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#41
Posted to rec.audio.tech
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Bi Amp question
"Arny Krueger" wrote in message ... "Trevor Wilson" wrote in message Don Pearce wrote in message news:497ce58c.160213187@localhost... On Sat, 24 Jan 2009 20:40:25 +1100, "Trevor Wilson" wrote: I look forwards to it. **Done. Go to: www.rageaudio.com.au Click on: Bi-amping. 3 scope traces, no text. "page under construction' **I supplied all the information in a post to Don in this thread. I have no plans to keep the page on my site permanently. -- Trevor Wilson www.rageaudio.com.au |
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#42
Posted to rec.audio.tech
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Bi Amp question
On Sat, 24 Jan 2009 22:30:03 -0500, "Arny Krueger"
wrote: If you biamp you get to at least benefit from the ability to make tweeters more efficient than woofers. And to amplify on this, although you will likely have personal quibbles (and, probably pretty hard to argue with, in a modern context), an amplifier can be made to be lower distortion if made "smaller", for any given amount of money. A smaller but faster amplifier for any given buck - like that. "A sadder but wiser girl for me." Extra points for those old enough to name the reference. Arf. My larger bitch about this whole discussion is that it has assumed that speaker drivers will both be fed by and behave *the same* when fed directly from an amplifier's super-low-Z output as from a high(speaker)-level crossover. This assumption isn't really very true in the region where it matters the most, in the region of the driver's fundamental resonance. Here, a high/speaker-level ("passive") crossover interacts in difficult ways with the drivers' impedances.... Stuff you and all serious folks know, natch. There are important advantages to defining each of a loudspeaker's drivers' individual driving voltages very carefully: It's difficult-bordering-on-impossible to define individual drivers' impedance interactions within the bandpass network of the "crossover". From a network-analysis-kinda viewpoint the whole thing stinks on ice. IOW, ain't no such thing as a real engineering-quality "passive" "crossover", because there's no such thing as an engineering- quality "load" for that crossover. Drivers are both complex reactances and motors, and the whole contraption wobbles. Given the sketchy, wobbly, weird, wangly nature of loudspeaker drivers, and their complicated interactions with *any* impedances between their own Pure Selves and whatever passes for voltage-source driving machines, AND whatever residual amplifier errors that any particular techically-savvy-net-person considers to Signify... And then we get into the territory of the proper shape(s) of the crossover itself. Here hearts are won and lost, wars are fought, but ultimately we all agree (...?). If we really want to discuss this topic, we'll want to discuss both the topics of loudspeaker summed responses from multiple radiators (see, as always! Linkwitz - done it, been there several decades before us) and musical distribution of energy, a moving target. Much thanks, as always, Chris Hornbeck |
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#43
Posted to rec.audio.tech
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Bi Amp question
On Sat, 24 Jan 2009 22:30:03 -0500, "Arny Krueger"
wrote: Don Pearce wrote in message news:497b908b.203989171@localhost Just FYI, the music is "I'm with you", a track by Avril Lavigne. Must be atypical, because the example I did with a 4th order butterworth crossover showed a nearly 7 dB difference, with the tweeter getting that much less signal. Also, tweeters are generally easier to make more efficient than woofers for reasons relating to box size and the laws of physics. If you biamp you get to at least benefit from the ability to make tweeters more efficient than woofers. This is the point, really. Music is like that; some goes one way, some goes the other and some stays pretty much the same. You can't construct a rule that allows you to generalise about what power you need for which bit of the spectrum. Interestingly, if you put a square wave through a crossover filter, the power requirement of the highpass amplifier can double. The reason tweeters tend to be more efficient than woofers isn't so much to do with box sizes and the laws of physics as the fact that they don't have to move far when working so it is easy to keep the entire voice coil immersed in the magnetic field. But remember what we are talking about here - not a system we are designing from scratch, but a purchased speaker which has already been balanced internally, but offers bi-amp terminals. d |
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#44
Posted to rec.audio.tech
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Bi Amp question
"Chris Hornbeck" wrote in
message On Sat, 24 Jan 2009 22:30:03 -0500, "Arny Krueger" wrote: If you biamp you get to at least benefit from the ability to make tweeters more efficient than woofers. And to amplify on this, although you will likely have personal quibbles (and, probably pretty hard to argue with, in a modern context), an amplifier can be made to be lower distortion if made "smaller", for any given amount of money. A smaller but faster amplifier for any given buck - like that. No quibble. It has always been easier and cheaper to make small, fast, high gain transistors than big ones. My larger bitch about this whole discussion is that it has assumed that speaker drivers will both be fed by and behave *the same* when fed directly from an amplifier's super-low-Z output as from a high(speaker)-level crossover. If you are free to design the drivers, then nominal (but not exceptional) losses and source impedance issues in the crossover can be largely compensated for. This assumption isn't really very true in the region where it matters the most, in the region of the driver's fundamental resonance. Here, a high/speaker-level ("passive") crossover interacts in difficult ways with the drivers' impedances.... It often is far more difficult to simply pay for crossover parts with adequate quality. Furthermore, there are functions you might want to put into the crossover that cost very little if implemented with a DSP, and cost an arm or a leg or have egregious losses if implmented passively. Things like phase shift networks and delays. |
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#45
Posted to rec.audio.tech
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Bi Amp question
"vMike" wrote in message
... Don Pearce wrote in message news:497acea0.88809281@localhost... On Fri, 23 Jan 2009 09:03:32 -0500, "vMike" wrote: My understanding of the benefits of bi amp with active crossover (and this may be incorrect) is that the passive crossover in the speaker sends small amounts of current back to the amp through the speaker wires creating a certain amount of distortion. Having active crossover with biamping eliminates much of that distortion whereas having biamping with passive crossover does nothing for that distortion. Any thoughts on that? Yes - it is incorrect. I'm not saying that all crossovers are entirely free from distortion, but it is all relative. The speaker driver it is feeding has distortion levels a hundred times as high. The bit about sending tiny currents back, creating distortion is actually technically incorrect too. If you are really considering bi-amping in pursuit of better sound, forget it. It isn't going to happen. All you will do is buy yourself problems and grief getting it all set up. Spend the money on music. d ok enough said. I will leave things well enough alone. Music sounds great already with what I have. many thanks mike I bi-amp with a dbx active crossover, an adcom 555 on the low end and an adcom 535 on the high. I'm pleased with the results. I crossover around 350 hz with the low side powering 4 10" woofers and the high side running an MTM style arrangement using a couple 5" mid-bass and a ribbon tweeter. One nice thing is that you do not have to worry about speaker impedances as much which makes it easier when using multiple speakers. The active crossovers give you a lot of flexibility to play with crossover point that you do not have with a passive crossover at the output. |
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#46
Posted to rec.audio.tech
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Bi Amp question
Don Pearce wrote:
