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
Cherry amps, by Digital Amplifier Company. 
Hypex certainly claims it with the NCore MP series, around which many brands have designed their Class D offerings:

https://www.hypex.nl/p/hypex-ncore-mp-amplifiers/
 

Most D-Sonic are stable down to at least 2 ohms.

Tim
You’ve got one of the greats in those Thiel CS5’s dsper, but are seriously hard to drive.

The OP has asked which Class-D can "DRIVE" a 2ohm load, not one that won’t occillate or blow up into a 2ohm load, and not be able to drive it fully.

I’ve seen no Class-D independently tested, be able to come close to doubling it’s 4ohm wattage when presented with 2ohms, and remaining stable and comfortable doing so.

This is a true test of being a great amp that can handle and "DRIVE" speaker loads such as Wilsons ect can present down to below 1ohm, including your Thiel CS5’s, they can go down to .5ohm at 20hz and remain at 2ohms still at 50hz!, and are still under 3ohms all the way up to 200hz!!!

None of the Class-D’s mentioned here will do these great speakers justice at all, the ones suggesting so are all tripping!.

Cheers George.
Nord Acoustics base most of their amps on Hypex and are entirely happy to state those amps will be able to drive speakers at 2ohms.  Independent testing has pros and cons and, having perused several hi-fi forums for some years, I've long since concluded the only "proof" is to demo and listen with your own kit and ears.

Coincidentally, I have the joy of a demo with a pre-amp in 5 days and, assuming the SQ makes me smile, I will need to partner it with a power amp.  A Nord One MP NC252 (entry level) is going to get a run, as is a Mytek Brooklyn Amp (NAD's own C 268 will also be given a whirl as it's there).  All are class D and a friend of mine, with decent ears for detail, rates the Mytek highly.  Just for transparency, my current speakers don't engage the 2ohms issue but future speakers may so that's something I keep in mind.

If the NORD comes close to the Mytek, it will give me the best part of GBP £1,000 for another piece of kit :-) .  In that event, I will exercise great self-control and (probably) not smile smugly at my friend....

@dsper Hope you find what you need / want.
the NC1200mp module can output 38 amps.  March audio has tested his with sine waves at full rated power for 6 minutes without oscillating, not a situation you are likely to get with music.  The Thiels are a horrific load, but I suspect NC1200 monoblocks would be up to the task. It would be interesting to try out.

https://www.audiosciencereview.com/forum/index.php?threads/march-audio-p701-mono-block-power-amp.6862/#post-152472
George, I think you are probably correct I but had to ask! 

My McCormack DNA-500 does pretty good and I suspect a real improvement is going to cost big bucks.

Dsper.
Yeah your speakers are one of the greats but need a equally great amp to do them justice, especially in the bass.

Those here that say x class-d can, can not show independent test resuts that show the 8ohm wattage doubling to 4ohms and then the most important one almost doubling again from 4ohms down to 2ohms.

This is the true test to see if an amp is able to "drive" properly into 2ohms and in your case .5ohms, and not just make some noise into it.

DESPER a pair of John Curl designed Parasound Halo JC1 monoblocks will do the job nicely, and not cost much used.

Cheers George
I believe the Rogue Hydra and Medusa are stable to 2 ohms.  I have the Hydra and it is a great amp.  
Those Thiels are monsters to drive. I owned the CS7.2 which was an easier, but still rough load on amps. The Parasound JC1's struggled and shut down a couple times even with them. I ended up with Krell FPB 650M monoblocks. Finding an amp that can control/make those older Thiels really perform at there best is limited imo. 
I am using an Apollon NC800 SL amplifier, based on Hypex nCore NC500, with special buffer using Sparkos SS2590 discrete opamps, to amplify my Thiel CS3.7, which run almost all frequency range near 2 ohms. Recommended, sound great, no background noise whatsoever.

If you need more power consider the nCore NC1200 based amplifiers (Nord, Apollon).

The new Purifi modules should be good to go for 2 ohms too.

I know someone using the Icepower IceEdge modules on his Thiel CS3.7's and he can blast it all he wants.  I have tested the IceEdge module to do 1000 watts at 2 ohms.  That is a lot of power but less than half on what a JC-1 will do.

I think very old design speakers with this kind of impedance don't make sense.  You limit yourself to amps and I have no doubt there are far more transparent higher efficiency speakers out there.....Check out Spatial, GR Research, Tekton.  These speakers are very sensitive and very transparent.  You could even make some speakers for very little that would be mucho better....and easier to drive.  Almost everything I have is DIY.

