High end Class D amps?
Look at the specs of the PuriFi modules, which can put out 500 watts into 2 ohms with 0.0003% THD.Look at what independent tested current it can do. Compare the "2ohm wattage" to the "4ohm wattage", and see if the 2ohm can come "close" to doubling the 4ohm, if so there’s no current limiting. If it’s similar or lower, then there is severe current limiting/sagging. Cheers George |
@milpai - You’re welcome. The "cubed" Brystons run cool, and the Apollons run very cool. I haven’t noticed a huge difference, though the Apollons probably generate less waste heat. My speakers are a pair of Janszen Valentina P8. Janszen rates them at 6 ohms nominal, 4 ohms minimum. I would imagine that, like other electrostats, they offer a highly capacitive load. I think the comment that Class D can’t handle low impedance speakers is audiophile truthiness -- it doesn’t reflect today’s technology. Look at the specs of the PuriFi modules, which can put out 500 watts into 2 ohms with 0.0003% THD. |
@mike_in_nc ,Thank You for the prompt response. Based on what you mentioned, I think you are listening "louder" to the Apollons, (maybe) because they are so clean?! I think that is indeed good.Are the Apollons warm/cool compared to the Bryston? One point I read with great interest was the "electrostatic main speakers". What speakers are those? Class D in general are accused of not being able to handle 2 ohm loads. Does your speaker dip to that level? If it was me, I do not care for numbers. If the amp is able to drive the speakers my speakers to level I like, I am happy.BTW your feedback is VERY helpful. |
@milpai - The Apollons haven't replaced my other amp yet; I'm still deciding. They and the Bryston 4B3 are really nice amps, so it's not simple. Their gains are different, and since I have subs in the system, it's not trivial to swap one in and the other out while keeping levels constant. Indeed, it's proven to be more fiddling and fussing than I'm up for. The experience gives me appreciation of what audio reviewers deal with. That said, things I notice about the Apollon amps are
|
tweak1, I think your right that Class D amps are not evolving as fast as computers, but they are evolving (for the better?) that is why I emphasized maybe as a matter of opinion. Your EVS 1200 is a good example of good sound doesn't become antiquated. I remember the first Class D amp that was successfully marketed and sold to the public, the PS Audio HCA-2 . Stereophile placed it in their Class A category and a reviewer stated that there would be many more designs to come but he doubted that any of them would sound as good as the HCA-2. Was he right? |
snarfie. You may have a point as far as availability of parts for an aging Class D amp but honestly like everything else you won't keep it that long. Class D amps may be like computers, always evolving which could render them obsolete in ten years (maybe)) compared to the latest offerings. For laughs I picked up the new Edge A2-300 (Swedish Made) Class D amp, I'm not laughing now. Retails for $500.00 plus shipping and kicks butt at 150 watts per channel with a refined, clear sound coupled with solid dynamics. Excellent performer! |
I was looking to change mine NAD C370 (For a class D amp) who had a faulty protection circuit which is fixed and some other nearby strategic capacitors where also changed for around 50,- Euro on cost an materials. Than it occurred to me that a total revision on my NAD was only 350,- Euro to make him even sound better (probable) an will last another 25 years or so. Another thing is i run 2 sets of speakers close monitoring an far-field the integrated preamp gives me all possibilities to use one of the 2 sets with one click of a button. If i buy a class D amp i have to consider too look for a new separate preamp involving cost. Another thing to think about if something go’s wrong (as with my NAD) spare parts are cheap an are there for the foreseeable future if a high switching class D amp containing probably also specific programed firmware (wich is not free availeble for upload) stops working it is likely you can dump it with in 10 years time. So i think we don’t have enough reliability data regarding class D amp’s but for sure regarding technolgy, low energie use an sound quality Class D amp’s are the way forward imo |
bluorion: You wondered about Mola Mola. Of this I can speak from experience. A pair came up locally for sale and I went to audition them. I was blown away by the dynamics at the seller's home, but unsure since the system and setting were very different. So the gentleman was kind enough to travel with me to audition the Kalugas in my system. Again, I was blown away. They made my Revel Salon 2's sing and explode like nothing I had heard prior. They easily bested my current Classe Audio CA-2300, as well as the former PS Audio Stellar 300's. I put them in and out of my system comparing the Classe. I heard much more dynamic bass...tight and controlled..but also heard sparkle and sounds I had previously not heard. Used, for under 7k. I now have added the Makua Preamp with internal Tambaqui. I believe it is the implementation of the the Class D technology, just as with any component, that makes it excellent or not. One should not evaluate all class D amplifiers as equal. I have my heavy amps downstairs...Audionet..and they are better. But the size, ease, appearance and sound of these Mola Mola components are winners! |
