I have recently paired an Audio Research DS225 Class D amplifier with an Audio Research tube preamplifier (SP8 mkii). I cannot believe how wonderful and lifelike my music sounds. The DS225 replaced an Audio Research SD135 Class AB amplifier. Perhaps the SD135 is just not as good as some of the better quality amps that are out there, but it got me thinking that amazingly wonderful sonance can be achieved with a tubed pre and Class D amp. I have a hunch that as more people experience this combination, it will likely catch on and become the future path of many, if not most audiophile systems. It is interesting that Audio Research has been at the forefront of this development.
I spend a lot of time in research how our emotion works regarding music.
When you compare different amps who play in Class A, AB, D or G they still are different regarding the aspects/properties of sound. And most still are not able to reveal all the different aspects/properties of sound.
When you look inside the most new amps of all different brands. The facts proof that manufacturers are using cheaper parts these days. When a market is decreasing you need to find a way to make your products still profitable.
So they start to use cheaper parts, and this is what we see now in almost all new amps. When we audition them most of them create a very limited level in diversity (layering) in sound.
This means you can sit in your chair and even after 4 months you still have never felt any kind of emotion of your music. For us as music lovers it is sad to see that how poor most products are these days.
The manufacturers have not the insight and knowledge to create better products so more people would become interested in new audio products. When we go to an audio show I am with my 46 years of age one of the more young people overthere.
It is 5 before 12 and we are aware that something has to change. Trial and error is also responsible for the fact that audio is a decreasing market. The facts proof that the quality people can get by trial and error is very limited.
Electrolytic caps aren't famous for having exceptionally low ESR, but
they're the only technology that's compact enough to provide the current
capacity required. The sub-optimal ESR leads to internal heating of the
capacitor. The heat dries them out, the ESR rises, that causes them to
make more heat, they begin leaking electrically, and they eventually
just short out and start frying silicon.
David Bernnig used a switching supply in his TF-10 preamp which was made in the early 1980s IIRC. I have a customer in town with one of those and it has the original filter caps in place- very much alive after all these years. He seems to have sorted it out- those filter caps run cold to the touch. The first statement in the above quote is false- electrolytics are the only technology that's compact enough to provide the **storage** capacity required, not current.
SMPSs don't need a lot of capacity because the switching frequency is so much higher. This means that a much smaller capacitor can be employed than in a 60Hz supply. I know some SMPSs did have some problems in the early part of the 2000s, mostly on account of some Chinese caps that were failing not because of switching frequency so much as the parts were just plain defective.
There’s a huge difference between a pre-amp and a power amp.
Correct, two different active Class-D subs and one SR reciever I’ve had on my HT system, have eventually blown their smp caps, and in a chain reaction taken out the class-d amp as well, luckily new plate amps were available, and at trade price, just cost effective to repair for myself only, no way for a customer, they would maybe have been better of as Ricev’s said junking it and buying a new one.
I too hav3 class D A great small company in Denmark Pascal Audiomake excellen5 digital modules. I bought the Danish Gato Audio 400-S then they build their own analog input output sections ,and International rectifier developed a super high speed switcch8ng for their 2 high power Mosfets my integrated sounds like a very sweet SS- Tube combination . Of course I upgraded the fuses ,and put a very good Oyaide Sunami Power cord and in processs of matching the wiring throughout. VH Audio has a Excellent Wire Thea Cotton centercore are multi Litz Small Wire awg21 solid core Upocc solid core Copper and thin porous Teflon which is the closestdielectric to air. Incredible wire, I did the whole Xover and cables ,speaker cables , now Amplifier power supply, and Loudspeaker terminals ,also to all replace any Brass to at least high purity phosphor Brinze or gold over Copper RCA Connectors,IEC input ,and Speaker connectors . Over 70 % of companies use Gold over Brass rca, IEC, and speaker terminals, Not Good but true.i sold audio for many years.. Itis a amazing upgrade the conductivity is 3-4x better ,which is a fact . just lookup metals resistance ,conductivity,and great wire throughout creates a fantastic synergy, I also use premium Xover parts and bypsss caps, and the Zobel networks I make for the back of a Loudspeakers is simple but effective ,and cost effective. if you or a friend is handy these are things to Strongly consider doing. You raise your systems potential at least 15% minimum is not more.
