joysjane
Won't be able to find out if the SX-1000's would power my speakers.I say lucky you, that was to me was more divine intervention. Cheers George |
Hello dsper, I haven’t been able to follow this thread as closely as I wanted, but has anybody suggested the Merrill Audio Veritas class D monos that use the Hypex NCore1200 power modules and 1200 SMPS? Here’s a review that states they don’t quite double power in power for each halving of impedance down to 2 ohms (400w @ 8 ohms, 700w @ 4 ohms, 1,200w @ 2 ohms) but they sound great and are stable down to 1 ohm): http://www.stereomojo.com/Merrill%20Vertitas%20Monoblock%20Amplifier%20Review/MerrillVertitasMonoblo... The Veritas sold new for $12,000/pair. With Merrill recently introducing a new line of Element series amps using the new and very fast switching GaN transistors, I’ve noticed numerous used pairs of Veritas monos for sale with an average asking price of about $5,000. I’m assuming many of these owners may be selling in order to purchase a pair of the new Element 116, Element 118 mono block amps or an Element 114 stereo amp. I believe a pair of the Veritas would be an excellent choice to drive your Thiel CS5s. My thinking is that any seller of a pair of amps they formerly invested $12,000/pair for would have cared for them very well and it shouldn’t be hard to find a pair in excellent condition. The best new options are probably the new Merrill Audio Element series amps using the new and very fast switching GaN transistors; the stereo Element 114 amp for $15,000 or one of their monoblock amps, the Element 116 amps for $22,000 or Element 118 amps for $36,000. Here's a review of the Eklement 116 monoblocks with comparisons to the prior model Veritas: www.enjoythemusic.com/superioraudio/equipment/0619/Merrill_Audio_Element_116_Veritas_Review.htm Best wishes, Tim |
noble100" I haven’t been able to follow this thread as closely as I wanted, but has anybody suggested" Why don't you actually read the thread in which you plan to participate rather than have the rest of the community hear read through you're content and sort it accordingly? |
joysjane Won't be able to find out if the SX-1000's would power my speakers.I say lucky you, that was to me was more divine intervention. Cheers George Hey George... update. Looks like we're gonna find out if the Class D amps will drive the Infinity Kappa 9's after all. Am in a transaction with a fellow a-goner for the purchase of the Wyred4sound SX-1000 monos. Will be reporting to this thread if they truly can drive difficult loads. |
This'll be good, the maker doesn't even dare to mention 2ohm let alone 0.8ohm. http://www.classicspeakerpages.net/IP.Board/uploads/monthly_2016_03/Kappa9Impedance.jpg.340a528e36b9... Cheers (sorry no) good luck George |
Here’s what the Aussie’s think about the Kappa 9’s after this guy posted them up for sale. I think the 2 pages of discussions on how they are to drive, killed his sale of them. Wilson Alexia’s are even harder as their lower most impedance is up even higher around 80hz https://www.stereo.net.au/forums/topic/116782-infinity-kappa-9-price-drop/ Cheers George |
Fello A-Goners, The Class D SX-1000 amps arrived today. First impression is this... I'm definitely blown away at the size of these mono block amps! They're tiny compared to my Phase Linear 700's in size and weight. Even my wife said WHAT! I go into this without ANY preconceived thoughts. I'm an open minded individual. Tomorrow will be hook up time, to do an evaluation, on these Class D amp's ability to drive some ridiculous low impedance speakers... Infinity Kappa 9's. We'll be able to put this discussion to a real world evaluation rather than what my brother's smother's friend of the family said! Stay tuned y'all............... |
Damn georgehifi, Didn't think there was ANY SPEAKER harder to drive than the 9's.... WOW! I know the Scintillas were close but DANG! Something I've noticed with hard to drive speakers. Given the right amplification they just seem to be more powerful at music reproduction than the high efficiency speakers. Especially in the bass region. |
Didn’t think there was ANY SPEAKER harder to drive than the 9’s.... WOW!You can add the OP’s Thiel CS5 also CS7, Wilson Alexia to that list also and there are many others. And to me also the "good" ridiculously hard to drive speakers are more extended, tighter more detailed in their presentation, this is usually because of the drivers used are inefficient more so the very complex xovers that are designed to be nearer perfect for these types of speakers create the low impedance loads . There’s no free lunch, easy to drive, simple xovers, efficient drivers, even the use of horns usually have compromises, the above difficult to drive speakers some may say are over engineered, so is a Buggati Veyron ect ect. Cheers George |
