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. |
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. |
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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. |
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 |
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 |
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. |
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............... |
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 |
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 |
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. |
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? |
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 |
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 |
That is one reason why I like the Stereophile test measurements as they can help you to understand about a specific amp.👍 yep, don’t listen to some of the manufacturers voodoo BS, they’re in sales mode and you know about car/real estate salesmen, you could almost group these guys in the same category |
A learning point for me from this thread is that it appears there are no standardized measurements for current and damping factor.@dsper This statement is tricky. But you are on to something - they can be misleading. 'Current' is the one that is bandied about the most and it can quite often be meaningless. Take a look at this link (which is an easy read) for why:http://www.atma-sphere.com/Resources/Common_Amplifier_Myths.php Now damping factor is the output impedance vs 8 ohms and is expressed as a ratio (IOW its standardized). What is less understood is that speakers require a certain amount of damping and that varies by design, even if the same drivers are used in a different box. Some speakers (certain open baffles for example) seem to work better if the damping factor is extremely low- 1/10th :1; and some speakers need as high as 20:1. No speaker needs more damping than that; higher damping factors are often deleterious to neutrality. Amplifier designers thus have a challenge- from their perspective a lower output impedance is good to insure that the amplifier has the proper 'voltage source' response which is to say that it can maintain a constant voltage output regardless of load. And speaker designers are **usually** expecting this too- but they are working with drivers that quite simply don't work right if they are overdamped! So its no surprise that confusion exists- because you can easily hear when the speaker is overdamped ('tight bass' being a symptom; while many audiophiles like this, it is in fact a coloration). It makes the right amp/speaker combination a lot harder than you would think and a lot harder than it supposed to be! |
joysjane, I do not know what more to say about the ST1000. I read great things about the amp before I bought mine. The ST1000 played loud but was lacking in dynamics and sounded bland. I was astonished how much better the Maggie's and Thiels sounded with good class AB amps. A learning point for me from this thread is that it appears there are no standardized measurements for current and damping factor. That is one reason why I like the Stereophile test measurements as they can help you to understand about a specific amp. Problem was the ST1000 was not reviewed by them and I could not find test measurements elsewhere. Thanks for listening, Dsper |
I’m pretty sure the Kappa 9’s are gonna suck/inhale these two mono blocks half way into the speaker cablesLove it 1000ASP ICEpower module Class-D getting sucked up the speaker cables. Like this https://cdn.cnn.com/cnnnext/dam/assets/150627043629-python-porcupine-exlarge-169.jpg |
Oh hell no... The Kappa 9's are my last pair of speakers. Will be selling my Legacy-Audio Focus & Infinity Prelude MTS' some time in the near future. My KSA Krell is great for the winter as we live in WY. I switch to the PL WOPL's for the rest of the year. They both make the Kappa 9's sing... And they damn well better! KSA rated to 4kw @ 0.5 ohm with the Claire Bros WOPL's testing to 513w per channel to 8 ohm. That's over 1kw per channel @ 8 ohms of Phase Linear bi-amp power that's sweet as honey! At eight-hunge for the two 1000's it's worth a go. I seriously doubt they can compete with my amps but, it'll be fun to see what Class D amps sound like w/the 9's. I'm intrigued by the small package & lack of weight. It's just a curiosity thing. I'm pretty sure the Kappa 9's are gonna suck/inhale these two mono blocks half way into the speaker cables, good thing I have some large ones, and pull my power cables tight on the outlets! Bahahahaaaaa...... Hey dsper... Huh, don't those Class D amps have a Damping Factor of 1000? That surprises me. I would have thought they would start to get harsh on the upper mids and higher freq's. |
So the Icepower 1000ASP had trouble with Thiel CS3.6. Well, they are a tough load through most of the frequency range. The 1000ASP should have an easier time with the Thiel CS3.6 than the 1200AS1/2 since the ratings are 2.0 ohm minimum load and 40 amps peak, vs 2.7 ohm and 38 amps peak for the 1200AS1/2. The 1200AS2 didn't pair that well with my Wilson Watt/Puppy's. If you compared the 1200AS2 to my Class A amps, it was no contest really. To be honest, I'm not sold on what @cascadesphil is saying about his EVS1200 amp being suitable for his Thiel CS3.6 speakers(based on Icepower 1200AS1 modules). I suspect he is using subwoofer's and this is masking the issues. It's too bad he never had a decent amp as a reference point to compare. Both his previous amps weren't sufficient for those speakers either. He should have paid attention to the Stereophile reviews for those amps as they were only mediocre. This is just my opinion. I'm sure the Icepower 1200AS1/2 do well with higher impedance speakers. |