On Fri, 23 Jan 2009 09:03:32 -0500, "vMike" wrote: My understanding of the benefits of bi amp with active crossover (and this may be incorrect) is that the passive crossover in the speaker sends small amounts of current back to the amp through the speaker wires creating a certain amount of distortion. Having active crossover with biamping eliminates much of that distortion whereas having biamping with passive crossover does nothing for that distortion. Any thoughts on that? Yes - it is incorrect. I'm not saying that all crossovers are entirely free from distortion, That is one way put it :-) passive crossovers are pain in many ways, they introduce a LOT of phase shift in the signal is such a way that the output from these crossovers alone!! never gives the input signal back. An other things is, without a passive network between the amp and the speaker unit, the amp wil have way better control over the driver. So that also is way better with active crossover and bi amping. Then we have the power requirements, one amp driving the entire range will have to be big enough to drive the bass. When the amp starts to clip, the passive filters directs these distortion products to the tweeter and they are very audible! No such thing happens with an active system. BTW you need LESS power with bi amping too. but it is all relative. The speaker driver it is feeding has distortion levels a hundred times as high. Steep filters add a lot of distortion too. The bit about sending tiny currents back, creating distortion is actually technically incorrect too. No it's not, the passive crossovers will shift phase and that IS distortion. ( not that per se active crossovers will overcome that problem, but some do ) If you are really considering bi-amping in pursuit of better sound, forget it. It isn't going to happen. All you will do is buy yourself problems and grief getting it all set up. Spend the money on music. I strongly disagree with almost everything you said. d Edmund |
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#47
Posted to rec.audio.tech
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Bi Amp question
On Wed, 28 Jan 2009 11:18:00 +0100, Edmund
wrote: Don Pearce wrote: On Fri, 23 Jan 2009 09:03:32 -0500, "vMike" wrote: My understanding of the benefits of bi amp with active crossover (and this may be incorrect) is that the passive crossover in the speaker sends small amounts of current back to the amp through the speaker wires creating a certain amount of distortion. Having active crossover with biamping eliminates much of that distortion whereas having biamping with passive crossover does nothing for that distortion. Any thoughts on that? Yes - it is incorrect. I'm not saying that all crossovers are entirely free from distortion, That is one way put it :-) passive crossovers are pain in many ways, they introduce a LOT of phase shift in the signal is such a way that the output from these crossovers alone!! never gives the input signal back. Gibberish. They introduce no more phase shift than an active design of similar slope. And it doesn't matter what signal they "give back" [sic] because the amplifier has such a low output impedance that it is shorted to ground. An other things is, without a passive network between the amp and the speaker unit, the amp wil have way better control over the driver. So that also is way better with active crossover and bi amping. No it won't. The loss in a passive crossover is low enough that the amplifier maintains full control. The ratio that matters is the crossover resistance to the speaker resistance - more than adequate, I can assure you. And of course when you bi-amp a domestic speaker the crossover is still in circuit - all you do is split the input, so no deal there either. Then we have the power requirements, one amp driving the entire range will have to be big enough to drive the bass. When the amp starts to clip, the passive filters directs these distortion products to the tweeter and they are very audible! No such thing happens with an active system. BTW you need LESS power with bi amping too. Entirely wrong. First off, you don't drive amplifiers into clipping, and if you find you are doing so, you need a bigger amplifier. And no, with bi-amping you do not need less power. I have already demonstrated this quite conclusively. but it is all relative. The speaker driver it is feeding has distortion levels a hundred times as high. Steep filters add a lot of distortion too. No they don't. Steep filters are as linear as shallow ones. Distortion can only be added by non-linearity. The bit about sending tiny currents back, creating distortion is actually technically incorrect too. No it's not, the passive crossovers will shift phase and that IS distortion. ( not that per se active crossovers will overcome that problem, but some do ) Wrong on every count. Phase shift is NOT distortion - it is in fact entirely inaudible. And active crossovers introduce the identical phase shift to passive ones of similar slope. If you are really considering bi-amping in pursuit of better sound, forget it. It isn't going to happen. All you will do is buy yourself problems and grief getting it all set up. Spend the money on music. I strongly disagree with almost everything you said. d Edmund Jolly good. d |
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#48
Posted to rec.audio.tech
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Bi Amp question
vMike wrote:
I am thinking of bi amping my speakers using the extra 2 amps on my 7.1 avr. Using the small v. large settings and adjusting the crossover, I can adjust the active crossover for the smalls to 350hz (matching the speakers crossover) so that the mids and tweeters primarily get upper frequencies. I do not have the ability to adjust the high pass crossover for the larges so the woofers will get the full range of frequencies which will then use the speaker's passive crossover. Is this limitation going to negate the benefits of biamping? mike In short. One of the big advantages in a active system is that the am are direct connected with the drivers. So make sure the amps are direct connected to the drivers without the passive crossover stuff. One big mistake often made with active systems is using a very steep crossover just because it can. That isn't going to work very well, what you need is a phase correct crossover.I don't know what 7.1 avr is and what woofers you have but if you can wire it as I told you,you be fine. Edmund |
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#49
Posted to rec.audio.tech
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Bi Amp question
Edmund wrote:
passive crossovers are pain in many ways, they introduce a LOT of phase shift in the signal is such a way that the output from these crossovers alone!! never gives the input signal back. Totally irrelevant, what matters is whether the acoustic output sums properly. An other things is, without a passive network between the amp and the speaker unit, the amp wil have way better control over the driver. So that also is way better with active crossover and bi amping. A passive cross-over implies a high output impedance driving the units, at least in the top. Then we have the power requirements, one amp driving the entire range will have to be big enough to drive the bass. When the amp starts to clip, the passive filters directs these distortion products to the tweeter and they are very audible! Yees. No such thing happens with an active system. Correct. BTW you need LESS power with bi amping too. Too simplified, you need the same total amount of power delivered to the units. Steep filters add a lot of distortion too. No. No it's not, the passive crossovers will shift phase and that IS distortion. ( not that per se active crossovers will overcome that problem, but some do ) Phase shift per se is not an issue. If you are really considering bi-amping in pursuit of better sound, forget it. It isn't going to happen. All you will do is buy yourself problems and grief getting it all set up. Spend the money on music. For Joe user who has an iteratively optimized passive cross-over that is entirely correct. A replacement active cross-over would need no less optimization. Just plugging multiple amps into the existing passive crossover is a concept that has merit for the amplifier sellers income only. I strongly disagree with almost everything you said. We can't all agree with Don. The user he didn't allow for is Timmy the DIY guy with a cookbook passive cross-over and no means to optimize it to the actual system. He will be less bad off with an active. Biamping to me reads as if no active cross-over is used, in which case the technical merit is at best zero. d Edmund Kind regards Peter Larsen |
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#50
Posted to rec.audio.tech
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Bi Amp question
Edmund wrote:
vMike wrote: I am thinking of bi amping my speakers using the extra 2 amps on my 7.1 avr. Using the small v. large settings and adjusting the crossover, I can adjust the active crossover for the smalls to 350hz (matching the speakers crossover) so that the mids and tweeters primarily get upper frequencies. I do not have the ability to adjust the high pass crossover for the larges so the woofers will get the full range of frequencies which will then use the speaker's passive crossover. Get a proper cross-over then. Behringers DCX may be a candiate PROVIDED you are qualified to align the system properly, including getting the line levels right for good s-n ratio. Is this limitation going to negate the benefits of biamping? For a simple answer: that is not what those settings have as purpose. If you want to experiment with an active cross-over, then get one. mike One of the big advantages in a active system is that the am are direct connected with the drivers. So make sure the amps are direct connected to the drivers without the passive crossover stuff. I tend to agree that loudspeaker drivers that are connected directly to an amplifiers gives the best they can. One big mistake often made with active systems is using a very steep crossover just because it can. That isn't going to work very well, Best active system I have heard yet crossed over at 200 dB pr. octave. what you need is a phase correct crossover. What he needs is a crossover that matches his loudspeakers as system consided and matches the requirements for making each and every unit perform optimally. I don't know what 7.1 avr is They guy is talking about finagling his el cheapo or somewhat costlio surround receiver to use as cross-over. It is plain silly. and what woofers you have but if you can wire it as I told you, you be fine. Allow me to suggest the OP's actual question before typing the answer. If there be information lacking, then ask for it up front. Edmund Kind regards Peter Larsen |