Here is a great post by a member here with Sonus Fabers that dip to 2ohms in loading presented to the amp, and his experience with a few different amps and one that can double down wattage all the way to 2ohms the bjt output Gryphon. https://forum.audiogon.com/discussions/i-listened-to-the-gryphon-diablo-today-what-an-experience/pos... Cheers George |
When some of the "impedance" number were being thrown around in this thread (i.e. < 1 ohm), I was not paying enough attention to realize that figure was for EPDR, equivalent peak dissipation resistance. This is a figure that calculates the peak power loading on the output devices in a linear amplifier when current/voltage are not in phase, it is Not the impedance or a measure of peak current. EPDR does not apply to a Class-D amplifier. It effectively has no merit in the discussion of a Class-D amplifier. For a Class-D amplifier, the impedance curve is sufficient. Even from a power dissipation standpoint, in a Class-D amplifier, the FETs are not operated in the linear region, so you don’t have the same device loading. |
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Just to restate, georgehifi has been pushing the EPDR "number" for certain speakers as a reason why Class-D will not work unless it can drive <2 ohms, as they have an EPDR (Equivalent Peak Dissipation Resistance) < 1 ohm. EPDR is a term that was developed to represent the peak power dissipation in output devices of linear amplifiers with reactive loads. It does not represent higher peak current or lower impedance, it represents higher power dissipation on the output devices that are operating in the linear region. As Class-D devices do not operate in the linear region, EPDR is not a useful criteria for them. |
As Class-D devices do not operate in the linear region, EPDR is not a useful criteria for them. So you believe the atmasphere statement, that his OTL’s can do a nice job of driving the Wilson Alexia’s as well?? also delusional🤦♂️ Give it up you two, looks like your colluding, maybe your his new Class-D partner? Like tweak is with ricevs. |
This is a class-D thread. No one is pushing anything. I am stating, quite clearly, that your "push" of EPDR as a relevant value is meaningless w.r.t. Class-D amplifiers. Given that EPDR is meaningless, we don't need to consider 0.9 ohm loading as you have pushed for the Alexia as it has not meaning within a Class-D discussion. The standard impedance which does not dip below about 2.5-2.6 ohms, is the relevant value for discussion. BJT has nothing to do with a Class-D discussion, but since you bring up EPDR, EPDR is most damaging to a BJT amplifier in real world conditions because of secondary failure that MOSFETS, and tubes do not experience. |
Now if only there were Class-D amplifiers that drove into 2 ohms without any trouble like the op asked ... oh, there are. Cherry Class-D do. Mytek will as well. There is nothing "sexy" about them, they just do the job they are designed to do. Obviously you have heard them with difficult to drive speakers? |
Just got done talking with Merrill of Merrill Audio. He says a lot of his customers are trading in their $12K Veritas mono-blocks on his new line of Element amps with GaN FETs. He said the older GaNs sound better than the newest ones, interesting. I've decided to buy a pair of pre-owned class D Veritas from him at less than half price, I'm going to pair them with a Levinson 326S preamp, Lumin D2 dac/streamer, Oppo 205, all balanced cables and Magnepan 2.7QR speakers. Merrill said all of his class D former Veritas and new Element amps are stable down to 1 ohm, George. Dsper, a $5K pre-owned pair of Veritas would be an ideal amp solution for any Thiels, Kappas or Apogees you care to use. Thread question answered, Tim |
Merrill said all of his class D former Veritas and new Element amps are stable down to 1 ohm, George. Yes, they may be stable that’s only half of the equation, so is a $199 30w NAD 3020 integrated from the 80’s, it’s also "stable" at 2ohm loading, and also on the OP’s Thiel CS5’s, won’t make much music though. But when I ask him "twice" to produce "true" rms wattage figures (preferably measured by an independent lab) just before clipping at 8, 4, and 2ohms, I was "then" met with a deafening silence. Only this and also being stable will indicate what’s going with an amp, into serious low impedance’s as the OP’s and many other hi-end speakers have. Cheers George |
