If a speaker is NOT time coherent, the fundamentals and overtones do not arrive at the exact same instant in time. The overtones arrive a little bit later. My understanding is that this does reduce the perceived dynamic contrast a little bit. (Note that a speaker can be "phase coherent" without being "time coherent". It’s not hard to put the drivers in-phase in the crossover region and claim "phase coherence", but among passive crossovers only a first-order crossover can be time coherent, and if the drivers are non-coincident, the system is only time coherent at locations where the geometrical relationship between drivers and listener falls within a narrow range.) Of far greater impact on system dynamics, in my experience, are thermal and mechanical compression and thermal modulation (the latter being the short-time-constant, but much less-well-studied, companion of thermal compression). These effects tend to round off the peaks. Thermal effects are typically negligible when a driver is only seeing a very small fraction of its rated power handling. Mechanical effects can arise from suspension system or motor system limitations at high power levels, and from suspension system hysteresis at very low power levels. The generally superior dynamic contrast of systems with prosound-capable drivers imo indicates that their negligible thermal compression, thermal modulation, and mechanical compression at home-audio listening levels are solving the most significant problems. Very expensive and/or multiple "hifi" drivers can sometimes achieve similar dynamic performance. Duke |
good advice, go listen to any top rated Vandersteen or Thiel or Dunlavey for that matter....they are all very sophisticated designs using top notch drivers, components and cabinets....the filter is hyper important...but the system, and system engineering matter.... btw a lot of the output in so called high efficiency designs is trash ( distortion ).... which the efficiency spec takes no note of..... |
btw a lot of the output in so called high efficiency designs is trash ( distortion ).... which the efficiency spec takes no note of..... Maybe true, but our hearts and ears buy speakers, not test gear, so it is worth listening with your geek off. But I do think that listening to Vandersteens as exemplars of low order crossovers is a good idea if that is your question. Of course, you can also listen to full-range (i.e. single driver) zero crossover speakers to see if they float your boat in terms of dynamics. Or for something truly different, build the Seas A26 kit: https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-cla... In terms of crossover slopes, it doesn't get much simpler than this. Best, E |
@erik_squires wrote: "I feel as if low order crossovers were actually significantly better in dynamics I'd have heard it. " I think true (acoustic) first order is more dynamic, ALL ELSE BEING EQUAL. All else is seldom equal. There is a tradeoff relationship between bandwidth and efficiency, and a true first-order crossover calls for a LOT of bandwidth. For a system with a 2 kHz true first-order crossover, we'd want the midwoofer to be approximately flat to 8 kHz, and the tweeter to be approximately flat to 500 Hz (with adequate thermal and mechanical power handling). We have to trade off efficiency to get this sort of bandwidth. Thus we don't see high efficiency speakers with true first-order (acoustic) crossovers. Pick your poison. My current poison of choice starts out with a 6 dB per octave initial rolloff and then accelerates to 24 dB per octave. This seems to work pretty well with some combinations of high efficiency drivers. Duke |
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I’ve owned phase/time coherent speakers from Quad (ESL 63), Meadowlark, and Thiel (CS6, CS3.7 and CS2.7), and a lot of other designs using higher order crossovers. I still have no idea if there is something audibly different and inherent to a first order crossover speaker, given all the variables involved. I can say that all the Thiels had a particular characteristic that set them apart from most speakers I’ve heard: a level of imaging focus and in particular, imaging "density" where, for lack of better explanation, it seems like all the sonic information related to an individual voice or instrument in the soundfield seems "lined up" right where it should be. No swimminess at all. It gives a real sense of solidity to the sound. I have heard such characteristics imputed to time/phase coherent speakers, but then again the Meadowlarks didn’t have this quality to the degree the Thiels have, nor did the Quads (though I find all electrostatics suffer from a lack of palpability to begin with, so apples to oranges there). I remember the first-order Dunlavy speakers having a similar density of imaging/tone/palpability like the Thiels as well. Tonally I’ve heard many gorgeous 2nd or 3rd order crossover speakers. Paul Hales was fantastic in this regard and his Transcendance speakers were among the most tonally beautiful and accurate sounding I’ve heard. But after a while I missed that sense of "thereness" and density I had from earlier Thiel speakers, and I eventually found my way back to Thiels. Again, just some anecdotes, not really an explanation for them. I still find all sorts of higher order speakers really fantastic, tonally, dynamically and otherwise. |
with outstanding reliability... IF you have a decent amp it is pretty difficult to blow up a pair of model 2 quarter million pair sold, so somebosys ear brain likes em... again it is a system, plent of engineering goes into the custom scanspeak drivers, filters, cabinets, etc.... I happen to think trading a db or five of ultimate output for better quality sound is certainly smart, especially in w world of hyper affordable high power amplifiers. can 6 db filter speakers damage hearing before breaking ? easy ...but is that your objective... |