Your source better have low output impedance as well. The NC500 modules are fairly low impedance on the input.Any one don’t be scared off doing this if your source is up to the task, 2k input impedance for the NC500 is not so bad, many retail class-D amps are that anyway. Even a 50ohm source impedance is fine into that, most high gain good dacs are contenders for this hook up. And the best buffer is no buffer. My dac is 1ohm output with 200mA short circuit current, nowhere near full volume, absolutely no problem . |
Your source better have low output impedance as well. The NC500 modules are fairly low impedance on the input. georgehifi8,196 posts01-03-2021 9:17pmOr even better if your source has balanced output and enough gain, feed it direct into the NC500 amp modules with no buffers at all, like I did, with my NC500 monoblocks. This is the least distortion and most transparent/dynamic you’ll get |
Ok so A) Sphynx is the regular tube buffered input upstream of the D module implementation and the Dragon is the TubeD, just to be clear. B) if by looking at a picture one can determine that bypassing select functions within the D module is not happening, then maybe so. If not, then having those differences is indeed a novel approach. And "We use only the modulator and mosfet output stage, and bypass all of the other circuitry on the amplifier modules" would seem to merit a listen or curiosity. After all, isnt it desirable distortions that make pure tube amps what they are anyway? |
It looks like in the Dragon they use the NC500. I assume they’re doing what every other manufacturer that uses this module they’re adding their sound with theirs or a third party external buffer.Or even better if your source has balanced output and enough gain, feed it direct into the NC500 amp modules with no buffers at all, like I did, with my NC500 monoblocks. This is the least distortion and most transparent/dynamic you’ll get Cheers George |
It looks like in the Dragon they use the NC500. I assume they’re doing what every other manufacturer that uses this module they’re adding their sound with theirs or a third party external buffer. IMO it’s preferable to leave the signal as transparent as possible and not muck it up with distortion but to each his own. |
I don't have access to the documentation for the Hypex modules used on these amps, but the connector is the same (except for one status line) as the Purifi module. There is no provision on the Purifi connector to bypass the driver circuitry. I suppose it could be possible to have jumpers on the card which would do this, but it seems unlikely since this circuitry (on the Hypex board) is an integral part of the feedback design that makes the Hypex module function. The Hypex and Purifi modules do expose the outer-most feedback loop, which is designed to provide a feedback connection from the speaker connections (or as close to the speaker connections as is practical). This is generally connected to the speaker output connections on the buffer board. It could be possible that Rogue is adding circuitry to this path to alter the Hypex module's transfer function, or someone integrating their front end buffer inside this feedback loop. |
djones51: I don't think that "insert" has to be literal! There is a myriad of pins on those modules that likely allow for other configs. Did you read any of the interviews provided or any others out there? I don't have a dog in this hunt, I'm just asking if anyone has any experience in comparing Rogue's basic tube buffered input style to their TubeD designs. As I've said, I live in an audio desert and shipping amps around gets kind of expensive quickly. From Dagogo - MO: What is really exciting to me is that these amplifiers are much more than just a tube circuit in front of a class D circuit. We use only the modulator and mosfet output stage, and bypass all of the other circuitry on the amplifier modules we are using. We actually combine the tube and buffer stages with the output section, using proprietary circuitry that makes the output section perform like a tube stage rather than solid state. What is quite gratifying is that we have had numerous class D naysayers wind up purchasing them. From Positive Feedback - So I built what is a basic Hypex-type amplifier, as that was the baseline on one side; and then I guess our top-of-the-line Apollo mono-blocks were the design goal on the other side. I never started off to make a pure digital circuit; I just built one without the tubes in it—though I knew that wasn't what I ultimately wanted. But I wanted that as base line: like, okay, here's what the Hypex Modules sound like used as they were designed to be used, to build the same kind of digital amps that a half dozen other companies out there are building with the Hypex Modules, the big difference being that we only deploy the switching MOS-FETs on the output section of the modules and otherwise we bypass everything on the modules that Hypex supply that everyone else uses—we are not using the Hypex Modules' driver stages or their input stages. Seems pretty evident to me that unless a respected and accomplished guy like M O'Brien is really being evasive, exaggerating or such, there is a decidedly different implementation of the tube portion and use of the Hypex modules, in those amps. Lastly, I really don't care about the details and as it's been stated, likely correctly numerous times in this thread, it's all about the implementation details. This would seem to be a different implementation. Just asking about experiences of any audible differences within the lineup, due to this implementation. |