BTW, the Stereophile review shows a 2 ohm load for the CS5....where does one half ohm come from?

https://www.stereophile.com/content/thiel-cs5-loudspeaker-measurements-0



Speakers like these Thiel CS5's, their bigger bother the CS7's, all Wilson Watt/Puppy, Alexia's mkI an mkII, also the Alex, Max ect ect ect and many other brands, have sound to behold when "driven" with amps that can do current, that can keep doubling the full output wattage for each halving of impeadance loading, and to say this type of speaker doesn't make sense, shows high degree of ignorance, bad hearing or never heard them "driven" properly.

Cheers George    


The CS5 is a very old design using not the latest drivers, caps, resistors, wire, etc. etc.  Any of the speakers I mentioned would kill it.   Comparing an outdated old speaker to newer speakers is ignorant. Check out the reviews on the Ulfberht......one guy thought it was better than his big Wilsons.....and these are $9000 delivered and 98 db sensitive.  No big current doubling into 2 ohm amps needed.  Sorry, low impedance speakers are silly....even the latest most expensive ones....simply silly.  When you can get moderately priced super transparent and easy to drive speakers under $10K.....these giant current hogging speakers are like an old model T.   May they rest in peace.

I am not saying the latest Wilsons, etc. do not sound good.  Its just that you have to be super rich to buy them and buy a super expensive high current amp to drive them (Parasound JC-1s are not even in the running for transparency in the $2K range today, however, they do make a fine bass amp) .  Save your money.  Give the money saved to those that need it.  Do you think it makes "sense" to spend lots of money on super expensive current hogging speakers and super expensive current producing amps when you can get as good or better sound with way less expensive high sensitivity speakers and reasonably priced amps?  Maybe you have a different "sense" than me.



The reason you are putting **** on this type of speaker, is that class-d won't drive them to their maximum sound quality. These types of speakers are engineered to be far closer to having ideal test mearsurements and sound perfection than easy to drive speakers, that are far more comprimised. 
I just could not resist - sorry - My Thiels were $2,600 delivered about two years ago, so I think it is just silly to pay any more for speakers🙂! 

I have tried tried Class D amps from W4S and Audio Research with Maggie 3.6's, Thiel CS 3.6's, and Thiel CS5's in my listening room. In every case, they could not get the job done. I have looked at Nord but they do not double down into 2 ohms so I suspect they could sound lean as well.

Class D is attractive because of all the good reasons but still evolving, I guess. And maybe, at least for now, driving 2 ohm loads is not important to class D amp manufacturers.

Perhaps I will ask the question again in another couple years!

Thanks for listening,

Dsper

@ricevs  - "I know someone using the Icepower IceEdge modules on his Thiel CS3.7's and he can blast it all he wants."

CS3.7 impedance has been measured at 2.4 - 2.8 ohms through most of the frequency range by Stereophile.

Icepower 1200AS1/2 has an minimum impedance of 2.7ohms.

I doubt very much the person you know using the $300 Icepower modules is getting anywhere near full potential on his speakers.

Back in the day (before internet sales), any experienced audio dealer wouldn't have sold an amp so badly unrated for this type of speaker. There's a reason both online reviews I've read suggest serious amps are required because these speakers are 'Pigs'.

I wouldn't be selling these modules to anyone using speakers with anything less than 4 ohms minimum.


Why do loudspeaker manufacturer's make ultra low impedance loudspeakers in the first place. lots of great speakers out there with easier loads to drive, many as good as, or better than Thiel. IMO.

IcePower is rating their module in a conservative way.  2.7 ohms is three 8 ohm drivers in parallel.  They are selling this amp for concert use and sub woofer use as well.  You don't want your loud concert shutting off because the amp is going into protection.  As I stated above, the IceEdge module measured 1000 watts into 2 ohms (1400 at 2.7 ohms) on the bench here yesterday.  It drives his Thiel 3.7 better than his previous Bryston and Modwright amps.  It is perfectly compatible. If you need more power than 1000 watts into 2 ohms then your speaker is really HARD to drive.  Certainly the JC1s will give you 2200 watts into 2 ohms.  But they do not sound that good by todays standard. 

There are many speakers around $2700 that would sound better and be easier to drive than an old CS5.  But, selling those speakers would be hard.

I could care less what class of amp will drive whatever speaker.  I have been using a 92 db speaker for years with a 25 watt class A amp.  Now I use my 600 watt a channel class D and get better sound.  I don't need 600 watts....25 was perfectly fine.  I just want the best sound possible.  As I said, I don't think low sensitivity, low impedance speakers make any sense.....not in todays world.  The times, they are a changing.

