What Class D amps will drive a 2 ohm load


Just asking.

I see specs into 4 ohms but nothing into difficult speaker loads (like Thiel CS5's).

Thanks for listening, 

Dsper


dsper
Atmasphere,
I follow what you are saying about how a voltage source SS amp invariant to impedance theoretically would sound bright driving an electrostatic speaker.  But in practice I don't find this to be the case.  Years ago, for fun, I put my tonearm leads into the line stage, bypassing the RIAA curve of the phone stage.  Of course, that produced very bright sound due to the 30 dB boost at HF compared to low freq.  With the stat speaker, impedances can be as high as 30-100 ohms in the upper/lower bass, and 1 ohm or less in HF.  This is more than the 10:1 ratio you cite, but still nowhere near as much as the inverse RIAA curve.  Still, according to your theory, the stat speaker should sound like a less drastic inverted RIAA curve, which I didn't find in the listening.  Also, all dynamic speakers have marked variations in their impedances, and your theory would predict that a SS amp would produce markedly different sound from different speakers in relation to each speaker's impedance curve.  But I have found similar tonal differences A/B'ing 2 amps on different speakers.  For example, SS amps generally sound brighter than tube amps, which I have found to be true regardless of whether I used dynamic or stat speakers.  I am puzzled by my different listening findings compared to your theory.

I wasn't saying that amps don't make much difference, because obviously I pursue finding amps that offer more clarity, etc.  But it is clear that whatever sonic differences there are among amps, the sonic differences among transducers like speakers are vastly greater.  This is also true of transducers like cartridges which are really inverse speakers.  
@ georgehifi

All the amplifiers in the world double when drop in ohm to half, but when you reach their current limit then you will not see the doubling when you drop in ohm
With the stat speaker, impedances can be as high as 30-100 ohms in the upper/lower bass, and 1 ohm or less in HF.  This is more than the 10:1 ratio you cite, but still nowhere near as much as the inverse RIAA curve.  Still, according to your theory, the stat speaker should sound like a less drastic inverted RIAA curve, which I didn't find in the listening.  Also, all dynamic speakers have marked variations in their impedances, and your theory would predict that a SS amp would produce markedly different sound from different speakers in relation to each speaker's impedance curve.

@viber6  this isn't correct. (BTW what I'm talking about here isn't theory, its more like audio history. The Power Paradigm is what was around before MacIntosh and ElectroVoice developed the Voltage rules in the late 1950s.) With most dynamic speakers (there are exceptions in high end audio) the speaker is meant to be 'voltage driven' so variable power output is what you're looking for in the amplifier in order to get flat frequency response. The idea is plug and play, no need to adjust any midrange or treble controls (like you see on older speakers, stuff from the 50s and 60s). Of course like anything else, this approach solves one problem while introducing others.


The brightness of an unequalized RIAA curve would **not** have been compensated by the way the ESL and solid state amps work together.  I think you will find though that the 10:1 ratio I described is generally pretty close- that describes Quads, Martin Logans, Accoustats and Sound Labs which are the ESLs with which I have the most experience. If you can find one that is outside of that (for example: 100:1) I'd be very interested in knowing about it!

Post removed 
Wow!
The Wilson Alexia's get into areas of the Kappa 9's for difficult to drive?
Did not know that, thought all Wilson's were very efficient speakers.

We're gonna need a bigger boat...
I’ve had Thiels for 12 years but have since moved onto to Magnepan 20.7’s. The best amp I ever found for my Thiel 2.7s was the Pass X series and a Pass x150.8 would probably work but an x250.8 would be better. As far as "digital" amps goe, if you poke around the Thiel users groups you’ll find that ALOT and I do mean ALOT of Thiel owners were using Bel Canto digital amps most often the Ref 1000 to drive them. I tried those amps with my own speakers and they worked really really well for my classical and jazz listening but not quite so well as the Pass products.
Bel Canto digital amps most often the Ref 1000, I tried those amps with my own speakers and they worked really really well for my classical and jazz listening but not quite so well as the Pass products.
I said pages back the "better" Class-D’s like the BC Ref-1000 will work, and probably to the owner sound fine with the op’s Thiel CS-5’s.
But "he" hasn’t heard the CS5’s at their best yet until he’s heard an amp that can do <2ohms without breaking a sweat far better, like the Pass X150.8, then he’ll know that Class-D was doing it hard.

