I am funny as hell, sad the moderators don't think so.
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Viber6, I believe most equipment designers/engineers are pretty clear that there are two aspects of designing a new piece of equipment, the engineering side of designing, then the black art of voicing. I believe both Jason Stoddard of Schiit and Paul McOwen of PS Audio have been clear that there is an aspect of equipment engineering where the science says changes shouldn’t make a difference in the sound, but yet they do. |
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George, I read what anybody has to say, but the only thing I trust is my own EARS. Do you believe the Electronic Institute rather than your ears? If so, then you believe your ears don't matter and therefore you have lost credibility. I bet that few or none of the Electronic Institute writers have commented about the audibility of any of their claims either. Many audiophiles like me are interested in accuracy of sound from listening, not in writing a postdoc thesis about circuitry/devices/etc. Bruno seems to have expertise in technical theory, but also does the listening. That doesn't mean that I totally agree with what he likes or thinks is accurate sound, but I respect him or anyone else who do both theory and listening. |
And you believe all he says, I believe my own findings and an Electronic Institute before any manufacture spruiking and trying to make a buck. Once again here is one main difference why a Class-D with Mosfet will not drive into a hard speakers load like the OP’s Thiel CS5’s like a good linear amp like the ones I have suggested with BJT (bi-polar) output stage. And Class-D’s don’t come in BJT From Electronics Foundations: Semiconductor Devices [Lecturer] BJTs tend to have better, more linear gain characteristics…and can give you a lot higher voltage gain than MOSFETs.…They’re also able to handle higher output currents…and have a lower output impedance.…That gives BJTs a huge advantage over MOSFETs…for building amplifier circuits…that need to provide a significant amount of output power…and or drive loads that have low input impedance.…MOSFETs are going to have a harder time…driving a low impedance load…because they have a higher output impedance.… |
Thanks for posting the info about the ME amps. They may sound excellent, but that is not the central issue discussed here. The issue is that you have not shown you understand the correlation of technical measurements with tonal qualities. Worse is that you keep dodging this issue as if you don't care about it. I'm not saying that I do understand the correlations, and most good designers admit that they don't fully understand either. That's why they design according to their technical concepts, but change and tweak based on listening. Bruno Putzeys has written that he works this way. I assume you respect Bruno, so why don't you follow his lead? |
Typical George, nothing to show, so attempts to distract. Here is your chance George, show us your designs and products. Wait, weren’t you going to stop replying to this thread a few days ago? I would still appreciate a response showing my calculations which refute your unfounded claims that a ML2 will outdrive a Ncore 400 amp into low impedance loads are somehow flawed. It should be easy for you given your expertise. |
Well you have just made yourself look like a total ? Read again and take it in, I didn’t say I built Peter’s amps who is a long time mate, and not at all in a good way. I said it’s what I’m using at the moment, mcreyn get a life, really!!! |
Wait, so George is Peter? It all started in 1976 when Peter Stein of “ME Sound” started manufacturing high-quality audio amplifiers in Australia. Sadly in October of 2003 circumstances led to the close-down of manufacturing operations. Since that time they have not left their loyal customers totally in the cold, but have been provided advice and repairs wherever possible, within the resources and time frames available. Many models and units were built during those 26 years and the advice I’ve heard is that they are extremely reliable and serviceable for many years to come. Notice he says manufactures. George has never designed a thing in life. Just resurrected a company from the dead, but it doesn’t appear any have actually been made and sold. http://www.meamplifiers.com.au/me-history-news.html Ironic that George calls others shills. Just part of his classic psychological projecting. |
design your own amp, send it to me You just need to search buddy, I’ve built some of the biggest pure class-A solid state that were water cooled, one that was a three man lift, explained in great detail in Audiogon and other forum pages if you could be bothered looking.!! This is what I use at present https://ibb.co/zNMMnpT https://ibb.co/8XqKvJd |