George, no negative comments here, please, but my point I am about to make is very relevant to the discussion, and just another person’s perspective. As most here who know me, I go wayyyyyy back with PWK and his Klipsch Heritage products. I have owned, borrowed, installed for others, and listened to, so many other speakers, and the same goes for power amplification. As much as I enjoy, and own, Heritage, I am certain, part of my enjoyment, comes from the driving amplifiers, simply " coasting along ". You do not hear a speaker, without a driving amp, nor, do you hear an amp, without a driven speaker. It is always, imo, and ime, the combination. Some of us hear an immediate " compression "; some of us hear certain " distortions "; some of us hear a lack of " damping " ( woofer control ), etc. If there are any questions, that reliable measurements cannot tell you, you simply need to try it....On another thread, I recommended to the readers, to read a review of the Peak Consult Dragon Legends, from Mono Stereo, last year, by the same reviewer who just reviewed the Merrill 118s, from Part Time Audiophile. After reading the Merrill review, and realizing I had read the speaker review a year and 1/2 earlier, I needed to read the speaker review, again. Richard Mak, the reviewer, does an excellent job, in both reviews, but, really highlights, greatly, the importance of the speaker / amplifier interaction, and most important, the expectations of the listener. Please read them both. Enjoy ! MrD.
Don't under estimate the Thiel CS5i's, they are truly special.
For about $3k you can get an nCore NC1200 based stereo amplifier from Nord/Apollon that drives 2 ohm speakers with 1200W. Plus your choice of Sparkos or Sonic Imagery discrete opamps to flavor to taste.

IMO this is a huge value.

I don't need that much power and settled on "only" 550W in 2 ohms of the NC500 for my Thiels. That is plenty of power, lowest distortion and non existing hiss and noise.
You guys are just p***ing against the wind quoting big watts, and not quoting the wattage for each halving of impedance at 8, 4, and 2ohms

It’s not about the big watts, Class-D P.A. amps like Crown ect can do that. It’s about the amp being able to come close to doubling it wattage for every halving of impeadance 8, 4, and 2ohms!

The classic massive Mark Levinson ML2 mono blocks at only 25w into 8ohms will sound better into into these speakers than any 10,000w Class-D, because it can double it’s 8ohm wattage all the way down to 1ohm ( 25w 50w 100w 200w). Which means it can "DRIVE" these speakers

Granted it won’t do party levels because after all it’s still only 25w at 8ohms , but it will p**s all over your ice power class-d for sound quality, into these types of speakers.

Cheers George

+1 George

"I know someone using the Icepower IceEdge modules on his Thiel CS3.7's and he can blast it all he wants. I have tested the IceEdge module to do 1000 watts at 2 ohms."

It was posts like this that sucked me into thinking these amps (Icepower 1200AS1/2) practically had no limit. Hopefully, anyone with speakers lower than 4ohm minimum won't get burnt by the hype.

Very few amps are capable of handling that.   In that Class D amps are very efficient, no reason to think they can't.  

Someone bring over a pair of Thiels and we can find out.  I've considered taking the Thiel plunge armed with my BelCanto ref10000m amps on several occasions.   

OP is asking about Class D amps rated for 2ohms. One of the suggested amps (1200AS1/2) is rated at 2.7ohms. This module also has a clipping indicator built into the controller. It would make sense to me that the clipping indicator was active to see how well the amp is doing. I doubt B&O had something like the CS3.7's in mind when developing this module.

Based on OP's last post,  it seem the question is if there's a Class D amp that drops down to 2ohms without any issues, while maximizing the speaker to it's full potential. Not a Class D amp that only allows a speaker system 40-50% of it potential. Is there a Class D amp that will do this, if so which ones. According to OP, the 2 that were mentioned failed.

You only need as much power as you need. The "rated" lowest manufacturer suggested impedance for the IceEdge is 2.7 ohms. But in "real life" it puts out 1000 watts at 2 ohms. What a manufacturer recommends and what is real are sometimes far off. Again, the person with the 3.7s can blast as loud as he wants and it sounds incredible. What more do you want? A spec that makes you happy? Reality makes the owner happy. You don’t need an amp to double its power as it halves its impedance at 2 ohm. You just need enough power at 2 ohm (or whatever ohm) to control the speaker (assuming you have a speaker that needs that) at the volume you listen...again, I feel such low impedance speakers are outdated and don’t make "sense".  Almost all amps (no matter what class) make more distortion (measurable) and have less damping factor the lower the impedance.  Hardly any amp measures good at 2 ohms.  Again, why have such a speaker?