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#51
Posted to rec.audio.tech
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Bi Amp question
On Jan 28, 5:18*am, Edmund wrote:
passive crossovers are pain in many ways, they introduce a LOT of phase shift in the signal is such a way that the output from these crossovers alone!! This is total nonsense. The phase shift of a crossover is determined by its transfer function, NOT be how it is implemented. Build a passive 2nd-order Butterworth crossover, and you will find that its phase shift is IDENTICAL to an actively implemented 2nd-order butterworth. Do it again digitially, and the phase shift will be, again IDENTICAL. never gives the input signal back. The ability of a speaker to reconstruct its input signal requires the ENTIRE system be designed as a system. And it can be done as well with active and passive networks, given a sufficiently skilled designer. An other things is, without a passive network between the amp and the speaker unit, the amp wil have way better control over the driver. Nonsense again. The total series resistance in a speaker is what controls damping, and that resistance is dominated and, in most cases, overwhelmed by the DC resistance of the voice coil winding, which is most often more than an order of magnitude greater than that inserted by series crossover components. So that also is way better with active crossover and bi amping. No, it is not, and provably so. Steep filters add a lot of distortion too. Are you just making this stuff up, or are you getting it from someone who's just making it up? The bit about sending tiny currents back, creating distortion is actually technically incorrect too. No it's not, Yes, it is. Please go study some real electrical engineering principles before you spout this stuff off. the passive crossovers will shift phase and that IS distortion. No it is not, ESPECIALLY when a competent designer has designed the overall response of the network to be the conjugate of the drivers. If you are really considering bi-amping in pursuit of better sound, forget it. It isn't going to happen. All you will do is buy yourself problems and grief getting it all set up. I strongly disagree with almost everything you said. And, with no disrespect intended, you do so from from a position of technical ignorance. |
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#52
Posted to rec.audio.tech
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Bi Amp question
On Jan 28, 5:34*am, Edmund wrote:
One of the big advantages in a active system is that the am are direct connected with the drivers. They are with passive networks as well. You have some real technical evidence to the contrary? One big mistake often made with active systems is using a very steep crossover just because it can. No, the BIGGEST mistake is a blind belief in just the points you have made. The BEST crossover is the crossover that is SPECIFICALLY and EXCLUSIVELY designed to work with the specific combination of drivers, cabinets and all that go to make the speaker SYSTEM. Secondary to this is whether it is passive or active. The notion that one can simply go an get an active crossover, hack it into an existing system and have it work better is extremely naive and boneheaded. A speaker is a SYSTEM, designed, hopefully, by the designer who is aware of the response of the drivers used in the way they are and then tailors the design of the network to integrate them all together. The crossover transfer function, topology and implementation is chosen SPECIFICALLY to compensate for the transfer function deviations of the drivers. The person designing the speaker SYSTEM has a far better understanding of the requirements of the SYSTEM than the personb whose designing some generic active crossover. How on earth could you think otherwise? That isn't going to work very well, what you need is a phase correct crossover. What is "phase correct" other than technobabble? Do you mean "linear phase" Do you mean "minimum phase" Do you mean "conjugate phase?" What? I don't know what 7.1 avr is and what woofers you have but if you can wire it as I told you,you be fine. Again, as a statement of fact, you have no idea, in a technical sense, what you are talking about, other than spouting popular culture and myth. |
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#53
Posted to rec.audio.tech
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Bi Amp question
Don Pearce wrote:
On Wed, 28 Jan 2009 11:18:00 +0100, Edmund wrote: Don Pearce wrote: On Fri, 23 Jan 2009 09:03:32 -0500, "vMike" wrote: My understanding of the benefits of bi amp with active crossover (and this may be incorrect) is that the passive crossover in the speaker sends small amounts of current back to the amp through the speaker wires creating a certain amount of distortion. Having active crossover with biamping eliminates much of that distortion whereas having biamping with passive crossover does nothing for that distortion. Any thoughts on that? Yes - it is incorrect. I'm not saying that all crossovers are entirely free from distortion, That is one way put it :-) passive crossovers are pain in many ways, they introduce a LOT of phase shift in the signal is such a way that the output from these crossovers alone!! never gives the input signal back. Gibberish. They introduce no more phase shift than an active design of similar slope. That active crossovers have the same phase shift doesn't change the fact that that is unwanted. Enlish is not mu language and I was very unclear with "give the input signal back" what I mean is, the sum of the output from a crossover with phase shift, is never equal to the input signal and there is no way to correct that with speaker units. And making a passive filter requires big C's and L's, then there is the tolerance of C's which makes it hard to get the required values end keep values for some time. these things are much easier to realize with an active crossover and as I said, there are no C's and L's between the amp and the driver. And it doesn't matter what signal they "give back" [sic] because the amplifier has such a low output impedance that it is shorted to ground. An other things is, without a passive network between the amp and the speaker unit, the amp wil have way better control over the driver. So that also is way better with active crossover and bi amping. No it won't. The loss in a passive crossover is low enough that the amplifier maintains full control. The ratio that matters is the crossover resistance to the speaker resistance - more than adequate, I can assure you. And of course when you bi-amp a domestic speaker the crossover is still in circuit - all you do is split the input, so no deal there either. Then we have the power requirements, one amp driving the entire range will have to be big enough to drive the bass. When the amp starts to clip, the passive filters directs these distortion products to the tweeter and they are very audible! No such thing happens with an active system. BTW you need LESS power with bi amping too. Entirely wrong. First off, you don't drive amplifiers into clipping, and if you find you are doing so, you need a bigger amplifier. well I agree but clipping still happens. o, with bi-amping you do not need less power. I have already demonstrated this quite conclusively. How did you demonstrate that? it isn't true. but it is all relative. The speaker driver it is feeding has distortion levels a hundred times as high. Steep filters add a lot of distortion too. No they don't. Steep filters are as linear as shallow ones. Distortion can only be added by non-linearity. The bit about sending tiny currents back, creating distortion is actually technically incorrect too. No it's not, the passive crossovers will shift phase and that IS distortion. ( not that per se active crossovers will overcome that problem, but some do ) Wrong on every count. Phase shift is NOT distortion - it is in fact entirely inaudible. Well it is very easy to prove you are wrong here. just add two identical sine waves with 180 phase shift, what will you hear? Hint ... nothing! So we can talk about how much it is audible but it is clear that there is an audible effect. d Edmund Jolly good. d Edmund |
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#54
Posted to rec.audio.tech
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Bi Amp question