There is indeed no hope for you. All your pseudoscience data is nothing more than pseudoscience because without listening correlation it is irrelevant to the pursuit of audio excellence. Accuracy in sound doesn't necessarily correlate with specs. It is obvious that you don't do any serious listening to confirm what you claim. To prove me wrong, present to this community your listening experiences that corroborate what your measurements say. Without your honest descriptions of your listening, your comments can be ignored. And your simplistic explanations of rolled off or extended HF based on setting of the switching freq output filter are ignorant until you personally measure a product and correlate with the listening. My credentials are many decades of having played solo violin in major concertos with orchestra, chamber music playing, and listening up close and further away in the hall. I have played examples of most of the great violin masterpieces of the 17th through 19th Century. It doesn't appear that your musical credentials are in my league. I am also an integrative medicine physician who knows that clinical observation must be correlated with objective lab, electro- and neurologic physiologic and radiological data. Just as it takes decades of clinical experience to know how to combine clinical and objective data in a useful perspective, it also takes informed listening and musical experience and competence to know how to integrate subjective and objective audio data. Even the leading electronics designers are still learning. They change parts and do their tweaks based on listening. If you claim to know more than anybody, design your own amp, send it to me, and I will tell everyone the truth about it. If it really is great sounding, I am in the market for SOTA and would happily pay you for it as well as proclaim that you really know what you are talking about. I will wait patiently. |
find out whether the phase shift has any relevance in your listening. If you believe there nothing to hear when you have 70 degrees phase shift at 5khz and still 50 degrees at 2khz!! then there’s no hope for you. https://ibb.co/JdrgGBH I have heard class D amps that sound euphonic/rolled off in HF, and others that sound harsh. All because of the setting of the switching frequency output filter and where it acts, either "too high" or "too low" "rolled off in HF" (too low) , and "others that sound harsh" (too high), with today’s 500khz switching frequency. Raise that switching frequency 3 x to 1.5mhz as you can with GaN, and you’ve got rid of the problem because the output filter can then also be raised 3 x higher, and then you don’t get that phase shift so low down into the audio band or the problem of as you say ("rolled off in HF, and others that sound harsh"), because the filter then can be set to do it’s job fully and rid the switching frequency completely and not effect the audio band with phase shift. It’s that simple, even the most technically inept should be able to understand, maybe! Or you can believe the ones that are trying to tell you it doesn’t matter. From day one Class-D has had this problem, because of it’s low switching frequency/filter. |
I will add that my class D Mytek Brooklyn amp is very neutral, revealing and smooth in the HF. It briefly shuts down at 300 watts into my inefficient electrostatic + parallel Enigmacoustics tweeter combination whose impedance is about 2 ohms in HF. SO WHAT--it plays music beautifully over 99% of the time. I am not complaining about its technical deficiencies. I am looking forward to ricevs' more powerful amp. |
george hifi, Maybe you do much less listening than analyzing specs. The Levinson ML2 fully broken in which I owned years ago was syrupy euphonic and veiled at low/moderate volumes with my electrostatic speakers. Instead of claiming ricevs is a promoter for his amp, why don't you spend a little money, find out whether the phase shift has any relevance in your listening. No risk to you, and then you could have more credible comments. Alternatively, have someone gather a bunch of amps whose specs are unknown to you, do comparative listening, and see for yourself whether listening tests correlate with the specs. The truth is that there is a very small correlation, but not enough to differentiate among good or great amps. I have heard class D amps that sound euphonic/rolled off in HF, and others that sound harsh. |
