Just an observation and a question. Are there 'high end' Class D amps out there that are just as good as Class A, A/B amps? I realize that's a sensitive question to some and I mean no disrespect---but whenever I see others' hifi systems on social media, all of the amps are A or A/B. There's always Pass, McIntosh, Moon, Luxman, Accuphase, etc. Where are the Class Ds? For folks out there that want more power for less efficient speakers and can't afford the uber expensive Class As, A/Bs, what is there to choose from that's close to those brands? Thanks
The more I thought about your system needs and the more I thought about how much multiple subs improved my system's bass realism and bass dynamic punch, the more I think it's likely to be a very good solution/upgrade for your system. The Swarm 4-sub system would provide near state of the art bass performance throughout your entire room and integrate seamlessly with virtually any type or model of main speakers that you use now or in the future. You'd just need to optimally adjust the level and crossover frequency controls on the supplied 1,000 watt class AB sub amp/control unit when you switch speakers. A pair of REL or SVS SB-1000 subs would also provide very good bass performance at your designated listening seat. This option would be about $1,000 less expensive but you'd need to optimally position each sub in your room, and in relation to your designated listening seat, using the 'sub crawl method' (you can google it or I could explain it to you) and optimally set the volume level and crossover frequency controls on each sub, rather than once for all 4 subs on the Swarm's amp/control unit. I think you'd probably like one of these bass sub solutions best because: 1. It would provide significantly improve your overall system bass power, extension, dynamics and impact. 2.
The bass will also sound faster, smoother, more detailed and well blended with your main speakers 3. You'll perceive the stereo sound stage image as being larger, more detailed and clearly defined as well as more 3 dimensional and real.
It's my opinion that one of these sub options will provide more overall dynamic punch to your system than the addition of a high powered class D amp. But, of course, it's your system and your choice.
audio2design Why would a Class-D amp care about phase angle?
Any amps do, but react differently to it, - phase angle when combined with the speakers impedance is called EPDR (equivalent peak dissipation resistance) and is what the amp really sees.
And it’s that combination that’s presented to amps, by many speakers, that can freak them out. Dismiss amp builder that says it a furphy,https://www.dictionary.com/browse/furphy
Here is just the Wilson Alexia, it rated as a 4ohm speaker, but!! combine that with the -phase angle it’s got and the amp sees 0.9ohm in the low bass!!!!
I will repeat my question, why would a class-D amplifier care about phase angle. The data you have presented only applies to thermal loading (hence dissipation resistance) in the linear region of semiconductor devices (It would apply to tubes as well, but don't think it would be much of an issue). Class-D semiconductor devices operate in saturation and would not be impacted by this.
I will repeat my question, why would a class-D amplifier care about phase angle.
I’ll repeat my answer in another way, negative phase angle combined with low impedance can as in the Alexia, gives a EPDR of load as seen by the amp of 0.9ohm load!!!! Now you go find a Class-D that will keep pushing even more current into that kind of loading like a good bi-polar amp can.
If you can hear it at a shop with speakers like the Alexia you'll be stunned at what just a good 100w bi-polar amp like Gryphon v any Class-D of any wattage, the Gryphon will be superior at those EPDR frequencies in the bass.
That value that you quote, EPDR has absolutely nothing to do with max current requirement. It is a synthetic value to represent thermal loading in a linear amplifier. It has no application to Class D amplification.
I suggest going back and understanding this better as your understanding is flawed.
Of course it does show if it’s capable of driving it.
I suggest going back and understanding this better as your understanding is flawed.
No, I suggest you go and find out what happens to Class-D when it tries to drive low impedances that I’m talking about, see if it can do the wattage doubling act down to 1ohm or even 2ohms as the impedance halves They are lucky to even gain any wattage below 4ohm, they usually start to go backwards especially at 2ohms which is current starving or limiting.
And if you deny that, show some independent test figures of class-D wattage at 8ohm, 4ohm, 2ohm, and 1ohm
I will state again. You clearly do not understand what this term EPDR means. It had absolutely no meaning for a class D amplifier as it does not work in the linear range. The only figure that matters is lowest impedance which in most speakers occurs where Class D amplifiers have very low output resistance.