Cheers George

Wow!
The Wilson Alexia’s get into areas of the Kappa 9’s for difficult to drive?
Did not know that, thought all Wilson’s were very efficient speakers.
Yes efficient 90db like many Wilson’s, but a right b***h of a load like most them also, EPDR (impedance + phase angle) down to 0.9ohm!!! in the bass.
OTL’s will drive them, and pigs might fly!! What was that Supertramp track? oh yes "Dreamer"

Absolute Sounds Alexia measurements for HiFi Review https://ibb.co/YWSSXPX
Stereophile measurments on the Wilson WP8’s https://ibb.co/LpTPmXt
" " " " Wilson Alexx https://ibb.co/nbGFGtB
" " " Wilson Sabrina https://ibb.co/8Kg5hJv

Cheers George
Having read this very interesting discussion in its entirety several times I have to ask the commentators a question since neither the pros or cons truly answered the original Inquiry. 
Let's say I want to take a plunge into class D but do not want to revamp my entire system  and  the speakers in user are rated at 90db efficiency with nominal impedance of 8 ohms 3ohms minimum.  Can a class D amplifier (let's use 300w per channel)do justice and get the best or close to the best from the speakers? 
Let's hear your opinions.
" Having read this very interesting discussion in its entirety several times I have to ask the commentators a question since neither the pros or cons truly answered the original Inquiry.
Let's say I want to take a plunge into class D but do not want to revamp my entire system and the speakers in user are rated at 90db efficiency with nominal impedance of 8 ohms 3ohms minimum. Can a class D amplifier (let's use 300w per channel)do justice and get the best or close to the best from the speakers?
Let's hear your opinions."

I've already noted how easily the AS1200 can drive my Thiel 3.7s.  These -  https://www.muraudio.com/sp1  (and it indicates 2 ohm minimum and they are not super efficient) were used by Merrill Audio at the 2019 Florida Audio Expo and sounded great.  I've seen a bunch of other examples at shows in big rooms (e.g. 2017 RMAF with a Wyred4Sound Class D driving Acoustic Zen Maestro speakers (87 db and rated 6 ohms nominal).  I think will any product, it is too general to just say Class D as if they are all identical (same is true of any other type of amp).
gillatgh
speakers in user are rated at 90db efficiency with nominal impedance of 8 ohms 3ohms minimum. Can a class D amplifier (let’s use 300w per channel)do justice and get the best or close to the best from the speakers?

You ask to get close to or the best from these speakers

Show a impedance graph with -phase angle overlay, as what you asked for can’t be answered properly, even using the 3000w!!! Behringer Class-D.

You say that speaker has a minimum load of 3ohms, if that’s in the bass and you have it in conjunction with a -phase angle of 50 degrees the amp could be seeing even 1ohm as a load, and I know of no class-D that can take that.

That’s why you never see Stereophile tests on Class-D’s that go down into the 2ohm testing, because they mostly **** themselves when it’s done.

Cheers George





I’ve already noted how easily the AS1200 can drive my Thiel 3.7
https://www.stereophile.com/images/archivesart/1208T37fig1.jpg

Yes they can drive them, but I’m 100% sure your not hearing the very best from them.
As your the one who asked " Can a class D amplifier do justice and get the best or close to the best from the speakers?"

