You and Ralph are both just in product protection mode, it's so obvious
Actually, no. Again, I suggest you read the white papers of Bruno Putzeys and perhaps some of his interviews. Quite plainly, you have mistaken impressions about how class D amps work.
This is probably a forlorn hope to explain this in common terms as in the past you've proven highly reticent to taking on new information that might be different from what you think. But I can tell you that all class D amps are not the same. Some do have phase shift and those are likely to be one of two types. If they run feedback, the filter isn't in the loop. Or else they just don't run feedback. For either of these then you do have to keep the switching speed as high as possible so the filter frequency can also be high.
But what you don't seem to have any idea about is self-oscillating class D amps. Self oscillating amps have so much feedback that as soon as you turn them on they go into oscillation. The oscillation is the switching frequency. As a result they can have a lot of feedback and in excess of 35dB is common. I think some of the Purefi amps have a total of 75dB of loop gain, which is an impressive feat. With this kind of feedback, the amp is then able to do two things. First, the feedback allows the amp to compensate for phase shift caused by the filter. Second, there is so much feedback that it actually allows the amp to compensate for distortion caused by the feedback itself. I think the only other amp that can do this that is not class D is made by Benchmark.
So this means that self-oscillating amps can have extremely low distortion, and output impedances so low that they are difficult to measure; 0.001th of an ohm being entirely possible. Such an amp will easily behave as a voltage source with a 2 ohm load. The only thing stopping them is the current capacity in the output section, the power supply and the heatsinks.
whatever! Like i said "I would back any time the Parasound Halo JC1+’s sound and drive-ability up against ANY Class-D into the loads the likes of the Alexia’s, B&W’s etc etc" And that's what this thread is all about!!
Its so obvious you are in ego protection mode. Ralph is not even talking about power......in fact, you are the one that brought up (for no apparent reason)....your thoughts on bandwidth and GaNs here. They have nothing to do with power and you know it. I sold 12 class D amps LAST YEAR and am making no more.....so what product am I protecting? You keep saying the same silly things over and over again. I really feel sorry for you.
BTW, I have said all that I know on this subject so I will bow out unless I see some info that needs help. I like to be helpful. I want people to be happy and buy the best and least expensive thing for their stereo or whatever.
Parasound JC1+ was measured at 1200 watts into 2 ohms (if it doubled all the way down to 2 ohms then it would put out 2000 watts).....which, by the way is exactly what the NC2000 does (2000 watts)....sorry, Parasound loses.
"Dreamer" I would back any time the Parasound Halo JC1+’s sound and drive-ability up against ANY Class-D into the loads the likes of the Alexia’s, B&W’s etc etc You and Ralph are both just in product protection mode, it's so obvious
Simple fact, very few amps.....including class A or A/B doubles its power down to 2 ohms. For instance, the Parasound JC1+ was measured at 1200 watts into 2 ohms (if it doubled all the way down to 2 ohms then it would put out 2000 watts).....which, by the way is exactly what the NC2000 does (2000 watts)....sorry, Parasound loses. By the way, the Merrill 118 class D mono blocks double all they way down to 2 ohms (1600 watts into 2 ohms)....much better than Parasound.
Doubling power does not matter. The only thing that matters is whether the amp has enough power at 2 ohms to drive the speaker at the listening level you want. George can rant on and on about this but this is the truth. 1000 watts into 2 ohms is 1000 watts into 2 ohms. Practically no one who has a 2 ohm dip speaker will ever use this much power unless you are in a huge room and play super, super loud.....this is the actual fact.....not anything to do with doubling power. George has never listened to any of these class D amps so what does he know about how they drive these speakers? You know the answer.
Title to this thread What Class D amps will drive a 2 ohm load
Simple fact is: Class-D cannot drive a 2ohm load and double it's wattage down to that 2ohms, load like a good linear bi-polar amps, end of story!
That is why with the many speakers similar to the Alexia, B&W etc loading, Class-D's are not a good match, even complimentary push pull N and P channel Mosfets are not, except amps that use only N channel Mosfets only.