Hi joysjane, FWIW as it might not be the same animal, I have a five year old W4S ST1000 and it could play Maggie 3.6's loud but with no control of the bass. It had trouble with Thiel CS3.6's and was a joke with the CS5's. In my set-up, a Coda CS (300 WPC 8 Ohms, 600 wpc 4 ohms) did much better but got constrained/harsh with the CS5's at higher volumes. My current amp, a McCormack DNA-500, is effortless with the CS5's. Any change now would be to eliminate my perception that I think I still hear a bit of grain or there is a lack of the sound coming out of a black silence. Based on listening to a X350, Pass might be better but they are hot and huge. Again, FWIW. Thanks for listening, Dsper |
Yep, WFS SX-1000 uses those same modules. Spec sheet specifies 2.0 ohm minimum load, as well as 40 amp current (peak). Unlike the Icepower 1200AS1/2 being rated at 2.7 ohms. Also included in the specs:
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joysjane Don’t think your gunna like this It seems the WFS SX-1000 uses the same B&O 1000ASP ICEpower module as the Bel Canto Ref1000M monoblocks. Stereophile say they turned them selves off when presented with a 2ohm load, which easier than the Kappa 9’s load which is a below 1ohm horror load. "Ref1000M monoblock offers very high power from its diminutive chassis. It does work best with higher-impedance loudspeakers" Maybe it’s time to sell the Kappa 9 if you really need to go class-D My friend with Infinity Renaissance 90 little easier load than the 9’s was trying to do the same with Class-D’s, didn’t work out either, went back to his big Krell, which luckily he didn’t sell. Cheers George |
One of the reasons I’d like to give these a go... Specifications
It’s gonna need every bit of those ratings to drive the 9’s! Without dropping a name I was advised they’re rated into 2-Ohms. It’s worth a go... |
Heck..if your going to spend over $3K you would be better off purchasing a pair of the Nuprime ST-10M's. The Wyred4Sound amps are not in the same league. Just look under the hood. The Nuprime power supply is much larger and their custom designed switching amp is equal to if not better than the B&O amps. The nice thing about Nuprime is that they display their top amps on their website with the covers off to assure you your getting your money's worth. Wyred4Sound will never display their amps online with their top's off. |
Seems odd to me but can I ask why you are purchasing these amps that are over $3K without even hearing/knowing they can drive these evil Kappa 9’s Good luck btw with these IcePower based modules https://ibb.co/hZJN3q5 Good test, looking forward to it and your findings, and hopefully anyone else’s that maybe present, if you could get them to furnish their opinions also. Cheers George |
Hello georgehifi, I may be purchasing a pair of mono blocks. They're Wyred4sound SX-1000's. Some of the higher power Class D amps. If the sale goes through I'll be sure to let you know whether they can drive a very difficult load speaker. To let you know what I'll be driving... A pair of original Infinity Kappa 9 speakers. This will end the debate of whether these Class D amps can drive some low Ohm speakers for sure! Right now I drive my 9's with 2 WOPL Phase Linear 700 amps along with my Krell KSA-250. The Krell drives them to realistic listening levels with zero issues. The WOPL's drive them as well but they do require active cooling. I keep my Kappa 9's in the "Extended" mode as that's a true measure of whether the amps can drive them or not. I have been very curious myself if these Class D amps are up to the task. Will let you know if I do acquire these... Skip |
Class D amps will have problems with 2 ohm loads especially if your in a condo or apartment building, since the switching transistors constantly modulate the current from the a.c. outlet and the available current can vary which time of day other tenants are using the most electricity. The solution? Stay away from class D amps that don't have large extra power supply boards that will handle low ohms when your current is low. For the money, the costly Nuprime Evolution One at $8K a pair has a massive bank of capacitors and will laugh at 2 ohm loads. No problem. Or their lower priced mono blocs, the ST-10M at $3200 a pair. It is always best to buy a Class D amp with a large power supply found in A/B amps. The Nuprimes are killer due to the fact their switching amps are custom designed in house protected by their own patents and former top design engineer at Spectral, Damien Martin, has been an ongoing consultant for the company. The Nuprimes are sleeping giants. |