Why oh why would anyone make a speaker with a 2 ohm load? It makes no sense. Some of the best speaker ever, have loads like this and even worse, that’s why they are some of the best. EG: Wilson Alexia 0.9ohm in the bass and many others. I couldn’t even be bothered to tell someone like you any more because you’d be deaf to it, as all your interested is selling your own Class-D IcePower 1200AS2 modules that have a woeful phase massive shift of 70’ degrees!!! between 7 to 15khz!!!! No wonder Class-D detractors complain about the uppermids/highs so much. https://ibb.co/JdrgGBH |
This is so weird. We have a guy here who thinks that one thing he makes up means something. No one else would make up such a story. You don't need double the wattage into 2 ohms to drive a 2 ohm load. All you need is an amp that is stable into 2 ohms and has enough power to drive the speakers. If your speakers are 87db at one meter....then lets say it is 83 db at your listening chair. That means 93 db will be reached with 10 watts and 103db with 100 watts. If that is as loud as you listen...I rarely listen this loud.... then a 1000 watt at 2 ohms amp will give you plenty of headroom. This is simple science. If an amp can double its power from 4 to 2 ohms that means it has a very stiff power supply. However, it does not insure that it sounds good with any load. This is just a static test. It means very, very little by itself. If you get 20 different amps that do 1000 watts into 2 ohms (with stability) then you will get 20 different sounds. Some will sound bad, some good and some great. The sound of an amp is dependent on hundreds of different things. One factor (a made up factor) does not make a good sounding amp. I made my amp sound way more dynamic and alive by doing various mods to it. The power did not increase, the amps it can draw did not increase......but the powerfulness and transparency of the sound increased. Why oh why would anyone make a speaker with a 2 ohm load? It makes no sense. It is not more linear and/or lower distortion to have lower impedances. If you have a speaker with a 2 ohm load that means you cannot use moderately powerful amps (that may sound better and be cheaper), you have lower damping factor and it is known by almost everyone that the lower impedance an amp has to drive the more distortion the amp produces. Only those designers stuck in a paradigm from the past will make speakers that way today (Wilson, etc?.). Even Magico has raised the impedance of their latest and best MKII speakers so they do not dip below 3 ohms. These guys are smart. The trend is for more sensitive speakers and/or powered woofers. This is a good idea. Look at the latest Spatial and GR Research open baffle speakers. In some models you only drive the mids and highs (92-96 db sensitivity at 8 ohms) and you have either servo woofs or powered woofs on the bottom. |
Are you serious! You buy it and drive the Op’s speakers then You are really in a world of denial. if you think this Class-D can out drive the 25w ML2’s "to a given level into these OP’s speakers." I’ll lay money on it also that those watts are not real or RMS, would be nice to see some independent test, at 8,4,and 2ohms You buy it and live with it, because you obviously think 3000w can sound better than 25w into the OP’s extremely hard to drive speakers. It’s like saying a 1/4mile dragster with 8000hp can get to the top of Pikes Peak hill climb faster than a 100hp rally car, delusional is the only word, even the most technically inept on these forums would think so. |
joysjane That’s right, it doesn’t matter how many watts you have, if you don’t have the current to back it up all the way down into 2ohms and less, with speakers like the OP has in the bass, you got s**t. Like I said the "puny" 25w Mark Levinson ML2 monoblocks will slay them "to a given volume level" Cheers George |
I have heard that Behringer,Was that with speakers like the OP has that are 2ohms and less for nearly all the bass. BTW that 3000w Behringer Class-D can be got now for $299!! at Parts Express now, with free!!! shipping. https://www.parts-express.com/behringer-nx3000-ultra-lightweight-class-d-3000w-power-amplifier--248-7012 |
1. Get a Class D amp.Crude way, but effective. Better to just see how they behave in tests not understated into 8,4, and 2ohm and see if they can do "close" to the doubling act for each halving of the impedance. My answer to the posted question,Excellent advice. Many manufacturers just under specify the 8ohm rating to allow their product to be in spec for the lower loads.Yes this must be observed, as many "cheat" by understanding the 8ohm or the 4ohm watts, just so the 2ohm look better. If all above is not taken on board, just buy a 3000!watt Class-D for just $400 and see how you go. https://www.storedj.com.au/behringer-nx3000-ultra-lightweight-3000w-class-d-power-amplifier Cheers George |