"Peter Larsen" wrote in message ... Edmund wrote: vMike wrote: I am thinking of bi amping my speakers using the extra 2 amps on my 7.1 avr. Using the small v. large settings and adjusting the crossover, I can adjust the active crossover for the smalls to 350hz (matching the speakers crossover) so that the mids and tweeters primarily get upper frequencies. I do not have the ability to adjust the high pass crossover for the larges so the woofers will get the full range of frequencies which will then use the speaker's passive crossover. Get a proper cross-over then. Behringers DCX may be a candiate PROVIDED you are qualified to align the system properly, including getting the line levels right for good s-n ratio. Is this limitation going to negate the benefits of biamping? For a simple answer: that is not what those settings have as purpose. If you want to experiment with an active cross-over, then get one. mike One of the big advantages in a active system is that the am are direct connected with the drivers. So make sure the amps are direct connected to the drivers without the passive crossover stuff. I tend to agree that loudspeaker drivers that are connected directly to an amplifiers gives the best they can. One big mistake often made with active systems is using a very steep crossover just because it can. That isn't going to work very well, Best active system I have heard yet crossed over at 200 dB pr. octave. what you need is a phase correct crossover. What he needs is a crossover that matches his loudspeakers as system consided and matches the requirements for making each and every unit perform optimally. I don't know what 7.1 avr is They guy is talking about finagling his el cheapo or somewhat costlio surround receiver to use as cross-over. It is plain silly. and what woofers you have but if you can wire it as I told you, you be fine. Allow me to suggest the OP's actual question before typing the answer. If there be information lacking, then ask for it up front. Edmund Kind regards Peter Larsen I don't think I was talking about finagling anything. I have a pretty decent system and the speakers sound awesome. I was just thinking that since I have two extra channels in the system that maybe I should use them if there was some benefit. I did a little bit of research and it seemed that if you have active crossovers then there might be a benefit. But I plan to leave well enough alone. Mike |
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#55
Posted to rec.audio.tech
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Bi Amp question
On Jan 28, 10:43*am, Edmund wrote:
Don Pearce wrote: On Wed, 28 Jan 2009 11:18:00 +0100, Edmund passive crossovers are pain in many ways, they introduce a LOT of phase shift in the signal is such a way that the output from these crossovers alone!! never gives the input signal back. Gibberish. They introduce no more phase shift than an active design of similar slope. That active crossovers have the same phase shift doesn't change the fact that that is unwanted. Nonsense. If my clients present me with a system with unwanted phase over some band, I'll design a crossover with just the right amount of complementary phase to correct it. Your blanket statement that "phase is unwanted" is simply wrong. Enlish is not mu language It's not your English I have issue with, it's your appallingly bad command of physics that's the problem. and I was very unclear with "give the input signal back" what I mean is, the sum of the output from a crossover with phase shift, is never equal to the input signal and there is no way to correct that with speaker units. And you're most assuredly, absolutely 100% wrong. And making a passive filter requires big C's and L's, then there is the tolerance of C's which makes it hard to get the required values end keep values for some time. I can get 5% tolerance on capacitors of the values I requi which is better, by not a small amount, than the tolerances on the drivers they're connected to. these things are much easier to realize with an active crossover and as I said, there are no C's and L's between the amp and the driver. Irrelevant. * And it doesn't matter what signal they "give back" Then why bring it up? Wrong on every count. Phase shift is NOT distortion - it is in fact entirely inaudible. Well it is very easy to prove you are wrong here. just add two identical sine waves with 180 phase shift, what will you hear? * Hint ... nothing! Please, spare us the uninformed, childish tricks. your silly little experiment does NOT demonstrate anything whatsoever about the audibility of phase. Try the following experiment: take any speaker, add 2 poles of all-pass filtering at about 500 Hz, and tell us if you can hear the difference. So we can talk about how much it is audible but it is clear that there is an audible effect. Your "demonstration" is absurd on its face. |
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#56
Posted to rec.audio.tech
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Bi Amp question
On Wed, 28 Jan 2009 16:43:36 +0100, Edmund
wrote: Don Pearce wrote: On Wed, 28 Jan 2009 11:18:00 +0100, Edmund wrote: Don Pearce wrote: On Fri, 23 Jan 2009 09:03:32 -0500, "vMike" wrote: My understanding of the benefits of bi amp with active crossover (and this may be incorrect) is that the passive crossover in the speaker sends small amounts of current back to the amp through the speaker wires creating a certain amount of distortion. Having active crossover with biamping eliminates much of that distortion whereas having biamping with passive crossover does nothing for that distortion. Any thoughts on that? Yes - it is incorrect. I'm not saying that all crossovers are entirely free from distortion, That is one way put it :-) passive crossovers are pain in many ways, they introduce a LOT of phase shift in the signal is such a way that the output from these crossovers alone!! never gives the input signal back. Gibberish. They introduce no more phase shift than an active design of similar slope. That active crossovers have the same phase shift doesn't change the fact that that is unwanted. Enlish is not mu language and I was very unclear with "give the input signal back" what I mean is, the sum of the output from a crossover with phase shift, is never equal to the input signal and there is no way to correct that with speaker units. It does not matter where the crossover is - the effect of phase shift is identical. And making a passive filter requires big C's and L's, then there is the tolerance of C's which makes it hard to get the required values end keep values for some time. these things are much easier to realize with an active crossover and as I said, there are no C's and L's between the amp and the driver. The loudspeaker crossover has been a done deal for a long time. Inside the loudspeaker is the right place to put it, because it is a necessary part of the speaker system. If one were to put it in the amplifier, one would need a different crossover option for every speaker the amplifier might need to drive. That is not a sensible option, particularly given that it would work no better. And it doesn't matter what signal they "give back" [sic] because the amplifier has such a low output impedance that it is shorted to ground. An other things is, without a passive network between the amp and the speaker unit, the amp wil have way better control over the driver. So that also is way better with active crossover and bi amping. No it won't. The loss in a passive crossover is low enough that the amplifier maintains full control. The ratio that matters is the crossover resistance to the speaker resistance - more than adequate, I can assure you. And of course when you bi-amp a domestic speaker the crossover is still in circuit - all you do is split the input, so no deal there either. Then we have the power requirements, one amp driving the entire range will have to be big enough to drive the bass. When the amp starts to clip, the passive filters directs these distortion products to the tweeter and they are very audible! No such thing happens with an active system. BTW you need LESS power with bi amping too. Entirely wrong. First off, you don't drive amplifiers into clipping, and if you find you are doing so, you need a bigger amplifier. well I agree but clipping still happens. o, with bi-amping you do not need less power. I have already demonstrated this quite conclusively. How did you demonstrate that? it isn't true. Look back through the thread - there is a post of mine with the evidence. but it is all relative. The speaker driver it is feeding has distortion levels a hundred times as high. Steep filters add a lot of distortion too. No they don't. Steep filters are as linear as shallow ones. Distortion can only be added by non-linearity. The bit about sending tiny currents back, creating distortion is actually technically incorrect too. No it's not, the passive crossovers will shift phase and that IS distortion. ( not that per se active crossovers will overcome that problem, but some do ) Wrong on every count. Phase shift is NOT distortion - it is in fact entirely inaudible. Well it is very easy to prove you are wrong here. just add two identical sine waves with 180 phase shift, what will you hear? Hint ... nothing! So we can talk about how much it is audible but it is clear that there is an audible effect. What does that have to do with phase shift being audible? Come to that, what does it have to do with anything? d |
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#57
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Bi Amp question
vMike wrote:
I don't think I was talking about finagling anything. I have a pretty decent system and the speakers sound awesome. Thank you for clarifying. I was just thinking that since I have two extra channels in the system that maybe I should use them if there was some benefit. I'd use them for extra loudspeakers. I did a little bit of research and it seemed that if you have active crossovers then there might be a benefit. That is quite correct. But I plan to leave well enough alone. Paraphrasing something I once read about computers: you can design loudspeakers or have time to listen to them, but hardly ever both .... it is possible to get something extraordinary by purchasing quality components and diy'in it all, but only cheap if a labor of love, if you weigh your own time at even a single USD pr. hour it gets costly. Mike Kind regards Peter Larsen |