Your request for tests from 8 to 1 ohm is meaningless and again has no relation to EPDR and a Class D amplifier.
Whether they current limit or not is representative of maximum power and designed thermal limits. What matters is THD at those power levels.
Until you increase your knowledge of Class D amplifiers and this term EPDR as it applies to amplifiers I feel this conversation will go no where. Unfortunately your knowledge in this area is not sufficient for us to have a meaningful conversation.
I will state again. You clearly do not understand what this term EPDR means.
You have no idea, https://imgbb.com/Zzsqsr0 If you have, stick one on your test bench and watch what happens with the same input to the wattage figures under 8ohm 4ohm 2ohm and 1ohm loading. Until then please take a pill, and push your Class-D out there beliefs to ones that will believe it.
This argument seems kind of silly. As with class A and class A/B, a class D amp's output power at any given load impedance is limited by its voltage and current capabilities.
In class A and class A/B amps, the output transistors are dissipating power proportional to the bias current and voltage across them. Most class A amps (although not all) are set up with enough bias to operate in class A only into 8 ohms, switching to class A/B into lower impedance loads. With adequate heat sinking (and a big enough power supply), their thermal capabilities can generally support enough current to double power into 4 ohms and again into 2 ohms (and some even again into 1 ohm), since the voltage across the output transistors carrying the current is lower when they are delivering the maximum current.
This is where EPDR comes into play, because if the phase angle requires high current while the output voltage is still low, the thermal limits of the amp can be quickly exceeded.
Class D amps operate differently, since the transistors are almost always either in saturation (where maximum current is flowing, but with very little voltage across them) or turned off (where no current is flowing). The only time they are dissipating significant power is when they are switching from on to off or back (this is obviously a simplification). but this is a small percentage of the time. This is how class D amps can be so efficient.
But there is nothing about class D amps that would prevent you from building an amp that doubled power as you halved impedance. It's just that there is not the same benefits to do this as their might be in a class A or A/B amp. The amp is not going to run much more efficiently at half the rail voltage like a linear amplifier will.
Since most speakers are nominally 8 ohms (or slightly less), most class D amplifier designs are optimized for this load. But that doesn't mean you couldn't build amp to do what you're describing. The Hypex and Purifi modules, for example, can be operated at a lower voltage with the same high-current power supplies to create an amp that can easily achieve what you are talking about.
If you ran a Purifi module at around 35v, it would be limited to about 30w into 8 ohms, 60w into 4 ohms, 120w into 2 ohms, and could probably achieve 240w into 1 ohm. But why would you want to do this since you could achieve almost the same power into 1ohm and get over 200w into 8 ohms without generating much heat by using a higher voltage supply.
You see @georgehifi, @jaytor understands quite clearly how your term EPDR has no meaning effectively for Class D as well as how your metric of doubling in output power at half the output load impedance has little meaning for Class D. You do not. You don’t appear to possess adequate knowledge in this area. This is very basic stuff. Please research amplifier topologies more if you have the skill set and you will see how misguided you are
Which I sorry to say you don’t understand. If you knew the difference of current ability between complimentary Mosfets v complimentary Bi-Polars into low impedances like the Alexia’s etc etc we wouldn't be having this, and you will see how misguided YOU are.
As to OP's question, the answer is yes, as of December of 2020. I am using one that qualifies. How many are there, I do not know. This one is not "close", it's clearly superior to most class A and A/B I have used. Tonally superior to the tube amps I have used. Bonus is that price per Watt is low. Win, win, win...
I've been reading your professional published audio reviews and your occasional posts here for years. I've always respected your knowledge, experience and opinions as well as your abilities to articulate sound quality and performance characteristics and differences. So the above is all true and I respect your judgment. Now, would you please not keep us in suspense any longer and spill the beans on the identity of your newly discovered class D high quality performer?
Don’t let the sheep make a line you can’t help but follow. Happy hunting.
As with any audio component these days, it's possible to get pretty good quality for a modest sum (say, under $1K for most component types). Clear improvements beyond this quality require considerably higher investment.
Consider a simple component like a film cap. A cheap no-name 1uF cap will cost about $0.30 qty 1 at retail. Stepping up to a better quality WIMA will increase the price to $0.50. Moving up to a SoniCap will increase the price to close to $10. A Miflex KPCU copper foil cap will increase the price to close to $75.