Cheers George
Post removed 
Yes - definitely getting the best from the 3.7s vs. other more expensive amps (and not just my opinion as others have heard it in my system with Class D and I'm not talking about non-audiophiles but people who have gone to shows and heard really expensive high end systems).  Now I'm not saying that there aren't products out there (as there are many products consisting of different amp classes) that might sound better (I can only offer actual experience, vs. theories which are just that and not particularly useful vs. actual in home listening and including the reaction of others who have heard it in my system in my room and no need to insult others who can hear vs. someone who has not heard the system in the room).  That does not mean that it is the last word in amplification. Upon my first listen (after breaking in a Class D amp), I was shocked how well it drove the 3.7s and how much better it sounded than two highly regarded non-class D amps with list prices of around $9k.

George, with all your comments on various threads, why not just start a new thread about the theoretical disadvantages of Class D?  Would not that be better to have all that discussion organized in one thread?  Once would think (at least I would, others can disagree of course)  that it would be far more productive than insulting other peoples (and a bunch of people who have had separates for 30- 40 years) hearing.  Personally, I just don't see the point of regurgitating the same comments with a complete lack of actual experience with the room and the components and speakers. When I had a friend who worked at a high end shop many moons ago and did virtually all his set-ups in deliveries with him (and I'm talking some two channel systems with around $150k in costs going back more than a dozen years), I learned very quickly not to say that for example a particular speaker is always wonderful sounding (I heard pairs of speakers I previously owned that sounded like complete crap in another room).  I don't take any of your comments personally (or those by anyone else btw).  I can't take anyone all that seriously who makes comments without actually hearing things (and I would have no problem if you heard it and posted all over here that my system actually sucked in your opinion).  Not trying to start anything.  Just think it would be best to get all points of view concentrated in appropriate threads (and would be fine if this thread was linked in a new thread - much betting than making comments that really are not that relevant - if you think they are, then why don't post your actual experience using Class D vs. other classes of amps driving Thiel 3.7s or 5s and if you don't have any that is basically what I'm saying - theories are fine and at one point the earth was flat according to one as well)
All I try to offer in any particular thread (and as noted per my last post I have lots of experience setting up systems and among the speakers that the store carried where my friend worked were Thiels and Maggies), and this will be my last word (regardless of how many more insults someone wants to hurl my way whether that is not be able to hear or not knowing what an impedance curve is, and an impedance curve I've already previously referenced here if someone actually read my comments which apparently some have not), is actual experience intended to provide additional relevant information to a question posed by the thread originator.  It is not intended to made judgments about other peoples tastes, listening habits, etc.

With forum like this one, I've already noted and quoted the Wikipedia definition of an internet troll in these threads.  It is just the way it is and nothing to get all excited about, it is the norm that there will always be a few.  For example, if someone asked a question about Magico speakers, which by the way I think are wonderful and have heard in a store more than once and at audio shows more than once, and I started making theoretical comments about something that they don't do well, there are probably some people after the first comment who might consider me a troll (it might be a bit judgmental for one comment).  If I continued making many comments over and over with no relevant experience to offer to the original poster's question, I'm sure there would be more and more people who would think that I'm a troll (and I'm not sure how I would argue that I'm not).

This is not to pick on a particular person.  It is just to make my point that it is probably best to start a new thread vs. make comments without actual hands on experience relevant to the topic.  As an example, at one point I bought a lightly used Bryston 14BSST (15 amp version) when I originally had Thiel 7.2s (and I've already posted this information within the Class D threads if anyone bothered to read). I used them in a huge room (probably almost 7,000 cu. ft. that opened into other spaces).  I listen to a wide variety of music, some of which is very dynamic.  The impedance of the 7.2s caused the amp to shut down a bunch of times.  I called the guy I bought it from who had Thiel 6s (which I heard many times and help deliver more than one pair) and only listened to small jazz combos in a small or average sized room and did not play things at the levels I might.  If I posted a blanket statement that the 14BSST can't drive or get the best out of any Thiel speaker, I don't think that would be either a factual statement or one that would probably be useful to someone posting a question.  An example would be the question posed here which deals with what Class D amps can drive certain things.  The original poster is entitled to seek information from others about their experiences and determine if there is something he or she would like to try in their system.  That does not mean that if they tried it, they would like it better than another amp or might find faults with how it sounds.  It is just more helpful when someone provides feedback about their experiences so that the person posing the question can come to a conclusion as to whether something is possible to use in their system.  That's all from me.
why not just start a new thread about the theoretical disadvantages of Class D?
No sorry, I don’t start threads asking for others to post negatives for me, I prefer to debate and show tech proof, on the pro’s and con’s of anything I feel need to be shown.