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#58
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Bi Amp question
On Jan 28, 10:50*am, "vMike" wrote:
I don't think I was talking about finagling anything. * Attempting to convert an existing speaker system to use an electronic crossover without the measurement facilities, the design documentation of the original designer, and without a whole lot of expertise in the 'domain IS finagling. I have a pretty decent system and the speakers sound awesome. Then why, on earth, try to fix something that, in your words, sounds awesome? *I was just thinking that since I have two extra channels in the system that maybe I should use them if there was some benefit. For existing speaker systems and a small investment in time, there is not benefit, and real potential to make things worse, and a fairly high probability of wasted time. But I plan to leave well enough alone. Excellent idea. |
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#59
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Bi Amp question
wrote in message ... On Jan 28, 10:50 am, "vMike" wrote: I don't think I was talking about finagling anything. Attempting to convert an existing speaker system to use an electronic crossover without the measurement facilities, the design documentation of the original designer, and without a whole lot of expertise in the 'domain IS finagling. I have a pretty decent system and the speakers sound awesome. Then why, on earth, try to fix something that, in your words, sounds awesome? I was just thinking that since I have two extra channels in the system that maybe I should use them if there was some benefit. For existing speaker systems and a small investment in time, there is not benefit, and real potential to make things worse, and a fairly high probability of wasted time. But I plan to leave well enough alone. Excellent idea. Well ... I don't care how awesome anything is ... I never stop trying to see if it can be better. Whether it is the sound system or the cup of espresso or you name it. My guess is there are a few other in the group who are the same. Thanks for you insights Mike |
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#60
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Bi Amp question
On Jan 28, 2:28*pm, "vMike" wrote:
wrote in message ... On Jan 28, 10:50 am, "vMike" wrote: I don't think I was talking about finagling anything. Attempting to convert an existing speaker system to use an electronic crossover without the measurement facilities, the design documentation of the original designer, and without a whole lot of expertise in the 'domain IS finagling. I have a pretty decent system and the speakers sound awesome. Then why, on earth, try to fix something that, in your words, sounds awesome? I was just thinking that since I have two extra channels in the system that maybe I should use them if there was some benefit. For existing speaker systems and a small investment in time, there is not benefit, and real potential to make things worse, and a fairly high probability of wasted time. But I plan to leave well enough alone. Excellent idea. Well ... I don't care how awesome anything is ... *I never stop trying to see if it can be better. *Whether it is the sound system or the cup of espresso or you name it. My guess is there are a few other in the group who are the same. Thanks for you insights Mike Well if you really want to biamp correctly then you need to pickup a 2 channel active crossover and you will need to open up the speakers and disconnect parts of the passive crossover in it. If the speakers are two way you will just have straight connections to the speakers from each amp. If they are three way you will need to preserve the portion of the passive crossover that handles the tweeter and midrange speakers. You will drive both of them with one amp channel and the woofer with another amp channel. Depending on the passive crossover design that may be as simple as just disconnecting the woofers from the crossover. But more complex passive crossovers may require other changes as well. It would also be useful to know the original designers intended crossover points as that would be a good starting point for your active crossover setting. For many commercial speakers the passive crossover circuit is fairly simple. The main question will be if the coils are labeled so that you could reverse the calculations and determine the intended frequencies. The vast majority of passive crossovers fall in 3 or 4 basic designs with some minor variations and possibly some notch filters. All are easily found on the internet. There may also be documentation on the speakers somewhere around that gives you the design crossover points without you having to figure it out. You could also ask the manufacturer. There is also the much rarer use of tri-amping with 3 way speakers. But you need 6 channels of amp for that. Then you get a 3 way active crossover and connect each amp directly to each speaker. No passive crossover components at all. The basic premise of biamping is that the larger power swings of the low frequencies can carry the higher frequencies farther into the extremes of the amp's total power range. Imagine that a high frequency sine wave is mixed with a low freqeuncy one that is also a higher voltage. On a scope you will see the higher frequency "riding" the lower frequency and the total voltage swing when both waves are in sync will be the sum of the two. By isolating the low frequency to a different channel the channel handling the highs is not dealing with the larger low freqeuncy voltage swings. It also allows you to choose amps that are more suited to each task. Some people will even run a tube amp on the high side since one of the big advantages of solid state amps over tubes is their power handling. |
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#61
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Bi Amp question
On Jan 29, 8:21*am, wrote:
What exactly is it about this topic that causes so much blither, mythology and technical hooey to be propagated as TRVTH(tm)? Well if you really want to biamp correctly then you need to pickup a 2 channel active crossover and you will need to open up the speakers and disconnect parts of the passive crossover in it. *If the speakers are two way you will just have straight connections to the speakers from each amp. *If they are three way you will need to preserve the portion of the passive crossover that handles the tweeter and midrange speakers. *You will drive both of them with one amp channel and the woofer with another amp channel. *Depending on the passive crossover design that may be as simple as just disconnecting the woofers from the crossover. *But more complex passive crossovers may require other changes as well. Almost ALL crossovers in ANY decent speakers will require this. PIcming the crossover point and slopes is the EASY part, and, often the LEAST important part of the crossover design. NOT A SINGLE ACTIVE OFF-THE-SHELF CROSSOVER DEALS WITH THIS. It would also be useful to know the original designers intended crossover points as that would be a good starting point for your active crossover setting. Again, the crossover points are NOT the problem. The taoloring of the crossover response to the SYSTEM is what's the issue, and every one of you go-out-and- buy-an-active-crossover for reasons I simply don't get ABSOLUTELY refuses to deal with that issue. *For many commercial speakers the passive crossover circuit is fairly simple. *The main question will be if the coils are labeled so that you could reverse the calculations and determine the intended frequencies. * NO, IT IS NOT. The MAIN question is why do you think you have more expertise on the design of a speaker than the designer did? The vast majority of passive crossovers fall in 3 or 4 basic designs with some minor variations and possibly some notch filters. No, they fall into two very distinct categories: those that work and those that don't. What you're proposing is a means by which someone can turn those that work into those that don't in as expensive a manner as possible. *All are easily found on the internet. There may also be documentation on the speakers somewhere around that gives you the design crossover points without you having to figure it out. THE CROSSOVER POINTS AREN'T THE ISSUE. The design of the crossover and the speaker TOGETHER as a system IS the issue. And you propose to basically ignore this piece of physics. *You could also ask the manufacturer. Who will tell you to one degree of politeness or another to go pound sand. *Some people will even run a tube amp on the high side since one of the big advantages of solid state amps over tubes is their power handling. And what's the advantage of the tube amp? In fact, what you're saying in fact is that the advantage to a high-power amp is that it has higher power than a low power amp. I'd agree to that assertion with a hearty "so what?" |
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#62
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Bi Amp question
wrote in message