To others here. Both the above posters have financial interests in selling their own Class-D current or yet to be released, this is why they have their backs up.
I did not see this earlier. Yes, you can buy mono blocks using the 2000 watt into 2 ohm Ncore 2k modules, the 3000 watt Hypex power supply with Weiss discrete buffers and Sparko regulators for $3200 the pair. This will drive the crap out of those hard to drive speakers.
The Mosfet output transistors themselves as well as the output filter, which both have not changed much since it’s inception. The
GaN output transistors are maybe going to change that with optional far
higher optional switching speed available, so then output filter can
also be far higher up, then there’s also no phase shift down into the
audio band. But this also needs small heat sinks to be used, as you can
see below.
This statement is 100% and certifiably false.
George, I suggest you read the white papers of Bruno Putzeys. Advisory: its is helpful to know a bit of calculus to follow along.
Your statement about the filter is incorrect if the amplifier is self-oscillating; even if the filter frequency is fairly low (80KHz for example) the feedback used in almost any self-oscillating class D amp allows it to correct the phase shift from the filter from affecting the audio passband.
You don't use GaN devices to increase the switching speed- it appears that Technics did it purely for bragging rights, not sonic merit. You use GaN Devices for their properties such as fast switching speeds, gate input capacitance, output capacitance and possibly lower deadtime. 600KHz is a very practical upper limit for switching with them, not because they can't go faster but because creating a low noise layout gets exponentially harder as frequency is increased. But you should be advised that MOSFET devices have been fast enough for a while that Technics could be easily using them at the same switching speed; Bruno is using MOSFETs rather than GaN devices in his Purefi circuits- think about that for a moment will you? Bruno is arguably the acknowledged master in the world of class D and he's not using GaNFETs. This is not to say that he doesn't acknowledge their benefits. Quite simply it just isn't as you've portrayed it above.
George, You are not even addressing his statement. Class D can already drive low impedances.......1100 watts from the NC1200 and 1000 watts from the mono 1200AS1 (all at 2 ohms). Tons of high end manufacturers use class d in their subs and in their powered speakers. Certainly, there are those very very few super low impedance speakers that need a welding amp to drive them.
The switching speed of an amp and the type of output devices have little to do with power (so why are you bringing it up?). The Technics does not have super low impedance driving capability (300 watts a channel into 4 ohms and no mention of lower impedance capabilities). That amp converts all analog signals to 24/192 and then fools around with the signal in the digital domain before it changes PCM to PWM.....really a digital amp.
I was talking to someone at IcePower some time ago about them using GaN transistors. They said the engineers were looking at them because they are so efficient they can be used in serious high power amps with less heatsinking. The IceEdge chipset is capable of producing up to 7000 Watts. Imagine what that amp could drive! There is no reason class D cannot drive even super low impedances....but why? Since the number of amps that need drive below 2 ohms is super limited....they why would a manufacture bother? You need higher voltage rails, more capacitors, more output devices, larger circuit boards, more cost, etc. Also......all amps create more distortion as the impedance lowers......I have never seen a measurement of an amp that did not measure worse at 4 ohms compared to 8......and then 2 ohms is even worse. Why would you want to listen to more distortion? High efficiency speakers and reasonable impedances make sense.
BTW, this (link below) has been available for years. No one has made a serious version, that I know of.....2000 watts into 2 ohms.....is that enough power?! It has built in op amp, somewhat low gain and low input impedance.....so probably would never sound as good as the NC1200 tweaked to the max........but, shows what can be done. Look at the size of that 3000 watt switching supply you use with it Much more can be done with GaNs as they are so efficient. https://www.hypex.nl/product/nc2k-oem/79
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?
The Mosfet output transistors themselves as well as the output filter, which both have not changed much since it’s inception. The GaN output transistors are maybe going to change that with optional far higher optional switching speed available, so then output filter can also be far higher up, then there’s also no phase shift down into the audio band. But this also needs small heat sinks to be used, as you can see below. But only one amp so far has utilized that combo this the unobtainable Technics $30K SE-R1 power amp.