New to this site. My first new amp in decades, bought Rogue Sphinx V1 integrated three years ago. Tube 12au7’s in pre with class D power. I bought unheard but was not disappointed. Rolled NOS Mullards into it. I think it is a good value. Doubles 100 to 200 wpc at 4 ohms. Nice phono for MM carts. Heavy transformer. Quality build. Have added a Schiit Loki four band equalizer to play with. Also reccently added Rogue Cronus Magnum, but that’s not a new design.
Laptop chargers, battery chargers, TV's, you name it.
-Which don't draw any more power than the Berning TF-10, FWIW. I had a USB power supply fail on me when I took it on the Grand Divide Mountain Bike Route, but that was likely due to vibration more than anything else- the Tour Divide (as its known) has a way of doing that.
You can mess up any amplifier operating class. The specific implementation is more important. Class A implies better quality than D or inverse F, but that "class" system is not a value scale. Class A sets the zero signal in the middle of the operating range, as to avoid the typical non-linearities at the extremes of the device's transfer curve. This was in started in the tube age. Many later semiconductor devices had poor linearity, which was "fixed" with gobs of feedback, and transistor power amplifier output stages almost exclusively have no gain, they just operate as voltage followers/current amplifiers. So linearity biasing is not the goal here, but avoiding ugly transitions when the voltage crosses the zero point. There would be more work getting a D amp to perform well, but of course as this thread has shown it is possible. The digitizer must be very good, operating at a high frequency and have good filters for the output. Higher frequencies will be easier to filter out and will have more resolution. The bit stream output from a DAC could be used to drive an output stage, perhaps skipping some time middle pieces. Change the power supply voltage and the gain changes. Obviously junk in the power supply will end up in your ears.
@kosst_amojan The Berning TF-10 is a tube preamp with about 10 tubes in it. It draws about 60 watts; that's about the same as my laptop charger.
Panasonic came out with a new formula for electrolytic capacitors some years back that allowed them to be a lot smaller with good performance. Chinese copies of that part proved to be unreliable but due to their price found their way into a lot of consumer gear- laptops, chargers, that sort of thing. So I've become hesitant to blame electrolytics for failures generally speaking, until I know more about the actual part used. If its one of those knock-offs, its going to fail no matter what.
Funny, I haven't read anyone comment about having owned both class d and a-a/b. I'm very interested in what they think. This thread, as well as the entire audiogon forum, is populated with either/or, one or the other, with very strong advocates in both camps.
Funny, I haven't read anyone comment about having owned both class d and
a-a/b. I'm very interested in what they think. This thread, as well as
the entire audiogon forum, is populated with either/or, one or the
other, with very strong advocates in both camps.
I haven't been paying close attention to this thread, so perhaps someone has already responded in a similar way.
I've owned many amps that use differing underlying technology. I'm including integrated amps in the lists below.
For class A/B I've owned the following brands - Rotel, Parasound, Krell, Lexicon, Marantz, and Emotiva.
For class D I've owned the following brands - Wyred 4 Sound, Peachtree, and Sunfire.
For tubed amps I've owned Rogue Audio and Audio Research.
I recently purchased a Heed Elixir integrated that uses what Heed calls "Transcap" technology.
I have not owned any pure Class A amps.
I think they all have strengths and weaknesses and what really matters at the end of the day is how they sound. A lot is going to depend on the way the designer understands and implementsed the technology and the level of the build quality and components.
Out of all the amps I've listed, the ones that I have liked best (and still have) are the Rogue Audio M-180 tube monoblocks, the Wyred 4 Sound Class D ST-1000 MKII, the Audio Research tube VSi-55 integrated, and the Heed Elixir integrated.
It's hard to imagine the entire market going in one direction or another. Designers may be more knowledgeable about a specific type of technology or prefer the way it sounds and so it seems logical there will continue to be diversity among design and implementation philosophies.