The OP asked a simple question... "What Class D amps will drive a 2 ohm load" Specs Shmecs, Opinions Shmapinions. My Brother’s Shmother’s Frother’s Caruther said. Ba-Loney! 1. Get a Class D amp. 2. Find some Kappa 9’s. 3. Set the the switch in the rear to Extended. 4. Crank up the music. 5. The Class D amp that doesn’t shut down will drive a 2 ohm load. I can say this after completion of the above five steps, This is gonna be one very short list of Class D amps... Bahahahaaaaaaa! My answer to the posted question, Stay away from Class D amps to drive low impedance speakers. By the way dsper... Truly a great pair of speakers. Enjoy them with whatever you pair them with. |
@Dsper — the "doubling thing" we love as audiophiles means that the amp will maintain its output voltage constant despite the drop in load impedance, which in turn means its power supply can adequately provide the increase in current needed to achieve said constant voltage. As you probably remember, volt/ohm= amp which means that every time you halve the ohm, you double the amps, voltage remaining constant. As power (Watts) is the product of volt x amp, it follows that keeping the volt constant means the wattage doubles. In the real world, however, only a perfect amp will do this and there are no "perfect" amps. Many manufacturers just under specify the 8ohm rating to allow their product to be in spec for the lower loads. Nothing wrong with that in my book, you still need a well-engineered product to achieve numbers close to doubling anyway. |
Keep it up Ralph, your not doing your Class-D venture any good service, by trying to pull the wool over people's eyes. There are far better linear BJT amps around than Class-D's for driving sub 2ohm impedances, all one has to do is look what happens to the Class-D's Stereophile tests when they do 2ohm load testing, some times they don't even try because they know it cant take it. |
George’s arguments are irrational.To which George replied: So you my friend are the irrational one not me.George's argument was both incorrect and irrational. This is different from saying that a person is irrational- the principle to use of course is 'attack the argument not the person'. Calling someone else irrational as we see here is a forum violation. In addition, it employed a logical fallacy known as a 'Strawman', since George was trying to say that he had been called irrational when that didn't happen. Logical fallacies are by definition false. |
George’s arguments are irrational. For him doubling down power is more important that the absolute power and current the amplifier actually gives. Sorry but this is wrong, have you ever listened to a pair 25w Mark Levinson ML2’s on a pair of hard to drive speaker like the OP’s? "to a given level" (because they are only 25w after all) they will annihilate any 500w or 1000w Class-D. This proves that doubling down (current) to below 2ohms into this kind of speaker load is the most important factor for sound quality, not wattage!. ( otherwise we would all own $400 3000W! Behringer NX3000 Class-D’s ) https://www.storedj.com.au/behringer-nx3000-ultra-lightweight-3000w-class-d-power-amplifier Although if you want to go louder then wattage becomes a factor also, so then the same kind of amp that can double with more watts is needed then. So you my friend are the irrational one not me. BTW You’ll never see a pair of ML2’s for sale used as owners die with them! |
I am so pleased that others with, apparently, endless patience and REAL knowledge, have taken the time to contribute positively to this thread. For me, it doesn’t matter that some of the posts have been made by suppliers / manufacturers. What matters is the quality of information and the clearly stated reasoning behind their position that the right Class D amp, properly designed and built, will drive heavy-load speakers. There is an obvious point to me: certainly for EU/UK law, products that don’t do what is claimed will very quickly mean suppliers / manufacturers will be brought to book in the context of trading / consumer legislation. Also, most suppliers presumably rely on reputation. If they supplied goods that didn’t do as claimed, that reputation would be damaged pretty quickly. To those who have contributed constructively, retaining their cool in the face of substantial provocation, I for one appreciate it. K (definitely not a seller of hi-fi equipment) |