Multiply this by the hundred+ components in a given product and you can see how the build cost for high end products can quickly escalate.
Whether these "upgrades" result in sound quality improvements that are worth the incremental cost is up to the customer, but since there is a fairly robust market in high-priced gear, many people believe it is.
But saying that you are just paying for name and aesthetics is just not true. Class D amplifiers can benefit from judicious use of higher quality components and more sophisticated design approaches as much as any other product.
And there it is, Ralph's new Class-D release must be soon as he's gone into full product protection mode.
How can anyone believe that "any" Class-D driving a pair of Wilson Alexia etc etc could possibly do anywhere near the sonic job that an amp like Gryphon Antllion or similar could do. Especially in the lower bass where the Alexia's are 0.9ohm loading presented to the amp.
Hey, maybe douglas_schroeder has found your first class D amp? If so, welcome to the club! But I think we're gonna need a bigger bandwagon. Love, Tim XOX
georgehifi, There’s no way to know how Ralph’s new class D amp will sound, or how it might compare to a Gryphon, or similar amp; but we do know that he has a pretty stellar reputation for the OTL amplifiers that he has produced to date, so I am going to bet that his class D amps will be something special. Customers will decide if that’s the case.
How can anyone believe that "any" Class-D driving a pair of Wilson
Alexia etc etc could possibly do anywhere near the sonic job that an amp
like Gryphon Antllion or similar could do. Especially in the lower bass where the Alexia's are 0.9ohm loading presented to the amp.
The answer is simple: Gain knowledge instead of made up stories.
I made a general statement, and I am not prepared to discuss at length. I have made a general observation, and that observation will be shown true or false over time as I build systems, but usually my first instincts have been correct.
Regarding comparison to the XA200.8, I have not done direct comparison yet, but I will. One of the XA200.8 has been back to Pass Labs for repair following my bone headed blowup wherein a metal plug of an IC was touching the output. Amazingly, the amp survived another four weeks before giving up the ghost. It's not back yet, so no chance to compare. I attest to the sensational service of Pass Labs; no arguing, no bickering, no guilt trips, no plea for me to cover return shipping, which would have been expected, given I hurt the amp; just, "We'll arrange pick up, get it done and back to you." That is a big part of why they are world class!
For any kind of meaningful conclusions, several systems have to be made. This amp is very different from the XA-200.8, but so far to my ears, as legitimate. I think this may settle out like the two motorcycles I own; Yamaha Stryker and Yamaha FJ-09; two very different rides, but I love them equally. I am not of the school where there is only one form of excellence in amps and systems. (If you are, great! So be it.) I have built too many rigs and used too many speakers, such that I do not wish to limit myself to one expression of fine audio. :) However, I do try to maintain a high standard for excellence across a variety of systems.
Especially since audiophiles love to jump to contusions, I usually withhold names of equipment before the time is right (publication). Sorry; sometimes you just have to wait.
I currently don’t make, sell, or market any amplifiers and have no skin in the game either way. I do understand quite well amplifier topology though.
georgehifi, given your obviously thin educational knowledge w.r.t. amplifier topologies and again obviously without the practical experience to compensate for that knowledge gap, perhaps you should be giving pause to the fact that people with far more knowledge of amplifiers theoretically and practically are all telling you you are wrong. Not just one, but everyone.
The answer is simple: Gain knowledge instead of made up stories.
These are words of someone either in denial or in product protection mode.
George, as a simple tip: the ability to admit that you were wrong is a strength, not a weakness.
In my quote above I was simply stating a fact. My advice is to study how class D amps work (the theory is simple) and keep in mind that with any current output device (MOSFET or GaNFET; the difference between them these days is slight) the output impedance is going to be lower than any traditional solid state amp, often by a couple of orders of magnitude. As I mentioned earlier, the PuriFi modules (not made by me, so clearly not in 'product protection mode') have output impedances that are tricky to measure as they are about the same as a few inches of 12Ga wire.
So this is not about denial, its physics. When you have an amplifier with an output impedance that low, it pretty well makes no difference what phase angles the speaker has nor its impedance, since both are several **hundred** times more than the output impedance of the amp. This simply means that the amp will be able to make constant voltage into that load.