The whole basis of your reasoning is that if the power does not double from 8 ohms to 4 ohms, and then again from 4 to 2, that it couldn't possible work right. There is no way you can make that determination without knowing exactly why a specific power limitation may exist at 2 ohms, and you definitely cannot use whatever logic you may think applies to a linear amplifier to a Class-D. |
It's apparent that georgehifi has appointed himself the official judge on this thread who administers the amp typology scales of justice with a big, heavy thumb on a particular scale and applies amp typology justice and fairness in the manner of a 15th century sadistic Russian czar. georgehifi: "Yes, they may be stable that’s only half of the equation, so is a $199 30w NAD 3020 integrated from the 80’s, it’s also "stable" at 2ohm loading, and also on the OP’s Thiel CS5’s, won’t make much music though." C'mon George, are you actually implying that a pair of the 1 ohm stable, 800 watt and highly praised Merrill Veritas mono-blocks won't make much music on the OP's Thiel CS5s? Here's a link to just one of a plethora of highly positive reviews on the Veritas and their music making abilities: ttps://www.tonepublications.com/review/merrill-audio-veritas-power-amp-mono-blocks/ Tim |
jetter, I have no skin in the game for Class-D, AB, or A. I am just the guy that actually understands what EPDR is, and why it does not apply to Class-D amps, and why it is particularly harsh to BJT amps, the type that a certain person pushes as the holy grail for low impedance, citing EPDR. I and Noble100 have given examples of amplifiers proven to work, and work well at 2 ohms. Here is an independent post from DIYAudio. That "max-current-limit", something a Class-D amplifier can do on a cycle by cycle basis, explains why you can design a Class-D amp with a derated 2 ohm output power without impacting sound quality. The statement about SOA (safe operating area) goes back to the EPDR, or why it is not applicable to Class-D. You will find similar posts on the Internet from people with a good understanding of the technology. There is another thing that comes into play: https://www.diyaudio.com/forums/class-d/43426-class-output-impedance.html |
Hey George, Here's a start to explaining of what @atdavid is talking about https://www.stereophile.com/reference/707heavy/index.html You can see that because class D amp output devices are either on or off, there isn't a portion of their operation that is in the linear region. As a result you don't have high dissipation in the output device at some portion of the waveform that the amplifier is amplifying. Based on your responses to atdavid so far it appears that you didn't at least use Google to help you out on this one. Here's a tip from from a well-known Greek individual known as Aristophanes:Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever. So whats it going to be? Please try and follow along instead of promoting fake news. Google is your friend- before going off on your rabbit hole theories, just try and see if you can find out about it first. Only this and also being stable will indicate what’s going with an amp, into serious low impedance’s as the OP’s and many other hi-end speakers have.I noticed this comment- what do you mean by being stable? 'Stability' is generally used in the context of a circuit's resistance to oscillation. Somehow I don't think that's what you meant, but just for the record all of our amps are stable into into any load impedance included a dead short. IOW you can't set them into oscillation regardless of the load condition. But you meant something else didn't you? Again Google is your friend:https://www.google.com/search?client=ubuntu&channel=fs&q=amplifier+stability&ie=utf-8&am...As you can see, stability has to do with oscillation, not anything else. |
Hi atmasphere, I have been thinking about what you wrote earlier in this thread: "...all amplifiers regardless of technology have higher distortion into 2 ohms which is audible as increased brightness and harshness. You can see this in the specs (if 2 ohms distortion is even specified, but you can also see it in the 4 ohm spec as opposed to 8). Further complicating matters is the critical nature of the speaker cable, which must be kept very short and also must have a fairly heavy gauge. At that impedance its very easy for the cable to contribute to the overall source impedance seen by the loudspeaker! In a nutshell, 2 ohm loudspeakers are impractical and the ability to drive a load like that is over-rated..." So...a couple of layman's questions: 1. Does this mean that differences between interconnects would be more discernible in a system that did not need to handle a 2 ohm load or is it that one would simply hear a different version of "brightness and harshness" ion a less efficient system? Bear in mind that I have never critically listened to a high efficiency system and probably do not understand transparency in the same way that you might. 