I have no idea how they sound but according to Anthem their M1 Class D Monoblocks if connected by 240 volt will drive into an open circuit or short circuit.
Flat frequency response into any load, without having to resort to digital conversion or equalization to compensate.
Stable into all loads including open circuit and short circuit.
Yes, I had seen that test. I would guess that the module only? (he he) does a little under 1100 watts into 2 ohms at 1% distortion. Plenty of grunt for 98% of listeners on 95% of the speakers in the world. I have never read a post that said any amp using these modules would not drive a particular speaker.......Can you find one? A powerhouse, for sure.
The Mola Mola amps are using the Hypex NC1200 module. You can buy mono block amps from $1700 a pair using these same modules. VTV Amplifier have $1700 mono blocks using the built in stock input stage and $3000 the pair with expensive Weiss discrete input stages using Sparko labs regulators. Even more high end is the mono blocks from Apollon that add better sexier, stunning looking chassis, wire, jacks, and separate linear power supply for the Weiss input op amps....these are $6000 the pair delivered to the US......the Mola Mola's are $17K! I doubt the Mola's would be as good as the Apollon. Check them out! These amp modules are rated at 1200 watts into 2 ohms (hence the name...NC1200). When the Mola Mola amps first came out the only way a manufacturer could sell an amp using these modules was to agree to sell mono blocks for at least $9K. This was to protect the Mola Mola brand. A couple of years ago Hypex finally stopped this restriction so now amps using these modules can be sold for way, way less. The Acoustic Imagery (now out of business) Astah amps ($9K the pair) were reviewed in link below. These amps used the built in op amp (equivalent now sells for $1700!!!).
Hi Dsper, While I am hesitant to chime in here, for fear of attack, this is what I think I know: I replaced my Classe CA-2300 (an amp I Ioved) with Mola Mola Class D Kalugas. They drive my Revel Ultimate 2 Salon 2's, a speaker not super easy to drive. The Kalugas are more dynamic, better bass control, faster, as well as more resolved on the high end. I honestly heard sounds I had not heard before, with no compromises to me. I compared back and forth several times before absolutely deciding the Mola Mola's were better to my ears. I previously had rejected Class D amps (PS Audio).
With this Bel Canto e1X, even the 8ohm to 4ohm is a tell to what the 2ohm wouldn’t/couldn’t do grunt wise. That wasn’t even considered to be measured as it would have fallen flat on it’s face like all Class-D’s do that I’ve seen, but at least it's stable into 2ohms and won't blow up. (so is a Nad 3020) 340Wpc into 8 ohms 530Wpc into 4 ohms
The output impedance of almost any class D amp is so low that doubling power as impedance is halved is no problem, even into 2 ohms.
The limitations are current capacity in the output section, current capacity in the power supply, heatsink capacity and finally issues surrounding the output filter. Its likely that the latter will be most problematic, which is why self-oscillating is attractive since it will allow the amp to correct for phase shift induced by the filter. Getting output devices that can handle the current is academic at that point- its all about how far you want to push it in the design- you face most of the same constraints you do with a class AB amp.
Bel Canto e1X, stable into 2 ohms. See recent Stereophile review.
Like I said, "stable into 2ohms" is a smoke screen furphy, to make the gullible feel it can happily drive 2ohms without strain, it just means it won’t oscillate and blow up, as Ralph also said two of his post back. So is a 1980’s 30w Nad-3020 stable into a "2ohm load", but there’s no way in the world it can drive it without any strain, if it could you would see the 4ohm wattage almost double into 2ohms, but that’s not given with the BC for a hidden reason.
Even the Stereophile tests show the eX1 can’t even get close to doubling from 8ohm to 4ohm!!!, let alone the 2ohm, it for sure would have gone backwards, instead of up if it was given.