Again, the crossover points are NOT the problem. The tailoring of the crossover response to the SYSTEM is what's the issue, and every one of you go-out-and- buy-an-active-crossover for reasons I simply don't get ABSOLUTELY refuses to deal with that issue. How effective are products like the DCX 2496 that implement crossovers by stringing together various modules? |
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#63
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Bi Amp question
On Jan 29, 8:48*am, wrote:
On Jan 29, 8:21*am, wrote: What exactly is it about this topic that causes so much blither, mythology and technical hooey to be propagated as TRVTH(tm)? Well if you really want to biamp correctly then you need to pickup a 2 channel active crossover and you will need to open up the speakers and disconnect parts of the passive crossover in it. *If the speakers are two way you will just have straight connections to the speakers from each amp. *If they are three way you will need to preserve the portion of the passive crossover that handles the tweeter and midrange speakers. *You will drive both of them with one amp channel and the woofer with another amp channel. *Depending on the passive crossover design that may be as simple as just disconnecting the woofers from the crossover. *But more complex passive crossovers may require other changes as well. Almost ALL crossovers in ANY decent speakers will require this. PIcming the crossover point and slopes is the EASY part, and, often the LEAST important part of the crossover design. NOT A SINGLE ACTIVE OFF-THE-SHELF CROSSOVER DEALS WITH THIS. It would also be useful to know the original designers intended crossover points as that would be a good starting point for your active crossover setting. Again, the crossover points are NOT the problem. The taoloring of the crossover response to the SYSTEM is what's the issue, and every one of you go-out-and- buy-an-active-crossover for reasons I simply don't get ABSOLUTELY refuses to deal with that issue. *For many commercial speakers the passive crossover circuit is fairly simple. *The main question will be if the coils are labeled so that you could reverse the calculations and determine the intended frequencies. * NO, IT IS NOT. The MAIN question is why do you think you have more expertise on the design of a speaker than the designer did? The vast majority of passive crossovers fall in 3 or 4 basic designs with some minor variations and possibly some notch filters. No, they fall into two very distinct categories: those that work and those that don't. What you're proposing is a means by which someone can turn those that work into those that don't in as expensive a manner as possible. *All are easily found on the internet. There may also be documentation on the speakers somewhere around that gives you the design crossover points without you having to figure it out. THE CROSSOVER POINTS AREN'T THE ISSUE. The design of the crossover and the speaker TOGETHER as a system IS the issue. And you propose to basically ignore this piece of physics. *You could also ask the manufacturer. Who will tell you to one degree of politeness or another to go pound sand. *Some people will even run a tube amp on the high side since one of the big advantages of solid state amps over tubes is their power handling. And what's the advantage of the tube amp? In fact, what you're saying in fact is that the advantage to a high-power amp is that it has higher power than a low power amp. I'd agree to that assertion with a hearty "so what?" While the speakers in question are pretty pricy it is my understanding the factory crossover uses cored inductors and electrolitic capacitors. A decent active crossover is probably better technically. Admittedly there may also be notch filters to compensate for specific cabinet/speaker characteristics that is not so easily reproduced in the active crossover. It would be interesting to see the actual schematic of their passive crossover. The sales hype goes on about "golf ball aerodynamics theory" being used in their port design which frankly sounds like total tripe. No doubt they might tell you they have some "revolutionary" new crossover design as well. Would you believe that? If I owned those speakers I would very likely not consider trying to biamp them. Partly for some of the reasons you point out. Does that constitute agreeing with you? :-) As to the tube amp, personally I have no use for them. But some do and one problem is that tube amps can not match the headroom of solid state amps within anything near similar costs. So the tube amp afficianado (NOT ME) can have his cake and eat it in terms of headroom for heart pounding bass while retaining that tube amp sound (what ever that is, again NOT ME). |
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#64
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Bi Amp question
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#65
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Bi Amp question
"Arny Krueger" wrote in message ... How effective are products like the DCX 2496 that implement crossovers by stringing together various modules? IMO any good digital active crossover is highly effective if implemented properly. Dick is suggesting (probably quite correctly) that most people do not have the knowledge and test capabilities to do so, not that it can't be done at all. In fact if starting with a new design from scratch, it is usually quicker and easier to get a satisfactory result using a programmable crossover IMO, given the same level of ability and test conditions. MrT. |
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#66
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Bi Amp question
On Jan 29, 1:40*pm, jakdedert wrote:
wrote: snip If I owned those speakers I would very likely not consider trying to biamp them. *Partly for some of the reasons you point out. *Does that constitute agreeing with you? :-) ?? Does someone have a link to the OP's speakers. *AARC, he id'd them by a model number (902?) with no brand. *Apparently it was something I 'should' know; or he actually listed the brand and I missed it. This thread is too long to search it out. jak I believe he has the B&H 802D's http://www.avrev.com/home-theater-lo...udpeakers.html |
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#67
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Bi Amp question
"Mr.T" MrT@home wrote in message
"Arny Krueger" wrote in message ... How effective are products like the DCX 2496 that implement crossovers by stringing together various modules? IMO any good digital active crossover is highly effective if implemented properly. Not necessarily. I've built enough speakers to understand Dick's point. If you just take say a good Linkwitz-Rielly crossover and hook it up to some drivers and give it your best shot at adjusting crossover frequencies and levels, you will probably miss flat response by quite a bit. This is, if for no other reason, because the transfer functions of the upper and lower half of crossover which may sum to flat response, also has those transfer functions multiplied by the transfer functions of the respective driver. This will yield a different transfer function from the one that sums so nicely to flat response. For example, many people hook up two drivers up to a Linkwitz-Reilly (4th order filters for high and low composed of 2 cascaded second order Butterworth filters each) crossover and think that they are going to get the Linkwitz-Reilly's smooth response through the crossover region. Problem is, adding drivers adds two more filters that may be themselves second order within an octave or two of the crossover frequency. We now have 3 cascaded second order filters for each of the upper range and lower range sections of the speaker speaker. Not exactly what we planned, eh? Dick is suggesting (probably quite correctly) that most people do not have the knowledge and test capabilities to do so, not that it can't be done at all. No, we've found that even if you have the knowledge and the test capabilities, you won't get adequately flat response with just a good crossover that lets you adjust crossover frequencies and levels. In fact if starting with a new design from scratch, it is usually quicker and easier to get a satisfactory result using a programmable crossover IMO, given the same level of ability and test conditions. This presumes that the crossover has the necessary other features, beyond just some complementary filters whose frequency you can adjust, and level controls. |
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#68
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Bi Amp question