but to be fair, probably why RV puts powered subs in his high end gear and also sells powered stand alone subs with a unique high power high pass system and filetrs for the main amp. your results may vary..... I stopped mucking about with kits and an FFT with a crossover cookbook in 1986.....I outsource that to a guy with ten patents, an autoclave, latest FFt and a chamber..... |
There is one company that I think deserves mention here: Induction Dynamics. I've only heard their two way speakers. They use a 4th order "brick wall" crossover in their speakers. My (admittedly limited) experience with other higher order crossover speakers had been that, to me, they didn't have the same expansive soundstaging as did well-executed first order designs. The Induction Dynamics speakers (remember--I only heard the 2-ways) were a striking exception to this trend. I was shocked at how expansive and 3D their soundstage was. Tonality was excellent also. As I recall, the drivers were said to be "inductively coupled" or something like that. In any case, this inductive coupling seemed to compensate for any "problems" (timing artifacts?) that may have introduced by using such a high (4th) order crossover. |
Well thanks to all who answered. My speakers are Montana XP that are 4 way with 24db/oct. crossovers. They are 4 Ohm with an efficiency of 93db @ 2.83V. Some people have told me that all these crossover parts are absorbing the dynamics to the drivers. While I feel the speakers are very neutral, not having any emphasis at certain frequencies, they don't seem to have the "aliveness" that I have heard from other brands like Spatial Audio. Now that may be something I would tire of in a short while, but without a long audition I wouldn't know. I have owned my speakers for many years now, and I don't have any immediate plans on changing them out. |
Higher order loudspeaker crossovers ABSOLUTELY and EMPHATICALLY rob dynamics!!! Insert a single capacitor in series with a driver, and the amount of sonic degradation will more than disappoint you. Multiply that by the complexity of a crossover, and the impact manifests itself accordingly. Although crossover complexity normally correlates with slope, it does not absolutely. Additional components making up things like Zobel networks, notch filters, L Pads, etc. must be considered, and why many (like me) believe they create more / larger problems than they solve. Think about not just crossover slope, but overall parts count, as well. Each part acts like a speed bump. Thiels employ first order crossovers, yet with all of the added circuitry, represent some of the most complex crossovers, with the highest parts counts around. THAT’S why they’re so difficult to drive, demanding of the partnering amplifier, and simply will not come alive unless fed correctly. Having owned and been around the entire JSE / Infinite Slope lineup, their obvious and fatal flaw is the very dynamics of the loudspeakers. Though they possessed many qualities such as notable timbre and ease of listening, they simply lack the ability to stop and start / react, ability to startle, and overall excitement IOW...dynamics. Perhaps the biggest reason the Frieds I was a part of had such fantastic dynamics and the overall ability to excite in a most beguiling manner was Bud sorting all of this out so long ago. Frieds used simple first order crossovers, with a minimum of components. Most who remember know he employed the series crossovers he learned from Dynaudio (even if they themselves don’t), which not only present a more natural and coherent presentation, and far easier load on the partnering amplifier, but the ability to implement a more gentle or steep (as desired) slope IN A FIRST ORDER(!) crossover; that’s impossible in the parallel networks used in 99.9% of the market. Bud’s raison d’etre was the resistive, not reactive, loudspeaker, all in the attempt to recreate his life changing experience of hearing Stokowski in Philadelphia as a child. In fact, Ralph Karsten told me he developed his Atma Sphere amplifier when he owned a pair of Frieds (or IMFs?) back in the day, which even today present an astoundingly wonder match with his amplifiers |
Trelja wrote: "Thiels employ first order crossovers, yet with all of the added circuitry, represent some of the most complex crossovers, with the highest parts counts around. THAT’S why they’re so difficult to drive." Sorry but I must disagree that there is a correlation between parts count and how difficult a speaker is to drive. But ime there IS DEFINITELY a correlation between the impedance curve and how difficult a speaker is to drive. I have been designing speakers to work well with Atma-Sphere amps, and in most cases specifically the little S-30, for thirteen years. In my experience it's the impedance curve, not the parts count, that matters. Of course you can ask Ralph whether my speakers work with his amps. Hope to see you at RMAF, whether or not we agree about crossovers! Duke |
trelja, I don’t buy your thesis; audiokinesis’ view seems more reasonable. I’ve owned a great many speakers (not to mention, like most here, I’ve heard countless speakers I don’t own). My Thiel 2.7s are in fact notable for their dynamic sense of liveliness. It’s one of their most salient features, and having auditioned a great many other speakers recently, they remain among the most lively and dynamic I’ve heard. And I’m driving them with 140W/side (CJ tubes) so it’s not like they require some powerhouse amps to come alive. As for infinite slope crossover speakers and high order crossovers robbing dynamics from the sound, it seems Joseph Audio speakers which use a variation of the infinite slope crossover design, ought to provide one counterpoint: Those who hear, own and review Joseph Audio speakers often remark on how dynamic they are. A sampling: Both rooms had dynamics and plenty of “jump” to them https://parttimeaudiophile.com/2014/11/08/rmaf-2014-audiohouse-rings-bell-with-joseph-audio/