That would then emulate Eric Squires on what he’s trying to do to Pass amps. https://forum.audiogon.com/discussions/the-imperfect-amp-pass-or-ayre/post?postid=1815745#1815745

BTW:  Bryston 14BSST (15 amp version)  beating this is nothing to crow over into the Thiel CS7's. If and amp had 60-100amp capability down into 2ohms and your Class-D better it then you'd have something. 

Cheers George
Dsper - 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.  Personally I always enjoy comments linking specific listening experiences with hypotheses on the connection to equipment design, rather than starting with design and the associated engineering factors to reach a hypothetical listening experience.  Also fyi Jim Thiel, as he is working on crossover updates fo some Thiel models, uses the Benchmark AHB2 as a modern reference (along with other older amps) as he fine tunes his mods. Not trying to put words in his mouth, but Ibelieve in this case reference meaning a neutral clean sounding amp with enough power to drive some challenging loads, but also at a reasonable price, in other words one many many users could consider as an excellent starting point for some Thiels, honestly not sure about the CS5, if i remember correctly those are some beastly beasts.  

Btw, despite wading through a fair amount of bs, I did learn a bunch about amps on this thread, so thanks.
I believe PS Audio Stellar M700 monoblocks
are rated to be stable down to 2 ohms.
Class D 350 watts at 8 ohms, 700 watts at 4 ohms
Thosb,
      I think you mean Tom Thiel, Jim passed quite a few years ago and Tom is active on the forums with many insights into getting the most out of the great Thiel designs. I have enjoyed this discussion also.

George
I believe PS Audio Stellar M700 monoblocks
are rated to be stable down to 2 ohms.
Into 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

@rambo21

I believe PS Audio Stellar M700 monoblocks
are rated to be stable down to 2 ohms.
Class D 350 watts at 8 ohms, 700 watts at 4 ohms

Spec sheet for Icepower 700ASC specifies 2.5ohms minimum.


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


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...

It's also interesting that Stereophile didn't bother reporting specified power rating at 2ohms
Yes 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
Yes, of course, Tom not Jim, how embarrassing, sorry.  And I corrected someone else on this a month or so ago.  Palm to forehead. 
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.

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.

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.
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
dsper
Trying to learn. Seriously.
Thanks for listening,
Dsper
These 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
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.
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





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
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. 


Damn fair question... because of the selling price.
If the moderators won't kick me off the thread I'll post what I'm paying for them.
At the purchase price I can't lose...
One of the reasons I’d like to give these a go...
Specifications
  • Design: Monoblock Power Amplifier, Class D.
  • Power Output: 570 Watts RMS into 8 Ohms, 1,140 Watts RMS into 4 Ohms.
  • MFR: 20 Hz – 20 kHz, ± 0.4 dB.
  • THD+N: 0.2% at Rated Output.
  • IMD: (CCIF): 0.0005%
  • Efficiency: 79%
  • Sensitivity: 2.95 Volts.
  • Output Impedance: 0.005 Ohms.

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...

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

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:

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.
 

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

It had trouble with Thiel CS3.6's and was a joke with the CS5'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.


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.





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).


Also this thread, we're talking with the CS3.5 Thiels, which are far harder to drive than the 3.6
Cheers George
I’m pretty sure the Kappa 9’s are gonna suck/inhale these two mono blocks half way into the speaker cables
Love 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
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




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!

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