I'm no EE but the board's "wiring" or circuit path into the Sphynx's modules seems infinitely less complex than what's going on in the Dragon board's circuits going into the Dragon's modules.If you look at the photos of the Dragon the hypex module plugs into the board the same as any other input buffer board. The tubes are not inserted into the hypex board and the input buffer board doesn't look anymore complex, that's not to say something in the buffer board could be different but the tubes in no way are inserted into the hypex, it's marketing speak for look we added distortion to a perfectly good amp. |
tweak1: " I have owned many different class D amps for over a decade. A few I would say would have benefited from a romantic tube somewhere in the system, BUT, D has gotten much better, especially in the high freqs, to where, IMHO, changing cables would be the better option. The Cable Company would be a good source to try a variety of cables I have a Tweakaudio EVS 1200, which uses the same IcePower AS1200 modules as PS Audio M1200, but are highly tweaked by Tweakaudio. No tubes anywhere in my system, and it's very detailed without being edgy" Hello tweak1, You made a couple of excellent points I can tell came from personal experience: 1. Class D, in my experience, is so accurate and neutral that it facilitates the perceptions of how changes upstream in the system effects the overall system sound quality. This applies not only to more significant system changes, like the source components and the quality of the recordings themselves, but also down to smaller changes like in the ics and power cords utilized. In my opinion, this qualifies as very high quality transparency. 2. I've come full circle about my thoughts and perceptions of combining tubes with class D amps. I began by using a VTL 2.5L preamp with an expensive set of 4 NOS Mullard tubes swapped in for the standard Russian or Chinese ones. I used this for several years with my class D amps and liked it so much I thought I'd never take it out of my system. But I happened to hear a Mark Levinson 326S ss preamp at a local hi-end shop. I was so impressed with its performance, especially the amazingly real stereo sound stage image it presented, that I bought a used one and tried it out in my system. Well, the midrange and treble sounds just as sweet and euphonic as the VTL with NOS tubes and the palpably realistic stereo sound stage illusion the ML presents was just too good to resist. So, I sold the VTL to a friend and I haven't regretted it since. So I've come full circle from thinking I had to have tubes somewhere in my system to discovering that my system without tubes can sound even better. The only qualifier is that it took a very good and expensive preamp to top the tubed VTL. My current opinion is that tubes combined with a class D amp usually results in very good overall sound quality. But I also agree that the quality of the midrange and treble performance, on good quality class D amps, has generally improved to such a degree that tubes may no longer be needed. As usual, it'll probably come down to the specific and unique amp/preamp combination utilized. Thanks, Tim |
As I've said, I'm no EE but the board's "wiring" or circuit path into the Sphynx's modules seems infinitely less complex than what's going on in the Dragon board's circuits going into the Dragon's modules. Rogue clearly describes inserting the tubes somewhere within the module path, both in their product descriptions online and in several interviews and reviews online with designer Mark Obrien (one is at Dagogo site, another is at Positive Feedback issue 60). Just sayin. |
Rogue isn’t putting tubes in the Hypex module. Go to their site and look at the inside of the Sphinx, those 2 small boards on the top are the hypex amps the huge board at the bottom with the tubes is theirs. Compare the hypex photos of the inside of the Sphinx to the stock photo at hypex they’re the same ucd 180’s http://www.rogueaudio.com/Images/Sphinx3insidemed.jpg https://www.hypex.nl/product/ucd180-oem/53 Here's the stock hypex module they use in the TubeD thing on a Dragon. http://www.rogueaudio.com/Images/Draginsidemed.jpg https://www.hypex.nl/product/nc500-oem/50 |
Thanks for adding your experiences with D amps, specifically hybrids which hold my interest. I have a Sphinx integrated now and have 2 sets of tubes on the way to roll (including the Mazdas...). One thing I failed to mention, concerning auditions, is that I live in Anchorage AK. There is ONE store in town that has ONE Primaluna amp on the floor. Seattle is over 2000 mi away. Unless Best Buy counts! Sure, some shipping back and forth possible but likely a few hundred $ per pop in the returned case as many vendors treat us as NOT continental USA. Trying real hard to wittle down to a few lines/implementations. So far as I can tell, every line mentioned using tubes is using them as input buffers. Only Rogue is doing (apparently) it different in their TubeD models by putting them "within" the Hypex module. No EE here, but was wondering if thats potentially a sonic step change from their previous buffer input style models like the Sphynx/Paroah. OK, back to the thread. |