https://www.stereophile.com/content/joseph-audio-perspective-loudspeaker-page-2 John Atkinson wrote in the review: ...the Joseph Perspective was free from coloration, and offered a musically involving sound with SURPRISINGLY WIDE DYNAMIC RANGE. https://www.vpiindustries.com/single-post/2017/12/05/HW-Review-3---Joseph-Audio-Pearl-3 Harry Weisfeld of VPI wrote about his experience with the JA Pearl speakers: (at a show) "the Pearls took over the room! They reproduced the power of the Hugh Masakela tape and 45 RPM vinyl with the experience of a live moment. The visiting customers went into that jaw-dropping mode you sometimes get but don’t expect at a show, we had it in spades." (Listening at his home)... The drums are no longer a noisy mess, they are perfectly recorded and sound as individual drum heads do. The soundstage was expansive yet perfectly focused. I have been playing this record for 50 years and this was truly one of the great presentations, right up there with the JBL Everest’s for speed and power. ....The $75,000 JBL Everest might be the last word in bass dynamics in a real-world situation but the Pearl 3s are pretty close. That is really saying a lot for the Pearl 3s as they are less than half the price of the JBL’s. The drum heads were rattling, the impact was startling, and the level was ear shattering like a real drum would be in your room and I had no headache. Every nick of the sticks on the rim came through crystal clear. You could feel the drummer breathing while working up one massive weight loss program. http://www.theabsolutesound.com/articles/joseph-audio-pulsar-tas-203/ More from the Absolute Sound review of the JA Pulsars: I listen to quite a bit of music with acoustic guitars. To properly reproduce the sound of a guitar requires a speaker that has the ability to reproduce both dynamic weight and power in the lower midrange and upper bass. Given their size it’s hard to believe that the Pulsars can pump out as much dynamic contrast in the lower midrange and upper bass as they do. Martin Simpson’s guitar on Randy Newman’s song “Louisiana 1927” from Prodigal Son [Compass Records] demonstrates the Pulsar’s lower midrange dynamics nicely. Even when a cello and resonator guitar join Simpson’s solo guitar the micro-dynamic contrasts don’t become compressed. All the subtleties of Simpson’s right-hand technique come through with no loss of detail even after the addition of an extensive “string section.” AND: Audiophiles often use the term “fast” to describe speakers that handle dynamic transients and contrasts well. Using this rather broad description the Pulsars are veritable light-sabers. https://www.soundstagehifi.com/index.php/equipment-reviews/658-joseph-audio-pulsar-loudspeakers Another review of the JA Pulsars: The speed of the Pulsar’s bass was revelatory with acoustic jazz. I played a lot of Bill Evans, and Scott LaFaro’s double bass sounded incredible, with all the sinewy twists and turns in his technique easy to follow -- and the pacing was perfect. That speed and clarity were perfect adjuncts to the tunes on Stoa, by Nik Bärtsch’s Ronin(CD, ECM 1939), in which Bärtsch leads his band through a series of acoustic workouts. The music is at turns bombastic and intimate, the band is incredibly tight and fluent, and the sound is splendid. I played the 15-minute opener, “Module 36,” a number of times back to back. It moves from a contemplative opening to a frenetically paced climax, and the Pulsars’ pace, rhythm, and timing were riveting: kick drums and bass lines were completely distinct, beautifully articulated, and had great impact. These speakers could provide a convincing facsimile of real bass wallop. So your claim that infinite-slope/higher order crossovers result in speakers that are not dynamic may be your own opinion, but it doesn’t seem to go much beyond that given the experience of many others contradict the idea. |
@c1ferrari , thank you very much. I think there are scientific explanations for many of our subjective observations. When the science and the observation seem to be at odds, then either the observation has a mistake in it or the science is faulty or incomplete. In other words, I don't see "science" as necessarily being "the absolute truth" on a given subject - it is just our (hopefully) best understanding of the subject at this point in time. |
I think there are scientific explanations for many of our subjective observations.Just to pollute the waters more, there are weaknesses behind the measurements as well as interactions that are very difficult to account for....such as an interaction with a specific amplifier...or how do you measure how a speaker images? We will always likely need science plus observation...and then of course we need different flavors for different tastes and different rooms. It never ends and can never be solved. ;-) |
@audiokinesis, "Sorry but I must disagree that there is a correlation between parts count and how difficult a speaker is to drive." I don’t see myself at RMAF this year, but share your warm sentiments, Duke. It’s been too long since we’ve gotten together, and would love to see you and your wife again. Hope you’re both doing well! I’m thankful this topic has opened up an interesting discussion. However, disagreement obviously does not mean disproven. Could you shed a bit more insight into how you landed on your assertion, and potentially provide some specifics, please? Obviously, from my time at Fried and your designs, we’ve arrived at different places. @prof, "My Thiel 2.7s are in fact notable for their dynamic sense of liveliness. It’s one of their most salient features, and having auditioned a great many other speakers recently, they remain among the most lively and dynamic I’ve heard. And I’m driving them with 140W/side (CJ tubes) so it’s not like they require some powerhouse amps to come alive." Two things, Rich. First, if you don’t consider 140 wpc of tube power A LOT, we are about apart as two people can get. I’ve had a lot of tube amplifiers in my system, and once they rise above 60 wpc coming from at least 4 output tubes per channel, I’ve most definitely reached