What Class D amps will drive a 2 ohm load

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.

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

Thank you golfnutz.

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

FWIW,

I went to the Purifi Audio website and found many charts and specifications for their 1ET400A, most of which I did not understand so I could have very well missed something important about relationships between the stats they quoted.

I did see this:
Output Power, Short Term
8ohm, 1% distortion = 227 watts
4ohm, 1% distortion = 450 watts
2ohm, 1% distortion = 450 watts with a footnote stating "Power is limited by overcurrent protection system (OCP) and highly dependent on thermal conditions."

Not sure what the footnote means. 

I went to the Spectron website for the Musician III Mk2 and they tell us "The current headroom is primarily limited by the amplifier’s ability to deliver high currents into low impedance loads. There are many well regarded speakers whose impedance dips down, some even lower than 1 ohm. When a musical note is played at frequencies where the impedance dips, the current demands skyrocket. When this happens with amplifiers that do not have large output current capability, they “current clip”. These transients will be both attenuated and quite distorted. Moreover, most other amplifiers only deliver their rated peak current for sometimes a fraction of the time called for by the music. Spectron amplifiers can deliver peak currents of 65 amps, with a staggering peak power of 3500 watts per channel for over 500 msec (!), which allows the amplifier to deliver the full transient (burst of music) without current or voltage “clipping”. ".

Their stats also state 0.3% THD up to 600 watts in 8 ohms. Could not find anything about distortion at 4 or 2 ohms.

Not sure what that does or does not tell us.

It appears the old adage about trying it in your listening room will tell the real story.

In the meantime, quit bashing my low impedance speakers as they sound wonderful to me in my listening room 😍!

Thanks for listening,

Dsper

This just gets more interesting.

I emailed, to both Nord and Appollon, the Stereophile measurements for the Thiel CS5's and both suppliers said that their amps would drive them.

For example, Appollon replied that their NC1200SL HYPEX NC1200 BASED AMPLIFIER "...is a perfect choice for your speakers and probably the only class d amplifier that will drive your speakers with ease at 2 ohm loads. The NC1200 module is specially designed for such low impedance loads. Any other class d amplifier will fall apart sound wise with your speakers but the NC1200 shines @ 2 ohms."

So what am I not being told?

Thanks for listening,

Dsper

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

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

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

Hi Noble100,

I have looked at Merrill Veritas amps but am not quite ready to part with my CJ preamp🤔.

Thanks for listening,

Dsper

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

Hi Atmasphere,

I tried some multi-strand 10 gauge copper wire on my Thiels. This replaced 16 gauge lamp cord. Fifteen foot lengths.

Can definitely tell a difference, an improvement. There is more detail, which seems to add better decay in general; cymbals sound more real.

Thanks for the advice,

Dsper