I THINK the tubes in PSA M1200s are specific. Not sure what the availability of other brands would be for rolling. I have owned many different class D amps for over a decade. A few I would say would have benefited from a romantic tube somewhere in the system, BUT, D has gotten much better, especially in the high freqs, to where, IMHO, changing cables would be the better option. The Cable Company would be a good source to try a variety of cables I have a Tweakaudio EVS 1200, which uses the same IcePower AS1200 modules as PS Audio M1200, but are highly tweaked by Tweakaudio. No tubes anywhere in my system, and it's very detailed without being edgy hth |
Hello akgwhiz and klh007, In looking back on my audio/video systems over the past almost 50 years and participating on this forum for the past 8 years, I realize I've learned a lot from reading but I believe I've learned just as much, if not more, from just being a bit adventurous and gaining more useful and relevant knowledge by seeking out audio and video experiences as much as I could. As the hip and woke kids say today according to my addled, old man imagination: "Get yer caboose off dat cushion and go for a good audition." What does all this hipness have to do with the topic of tubes and class D amps on the previous 2 posts? Well, if you're curious, the best way to learn and experience the overall sound quality combination is to go for an audition, or take advantage of a free in-home trial period in your own system and room. You be the sonic adventurer, learner and discoverer. There will be no need for verbal descriptions or using our less than accurate imaginations. You'll be able to very thoroughly know the actual sound quality results and make a very informed decision about whether or not you prefer a touch of coloration with your main dish character of very neutral typically delivered from a class D amp. Best wishes, Tim |
Following this thread and it's very enlightening. Too many good, thought -provoking entries to comment on. Curious if anyone has heard or compared a new gen Rogue Audio amp using their unique topology that deploys a tube "within" the Hypex module circuit (TubeD, tm)? Only the Dragon and Hydra amp have this. As D is quickly evolving, does this have merit, is it audible? |
@phillyb @noble100 Such interesting dialogue. I admit I don't quite understand a lot of the specific acoustic specs, etc....but I enjoy reading others' opinions about them. It makes me wonder about brands such as Mola Mola, Merrill and JR that always get such rave reviews about their sonic qualities. Do they meet or succeed these sonic measurements that you mentioned---and do more reasonable class D brands (D-Sonic, W4S...) not meet these measurements? |
Hello phillyb, I've shared, and continue to share, your enthusiasm for high end class D amplification for over 6 years now. Class D, in my experience, not only has the clear advantage over more traditional amp types in size, weight, operating temperature, relative cost and electrical efficiency, it also provides excellent overall sound quality results that are already very competitive with the other amps regardless of type or price. I also agree with you that this amp technology is still in its ascendancy. My only hesitation in universally and fully recommending class D amplification to everyone, is the concern that not everyone seems to share our enthusiasm in its sound quality performance. Many individuals have claimed for years that they perceive deficiencies in the sound quality performance of class D amps and some have even developed and promoted their own theories as to why, such as georgehifi's consistent proclamations that the class D carrier signal switching frequency is too low and needs to be north of 1 MHz to avoid sonic artifacts in the audible range. The main issue has been the reality that I, and apparently many other class D amp lovers/users, have completely failed to notice any of these supposed sq deficiencies in their own varied and preferred class D amps. This has naturally resulted in users doubting the sincerity of the class D amp naysayers' claims of sq deficiencies. Yes, virtually all agree that there were sq deficiencies in much earlier examples of class D amps but not on the numerous better examples produced within the last decade or so. The truth is that if class D amp users perceive none of these claimed sq deficiencies in their own amp's performance then, by definition, none exist since our perceptions literally are each of our realities. I still believe it's important to keep an open mind, however, especially in this hobby. So, even though there remains a complete lack of legitimate scientific evidence supporting these supposed claims of deficiencies in the sq performance of class D amps, I still don't think it's wise to dismiss the remote possibility that these sq deficiencies actually do exist and that some individuals may be sincerely perceiving them. After all, it's well known that there are gaps in scientific knowledge and that there's a high probability that important future discoveries will be made about the dynamic and technical forces involved in class D audio reproduction and perception. Perhaps, it will be discovered that some individuals are just more sensitive to certain yet to be identified and measured characteristic(s) of class D amplification. Because of the above, I strongly suggest that anyone interested in the high quality sq performance and other benefits provided by a high end class D amp, should audition one prior to purchase to guarantee complete satisfaction. Enjoy, Tim |