the serious power and slam territory. I should clarify that with several of the loudspeakers I used which implement first order crossovers, I produce the sort of dynamics that has people just about jump out of their skin with 10 - 35 wpc tube amplifiers. Secondly, although I have the highest level of respect for Jim Thiel and his designs, few have ever been as famously unsympathetic towards amplifier designers. Along those lines, I have nothing untoward that position, and in fact, respect his conviction. Your Thiels can most assuredly produce dynamics, but require amplification that can also just about serve welding needs to do so. A simplified crossover would change that, without question. Again, I do not question Jim Thiel. His design choices produced exceptional loudspeakers with may notable qualities, and the success of his venture testifies to that. Just that ease of drive was never one of them. Thank you for providing the reviews for the JA loudspeakers. Note the comments from Atkinson come from partnering the speaker with MBL and Pass Labs amplifiers, again something different than what I consider the demands of a first order crossover. Finally, as an actual example to illustrate my point of the impact the slope crossover imparts on the loudspeaker’s friendliness to an amplifier, I will bring up the PSB Gold i and the Vandersteen 2. Both speakers come close in their drive complement and stated sensitivity, and differ in the choices implemented by their respective and very talented, very successful desigers. Richard Vandersteen staked his claim on first order crossovers, Paul Barton employs steeper slopes. I do not imply it’s an apples to apples first order vs higher order crossover comparison, but I definitely think we have two end products that we can put in a drag race for our discussion here. The Vandersteen 2 attained as much popularity as any loudspeaker in the past generation, partly because they present a friendly load to an incredibly wide swath of amplifiers and so implicitly have a huge potential customer base. The Gold i, while also selling into the thousands present a surprisingly tough load. When I sold them would only come alive with the brute force Carver Lightstar amplifiers, though would come close to knocking walls down with them. That’s dynamics, but again, with huge demands. Not even the big Adcom monoblocks could wake them from what I considered slumber. As the HEA market pivoted towards tube amplifiers over the past 20 years, the ubiquity of the Gold i collapsed. Again, crossover slope absolutely rob dynamics. Substantially so |
Which is better, red wine or white? Bourbon or single malt? Crossover comes down to integration. There are no flawless drivers. The designer must make decisions as to whether the 4k bump in the woofer/mid is tolerable or not. He may choose to live with it as low order summing floats his boat. First order sum nicely but do little to manage driver flaws and absolutely nothing for time coherence. Like all things audio, crossover BS is waist deep. Reading some manufacturer's material is funnier than the comics. |
Trelja wrote: "Could you shed a bit more insight into how you landed on your assertion, and potentially provide some specifics, please?" I assume this is the assertion you’re talking about: "I disagree that there is a correlation between parts count and how difficult a speaker is to drive." Well my wording was imprecise; here is what I should have said: "I do not think there is a causal relationship between crossover parts count and how difficult a speaker is to drive." (There can be a correlation without causation.) I have designed many speakers specifically to work well with high-damping-factor tube amps (such as the Atma-Sphere S-30 mentioned above). Here are four things that make for good synergy between such amps and a speaker: High efficiency; fairly high impedance curve; fairly smooth impedance curve; and if the impedance curve is not smooth, then the target frequency response should take the amplifier’s output impedance into account. Smoothing an impedance curve calls for additional crossover parts. I have tried it both ways: Tailoring the response specifically for the high-output-impedance tube amp and not caring what the impedance curve looks like; and using additional crossover parts to smooth the impedance curve. Not only is the latter sonically superior when done right (in my opinion as the crossover designer), it also results in compatibility with a much wider range of amplifiers. Most of my work is in prosound. Among other things, I build high-end bass guitar cabs. Many of my designs use bypassable notch filters for response shaping to give the bassist at least two distinctly different voicings from the same cab. With the notch filters bypassed (via a switch on the back of the cab), there is no filtering of any kind on the woofer. I do not hear any difference in dynamics between filters engaged and filters bypassed. But more significantly, neither do any of my customers, to the best of my knowledge. However what my customers CAN hear is, the cab starting to compress at high power levels, regardless of how the switches are set. So this is anecdotal evidence that thermal effects have a more audible impact on dynamics than crossover parts do (at least at the quality level of the crossover parts in my bass cabs). I am friends with a recording engineer who has asked me not to drop his name. He has for decades been testing the dynamic compression of various loudspeakers that he has had access to. What he looks for is, how much does the speaker compress the peaks? This would be a short-term effect, which has not been studied in nearly as much depth as have long-term compression effects. (Had an interesting exchange with Floyd Toole on the subject once - details if you’d like.) Anyway my recording engineer friend sets the volume to his reference level and then hits the speaker with what should be a 20 dB peak, to see if the speaker delivers the full 20 dB. Most