Actually I have owned Class D and class A/B amps....
Aragon 4008 Mk.2 stereo A/B -- Nice but limited performer.
Rowland 7M balanced high bias mono class A/B -- Wonderful golden tone... Absolutely captivating, with huge sound stage and power reserve... but does not compete with current designs in resolution and distortion.
Rowland M312 stereo class D -- Fabulous 2nd generation class D based on ICEpower 1000, with PFC rectifier prefixing the regulated SMPS, and Lundahl input transformers... Would stand up even today, IMO.
Early production Rowland M625 stereo class A/B... Very sweet and transparent... But could run out of gas on extreme transients.
Rowland M725 mono. Original non-S2. Overcomes all limitations of original M625, and edges above M312.
Rowland M925 mono class D -- An incredible performer in a class of its own that I have owned since 2013... I adore it... I have not heard an amp yet that exceeds it in its totality. A total keeper.
Rowland M535 bridgeable class D -- I am evaluating a bridged pair... Jaw-dropping music maker, particularly considering that each chassis in stereo mode lists a smidgeon below $6K.... IMO worth a few times its list price. If M925 did not exist, a pair of M535 would be my long term choice.
You seem like the perfect candidate to get the GaN amps
I have owned 4 different gen class Ds, Parasound A21, and a behemoth Kinergetics KBA 75, which I think was puree class A. It grabbed a hold of the heads on my then Genesis Vs, like none of the other amps I tried on it
Hello Tweak1, are you referring to amps designed around Gallium Nitride transistors? I have had a mono amp in my system designed around Gallium Nitride (GaN) transistors for just a few days last spring. It was a still incomplete but lovely prototype of the now released Merrill Element 118 monos. At the time, it was not fully broken in and still showed some minor artifacts. In spite of that, it showed high promise, Yet I could not get a complete idea of its performance within the limited hours of up-time.
I have had a mono amp in my system designed around Gallium Nitride (GaN)
Which EPC "evaluation" board was this last spring? as this is the only way to get them as far as I know?
As far as I know this board is the only one EPC (using GaN transistors) that’s been released so far, The EPC0106 at $1338.00 usd, no transistors only yet.
I have an NAD C 268 class D amplifier, NO PREAMP, and mac mini DAC using 3.5 mm line out and the sound is MAGICAL and I've heard just about everything. I think the main is reason is that there is no preamp, but for whatever reason, the sound is just incredible.
One point to consider with most digital is when they fail many are not repairable.They can dump a load of current and burn your speakers depending on the protection circuitry. Any professional repair center can keep your old systems running for life. Retro rule in my opinion, going back to the nad 3020.That ones tone is mind blowing. Haven't found a digital which can compete.Most digital are to clean for my ear.
^Yes, George. and that was th case with all previous class Ds that I owned, but, the Audio alchemy is different. I can hear the resonance and warmth of same inside acoustic guitars, coronets...
FYI: as much as I hated to, I sold my Hattor XLR, but the Audio Alchemy DAC/Pre is damned nice and pairs perfectly with my AA stereo amp
kosst_amojan said... "people replacing SMPS's every day and every guy who's ever worked on CNC machines. There's nothing cheaply or poorly engineered about Mazak or Haas machine tools and they can't seem to make these power supplies last."
Heat buildup inside any CNC machine beyond the intended tolerances of said machine will most definitely put a strain on all internal parts. Not to mention the vibration from motors and the humid conditions in and around the machines from in shop humidity levels and the coolants used to reduce friction. There are many variables in an industrial setting to make any well designed piece of equipment go south in a hurry...
Hello George, as far as I know there were no "evaluation boards" of any kind in the Merrill Element 118 prototype. The circuit is entirely designed/implemented by Merrill from the ground up using discrete components, including the in-circuit application of GaN transistors.
For more information, you may want to contact the company.
For more information, you may want to contact the company.
Regards, G.
If they are using these EPC GaN transistors in this prototype, the only reason would be to be able to attain a far higher switching frequency speeds to 1.5mhz like Technics with the SE-R1. Can you point to a link where you saw this is stated??