"Arny Krueger" wrote in message ... "Mr.T" MrT@home wrote in message "Arny Krueger" wrote in message ... How effective are products like the DCX 2496 that implement crossovers by stringing together various modules? IMO any good digital active crossover is highly effective if implemented properly. Not necessarily. I've built enough speakers to understand Dick's point. If you just take say a good Linkwitz-Rielly crossover and hook it up to some drivers and give it your best shot at adjusting crossover frequencies and levels, you will probably miss flat response by quite a bit. Re-read the "if implemented properly" again. And the fact that you specifically mentioned a digital programmable crossover. But I do admit my "any good digital active crossover" claim does in fact rely heavily on the definition of "good" :-) Dick is suggesting (probably quite correctly) that most people do not have the knowledge and test capabilities to do so, not that it can't be done at all. No, we've found that even if you have the knowledge and the test capabilities, you won't get adequately flat response with just a good crossover that lets you adjust crossover frequencies and levels. Of course, fortunately we can adjust more than that. If not then obviously you need a better box :-) In fact if starting with a new design from scratch, it is usually quicker and easier to get a satisfactory result using a programmable crossover IMO, given the same level of ability and test conditions. This presumes that the crossover has the necessary other features, beyond just some complementary filters whose frequency you can adjust, and level controls. Correct. MrT. |
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#69
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Bi Amp question
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#71
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Bi Amp question
wrote: While the speakers in question are pretty pricy it is my understanding the factory crossover uses cored inductors and electrolitic capacitors. A decent active crossover is probably better technically. Admittedly there may also be notch filters to compensate for specific cabinet/speaker characteristics that is not so easily reproduced in the active crossover. I have to wonder what filters are "not so easily" implemented in a fully programmable digital active crossover these days? I think the only real limitation would be the firmware/software or the programmer. MrT. |
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#72
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Bi Amp question
On Jan 29, 11:58*am, wrote:
On Jan 29, 8:48*am, wrote: THE CROSSOVER POINTS AREN'T THE ISSUE. The design of the crossover and the speaker TOGETHER as a system IS the issue. And you propose to basically ignore this piece of physics. While the speakers in question are pretty pricy it is my understanding the factory crossover uses cored inductors and electrolitic capacitors. How is that at all relevant? *A decent active crossover is probably better technically. * Not if it is not explicitly designed to be integrated in to the system, it isn't. Is there any reason why you are insisting on ognoring this very crucial point? How is the issue of "cored inductors" in any way relevant? I'd much rather have a passice crossover with cored inductors that gets me the right response than the best active generic active crossover in the world. Admittedly there may also be notch filters to compensate for specific cabinet/speaker characteristics that is not so easily reproduced in the active crossover. * Well, thank you for your mild "admission," but it's something that has been well known and well understood by any number of competent speaker designers for decades, and you just getting around to "admitting" it? Your admission suggests, then, that off-the-shelf active crossover are likely NOT to be better than the purpose designed passice networks in a competently designed speaker SYSTEM, eh? It would be interesting to see the actual schematic of their passive crossover. * Which in and of itslef would tell you relatively little. without ALL the design criteria and factors that went into the SYSTEM design, you're not going to understand the SYSTEM. The sales hype goes on about "golf ball aerodynamics theory" being used in their port design which frankly sounds like total tripe. * No, because right surface profile is capable of substantially alleviating effects due to boundary- layer turbulence. No doubt they might tell you they have some "revolutionary" new crossover design as well. "No doubt" and "they might" seems a bit contradictory. Would you believe that? Would I believe what? |
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#73
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Bi Amp question
On Jan 29, 6:03*pm, wrote:
On Jan 29, 11:58*am, wrote: On Jan 29, 8:48*am, wrote: THE CROSSOVER POINTS AREN'T THE ISSUE. The design of the crossover and the speaker TOGETHER as a system IS the issue. And you propose to basically ignore this piece of physics. While the speakers in question are pretty pricy it is my understanding the factory crossover uses cored inductors and electrolitic capacitors. How is that at all relevant? *A decent active crossover is probably better technically. * Not if it is not explicitly designed to be integrated in to the system, it isn't. Is there any reason why you are insisting on ognoring this very crucial point? How is the issue of "cored inductors" in any way relevant? I'd much rather have a passice crossover with cored inductors that gets me the right response than the best active generic active crossover in the world. Admittedly there may also be notch filters to compensate for specific cabinet/speaker characteristics that is not so easily reproduced in the active crossover. * Well, thank you for your mild "admission," but it's something that has been well known and well understood by any number of competent speaker designers for decades, and you just getting around to "admitting" it? Your admission suggests, then, that off-the-shelf active crossover are likely NOT to be better than the purpose designed passice networks in a competently designed speaker SYSTEM, eh? It would be interesting to see the actual schematic of their passive crossover. * Which in and of itslef would tell you relatively little. without ALL the design criteria and factors that went into the SYSTEM design, you're not going to understand the SYSTEM. The sales hype goes on about "golf ball aerodynamics theory" being used in their port design which frankly sounds like total tripe. * No, because right surface profile is capable of substantially alleviating effects due to boundary- layer turbulence. No doubt they might tell you they have some "revolutionary" new crossover design as well. "No doubt" and "they might" seems a bit contradictory. Would you believe that? Would I believe what? Ferrite core and electrolitics are generally accepted to be inferior to air core and polypropylene for use in crossovers. They certainly are cheaper. Cheaper is not what I expect to find when I look under the "hood" of speakers in that price range. And the best solution for port turbulence is no port. That they used "theory" when designing their port suggests that they didn't really test anything, they just think that the theory is applicable. You think they tested? Without a schematic of their crossover we are just speculating as to how it compares to a standard active crossover. For all you know it's a vanilla 12 db circuit. In this price range I would expect more but I also expected air core and polypropylene as well and I was wrong there. |
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#74
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Bi Amp question
wrote in message ... On Jan 29, 11:58 am, wrote: On Jan 29, 8:48 am, wrote: THE CROSSOVER POINTS AREN'T THE ISSUE. The design of the crossover and the speaker TOGETHER as a system IS the issue. And you propose to basically ignore this piece of physics. Dick, I've seen a number of so-called "audiophile" loudspeakers that have very simple crossovers, some as simple as a single capacitor, but many which consist of simple LC sections, with perhaps a single resistor to reduce tweeter levels. Many such manufacturers make a virtue of their simple crossover design. Now I know this is all marketing, they make a virtue of their limitations, but is there any reason that someone with one of these loudspeakers couldn't use a DSP-based electronic crossover? I ask also because a project I have in mind for the future is to change the crossover in the Tannoy 15" Dual Concentric for an electronic one. Looking at the circuit diagram of Tannoy's crossover looks like something that could be replicated with an electronic device. Am I missing something? Best regards S. -- http://audiopages.googlepages.com |
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#76
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Bi Amp question
On Jan 30, 8:35*am, "Serge Auckland"