deliver less, maybe 16 or 17 dB. A few deliver the full 20 dB. His observation is that loudspeaker efficiency is the best predictor. And among those speakers with less efficiency that still do well, power handling tends to be unusually high. This doesn’t PROVE that crossover type and/or parts count makes less of a difference than power compression, but it does indicate pretty good correlation between good dynamics and drivers that are just loafing along. Note I would agree that, all else being equal, a time-coherent loudspeaker should have superior dynamics because the fundamentals and overtones are all arriving at exactly the same instant. Time-coherence implies first-order acoustic crossovers, if we’re talking about passive loudspeakers. A first order electrical filter doesn’t necessarily give us a true first order acoustic rolloff, so to achieve that target response, additional crossover parts are usually required. Driver compression mechanisms (thermal, mechanical, flux modulation) are documented. They are real. I cannot think of anything about a series crossover that would mitigate any of these effects. I’ve owned two Frieds and spent a fair amount of time with an IMF speaker, and imo they didn’t begin to compete with the likes of Klipsch Heritage Series in dynamics (though they were imo superior in other areas). A first-order series crossover topology may be the theoretical ideal from a dynamic range standpoint (assuming it results in true time coherence), but if driver compression effects dominate, it may not matter very much. @trelja, can you tell me what the actual mechanisms are by which crossover parts count and/or conventional crossover topologies constrain dynamics? There may be effects I’m unaware of that are worth taking into account, even if they aren’t necessarily the primary cause of compression. You may be correct that a steep crossover slope constrains dynamics, but can you tell me why? The "why's" interest me a great deal. Thanks! Duke |
Time-coherence implies first-order acoustic crossovers, if we’re talking about passive loudspeakers.First order crossovers phase sum electrically. Time coherence would only occur with mechanically identical drivers. As this is seldom the case, physical displacement is required. Asymmetric slopes may give better integration depending on the drivers. |
There is no correlation between part count and difficulty of driving. In fact, after a crossover is done, say you end up with a dozen parts, you might often add a few more to reduce impedance peaks and make the speaker operate more consistently with tubes. But the original poster asked about "high order" crossover slopes. This too me means 4th or higher. 1st, 2nd and 3rd are super common. Of course, there's always some one with a pet view point. In this case, full range, one driver, no crossover speakers. They're fine I guess. |
If memory serves, time / phase coherent speakers often use 1st order tweets, 2nd order on the mids, along with physical offsets. But as I have mentioned, I've heard them and they were not for me. I didn't think that dynamics was a particularly stellar reason to buy them. << shrug >> Comments I have heard from those who have played with DSP to force speakers into submission in the time domain indicate better location of instruments, but not something I'm going to worry about much. Buy what you like. Best, E |
@audiokinesis, "@trelja, can you tell me what the actual mechanisms are by which crossover parts count and/or conventional crossover topologies constrain dynamics? There may be effects I’m unaware of that are worth taking into account, even if they aren’t necessarily the primary cause of compression. You may be correct that a steep crossover slope constrains dynamics, but can you tell me why? The "why’s" interest me a great deal." Thank you, Duke. The "why’s" interest me a great deal, as well! That’s where the fun and advancement come from. I believe the issue under consideration is actually quite a simple thing. To make the point let’s go back to Electronics 101. Resistors represent a fundamental component in the toolbox. Resistors reduce voltage, reduce gain, reduce dynamics. We use that to our advantage. When a mother, wife, roommate, dorm captain, guy sitting next to us on the bus, police officer, etc. tell us to turn the sound down, we make things quieter by adding more resistance to the respective audio signal, and (hopefully) restore the peace. We reduced the volume / dynamics from an objectionable level to something others can accept. That’s obviously what the volume control on a preamplifier does. We also use resistance to reduce the voltage through the succeeding stages of our power supplies to suit the needs and limitations of the downstream components. Likewise, as tweeters traditionally play louder than woofers, we use resistance to lower the tweeter’s voltage which translates to volume and dynamics to some level closer to the woofer in order to balance the sound between the two drivers out, and produce an overall better result. Resistors, no matter how small cannot and do not add voltage or volume or dynamics, and they cannot and do not leave the voltage or volume or dynamics unchanged. Resistors, no matter how small, reduce the voltage, reduce volume, reduce dynamics. Add resistors, no matter how small, to loudspeaker crossovers, and we reduce volume / dynamics of that loudspeaker. Inductors are another fundamental electronic component, and typically a part of the crossovers discussed in this thread. They block part of the musical signal from getting to a driver, intentionally so, as we cross over from one driver to another. Every piece of wire, regardless of its elemental composition or length, has resistance. Increase the length of wire and we increase its resistance. Longer wires have measurable and meaningful levels of resistance. Inductors are made from a long (can be 50’, 100’, or even 300’) piece of wire, coiled upon itself. In fact, one specification of an inductor will be its