Just found it, as yes they do state because of the GaN transistors ""which allows fast switching" but it puzzle me that they don't state how fast they switch at like Technics does at 1.5mhz. And just like the Technics not cheap either at $36k
While there are lots of fun puzzles left in the world of audio technology, solving them may or may not have appreciable benefit to end listeners.
That’s something only listening for yourself can decide.
Selling you a problem you didn’t have in the first place is what drives the industry.
The trouble with the Techniques amps is that you can't attribute their sound just to 1 technology. This is a pretty remarkable amp, but there's also DSP speaker impedance correction going on. You cannot say "great amp, must be the super fast switching speeds" unless you can eliminate other variables.
Are fast transistors cool? Of course they are. But great Class D amps have been around for ages.
Yet here is George, standing outside an airport with a sign saying "Planes can't fly!"
George, Merrill is not so much interested in achieving high switching frequencies. He seems to be using GaN to reduce dead states.
BTW, here is the latest Merrill newsletter, where he talks about the Element 116, which he will sell for about $22K. a further trickle-down Element 114 will eventually retail for about $12K.
I'm happy for manufacturers to be pushing the envelope. That's great. All I'm saying is that the idea that the next great thing is just around the corner and it's the end of all audio is a little over hyped.
There's always a next-great thing. In the case of fast transistors, cool. Show me an audible benefit that everyone can hear before I get that hyped up about it.
There’s always a next-great thing. In the case of fast transistors, cool. Show me an audible benefit that everyone can hear before I get that hyped up about it.
It’s what the present Class-D "cons" are all about, listen to a SE-R1.
I’d lay money on it, that you’ll put one of the first with your hand up for one when it suits your pocket. And your old one with the lower switching frequency, will become unsellable junk save for use as a bass amp.
Show me where it is stated that the Merrill uses higher than 500K for its switching frequency. In fact, Merrill stated (on this site) that higher frequencies for switching were harder to do. I hope Mr. Merrill steps in here and clears this up. What he seems to claim is that the zero dead time using GaNs plus his zero feedback circuit are what makes the great sound.
Nuprime is using 700K in their latest amps and they are said to be making some very nice sounds.....also has 1meg input impedance and very trick power supplies with discrete front end. Their amps are using Mosfets on the output.
The new IceEdge modules have "dead time compensation".....maybe that is why they sound so good.
Yep George, 'tis all one dark ominous conspiracy at the expense of brave audiophiles worldwide... There are rumors of a mysterious kabala of notorious class D mongers to undermine the Faith of righteous audiophrenes. Could even be the "deep HiFi State at its most nepherious purposes"... 'Best continue to read 'em safe reviews and specs instead of getting out of the house and exposing your ears to the spiritual corruption of unsafe audiophilic experiences *Grins!*
George makes up something untrue about Merrill amps and all he can do is say that whatever I say is biased because I am selling something. The truth comes from different places.....even from manufacturers. My amps will speak for themselves. If they are good, they will sell. Trust no one (neither George, nor me nor anyone). Trust your ears. Listen and decide. You cannot know anything about how something sounds without listening to it. Class D (and all classes) are getting better and better. Whatever you heard before is not what is best today.
All class D amps have the switching noise superimposed on the audio signal. However, how much does a low level 500K sign wave affect the sound you hear? Pretty dang far out of the audio band. It does make sense to use a higher frequency so you can filter higher and have even less noise......but how much does it do audibly? Only those that have tried it know. All else is a guess. Personally, I believe it would make more difference to use better coils and caps on the output of the amps. Cryoed PCOCC inductors and super capacitors would give way better sound. No one is doing this. The future is bright indeed.
Now, single speed DSD has a problem with noise, for sure. The noise at 50K is a lot and that can fold down into the audio band. I read somewhere that double speed DSD has 40db less noise at 50K (40db is 100X!!!). No wonder it sounds better. Quad speed is a little better yet.