No way an old Levinson sounds as good as this mono tweaked IceEdge. But George will just keep repeating the same old lines (he hates class d...unless it has GaNs and has 1.5 meg switching). 100 watts into 2 ohms is not 1000 watts at 2 ohm. And my IceEdge modules beat my super simple super tweaked custom mono class A amps (also 25 watts a channel and will double/double all the way down to 100 watts into 2 ohms).

The IceEdge module is current limited at 38 amps.....it is not unlimited. No one ever said it was. It will drive 95% of all speakers to whatever levels someone needs and sounds very, very good. Not state of the art...but very good. Again, here is what it actually does: (600 watts into 8 ohm, 1200 watts into 4 ohms, 1400 watts into 2.7 ohm and 1000 watts into 2 ohm). If you need more power than that then you must look elsewhere.
And my IceEdge modules

And there is is! the plug yet again.

1200 watts into 4 ohms and 1000watts into 2ohms
And there it is, s***'s itself, can't deliver into 2ohms
Anyone know why Thiel designed such hard to drive speakers when there are so few if any amps around capable of  driving them to the max?


A few minutes ago (14:00ish hrs GMT), I spoke with Colin at Nord Acoustics primarily with my own system in mind.

However, I remembered this thread and mentioned it to him. Colin is positive that even Nord's entry level "MP" amps will, in almost all cases, be able to drive speakers at 2ohms.  I'd say to the OP, contact Nord directly and run your thoughts by them.  I'm pretty sure the last thing Colin will want to do is sell an amp that turns out to be useless!

It's disappointing that this thread descended into an echo of 99% of cable threads....

PS:  For the avoidance of doubt, I have zero vested interest in any audio equipment manufacturer or supplier.
Anyone know why Thiel designed such hard to drive speakers

Not just Thiel, there's many others that strive for perfection and they're usually the most expensive.
 
Xovers/drivers ect, are complicated to get everything to operate in the most linear function and best specifications without having many compromises, that most efficient speakers tend to over look for the sake of efficiency.
That's why you need great amps usually with great speakers otherwise you don't get what's the speakers capable of giving you, if not you compromise the speakers performance. 

Cheers George    
I'd say to the OP, contact Nord directly and run your thoughts by them. I'm pretty sure the last thing Colin will want to do is sell an amp that turns out to be useless!

Now your twisting things by saying "useless".
Of course it will "work" and he will say so, but will it get the very best out of the speakers?, DEFINITELY NOT! especially in the bass where they are a pig of a load.
I have a Classe Class D Sigma Amp 2 driving Wilson's which I am told dip down to 2 ohms.  They sound GREAT.

Here is what Classe states:

All amplifiers except the CA/CT-5300 have a virtually linear doubling of output between 8 ohms and 4 ohms but since it can be a misleading figure, we do not supply details of their performance at 2 ohms.

This by no means implies that our amplifiers cannot operate at 2 ohms, which they obviously can. Impedance varies with frequency and most high quality speakers have the capacity dip to 2 ohms. Since our amplifiers are specifically designed to drive the world’s best speakers, they will have no problem driving a 2 ohm load.

Nevertheless, driving 2 ohms in the real world requires an enormous amount of power, which is sometimes technically unavailable from the AC mains power outlet. This means that these types of specifications are vulnerable to external conditions, and can therefore be misleading. Clearly, we do not want our customers to make decisions based on potentially misleading information.


I have seen some commercial speakers from Focal introduce a 2 Ohm low deliberately in the crossover. Took quite a number of caps and resistors too.


My guess is that amps with low impedance around 100-150 Hz sound more discerning, more snobbish of amplifiers. "Look at me, I can only be driven by high current amps, so I must be better."


I have also seen designs from Infinity which were an utter part crap fest. My guess for them is that at the time they were designed good simulation and measurement tools were far too expensive, and they reached their sound empirically with no concern for the amps. You may think "well, nothing wrong with voicing by ear" but the designs I’m talking about could easily have achieved equivalent results with easier to drive impedances.


Kudos to Joseph Audio for going the other way, and actually adding crossover components which make them easier to drive by a wider range of amps.

Best,
E
I have a Classe Class D Sigma Amp 2 driving Wilson's which I am told dip down to 2 ohms. They sound GREAT.
Not saying they don't, but if you have Wilsons that go to 2ohms (your not saying what ones) then your not hearing them at the their best. And you maybe happy with that, because you don't know better.