resistance. In other words, on some level since an inductor consists of a long piece of wire, an inductor is a resistor. Again, resistors reduce dynamics. Use an inductor, and you’ve increased resistance and reduced dynamics. Moving from the typical 16 or 18AWG to an 8 or 12AWG often brings the comment of the obvious increase in dynamics and slam. Why? Because its resistance has decreased. Not to the zero not having the inductor at all would represent, but it shows adding components adds resistance which reduces volume and dynamics, and vice versa. Capacitors are another fundamental electronic component, and like inductors, usually a part of crossovers discussed in this thread, and also block part of the musical signal from getting to a driver, intentionally so, as we cross over from one driver to another. Capacitors also have resistance, commonly noted as ESR (equivalent series resistance). No need to repeat the same statements as inductors, other than to say add a capacitor and we’ve added resistance which reduces volume and dynamics. The number and position of inductors and capacitors in the crossover leg in the typical parallel network determines its slope. Second order crossovers have an additional inductor and capacitor from a first order crossover. Third order crossovers have another inductor and capacitor from a second order crossover, and so on. Like for like, fourth order crossovers have more inductors and capacitors than third order crossovers, which have more inductors and capacitors than second order crossovers, which have more inductors and capacitors than first order crossovers. Beyond that, there are compensation networks, made up of additional resistors, inductors, and capacitors a loudspeaker designer may add to the basic layout to suit their design goals. These will also to varying degrees, add resistance to the overall crossover. Additional components work in an additive, in terms of resistance, manner. As previously stated multiple times, adding resistance reduces volume and reduces dynamics. Again, crossover slope absolutely rob dynamics, substantially so |
@trelja , thank you for taking the time to explain your position. My understanding is that series resistance decreases the voltage going to the driver (perhaps more precisely, it decreases the voltage drop across the driver). So it decreases SPL accordingly. I think we are in agreement there. But dynamic contrast is not the same thing as sound pressure level. Dynamic contrast is about CHANGES in sound pressure level. So dynamic contrast is about voltage ratios. A voltage ratio of 10:1 is a 100 fold increase in wattage, and therefore a 20 dB increase in SPL (ignoring compression effects). And adding series resistance has no effect on voltage ratios. Say we have an 8 ohm driver, and we increase the voltage going into the speaker from 1 volt to 10 volts. The voltage ration is 10:1, and assuming no compression effects, the SPL that the driver is producing goes up by 20 dB. Suppose we put a 2 ohm resistor inside the box in series with the driver, and we send 1 volt into the speaker. Now the driver sees .8 volts. If we increase the input to 10 volts, the driver sees 8 volts. The voltage ratio is exactly the same, 10:1, so assuming no compression effects, the SPL that the driver is producing goes up by 20 dB. So it is not obvious to me that series resistance reduces the voltage ratios that a driver sees, and therefore I do not see how it would reduce the dynamic contrast. The volume level being reduced is not the same thing as the dynamic contrast being reduced. Am I missing something? Duke |
Good answers, Duke. Thanks for stepping into the batter’s box! I would add there are many crossover parts, mostly capacitors, that cannot pass small signals and/or very large ones. When a crossover can be made simple, this can be easy to hear unless the drivers are lame, which is another big problem. Duke, you allude to that in your comments about hearing those bass-guitar drivers compress the input signal. When a completed speaker cannot pass small signals, for whatever reason, this means it does not pass low-level details. It produces what I call an ’On-Off’ sound, meaning the music has a ’Jump’ to it but lacks any Grace or Swing, two signals that are 'Small Changes'. Many audiophiles and designers are not wired to hear those, but let’s not go there. When the delicate signals that an Atmasphere S-30 can pass are blocked by such a speaker, the music will be boring so that amp ’must not work for these speakers’. True-- the preferred amp, or cables, DAC, or preamp fills in those small-sound gaps with its less distinct, more smeared sound. Which is what one usually gets when an amp employs more and more output devices, for example. I have heard smeared-sounding speaker wires be made more ’analytical’, more distinct sounding by using the same company’s interconnects. Used with all sorts of other speaker wires, those interconnects were clearly ’Off/On’ sounding. These were the only wires in this reference system, fyi. I have heard the same from some amps paired with their matching preamps. Keep on listening!Roy |
Thank you Roy!! If you see any mistakes in my posts, PLEASE correct me! Roy makes the best-imaging speakers I know of. If I hadn’t crossed over to the Dark Side and become a manufacturer, I’d still be a dealer for him. Anyway just to clarify a bit, imo my bass cabs actually have pretty good woofers - my point was that thermal compression can be fairly audible when it sets in. The bass guitar world is less prejudiced against little guys than the high-end audio world. If you’re REALLY bored, one of my bass cabs was just reviewed by Bass Gear Magazine: http://https//www.bassgearmag.com/audiokinesis-changeling-c112t-bass-cab-real-world-science-fiction/ They seemed to think it didn’t suck too bad. Anyway I hear what you’re saying about capacitors. I’ve not paid much attention to capacitor quality in the past, kinda just threw some money at the issue and hoped for the best. Recently I’ve gotten some valuable advice from someone who knows a lot more about capacitors than I do, so I changed a few things and yup it makes a difference. I’m going to start listening for the "On/Off" phenomenon you describe. Totally agree with you about the importance of low-level details. THANK YOU for the heads-up! Duke |