Class D is the future. Boomers stop bashing it, its a maturing product now. PS Stellar 1200 is sweet, Red Cherry, Merrill at a lot more money would give any amp made today regardless of cost a run. Now a pure tube system and I mean pure tube, with tube rectifiers will have its own unique sound, and many enjoy that. But solid state vs. Class D well it’s a toss up when you here a well made class D. As I age class D will be for me, no more trying to lift 100 lb. plus amps, in fact if buying today I look more at class D amps then the big solid state Amps or tube amps in the 30-60 lb. range tops. |
I purchased a Rotel class D five channel amp (RMB-1575) just for curiosity. It’s a very honest 250 wpc @ eight ohm and 500 wpc @ four ohm. I have it connected to my RBH Reference system, a pair of SV-T2, a SV-6200c and two 770 mounted rear wall. Their all four ohm. It sounds incredible and can it ever shake the house. It’s a beautiful sounding amp and I’ve enjoyed it also in two channel mode. .........however, I replaced it with a Crestron CNAMPX-7x200.....a 100lb block of AB power. This amp is incredible sounding at 350 wpc x seven channels. It’s suprised me that the Rotel was not totally spanked. It’s just so light and cool to touch it seems wrong. |
bluorion: "So having a 30-day trial period is nice. W4S offers a 45 day trial---that was another one on my list. The ICs I'll be using with the amp will be Audioquest Big Surs. Do you recommend any particular brand with he D-Sonics? Again, thanks for the thoughtful posts." Hello bluorion, I've read good reviews on the W4S class D amps but have never personally listened to them. I'm much more comfortable recommending the D-Sonic M3 monos mainly because I've been using them for over 6 years now with 2 different pairs of main speakers, originally with Magnepan 2.7QRs and currently 3.7is, and they've performed exceptionally well on both. As far as I know, a comparable pair of W4S monoblock amps could perform just as well or even better than the D-Sonics. You'd probably need to home audition both with your Luxman to find out for certain. If you'd like more than 30 days to audition the D-Sonic amps, I know if you call or email the owner, Dennis Deacon, and request a longer free in-home trial period, he typically extend the time period upon request. Your Audioquest Big Surs are high quality cables and should perform very well as ics. I use custom balanced xlr cables as ics but I believe you'll need to use unbalanced rca cables due to the pre-out connections utilized on your Luxman. The D-Sonic amps offer a choice of inputs, balanced or unbalanced. with a switch also required to be set appropriately on the back of each amp. Later, Tim |
I didn't feel like listeningI think you hit the nail on the head. Some 35 years ago I purchased from a gentleman who after our 1st 2 transactions became a friend who shared what was valuable and I've found to be true, that any gear we have should make us *want* play music more. Everything else (soundstaging, detail, bass, etc etc) is just icing. We freely lent each other gear to try out for a while to see longer term what gave us the *feeling* of "I almost can't wait" to turn on the gear. I've found that *sensing* so to speak, to be the "magic" and can get lost when swapping pieces in search of improvements in resolution, soundstage, bass, etc. After all these years, I still miss the higher noise/hiss Infinity FET preamp I bought from him and traded to someone else that brought a Bedini over. FWIW, They had a well used grand piano that his wife played and how I discovered Maggie Tympanis and ARC gear, I carried in amps too heavy for him lol. |
Hello madavid0, I have the D-Sonic M3-600-M monoblocks, their previous model that I bought about 6 years ago and that utilizes Anaview/Abletec class D power modules. D-Sonic's current model are the M3A-600-M monoblocks, that utilizes Pascal Pro2 power modules. These are the same modules that Jeff Rowland chose for his very expensive, but also very positively reviewed, Rowland Continuum 2 integrated amp. The owner of D-Sonic, Dennis Deacon, told me years ago that he determined that neither of these modules requires an input buffer and that performance and sound quality didn't improve when he used one, so neither of these models use an input buffer. He also stated he was forced to source newer class D power modules in the M3 monos model because the prior Anaview/Abletec modules were discontinued. He said he chose to utilize the newer Pascal Pro2 modules because he thought they offered slightly better sq performance but, overall, they sounded very similar to the older Anaview/Abletec modules. I'd suggest you consider either a used pair of M3 monos, if you can find a pair for sale, or a new pair of theM3A monos. I can state with certainty that neither of these amps have any of the deficiencies you described. In fact, I consider their exceptionally smooth and detailed midrange and treble performance, along with presenting a 3-D stereo sound stage illusion with very solid, stable and palpable images, as two of their main attributes. While it's true that these are only two of the numerous positive attributes these amps possess, they're also two of my favorite and must have attributes in both a peamp and an amp. I definitely enjoy these qualities far too much in a home audio system to even consider buying any preamp or amp that lacked them. Hopefully, your used Odyssey Kismet amp will also possess these qualities in spades. Merry Xmas, Tim |
