowers impedance and highs highers impedance. What happens when you measure a speaker's (any) coil with a multimeter? You put 2.83 Volt DC RMS on the coil and measure it's drops, calculating the resistance (the MM does this fo you), this is for you not to feel tempted to say there's no resistance... Believe me man I'm tired of fixing amps due to connexions like these, I know what I'm saying. Glad to hear from you! Enjoy! |
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Gold Member Username: KeggerMICHIGAN Post Number: 1222 Registered: Dec-03 | "Because impedance is the resistance the coil presents to the amp when this one applies an AC signal, right? " your right but if there is a xover on the driver the amp will only see the coil when the frequencies the xover lets through reach it. that's why you can't measure a speaker with an ohm meter. and like i said take a typical 8ohm 2way speaker. it has "generally" (2) 8ohm drivers in paralell so you think ok (2) 8ohm drivers in paralell will yield a 4 ohm load. but when setup with a proper xover it is not 4ohm but 8ohm. because the xover shows 1 driver at a time to the amp at a given frequencie. if you took to full range speakers of 8ohm's and wired them in paralell you would get a 4ohm load. yes! I build speakers and one of the main things is getting your impedance correct. look at any speaker builder site with a speaker plan and they will show you the impedance curve. covering the whole speaker range. when a speaker says it's 8ohms it really isn't 8ohms. it may be 8ohms at 20hz and 15ohms at 60hz and 6ohms at 2000 hz and 8ohms at 6000hz and 20ohms at 20khz. it's all over the place. the job of the xover is to do it's best of keeping the impedance as flat as it can over the entire spectrum. generally where the 2 divers overlap in the frequencies they play are at a higher resistance so when they are in paralell the impedance doesn't drop to low. glad to hear from you too. and i'm not trying to belittle anyone just showing how when a speaker is designed it's more complicated then (2) 8ohm drivers in paralell equals 4ohms. "when a proper xover is designed" have a good one! |
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New member Username: Nobig423Post Number: 4 Registered: Apr-04 | Well, I've followed this for a few days and thought I better go back and read Dave's original post. It's not bi-amping...although there are separate A and B speaker outputs, only one amp for each front channel. So its bi-wiring...technically, both set of cables should run from speaker terminals A on the denon to the un-jumpered terminals of the speakers. The crossover(s) are still functional, just electrically separated into low and high frequency portions. So, the load that the amp sees at a given frequency would be therefore be unchanged, right? Here's a link to a very technical discussion of bi-wiring written by someone in the know..... http://www.geocities.com/jonrisch/biwiring.htm |
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Silver Member Username: SoccerPost Number: 269 Registered: Apr-04 | No, I don't agree with Keeger. Why? ALL manufacturers rate their speakers at 1014Hz. One should expect that by unjumper a speaker, the imp would stay the same, but no: With the jumper on, there's a part of the xover that matches the high and low sides, so that the amp sees 8 ohm at 1014Hz. With the jumper off, that part won't work, thus the difference between biwiring and biamping, so in reality the amp will (depends on amp's design) see 2 8ohm sets in parallel. But even if the speakers xovers are state of the art and can still match the imps., the real prob lies in the amp. Why? Try to follow me: supposing it's a state of the art xover, it would be the same feeding highs with A channel and lows with B channel as feeding one speaker set with A channel and another speaker set with B channel, right? The prob lies here, when they say use 12-16 ohm sets of speakers when using both A and B channels! If you know a bit of amps design, you will wonder "why do they say this"? Because this amp is designed to put both sets in parallel, thus the need of impedance increase, so the amp will see 6-8 ohm! Yes? Enjoy |
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Silver Member Username: SoccerPost Number: 270 Registered: Apr-04 | Imagine this: The amp has 3 pairs of PNP/NPN power transistors in each left and each right channel, both on A and B sets. That makes a total of 12 pairs, but only 6 are used when driving one set (let's say A). When you also use the second set (B), you put in parallel 3 pairs of the right side of the set A with the 3 pairs from the right side of the set B, the same for the ste's left sides. When you do this, you double the max output current, but still need to fulfill the impedance requisites which will stay, inside the amp at the output devices level, in the 6-8 ohm range; but now you have 4 speakers, how must you wire them to give that imp? You can't, 'cause the A and B are now shunted (inside), thus the manufacturer need to impose 12-16 ohm so that the output devices will see an overall imp of 6-8! This is where the prob is! Enjoy |
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Gold Member Username: KeggerMICHIGAN Post Number: 1234 Registered: Dec-03 | joao ferreira I think were just going to have to agree to disagree. because this statement "among others" "ALL manufacturers rate their speakers at 1014Hz." contridicts everything i've learned about speakers. "at least from the speaker building community" |
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Silver Member Username: SoccerPost Number: 272 Registered: Apr-04 | I apologise if in any way I hurt someone's believes (that was never my intent), but it's true. Surely you can build a crossover to flat the imp from 30 to 17000 Hz, but it will never be a straight line (rather a big curve) and your reference point will always be the 1014 Hz mark, commonly the 1Khz signal. but ask the builder community, when they're designing a xover, where do they start from? It's only my opinion, anyway, but I still say the prob lies on this amp's design, not on the xover. Enjoy |
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Gold Member Username: KeggerMICHIGAN Post Number: 1236 Registered: Dec-03 | joao ferreira i'm cool were allright we both just have strong beliefs in how this is accomplished. and as I stated earlier! "when a speaker says it's 8ohms it really isn't 8ohms. it may be 8ohms at 20hz and 15ohms at 60hz and 6ohms at 2000 hz and 8ohms at 6000hz and 20ohms at 20khz" so at least we agree on 1 thing speakers are not a flat impedance. we had a rational arguement without anyone getting into name calling or abusive language. it's all good bro! I think we both just realize were not going to convince each other. |
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Silver Member Username: SoccerPost Number: 274 Registered: Apr-04 | Ok, I just hope I'm wrong and Dave doesn't blow the amp. Cheers, M8! Enjoy |