wrote: wrote in message ... On Jan 29, 11:58 am, wrote: On Jan 29, 8:48 am, wrote: THE CROSSOVER POINTS AREN'T THE ISSUE. The design of the crossover and the speaker TOGETHER as a system IS the issue. And you propose to basically ignore this piece of physics. Dick, I've seen a number of so-called "audiophile" loudspeakers that have very simple crossovers, some as simple as a single capacitor, but many which consist of simple LC sections, with perhaps a single resistor to reduce tweeter levels. Many such manufacturers make a virtue of their simple crossover design. Now I know this is all marketing, they make a virtue of their limitations, but is there any reason that someone with one of these loudspeakers couldn't use a DSP-based electronic crossover? I ask also because a project I have in mind for the future is to change the crossover in the Tannoy 15" Dual Concentric for an electronic one. Looking at the circuit diagram of Tannoy's crossover looks like something that could be replicated with an electronic device. Am I missing something? Best regards S. --http://audiopages.googlepages.com He's assuming that the crossover in question has additional components beyond one of the common crossover designs. Such as additional filters to compensate for peaks or fall off somewhere. A point I say is just theoretical until we see the schematic of the crossover in question. An active crossover is an acceptable substitution for a basic no frills passive crossover. It is essentially the same thing substituted further up the signal path. If you wish to experiment, it's far easier than changing passive components at the output stage. And if you really want to you can get active equipment that will also let you introduce and adjust other filtering effects as well. True, there is a school of thought that additional complexity in the crossover just introduces as many problems as it creates. As you know the speaker is not a straight load, it has inductive properties as well. Some would point out capacitive too. And the load the cabinet places on the speaker has yet another impact. Of course all this varying with frequency. While the complete behavior is pretty easy to observe at one frequency it's a whole nother beast to determine what the total effects of the speaker, cabinet, and crossover components are on that vastly more complex music signal. Never mind measuring the effects of port design on turbulence. Imho all that's what's behind the simple is better school. Some of the same proponents of biamping also recommend simple no frills 6 db or 12 db crossovers from the mid/tweeter section. There are a number of camps and they all have their pluses and minuses. Some people would point out that all the complicated reflections in the typical home listening room negate the bulk of this fine tweaking anyway. |
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#77
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#78
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Bi Amp question
On Jan 30, 11:14*am, (GregS) wrote:
In article , wrote: On Jan 30, 8:35=A0am, "Serge Auckland" wrote: wrote in message .... On Jan 29, 11:58 am, wrote: On Jan 29, 8:48 am, wrote: THE CROSSOVER POINTS AREN'T THE ISSUE. The design of the crossover and the speaker TOGETHER as a system IS the issue. And you propose to basically ignore this piece of physics. Dick, I've seen a number of so-called "audiophile" loudspeakers that have very simple crossovers, some as simple as a single capacitor, but many which consist of simple LC sections, with perhaps a single resistor to reduce tweeter levels. Many such manufacturers make a virtue of their simple crossover design. Now I know this is all marketing, they make a virtue of their limitations, but is there any reason that someone with one of these loudspeakers couldn't use a DSP-based electronic crossover? I ask also because a project I have in mind for the future is to change t= he crossover in the Tannoy 15" Dual Concentric for an electronic one. Lookin= g at the circuit diagram of Tannoy's crossover looks like something that co= uld be replicated with an electronic device. Am I missing something? I think you have to consider the crossover-driver interaction. If you duplicated passive with active, the driver does not see the same thing. It sees the amplifier output. You have to duplicated the whole action of the passive crossover in the active crossover. greg Best regards S. --http://audiopages.googlepages.com He's assuming that the crossover in question has additional components beyond one of the common crossover designs. *Such as additional filters to compensate for peaks or fall off somewhere. *A point I say is just theoretical until we see the schematic of the crossover in question. *An active crossover is an acceptable substitution for a basic no frills passive crossover. *It is essentially the same thing substituted further up the signal path. *If you wish to experiment, it's far easier than changing passive components at the output stage. And if you really want to you can get active equipment that will also let you introduce and adjust other filtering effects as well. True, there is a school of thought that additional complexity in the crossover just introduces as many problems as it creates. *As you know the speaker is not a straight load, it has inductive properties as well. *Some would point out capacitive too. *And the load the cabinet places on the speaker has yet another impact. *Of course all this varying with frequency. *While the complete behavior is pretty easy to observe at one frequency it's a whole nother beast to determine what the total effects of the speaker, cabinet, and crossover components are on that vastly more complex music signal. *Never mind measuring the effects of port design on turbulence. *Imho all that's what's behind the simple is better school. *Some of the same proponents of biamping also recommend simple no frills 6 db or 12 db crossovers from the mid/tweeter section. *There are a number of camps and they all have their pluses and minuses. *Some people would point out that all the complicated reflections in the typical home listening room negate the bulk of this fine tweaking anyway.- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - Legitimate point. |
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#79
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Bi Amp question
wrote in message ... On Jan 29, 1:40 pm, jakdedert wrote: wrote: snip If I owned those speakers I would very likely not consider trying to biamp them. Partly for some of the reasons you point out. Does that constitute agreeing with you? :-) ?? Does someone have a link to the OP's speakers. AARC, he id'd them by a model number (902?) with no brand. Apparently it was something I 'should' know; or he actually listed the brand and I missed it. This thread is too long to search it out. jak I believe he has the B&H 802D's http://www.avrev.com/home-theater-lo...udpeakers.html Yes they are B&W 802D's mike |
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#80
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Bi Amp question
On Jan 30, 8:21*am, wrote:
Ferrite core and electrolitics are generally accepted to be inferior to air core and polypropylene for use in crossovers. * Spare me the "generally accepted" nonsense. It's "generally acceped" that active crossovers are better than passive crossovers. It's "generally accepted" that CD output has stair-step waveforms. It's "generally accepted" that LPs have infinite resolution. It's "generally accepted" that digital audio can't resolve time events less than a single sample period. It's "generally accepted" is a cover for grotesque stupidity and laziness in the audio world. They certainly are cheaper. *Cheaper is not what I expect to find when I look under the "hood" of speakers in that price range. * That's because you are in no position to make that sort of judgement. Loudspeaker design of ALL kinds is primarily a balance of competing priorities, a very important one is cost. The money saved on the difference between two different kinds of cap or coil is actually a very SMALL part of the total parts budget of most loudspeakers. The cabinet, the drivers, non-direct labor costs, dealer profi are all much larger. A typical speaker in the specialty (non-mass market) audio business will have, at most 20-25% of its retail price tied up in direct materials cost. Of that, 80% is cabinet and drivers. That leaves EVERYTHING ELSE, like sipping carton, the TOTAL crossover, and so on, taking up, at most, 5% of the total retail cost. changing from a $2 coil to a $4 coil might add on the order of $20 to the total retail price of a loudspeaker. It's NOT a cost issue and to claim so or get upset exposes a great deal of naivety about how the loudspeaker business HAS to work. And the best solution for port turbulence is no port. Bullsh*t, in a word. Look, you're ding a superb job of revealing to the assembled crowd how little you know. Id recommend stopping while you're still slightly ahead. Vented design provides a number of very valuable design advantages to a competent designer. That there are incompetent designers and, more importantly, arm- chair commentators who are clueless about such matters, but fortunately none of them stand in the way of competent designs. To quote and old sage, "any idiot can design a loudspeaker and, regrettably, many do." It's correlary is "any idot can have an opinion about stuff he doesn't know about, and, regrettably, many do." *That they used "theory" when designing their port suggests that they didn't really test anything, they just think that the theory is applicable. * It suggests nothing of the sort. You think they tested? You have anything otherv than your uninformed opinion they did not? Without a schematic of their crossover we are just speculating as to how it compares to a standard active crossover. * I would kindly suggest that you refain from the use of "we" here, because "you" really have no idea. I, on the other hand, have spent the last 35 years designing and measuring this stuff, and have, in fact, measured thousands of examples of such. For all you know it's a vanilla 12 db circuit. * If it's B&W we are talking about, I'll bet you $1000 and give you 4:1 odds is it not. You want to take the bet? In this price range I would expect more but I also expected air core and polypropylene as well and I was wrong there. That's because your expectations are a result of lack of information, expertise and not a small amount of ill-formed preconceived notions. Unless you have something other than amateurish handwaving, I'm done. |
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