I think one needs to look at loudspeakers as the sum of their design and parts. Focusing on one aspect like networks not really useful for if wanting greater dynamics in loudspeakers one looks for a more dynamic design and it could have a good num of network types while still achieving that performance goal. Personally I prefer simple networks and physical alignments but the reason I prefer simple if possible is the increase in detail and soul not dynamic range. When I design if requiring too complicated a network I redesign I look at it like a design flaw . But with all things YMMV. |
@trelja " Resistors represent a fundamental component in the toolbox. Resistors reduce voltage, reduce gain, Yes, right right .. ... reduce dynamics" Woah, no, they don’t. They could only do this if they were non-linear. Resistors are the most linear parts in the entire audio chain, except wire. If you are going this way, you might as well get rid of every volume control and only listen at full output. Hahaha. :) I think you are confusing output level (dB SPL) with the ability to present music without compression. The latter is how I define dynamics. High sensitivity drivers like in horns have the advantage in dynamics not because they are loud, but because they suffer much less from thermal compression. That is, the coils and motors heat up less and can handle more heat. While resistors and other crossover components and even drivers may suffer from this, it is up to the designer to keep all of them well within spec. None of this makes the argument that high order (4th) is less dynamic than low-order (1st, 2nd). This is why I use 5W resistors when 2W are called for. :) Best, E |
@audiokinesis "So it is not obvious to me that series resistance reduces the voltage ratios that a driver sees, and therefore I do not see how it would reduce the dynamic contrast. The volume level being reduced is not the same thing as the dynamic contrast being reduced." @erik_squires "Resistors are the most linear parts in the entire audio chain, except wire." While I’m trying to keep my posts as brief as possible, I’m glad the topic of resistors came up. I also used to think like the points raised. As I built speakers, I spent an incredible amount of time on crossovers, listening and auditioning, tweaking values and configurations, then doing it all over again. Moving up in complexity did impact dynamics, to the point of losing the ideal match between amplifier and loudspeaker because of it. I also noticed the damage resistors did to the sound, and it left me perplexed. Even the best resistors I found sounded surprisingly and disappointingly bad (though not nearly as bad as capacitors) in comparison to nothing. Later, I began building amplifiers, and noticed how even more profound the effect of resistors really are. Along the way, I was fortunate to work as a material scientist / R & D chemist during the time when electronic materials needed reformulation because of the environmental legislation (CE, ROHS, etc) requiring the elimination of materials such as mercury, lead, cadmium, etc. Among our many products, my company provided the resistor materials to CTS, Dale, General Motors, Ohmite, TRW, Vishay, and others that manufacture the resistors such as get used in HEA, although our audio world is like a bucket of water in the ocean. It proved the most exciting time in the industry since the 1960s when the original formulas were developed. I was incredibly lucky to be at the right place at the right time to do such work in going back and essentially getting to start from a clean sheet of paper, and to learn how such technologies impacted our hobby. Knowing what’s actually inside quickly proves thinking those resistors coming anywhere close to the copper and silver wire we employ in our cabling and internal wire as simply and fundamentally wrong. It opened my eyes to why resistors sound so poor, with some sounding much worse than others. One of the fundamental characteristics of resistors is temperature coefficient of resistance (TCR), which you can find in most resistor product / sales literature. TCR quantifies how much the value of the resistor changes in relation to temperature, down to -55C and up to 125C. As most of the world (especially, the military) considers it imperative a resistor not change value in relation to temperature, a neutral (0 PPM - parts per million) TCR is the goal of most companies producing resistors. And in fact, most modern (unlike the old carbon composition) resistors do exceedingly well with that, carrying a TCR of +/- 50PPM or even +/- 25PPM. Not getting too technical, except to say that means the resistance in relation to temperature remains quite stable. On the other hand, we know the resistance of metals typically behave quite the opposite of that, as resistance rises (substantially, in fact) with temperature, which we refer to as positive TCR. For example, the resistance increase of copper is 0.393% for every increase in degree Celcius, and vice versa. As I said, it’s substantial. That’s exactly what Duke described in terms of thermal compression of a driver, which definitely trumps crossover design and implementation - when it comes to dynamics and everything else. At some point, the resistance of the voice coil due to its temperature rise precludes it from behaving as it did previous to that in handling the signal passed to it. How do we produce resistors with the impressively neutral TCR specifications I mentioned? The formulations, logically, include materials that have substantially negative TCR profiles to balance / shift things from positive toward the desired 0 TCR. What sort of materials possess