dsperThese are the facts Dsper. you have a great speaker that demands in turn a great Linear amplifer to get the very best sound out them, not one that has compromises. 1:Stereophile bench tests the CS5 "Means that the amplifier with which it is used MUST HAVE ample TO SAY THE LEAST current capability, if the sound is not to become anemic. Amplifiers with limited current delivery to become starved in the low bass <2ohms, with a potentially disastrous effect on dynamics." 2: I have yet to see a Class-D measured by Stereophile to do what good linear amps can into loads <2ohms and that is to "almost" double wattage for each halving of impedance, 8 to 4 to 2ohms. 3: Stereophile I also do not think have ever shown a Class-D full power wattage into 2ohms without it freaking out or switching off, this proves they are not comfortable into 2ohms like linear amps can be. Cheers George |
thosb wrote:"..hopefully you have checked out the Thiel users group thread, lots of good discussion on amp pairing, lots of good discussion on how to get the most out of the CS5s, more focus on what listeners are hearing rather than technical debates..." Thank you for the reality check. There is a lot of good technical advice here from a variety of folks who responded on this thread. The problem, of course, is how much a non-tech type can absorb. For example, I still do not understand phase angle and its implications (among other topics). I guess I was hoping for a magic bullet to my original post but that, of course, is unfair to everyone. I am not sure the pocket book can deal with a switch to a more efficient speaker and all the opportunities/changes that might require; so I probably will wade through all 6800 plus responses on the Thiel Owners thread again...I am retired so that should not take too long...😊 Thanks for listening, Dsper |
Can I make the same comment that higher impedance is receptive to noise, in the same context that lower impedance adds distortion.Probably not. The impedance of a 16 ohm loudspeaker will not affect noise floor at all. But many 16 ohm loudspeakers are also fairly efficient, and if there is noise efficiency means that you will hear it. |
Can I make the same comment that higher impedance is receptive to noise, in the same context that lower impedance adds distortion. Seems like most of the Class-D amps Stereophile measured included power ratings at 2ohms. It just thought it was weird they didn't include those measurements for the M700 amps. |
It's also interesting that Stereophile didn't bother reporting specified power rating at 2ohms, but did mention THD rises into 2ohms at higher frequencies.This is true of all amplifiers; if high fidelity reproduction is your goal, lower impedances should be avoided so as to reduce distortion from the amplifier. The distortion generated by driving a lower impedance is mostly higher orders and is audible as brightness and harshness. You really don't want to make any amplifier work hard to drive a 'difficult' load. The result can be seen in measurements of any amplifier. |
It's also interesting that Stereophile didn't bother reporting specified power rating at 2ohmsYes this is always and indication, that it's not happy doing those loads, it may handle them and make some noise into them, but then so can the NAD3020 integrated, can they get the best from the OP's CS5's? I doubt it very much. Cheers George |
That was my point George, someone mentioned the Stellar M700 goes down to 2ohms, and the specs are only 2.50ohms. It's also interesting that Stereophile didn't bother reporting specified power rating at 2ohms, but did mention THD rises into 2ohms at higher frequencies. Like everything else, you get what you pay for and there is no free ride with Class-D amps (with reference to low impedance speakers). We define clipping as when the percentage of THD+noise in the amplifier's output reaches 1%, and fig.5 indicates that the M700 slightly exceeds its specified power of 350W into 8 ohms (25.44dBW). Into 4 ohms (fig.6), the M700 clips at precisely the specified 700W (25.44dBW). Fig.7 plots the THD+N percentage against frequency at a level at which I could be sure I was looking at distortion rather than noise: 20V, which is equivalent to 50W into 8 ohms, 100W into 4 ohms, and 200W into 2 ohms. The THD is very low at low and middle frequencies into 8 and 4 ohms, but does rise into 2 ohms and at high frequencies. Read more at https://www.stereophile.com/content/ps-audio-stellar-m700-monoblock-power-amplifier-measurements#rLo... |
Here’s a new model that claims it can handle 2 ohms.This amp goes backwards in to 2ohms!!, like I said above with the NAD reference Spec sheet for Icepower 700ASC specifies 2.5ohms minimum.Same deal with this, what it’s true 8ohm, 4ohm, 2ohm "wattage figures"? do it "increase significantly" (almost double) as the impedance goes down. This indicates an amp that will drive effortlessly the OP’s kind of speaker to it’s full potential. Cheers George |
Here's a new model that claims it can handle 2 ohms. http://lkvresearch.blogspot.com/2019/04/lkv-veros-pwr.html#!/2019/04/lkv-veros-pwr.html |
I believe PS Audio Stellar M700 monoblocksInto the OP’s speakers this statement means nothing, unless they can back it up with, "this amp can also almost double it’s wattage for each halving of impedance down to 2ohms". You can put a 2ohm load on an 1980’s Nad 3020 integrated and it will remain stable and not oscillate or blow up also. But will it drive to OP Thiel CS5’s? NO!!!! It will make a noise out of them. Will it get the best out of them? "NO WAY IN THE WORLD!" Cheers George |
