What Class D amps will drive a 2 ohm load

Looks like there’s still no takers willing to put it on the line, and post up the 8ohm, 4ohm, 2ohm wattage measurements just before clipping, to see if they are "almost" doubling the wattage for each halving of load, so to prove if their amp/s are going to drive these types of speakers close to their best, not just "satisfactorily"!

George, you like to promote GaNFETs as a thing in class D amps. But from this post is seems that you are unaware of something that GaNFETs bring to the table: very low 'on' resistance, often less than 100 milliohms. The devices we are using have an 'on' resistance of 60 milliohms.


That's lower than most linear output transistors! So a class D amp has no worries behaving as a voltage source provided the power supply can provide the current required into lower impedances. IOW less technical terms this simply means that doubling power into 2 ohms is no worries as far as GanFETs are concerned (and for a lot of other switching transistors as well). Our prototypes can double power into 2 ohms and we're not even trying to make it do that. It comes with the territory.


Whether its worth it or not is an entirely different subject as 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. Sure, we like to play with muscle power and boast about it, but in the end it doesn't matter if you can weld with your amplifier; its intention is to sound like real music (not a hifi, unless its intention is simply to make money) and no amp is going to do that driving such a low impedance.


Another way of putting this is if you want to get the most out of your amplifier dollar investment, that dollar is best served by a loudspeaker that is a higher impedance, assuming that high quality sound is your goal. Any loudspeaker manufacturer can cause their speaker to sound smoother and more detailed by raising the impedance because when the amp makes less distortion, it sounds smoother and more detailed...  Funny thing is, everyone knows this, its not some sort of hidden inner sanctum secret. But we still see these silly low impedance arguments when the simple fact is that the low impedance doesn't benefit anyone. You'd think that in high end audio where sounding real as opposed to sounding like a hifi is well understood, but here we are in the 21st century and this nonsense is still going on...

+10 atmasphere for putting that one to rest.

Hello George,

     For class D amps that double their output as impedance is halved down to 2 ohms, it looks like all the new Merrill Element amps, also using the new GaN fast switching transistors, all are capable but they're expensive, starting at $15K/pair for the Element 114 mono-block amps:

https://merrillaudio.net/products/

     However, Merrill's previous Veritas monoblocks, came close to doubling power down to 2 ohms at low rated distortion levels:

https://merrillaudio.net/veritas-mono-block-power-amplifier/#1519988773686-7ab00bcd-5607

     I don't know dsper's budget, but I've been considering buying a used pair of these and most are listed at about $5K/pair. I consider a pair of these in good condition the likely best bargain solution. New, the Veritas were priced at $12K/pair.

     The OP, dsper, was inquiring about a class D amp that could handle his speaker's crazy low impedance loads of less than 2 ohms without freaking out.

     Since this new amp from Purifi Audio was born out of the research work of Class-D pioneers Bruno Putzeys (of Philips, Hypex and Kii Audio fame) and Lars Risbo (Toccata Technology and Texas Instruments) and can handle speaker impedance loads under 2 ohms, even if it does so at less than ideal wattage and distortion levels, I thought dsper still might want to give it a try, anyway.  If Purifi offers the typical internet-direct free in-home trial period, there's literally no risk to dsper from giving it a whirl.

Tim  

Our prototypes can double power into 2 ohms and we’re not even trying to make it do that. It comes with the territory.

+10 atmasphere for putting that one to rest.

Nothings been put to rest, let’s see the independant test or even his own, that show the rms wattage doubling just before clipping (same distortion) with all three 8, 4, and 2ohm loads, then I’ll eat my words, and congratulate you on doing something that other Class-D’s can’t. I’ve asked the same from Merrill twice now and got no answer.

And btw, I’ve never claimed the new GaN Technoglogy could drive these speakers properly and double at all 8 to 4 to 2ohms loads either, they just sound better than the old technology, but I wouldn’t recommend them here either.

So dsper find yourself a brute linear amp/s with BJT (bi-polar) output stage, with high bias Class-A used somewhere to get the best from your highly regarded speakers.
Do not get sucked into by these Class-D spruikers because you won’t get the best from your speakers.
Or (I wouldn’t) sell your speakers and get something easier to drive that doesn’t reach down to sub 2ohm loads in the frequency range, then you can by a GaN based Class-D which will sound very good.

Cheers George

and can handle speaker impedance loads under 2 ohms,

dsper That statement it’s should tell you something, they "can handle" a 2ohm load.
My car "can handle" being reved to 8,000 rpm. My hands "can handle" 60c on a Class-A heat sink for a few seconds!

Your speakers are at 1-2ohms for nearly 3 octaves in the bass
"JA which 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."

Like I said above " find yourself a Krell type ect linear amp/s with BJT (bi-polar) output stage, with high bias Class-A used somewhere to get the best from your highly regarded speakers."

Read these amps that were tried and you’ll get an idea of what’s needed to get the best from your speakers.
.

JA Stereophile.
" The best one I heard was the Krell KSA-250 (their latest product—though by the time you read this there will be a KMA-600), followed not too far in second place by the older Krell KSA-200.
The newly arrived Threshold SA/12 monos had plenty of overall power, but lacked the drive at the low end possessed in such quantity by both Krells, and had a refined, neutral upper range that seemed to leave the Thiels lacking in sparkle.
Until now, my favorite overall amplifier has been the Mark Levinson No.20.5, but it simply didn’t have the low-end punch necessary to bring the CS5 to life"

Cheers George