negative TCRs? Semiconductors (materials that only conduct electricity under certain conditions) or non-conductors / insulators such as ceramics (bismuth trioxide most famously, but also compounds like titanium dioxide, barium titanate, boron triphosphate, calcium oxide, and on and on and on) and infinitely (literally) varied glass formulations. Although these materials may not conduct electricity themselves, they can exert a strong enough influence on the resistor as a whole to bring the TCR down to the desired level. Glass provides the fusing material for the resistor to attach (literally melts and fuses) to the substrate as it goes through the especially violent sintering process in a high (1100F - 1600F) temperature furnace, as well as the means of forming the conductive (quite far away from what "wire" looks like) matrix of the metallic conductive components, as well as often (and, hopefully) benefiting the TCR situation. In fact, as the old timers used to say, "It ALL comes down to the glass." The main driver for formulating new products was the elimination from lead and cadmium from the glass. Lead oxide, which as in other fields such as leaded crystal and decorative glass, yields very low temperature melting, wonderful performing glass, and provided the extremely high-performing resistors that came out of the 60s. The presumption of most around the world was the new "green" materials would never come close to the ones they were replacing due to the removal of lead and cadmium. In fact, most of our competitors green products looked downright scary. Through a two-pronged approach, but mostly from the grace of God, I was fortunate to actually end up with resistors that were superior to the old products, to the astonishment and disbelief of my boss who developed our products in the 60s. Our testing showed them to be the finest, highest performing low resistivity (0.01 Ohm/square - 10 Ohm/square) resistor material in the world. Wirewound resistors fare no better, as instead of using the sort of wire materials we might expect in HEA, they consist of alloys of base metals such as nickel and chromium, again with negative TCR compounds as part of their proprietary formulations to produce the desired neutral TCR specification. I mostly avoid the religious wars on cable, fuses, etc., but my experience makes me to allow for the possibility of yielding positive results by employing much improved conductive materials. And instead of a 0.5" or 1" wire in a fuse, consider the very, very many feet that makes up a wirewound resistor. As one can imagine, reducing the TCR of such heavily positive materials down to 0 or 25, 50, 100, or even 500PPM, typically requires substantial amounts of these negative TCR materials. To anyone who has chased audio cable with increasingly pure levels of copper or silver, say from 99.9% to 99.9999% through the reduction of compounds (what we call impurities) like oxygen in the quest for improved sonic performance, this admittedly must come as more than a shock. Conductive content as part of the overall (conductors, sintering aids, glass, additives, dopants) end product could even drop as low as 5 or 10%, though it’s typically far higher in order to produce a reliable conductive matrix. Products get sold as a series, normally each product representing a decade of resistance 10X higher or lower than the next in the lineup. More conductive products contain more of the conductive material. Less conductive (more resistive) products contain less, up to a point, that is. At some point, a lack of conductive material no longer supports a conductive matrix, and one moves up to a different series, featuring a higher resistance element as its conductor. It may sound less pristine and "right" than we imagined, yet while still leaving out a lot of the details, that’s how resistors get made. Look at electron micrographs of the end result, and some will leave you to wonder how any HEA component using them could ever allow the purity and beauty of the music to pass through without looking like a car wreck. Does anyone still think resistors are close to "wire"? And is it now even just a little easier to think the pinball trip through these resistors could possibly negatively impact dynamics, or by multiplying their number or complexity of the circuits that employ them could result in same? |
@ trelja, Wow, THANK YOU SO MUCH for that in-depth education!! I think you have just explained something I observed years ago but did not understand. In the course of my own crossover builds, I found that a cluster of resistors paralleled to get a particular target value sounds "more open" (better dynamics?) than a single resistor of the same type having that target value. Presumably this is because the more resistors soaking up the heat, the less the actual temperature rise will be in any one of them, thus the less change in resistance. So my crossover boards all have these big unsightly clusters of resistors. Because our hearing is logarithmic, with a doubling of perceived loudness calling for a tenfold increase in power, an efficient speaker system has an inherent advantage in the thermal domain. There may well be other dynamics-reducing effects that come into play in a steep crossover which are related to the rolloff itself. As mentioned earlier, I think time-coherence should offer the best dynamic contrast, all else being equal, by delivering all the harmonics of a note at the exact same instant. Perhaps it's not either/or, but rather the further from time coherence we get (via steep slopes), the more the dynamics are degraded. I haven't done any actual A/B comparisons, but I THINK that my current hybrid filter (first-order in the crossover region, accelerating to fourth-order further away), does sound more dynamic than my previous builds with similar drivers. Thank you very much Trelja for taking the time to explain what's going on with resistors. As usual the real world is a lot more complicated than my simplistic model of it! Duke |