2. What is your opinion about ten or twelve gauge stranded copper wire as a speaker cable for Thiel CS5's? Is it even audible for ten foot run compared to fourteen or sixteen gauge? Excuse me for hijacking my thread. Thanks for listening, Dsper |
Please join us in welcoming the amp500 to the world. It has been several years since Peachtree has offered an amp only product and...OH BOY...are we back! The amp500 features a staggering 500 watts per channel into 8 ohms and drives speakers all the way down to 2.5 ohms and up to their full potential. It features a custom designed, class-A, input stage and balanced and unbalanced inputs for compatibility with virtually any preamplifier, receiver or integrated amplifier. All housed in the same beautiful chassis as the award-winning nova line. Suggested Retail Price of the amp500 is $1999, but for a very limited time we are offering it to Peachtree customers exclusively for $1499 |
The amp500 features a staggering 500 watts per channel into 8 ohmsWhy stop there at 500w, get a 3000!!!! watt one for $429 https://www.storedj.com.au/behringer-nx3000-ultra-lightweight-3000w-class-d-power-amplifier It features a custom designed, class-A, input stageEvery amp I know of also has Class-A input stages, and "why suddenly is the Class-A linear the preferred way for the input", why not for the output as well??? Cheers George |
George: "Every amp I know of also has Class-A input stages, and "why suddenly is the Class-A linear the preferred way for the input", why not for the output as well???" Hello George, I don't think anyone's claiming a class A input stage isn't an excellent typology for an input stage since the class A typology is well known for it's very high sound quality performance. At low preamp stage input voltages, the excess heat generated by the highly inefficient class A typology circuitry constantly being in operation is not a major cause for concern. While the extremely inefficient class A typology for an output stage is also excellent for sound quality, the excess heat generated by the highly inefficient class A typology circuitry constantly being in operation is definitely a major cause for concern since it's easily able to significantly raise the temperature in a typical domestic room. But you already knew all this, George, before you made your comment. My question is why, knowing all the above, you even bothered to make it? Obviously, one of the major advantages of utilizing class D output stages rather than class A output stages is its electrical efficiency and resultant dramatic decrease in the amount of electricity that is wasted by simply being converted to excess heat. Class A is about 10% efficient and class D is in excess of 90%. Class A amps are typically expensive, operate at very high temperatures,are very large and heavy due to the numerous, large and heavy heat sinks required in an attempt to dissipate the large quantities of excess heat produced as a result of their extreme electrical inefficiency. Class D amps are typically less expensive, operate at much lower temperatures, are much smaller and lighter due to the their lack of need for heat sinks required to dissipate the very small quantities of heat produced as a result of their extreme electrical efficiency. The difference can be demonstrated clearly by a raw egg. Drop one on a class A amp at peak operating temp and you'll shortly produce a fried egg. Drop one on a class D amp at peak operating temp and you'll just have a raw egg mess that will remain until you decide you may want to clean it up. Besides the advantage of your amp not acting as an HVAC component, there's also the class D advantage of cooler operating temps likely resulting in improved reliability and longevity due to the well known principle that sustained excess heat is a major factor in electrical component part failures. However, I believe an individual's amp choice is likely made primarily on the basis of perceived sound quality and price to performance ratios, with amp typology traits being less important to most. I think Class D amps need to be leaders on these two factors to achieve continued success. Tim |