@noble100 Yes, Bruno has been able to design class D amps with loop gain north of 75dB!!
He did acknowledge to us that there was a typo in one of his papers when we pointed out a math error regarding the oscillation criteria. It was not an error in the paper itself though, it really was a genuine typo. Brilliant guy.
Thank you, atmosphere, for your numerous interesting and very informative posts. Class D Hypex and UcD power module designer, Bruno Putzeys, has stated that there's no such thing as too much feedback and that he's able to make a class D amp sound however he likes but decided his goal would be accuracy. Here are a couple interviews with Bruno Putzey about class D I thought members on this thread might find interesting, relevant and informative:
A class D amp can do 2 ohms if the intention is there on the account of the designer. Several things have to be present to really make this so.
* the amplifier must have sufficient current handling ability in the output transistors and power supply * the amplifier must have sufficient heatsinks as they will run hotter driving 2 ohms * because of the output filter considerations, the amp should be self-oscillating. In this way it is possible to run enough feedback to allow it to correct for phase shift otherwise imposed by the filter.
What's wrong with Behringer? I use a pair of their 12Ks and a pair of 2496 active XOs and they WILL drive ANY load. I use them for 40-400hz . I've never listen to them other than bass duty.. Flawless.. I've used them for sub duty also 40-60 or less.. They can move a lot of air... a whole lot...Very Very low distortion.... No noise, I love um.. Their not a Nord, but sure work... I'm gonna add a fan switch, off / on for low low listening, other than fan noise...The 12ks are great..27 lbs...
Like I said so many times now, a "stable" amp into 2ohm load means it
won’t oscillate blow up and take out speaker drivers, but it does not
mean it can drive the loads we are talking about here.
Yes.
'Stability' only refers to oscillation or the lack thereof. It says nothing about low impedances, unless the amp oscillates when presented with a low impedance.
Tell you what, you suggest an amp at 1000.00 USD New. It has to have just half the specs of the hypex or ice modules. 1000.00 USD New? Class A, AB, anything that sound as good, stays cool, low cost to run, quiet, and 1/2 the wpc, heck a 1/3, a 1/4. Now let's add, able to change the sonic signature, in 15 min, all over the map.. Now lets add can carry 2000 watts under each arm..
Everything I read, where you point to someone's quote, the article are single quotes, from a single source, and a single opinion, or 1989 speaker adds about how they still make it.. SO!!!
So they still make a poorly designed XO, heck I can do that.. Really I can screw up, make a mess, and say it's still a great product. Even if it's NOT...
Is there a reason? I think you got a house FULL of class Ds, are you a class D junkie on the down low.. Joined the A/AB club and it's blood in and blood out? 1% amp gang or something..
Class A-Z amps are the bomb What happened to Ds I like double Ds, a pair. WHY AREN'T Class D amps the bomb?
Like I said so many times now, a "stable" amp into 2ohm load means it won’t oscillate blow up and take out speaker drivers, but it does not mean it can drive the loads we are talking about here.
Ok 550 watts not oscillating, won't drive a speaker correctly? Wow, never heard of such a thing. 550 watts at 2 ohms is 550 watts at 2 ohms. It gives a time it will hold that 550 watts too. Mac says STABLE, it mean stable and ABLE.. Not just able for a second or two. You keep saying what you mean, NOT what the manufacture mean. Stable is stable.. I'm sure some of the claims of amp manufactures is bogus, but the class D Hypex and ICE amp specs have withstood the test of time for many many years now. not a lot of problems.
Thiel
dontnwaste time w D
get class A/AB for best sound
w D 40?
I can figure it out, proof your stuff mate.
Thiel is not a problem, they will sound wonderful, NC400, 500, or 1200 all will drive them..The two latter have buffer board options..
Class Ds with Sparkos or SI are class a opamps, LEARN, before you speak..That type of stuff just isn't talked about. CLASS A. That is the reason the upgraded buffer boards make such a difference in Class Ds, Upgraded voltage regulators and class a opamps, night and day.