True, I can take that one both ways. He does trash his reputation when he’s product protection mode, as there's not much new tube amp sales going on anymore.
@aolmrd1241, This is just speculation, but I looked at Doug's equipment list for a recent review and this was the last piece listed in amps,
Tri-Art Audio Series B 60W Class D with Tube Linear Power Supply, link; https://www.triartaudio.com/?page_id=3997 Single ended Class D, 60WPC, I can't find a price?
This goes beyond Dunning-Kruger it is just bizarre. We aren't arguing over something subjective or subject to opinion. This is clear cut, basic operational details. It is almost at conspiracy level. I don't understand it.
"True, I can take that one both ways. He does trash his reputation when he’s product protection mode, as there's not much new tube amp sales going on anymore."
I was actually speaking about you George. I think that you were being unreasonable, and in this case, made yourself look bad.
I don't know it seems to me that George is coming from a position of a lot of experience and the fact that he's holding his ground here suggests to me that he's on the right side while you guys are just compensating with confirmation bias and group-think. Many people don't care at all about what is true, only that they feel good about something, so when someone is willing to call out something as being garbage many people won't want to hear it.
another good discussion thread devolved and down the toilet
except for us bored souls who habitually hang out here, who in their right mind would come here for some real insight and good info -- and read this mean spirited crap???
especially people who are ’in the industry’ -- why would you pollute your own backyard?
leaving aside the obvious trolls who have nothing better to do than post 300+ posts in 45 days since joining, zero transactional feedback, no system disclosed, stirring the pot every post?
George is coming from a position of near 0 experience with actual class-D amplifiers and I expect almost 0 experience at the architectural / design side of amplifiers at all. He only knows what he reads, with limited direct listening experience. Because he does not have the right experience or knowledge, he misinterprets what he reads and draws erroneous conclusions. He is not "holding his ground", he is standing in one place stomping his feet up and down.
As others have pointed out, there are Class-D amplifiers that sound excellent, and not just the one that george is enamored with, and likely only from knowing 1 raw specification about that amplifier. George isn't calling anything out.
I am currently listening to a Cherry amplifier and I must say, I am rather impressed with it.
madavid0141 posts12-01-2020 11:20pmI
don't know it seems to me that George is coming from a position of a
lot of experience and the fact that he's holding his ground here
suggests to me that he's on the right side while you guys are just
compensating with confirmation bias and group-think. Many people don't
care at all about what is true, only that they feel good about
something, so when someone is willing to call out something as being
garbage many people won't want to hear it.
George is coming from a position of near 0 experience
Really??? so you think a Class-D with a tube rectified power supply and a chassis stuffed with pillow fill is the answer to the woes Class-D has?. Good luck with that sunshine.
I tried to tell you the answer, with higher switching frequency (3x the norm at 1.5mhz) using GaN output transistors as Technics did with the $$$$$ SE-R1 so that then switching frequency output filter can then be set also 3 x higher thus stopping any phase shift down to 1khz as it is now with all Class-D’s
As for driving low impedance combined EPDR even lower, not even the GaN can compete with bi-polar A/B amps there, they still rule the roost.
George is correct. Lack of switching bandwidth is the problem. I know Bruno Putzeys claimed differently in an old interview, but he's mostly a self-promotor so no one should take what he says as gospel truth.
I tried the low-end Technics integrated which only had around 800 or 900 kHz of bandwidth and was generally unimpressed even if it wasn't terrible. There is going to be a huge difference between that and the SE-R1 which I haven't listened to.
I also own a Cherry amp, the older lower end one with the external power brick. I was told Cherry was the revolution of class D, etc etc. It wasn't THAT bad, but it didn't hold a candle to my Odyssey Stratos. It's currently on PC speaker duty.
I don't think you guys really appreciate how deadly to euphonics that traditional class D output filter is. I didn't start out hating class D I developed that position after being burned many times being told this or that class D module was the revolutionary savior of the topology. I remain interested in GaNFET because it seems like that is what will finally be able to pull class D into the realm of quality audio.
You must have a verified phone number and physical address in order to post in the Audiogon Forums. Please return to Audiogon.com and complete this step. If you have any questions please contact Support.