Look at complimentary BJT’s with massive power supplies that I’ve been suggesting for these loads, then look at your Class-D Mosfets usually not complementary as the P channel stinks, then the 8th grade maths don’t mean ****..This statement is false. One of the advantages of a class D circuit is that since the output devices are only switched on and off, matching the devices is unimportant and the need for a complementary device eliminated. McIntosh MC2KW is class AB and has 2,000 W in 8, 4 or 2 ohms. In his book it is a bad amp with not enough current because it does not double down too...Yes- as long as it can behave as a voltage source, doubling power is unimportant. Our amps don't even act as voltage sources and they've been getting awards in the high end press for decades now. Its a common audiophile myth that doubling power is the most important thing about an amplifier when other aspects such as distortion or bandwidth are often far more important. A myopic viewpoint is often limited... |
George's arguments are irrational. For him doubling down power is more important that the absolute power and current the amplifier actually gives. Typical audiophile rule of thumb that has no backing on actual physics and basic math. McIntosh MC2KW is class AB and has 2,000 W in 8, 4 or 2 ohms. In his book it is a bad amp with not enough current because it does not double down too... |
Wake up and smell the roses. This is it for me, as this thread has just become a hand full of manufactures/retailers trying to make some $$ from their new ventures into Class-D Just look at any of the many Class-D test in Stereophile, when they test bench a Class-D with 2ohm loads, they either crash and turn off, goes backwards in watts compared to 4ohm, or it just current limit and s***s themselves. BYE BYE https://www.sccpre.cat/mypng/detail/275-2758889_emoji-world-bye-bye-emoji.png |
George, You seem to misunderstand how amplifiers work. Take your ML2 monoblocks. They put out 14.14 volts max to make their 25 watts at 8 ohms before clipping. At 8 ohms, they are flowing 1.76 amps of current. At 4 ohms, they are still at 14.14 volts, but 3.53 amps of current. 2 ohms, now up to 7.07 amps and 100 watts of output. We will ignore anything below that, as the CS5s don’t dip below 2 ohms until the subsonic range (and even trying to put 100 watts through the 8" woofers below 20hz will cause them to exceed their excursion limits). Now lets take a Class D amp, say the Ncore NC400 for DIY. It is rated at 200 watts at 8 ohms, 400 at 4 ohms, and 580 at 2 ohms. It has a maximum current capability of 22 amps per the manufacture. Lets only run it at 100 watts into 8 ohms, where it will be 28.28 volts and 3.53 amps. 4 ohms, still 28.28 volts nets us 200 watts, and 7.07 amps. 2 ohms, still 28.28 volts, 400 watts output, now we are at 14.14 amps, or twice the current of the Levinson and still well under the manufacture's limit of 22 amps. An amplifier doesn’t put out more current than a speaker needs to reach a set voltage. The Ncore will maintain twice the power output as the Levinson down to 2 ohms (and below even). These are the laws of physics and why amplifier designers speak in terms of voltage, not current capability, except to establish the minimum impedance a given amplifier maintain its voltage. Put another way, even a cheap receiver can drive 2 ohm speakers, but will do so at a far lower output than at 8 ohms. |
Yes you use this old chestnut everytime as it suits you to bring it out every time your OTL’s are brought into question doing the same thing.This statement is false. Our OTLs don't double power and in fact are not intended to act as a voltage source. They are intended to act as a Power Source. So it’s simple for all, instead of doing war and peace to confuse everyone as he usually does.While this comment is a bit of a word salad, if I make it out right its mostly correct and doesn't repudiate anything I've said. Just about any class D amp that can make 1000 watts won't have any troubles making as much power as the ML2 will do into 2 ohms (100 watts) so what this comes down to isn't whether the amp can do 2 ohms better, its simply if it sounds better at all. |
George, the quote above suggests that you do not understand how a voltage source works Yes you use this old chestnut everytime as it suits you to bring it out every time your OTL’s are brought into question doing the same thing. So it’s simple for all, instead of doing war and peace to confuse everyone as he usually does. dsper OP here’s is the proof, Thiels CS5 that have impedances that reach down to below 2ohms will get "driven" and sound far better "up to a given level" with the 25w!!! Mark Leveinson ML2 monoblocks, but certainly not louder than 1000w, 2000w or even 3000 watt Class-D amps, because the ML2’s can do the doubling act into lower impedances right down to 1ohm |