All the class Ds I use will drive the loads correctly..Simple. They all require GREAT VAC to get there. Hypex an ICE both require a good source of VAC, via the spec sheet. They both give specs at 100, 110 120 volt. As I said. The supply is the key to any heavy load. VERY tight connection and 120 VDC, class Ds will hold their own with any of the big names, at many times the cost. I own Pass, ML, and Krell currently. For SS I'll take the Nords, Pass is as good if not better, but they cost.... 3 times and will never run as COOL...Sure like the sound, though, in the winter, krells will heat the whole house, and very expensive to work on.
I thought it was clear that I am a manufacturer. My apology to the OP if that was not clear. I am not sure why I am not listed as a manufacturer as Audiogon knows that I am a manufacturer as I have registered as a manufacturer.
I personally own the Apogee 1 Ohm Scintillas and class D does wonder on these speakers. Hope that helps
🤦♂️
I have witnessed class D driving Thiel CS5
And It has no problem of driving the Thiel at all and sounds fantastic.
My friend own Krell FPB600.
🤦♂️
36 posts nearly every one on Class-D amplification🤷♂️
You have been asked before by other members.
h2oaudio, welcome. A friendly note: the expected courtesy here is for those that are in the "business" regardless of how small an enterprise it may be, proclaim that each time they post. This is especially true if they're listed as a "private user".
I have witnessed class D driving Thiel SC5 which belongs to a dear friend. And It has no problem of driving the Thiel at all and sounds fantastic. My friend own Krell FPB600. I also know a customer who has the Kappa 9 and he likes his class D more than his McCormack DNA amp. I personally own the Apogee 1 Ohm Scintillas and class D does wonder on these speakers. Hope that helps
Too many manufacturers here bend the truth and "con the readers" in their advertising into believing, that if they say their amps are "stable" into 2ohms, they can drive 2ohms loads easily, this is a "con" and needs to stop.
Like I said so many times now, a "stable" amp into 2ohm load means it won’t oscillate blow up and take out speaker drivers, but it does not mean it can drive the loads we are talking about here. If it did, then as I say once again, a Nad 3020 could drive the Sony SS AR1 talked about in another thread, or Wilson Alexia’s because "it’s also stable into 2ohms", which it has no chance of doing, and there are vary degrees of this, right up to big expensive amps
Look at unbiased tests and see if an amp can do it by looking at it’s wattage doubling performance into 8ohm, 4ohm then 2ohm and remain stable doing it, then you’ll know if it’s comfortable and able to drive 2ohms and "yawning while doing it". Many can double from 8 to 4ohms, but fall off a cliff when presented with 2ohms, these manufacturers usually only give 8 and 4ohm wattages hoping you’ll think it can do it into 2ohm as well, almost another con.
The term 'stability' refers to the ability of a circuit to not oscillate. In the context as seen in this thread where it refers to doubling power as the load impedance is halved, it is being misused. IOW a circuit that is unstable is prone to oscillation; one that is stable won't oscillate.
So is a Nad 3020 integrated 2ohm stable, just means it won’t oscillate. Doesn’t mean it can drive that load to it’s fullest without breaking a sweat, same goes for the Mac.
As I said before a $100 30w 1980's Nad 3020 integrated is also "2ohm stable" but sound like s**t into a 2ohm load, but hey! "it's 2ohm stable!!!"
Cheers George
MC275 is a valve amp, no doubling..., most valve amps don't double, why? VTL, Mac, Cary Audio, Carver? why? I don't know why.
The wattage is the same at 8,4,2 ser or par. It didn't sound like like shi? same non ser or par. 16,8,4 either 75 wpc or 150 (186 act) ser or par. There is no doubling. It sounds good at 2 4 6 8 10 12 16, NO DOUBLING..Run warmer, yes, run hot yes, sound bad NO...Same with the class D, they may not double at 2 ohms but they sound, SOUND better than anything close in price. It was mentioned the THD was and is higher the tougher the load, BASS is not a problem. At 20% THD in the bass most people can't tell the difference..Even good ears, 3 out of a 100, might be able to hear 20 plus %. maybe..I'm at less than 5% using phase plugs, and basket termination. and class Ds.