My question is why, knowing all the above, you even bothered to make it? It features a custom designed, class-A, input stage Why even mention it on a class-D amp like it’s "special" (it features!!), as all amps have "class-a inputs" is what I refer to, no one in their right mind would make an input stage Class-B!! |
Hello George, Agreed. While there's currently no such thing as a class D input stage there is a company, Mola Mola, that offers a class D preamp and pair of class D mono-blocks that have output and input stages specifically designed to perform optimally when used together; the preamp is called the Makua and the matching mono-block amps, based on Hypex NCore 1200 power modules and and smps (switch mode power supply),are called the Kalugas. The part owner and chief designer of Mola Mola, Bruno Putzeys, is also the inventor of ucD (universal class D) as well as class D Hypex NCore technology. He designed the Makua and Kalugas, as well as a unique and optional class D internal dac board for the Makua, that are designed to specifically perform optimally with each other. I'm planning on buying pre-owned examples of all 3 of these Mola Mola products, which have all received numerous excellent professional reviews, within the next monthor so for about $12-14K. I'll post my impressions on all 3 of these once I have adequately had the listening time to form them. I'm sure you'll be awaiting my thoughts with bated breath. Tim |
joysjane: "Stay tuned for my first-hand experience as to how these amps drove my original un-modded Infinity Kappa 9's. One of the amp killing speakers..." Hello joysjane, Wow, a teaser on the W4S SX-1000 class D amps and how they worked driving your very low impedance load and notoriously difficult to drive Infinity Kappa 9 speakers. Full details next on News at Eleven? Off the record, on the Q.T. and very hush-hush? Very tantalizing, great job! You got me hooked, I'm certainly not touching that dial. Drum roll, please? Tim |
Bahahahaaaaa... You's are funny, got me laughing. House is still standing. What happened... The wife called me saying the boxes arrived. She then asked me, there's amps in these two boxes? So, had to explain what they were, why they were so small and why they weighed next to nothing. All I got was an ok. Removed the WOPL 700's and hooked up the SX-1000's. I let the amps play on a repeat cd at a low level with the Kappa's in the "Normal" switched position starting early in the morning. Let that roll until 3:00 in the afternoon. Time to start listening... At half volume I listened for about an hour. All was ok so, time to crank it up. Turned up the volume to 3/4 on the Oppo (the 105D is driving the amps directly). Listened for another 30 minutes and all is still ok. Time to get down to amp-busting' Kappa 9's, lowered the volume to 1/4 and switched the speakers into "Extended" mode. I've put many of my amps into protection mode with the Kappa's in "Extended" mode. Being a little leery of these tiny amps I started out at 1/4 volume listening to various CD's, SACD's and DVD-A discs. All is well after 30 minutes so, time to crank it up a bit. At 1/2 volume now, stayed at this level for an hour while checking if the amps were getting warm. This is the point of no return for many amps I've tried. Half volume and up with the 9's in "Extended" mode is a brutal test for any amplifier. Ok, I'm starting to get curious. I'm getting up and down, feeling the amps to see if there's any sign of temperature increase. Feeling the sides, the top, the front & back... no temp increase. In comes the wife from running around town. I haven't given my assessment of the sound for a reason. It will come later. I'm listening, the wife walks in and is looking at the speakers with a puzzled look on her face. She turns to me and says... what's wrong with speakers? Something's missing, I don't like it. That's the extent of her ability to evaluate what she hears. More on this later... Time to turn the volume up to 3/4 and listen. Put in some dynamic music... John Lee Hooker's "BOOM BOMM" 24/96 DAD. The SX-1000's are still pushing the Kappa 9's in "Extended" mode. Many amps have shut down at this point and, only a few have passed the next level test. Volume up to 100% and let's have a go. After 2 minutes I get some very loud snaps coming out of my EMIT K & SEMIT K drivers on the left channel speaker. Right channel speaker ok. Wife comes running in from the kitchen asking what was that? I got to the volume control as quick as possible and turned the system down. CRAP!!! Not sure what happened. I have the protection on my crossovers