Cheers George
Kudos to Joseph Audio for going the other way, and actually adding crossover components

That’s just adding series resistance to the perceived load to make it look higher to the amps output stage so it doesn’t complain, and what that does is lower the damping factor and raise the output impedance as seen by the amp 

You get a similar effect by using a ZERO output transformer with amps that aren’t right, and we all know know that is just a band aid fix, better off having the right amp to start with.
what about jeff rowland’s class d amps ?
all from the old stereo 102 through to the 201/501 monos and up to the current 825/925 etc can double their power into 4 ohms.
i’ve heard the big ones behind speakers like magnepans, martin logans and apogees, so they should have no problem driving the thiels.
Now your twisting things by saying "useless".
Of course it will "work" and he will say so, but will it get the very best out of the speakers?, DEFINITELY NOT! especially in the bass where they are a pig of a load.

George, once again you post with a hostility that is uncalled for. There was nothing "twisted" about what I said. It was fair use of English language. The provocative language you use does not reflect well on you or your credibility. If you are so sure of the view you state, why don’t you let Nord (and others) know they are wrong? That’s a rhetorical question.
Then why did you say "useless"
Of course it will work, class-D just won’t get the best from these speakers especially in the bass, and some maybe happy with that not knowing any better.
But I think if anyone had a speaker that was regarded as Stereophile "Class A" in the "full range" category, and one of Thiel’s all time master pieces, you would like to get the best out of it.

Stereophile JA " All in all, the CS5 is both the most thoroughly worked-out speaker design I have ever come across and perhaps the best-measuring loudspeaker I have yet experienced."

" The Manley 500s, which I held off hooking up for a long time, were, as nearly as I could determine, simply unable to deal with the CS5's cruel 2 ohm impedance at the low end." 
The Manly 500 watt monoblocks https://images.reverb.com/image/upload/s--i_Cjxmnb--/f_auto,t_supersize/v1552409073/zucn7la3dmcwphn2...


George, I appreciate that you responded with a more constructive post. I’m not going to get further involved as, for me, hi-fi is about the music more than the equipment although the latter isn’t without interest. I also don’t pretend to have the level of knowledge evidently demonstrated by numerous contributors to these forums.

As for the vexed issue of speaker loads and compatible amps, my kit (now and potential) is unlikely to engage that conundrum in the foreseeable future, although, part of my curiosity wishes I was able to arrange a real world listen to a heavy-load speaker pair with a quality Class D amp :-). Sadly, I’m not in a position to do so!

For context, my own system is relatively lowly and even if a demo goes well later this week (a distinctly non-classic NAD C 658 - hence my own interest in adding a power amp), the new kit will hardly be mentioned in the same breath as much of the equipment discussed within the forums.

In any case, I sincerely wish everyone happy listening and/or hi-fi hobbying.

I’m not going to get further involved as, for me, hi-fi is about the music more than the equipment although the latter isn’t without interest. 
Now that reeks of a copout.

I also don’t pretend to have the level of knowledge evidently demonstrated by numerous contributors to these forums.
Yet your not willing to take it onboard when it's presented to you in simple terms that anyone can understand.
Wow George.  What a shame.
That’s just adding series resistance to the perceived load to make it look higher to the amps output stage so it doesn’t complain, and what that does is lower the damping factor and raise the output impedance as seen by the amp

@georgehifi - You literally have no idea what I was talking about, so your reply is wrong in the specific and wrong in the general.

 
Best,

E

^^ +1 @erik_squires yes, that response on George's part surprised me as well.
last thing Colin will want to do is sell an amp that turns out to be useless!

I never insinuated Class-d's would be "useless", I said Class-D's into these types of speaker loads won't get the very best out of them, end of story. 
Hello georgehifi,

FYI, You’ve been using the abbreviation "ect" rather than the proper "etc.’ to refer to the words of Latin origin "et cetera". Translated literally from Latin, et means ’and’, while cetera means ’the rest’.
An easy method to remember the distinction is that etc. means et cetera, while ect is the typical involuntarily sound people make after reading one of your posts.

You’re welcome,
Tim
My guess is that amps with low impedance around 100-150 Hz sound more discerning

Sorry if it wasn't clear, but I meant:

"My guess is that _SPEAKERS_ with low impedance around 100-150 Hz.... "

Apologies for any confusion, I hope that to most it would have been clear I made that mistake.

Erik
OKAY......

This is the OP again...it sounds like I am hearing Class D might not be the best for tough, low impedance load speakers.

If that is indeed the case, why is this and what has to change in Class D design to achieve it?

Please respond realizing I know that doubling down from 4 ohms to 2 ohms by an amp is a good thing; but I probably cannot explain why this is so.

Trying to learn. Seriously.

Thanks for listening,

Dsper