I use to swear I'd never use a class D. Then I listened, with my ears, not my mouth, it's stereo then, not mono. I just shut up and learned, like a good mechanic, I learned.. Their, quieter, less expensive, 15 watt idle, lighter, cooler, VERY easy to work on, opAmp swaps a breeze, black background, ZERO floor noise. 1 ohm able 2 ohm stable, and no HYPER bright, blistering sonics like some amps. I don't care what's being used for speakers, if a class d Nord One up can't make it sound GREAT, move on. I bought Wyred 4 Sound and Nord, ICE, and Hypex.. Both have some neat features..Expansion wise
Mac says 2 ohm stable, it means STABLE, nothing more nothing less. It works there, not badly, not anything, but stable.. Nad is not 2 ohm stable it is 2 ohm ABLE, can hit a 2 ohm load, not trip a breaker, not sustained, just able to hit 2 and not blow up, blow fuses, the normal stuff from tough loads. Car audio .5 ohm stable loads. The size of the supply conductor, as I stated before, the key to low ohm loads. TIGHT connection, Very tight, required, not hand tight, wrench tight.. Increase the ability to deliver the AMPS, to the AMPS. Stable AC supply = stable amp...
Mcintosh MC275s in par or ser mode were "2 ohm stable"
I've said it before, there is a massive difference in sound driving a speaker that's <2ohms correctly, and saying an amp is just "2ohm stable" and another that can drive down to 2ohms by almost doubling it's wattage down to it, and "remain stable doing it".
As I said before a $100 30w 1980's Nad 3020 integrated is also "2ohm stable" but sound like s**t into a 2ohm load, but hey! "it's 2ohm stable!!!"
One other thing, even VTLs that were sent back to the factory for the drop from 5.2 to 3.6 ohm, still didn't run the strathearns right. No valve amp at the time except Mcintosh MC275s in par or ser mode were 2 ohm stable, Mcintosh was! Crazy ay, old Mac, 2 ohm stable..I think even GG were too.
I've owned Kappa 9. X before and after mods to the XO. 10 plus years ago. I sold those speakers and the guy LOVES them. I did too, to tell the truth.
Ampzilla 2000 were the only amp that I owned at the time that would drive ANYTHING, including those.
They were touched by Mr B himself. I got them to actually drive .5-2.0 ohm strathearns ribbons. True amp killers at the time worse than Kappa 9. They were flawless, got hot but NEVER shut down. THE KEY was supply voltage for me. 20 amp circuit per amp.
The same when I sold them and went to class Ds. It was a supply and demand issue for me.
A single 15 or 20 for two monoblocks just couldn't provide the UMPH!! (mechanics term) without loosing the dynamics that Strathearns can provide. It took two dedicated circuits and voltage maint. of 120. The class Ds sounded stunning, even more so after a break in. How did I find out? The guy that bought the Kappa 9 went to class Ds at least a year before me. He almost got rid of them and he installed 2 dedicated 15 amp circuits from a single 15. He was amazed the difference in BASS response. From Krells to class D and once the electrical issue was ironed out, it sounded better than the Krells. ZERO floor noise, zip, nada, nothing... Goes to show that the amps PS is a big factor in how it performs. Krells, Big Macs, Pass, serious power supplies.
The class D sounded BETTER, than ANY amp I've used to drive True ribbons, or planars. As a matter of fact, the only place I run a different typology is in the mids and highs, that only with a GREAT valve amp (over 22K spec), and normally in the winter..700hz down nothing but class D. Just the best.. I use Nords One Up rev B,C,D NC500s x 7 and never a problem. Sparko and SI OpAmps.
I still have a shop full of great amps, and use them, sound great, but these class Ds are SO COOL....
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