by-passed. Have never had this happen. I looked at the EMIT & SEMIT drivers on the left speaker to see if there was any arcing visible on the membranes. Nope, all looked normal. Let everything rest for a half hour and then started bringing up the volume. Wanting to make sure I didn't fry something. Music came back as before. Whew... hoping I dodged a bullet. I want all to know that I'm in no way a qualified listener/evaluator of equipment and/or speakers. I also can't give any measurements of what this listening session produced... to/for ME. What I am is a person who enjoys his system and the music that's played on that system. I do know what my system sounds like and feel I can give an accurate blah blah of what I heard. Now let's get to the sound produced. And also to what the wife had observed. At lower levels the music seemed to have lost weight/slam/punch. This loss was in the lower frequencies. This is exactly what my wife had heard. She's not sure what was missing but, she knew something was missing. I didn't prod her or guide her for an explanation but what she said was "Where's the bass"? As the volume went up the bottom seemed to increase but, the Kappa 9's sounded anemic. These Infinity's are everything but anemic! I also found the same thing when driving the amps with my DV-AX10. Just to make sure it wasn't the Oppo producing what I was hearing. I'm gonna be the first to say I didn't think these amps had a chance. I was surprised my Infinity speakers didn't throw the amps into protection mode... I did try. In no way did I think they could drive one of the most difficult speaker loads ever produced... they did. When I heard those loud snaps... I'm not gonna say that the amps started clipping at full volume. I do know what other amps sound like when clipping, I don't know what a Class D amp sounds like when clipping. |
I want to add something to the Class D monos driving my Infinity’s... With the noticeable lack of bass at lower volumes I must pose a thought I’m having. Is the lack of bass/bottom caused by the crazy impedance load of the Kappa 9’s when being driven by these amps? I have a pair of Legacy-Audio Focus speakers tucked away. They do not lack any bottom end with any amps I’ve driven them with... maybe because they’re a much more efficient speaker than the 9’s might that bottom return with these Class D amps? I don’t know. Y'alls thoughts regarding the impedance of the Kappa 9's... Maybe one of these days I can wrestle those heavy bastards out and hook up the SX’s. Kinda doubting that will happen as I’m not getting any younger or less broken. I was really hoping the Class D amps would provide this. I’m gonna start reducing the amount of gear I have and would have loved amps the size and weight of these Class D’s. I could have moved them around easily. But, the Infinity’s are staying... the rest are going bye-bye. So, I now have to carry those heavy/awkward Phase Linear Clair Bros WOPL amps back up the stairs and re-configure... Damn! One more thing, about my cables in the system that was tested... Cardas Golden Reference power cables, Monster Sigma Interconnects with Monster Sigma Speaker cables (ME2’s). Not junk cabling for sure. |
Rather than saying from an earlier post, I'll just paste it in again (from the spec sheet): Overload Protection - In case of high-amplitude continuous low frequency signals in loads lower than 4 ohms the power supply may not be able to deliver the required amount of power to the amplifier and the supply voltage will drop. The overload protection circuit will then lower the threshold of the input soft clipping circuit until the output power has been reduced to an acceptable level. As a result the amplifier will not shut down because of under voltage and the music will still be playing but with a softly shaped audio signal. Pretty much what I expected. Your experience is basically the same as my except I was using the IcePower 1200AS/2 modules (2.7 ohm rated) with Wilson Watt/Puppy's. I believe you were using the 1200ASP modules (2 ohm rated). Not just the bass, but I noticed it in the midrange as well. It became very sterile to the point I couldn't listen anymore. Stereophile also uses the word 'Anemic' to describe this behavior when an amp is under powered for a given pair of speakers - which I think is a good descriptive. I tried using subwoofers to 'fill-in' more musicality, but it really didn't help that much either. One thing you can say about the B&O Icepower modules, and I give them credit, they really do try hard to keep things going even in Overload Protection (no blown fuse). |