My two cents: 1) George is an extremely rude individual. Would you honestly speak to people in person the way you do here? Why go out of your way to insult an engineer who designs and builds excellent products and is wiling to impart information? Are you willing to share your audio CV so we have an understanding of your expertise, as your comments do not suggest you do not have much of an understanding of even basic electrical concepts (i.e. ohm’s law)? 2) Atmasphere is extremely patient. Thank you you for continued information. Your posts are always informative for those looking for more technical information without getting deep into the math. |
George, the quote above suggests that you do not understand how a voltage source works.This statement is false. The ability to double power as load impedance is halved has nothing to do with how well the amp will play bass In case you don't understand what a voltage source is, solid state amps that can double power as impedance is halved are behaving as a voltage source. Having a low enough output impedance is for the most part what makes for a voltage source. A voltage source is defined as a circuit that can make the same voltage (not power) output into whatever load it drives. Now no circuit can really do this perfectly; perfection does not exist. So constant voltage is considered load invariant under the Voltage Paradigm rules. Historically ElectroVolice and MacIntosh led the way to this concept back in the late 1950s. To be a voltage source, the circuit does not have to double power as impedance is halved. But it very much has to be able to cut power in half as impedance is doubled! This is why tube amplifiers can operate as voltage sources and its also why a solid state amp that can't double power into even 4 ohms can nevertheless still play bass correctly into a 2 ohm load. Whatever power it makes into 2 ohms, to act correctly without distortion it will be half of that into 4 and half again into 8 ohms. So for those amps that do not have the power supply capacity, or the current capacity to survive higher powers in the output section, or for tube amplifiers which are well-known to not double power as impedance is halved, the designer simply has to make sure that the amplifier has enough negative feedback so as to reduce the output impedance such that the circuit behaves as a voltage source into the expected loads. If the amplifier innately has a low enough output impedance it may not need the feedback to achieve constant voltage operation. An example of this are the Ayre amplifiers. But any class D amp (GaNFET or not, even sans feedback) has a low enough output impedance as well. So as long as they are operated in their linear region 2 ohms is no problem. Again, this is defined by output impedance. In the case of a class D amp, the output impedance formula is dominated by the 'on' resistance of the output devices. Even in an older MOSFET based class D amp, the output impedance is usually well below 0.1 ohm, meaning that they will have at least 20:1 damping factor into a 2 ohm load. If the amp runs feedback (and most of them do) the output impedance will be even lower than that. The real issue of a class D amplifier driving 2 ohms is actually the filter at the output. What I regard as a bit odd here is that while you have acknowledged numerous times in other discussion the issues of a filter at the output of the amp, in this particular discussion you've not brought out this salient fact even once! This leads me to think that you have no idea what you're talking about. (Please note that what I think you know and what you actually know are likely two different things.) BTW, the way to deal with the filter issue is to design the filter to operate at as high a frequency as possible- hence the advantage of GaNFETs as they allow a much higher filter frequency since the switching frequency is so much higher. This allows the filter to still be effective for hifi purposes when presented with a 2 ohm load. You like to routinely discount my comments out of hand and insult me at every turn, despite the fact that I went to school for this sort of thing and actually design amps (including GaNFET class D amps) for a living. You're a fan on Nelson Pass- why not ask him? |
what’s wrong with efficient easy to drive horns? If you need to ask that, you should delve into the measurements of both a bit To have that efficiency and easy load ability. Measurement tests show they are always compromised when compared to a highly tuned speaker eg Wilsons ect ect, that will be far more inefficient and much harder load, that yes need far more serious drive characteristics from the amp/s Bit like comparing a high octane highly tuned multi cam/valve Ferrari V8 motor, to a low octane V8 Ford iron slug from the 60’s. Cheers George |