It will be at least 5 years before there is an absolute state of the art class D amp. There might? be something like that available now in class A in the AudioNet latest amps ($105K the pair)......or maybe the D'Agostino monsters ($250K the pair.....and 574lbs each).
Sorry, but we wouldn't even be having this discussion if great class D amps had been around for ages.
Judging by the measurements I keep seeing, great class D amps still haven't arrived.
That's the first mistake.
Look, I use technology a lot. A LOT!
I believe in it, but I also know the limitations. It is one thing to measure distortion given our most common measures: TIM and THD+N They may tell us very little about how this is perceived or how it affects music reproduction to the human ear/brain/pleasure centers. I can critique practically ANY amplifier to death.
And also, take a look at some of the most highly touted amps out there. They aren't exactly stellar spec performers.
My point: Human beings perceive sound differently than pure specmanship. If you want to go "by spec alone" then you really can't make any claims at all. I'd argue that based on the literature, some Class D are excellent amps and no one can hear better. My point? Your own ears are FAR better judges of quality and pleasure. Find me a measure that compares pleasure to transistor speed and I'll be really interested, but claiming that there's X parameter that Class D amps have to overcome before you admit they are excellent is hard for me to accept.
Do you know what I cannot argue against? People saying "I heard Class D amps by X manufacturer, and I did not like them because they sounded like ..."
That's fine.
But me? I've heard great Class A amps from highly touted makers and I preferred Class D.
And here we are back to my overall thesis:
Buy what you like listening to, specs and other people's opinions be damned. It's your wallet, and your time on earth that is important. No specs, no transistor speed, no class (A/B/D) matters when it comes time to spend your money. Make yourself happy. What I lack, is a belief that a specific set of technical specs can be made so much better in Class D that they would change everything. Sorry, I like what I have. Show me not the spec but the performance and I may want more.
I am glad you know what you like. However, you are just guessing. You have never heard class D......so what do you have to contribute here? Just the same old "I don’t like how they measure, so they must not be any good". The fact is, that many have abandoned their class A/B, class A and tube amps for class D amps. This is a fact. I would never say that class D is better than any other class.....but in the last 5 year it has matured to be an equal competitor.
My own designed dual mono stereo 25 watt class A amp is very much like the Pass F5, except it uses dual differential pairs in the front end instead of just 2 jfets. The output stage is 3 parallel push pull mosfets and single feedback to the differential stage. 1.6 amps bias, only two resistors in series with the signal, DC coupled, no compensation, no current limiting, no binding posts (hardwired), 500 watt Plitron transformer for each channel, tons of power supply caps bypassed with modded Wimas, PCOCC wiring, damping of heatsinks and boards, no steel plates on transformers, no fuse, etc, etc. It sounds really, really great. But my modded IceEdge modules sound better. Now I am rebuilding the class A amp so it is in two chassis (the power transformers were interacting and to close to the circuit) and using even better resistors and wire and hopefully it now can compete or even beat my class D amp. We shall see. However, I could never produce the amp as it has no protection and who wants a 25 watt class A amp when you can get a 600 watt amp that sounds as good for less money and uses little heat and has an output impedance under 10 milliohm and input impedance of 150K!?!
If you go to Audio circle and go to the Nuprime circle and click on the thread on the Evolution One amps you will find a link to a review of their amp on Hifi-advice that is an interesting look at class D and its history. For some reason I cannot put here the link to the review. Worth reading.
Have you guys seen the AGD Gantube monoblocks?.....way cool! Check it out. Gans in a tube with 768K switching frequency. $15000 the pair. AGD production dot com. Rave review on Positive feedback.
Which measurements, @kosst_amogan for which specific Class D amplifier?
Be specific.
Most Class D amps measure very well, if not superbly, especially compared to some megabuck Class A amplifier. To write more, it’s not that I am dismissive of specs altogether, but rather that once amps get to a certain level of quality, the specs alone do NOT describe anything useful about the sound.
For instance, I’ve yet to see an amp with 0.01% distortion actually always sound better than another with 0.05% distortion at the same frequency and output power. In fact, below 0.1%, I doubt any amplifier sounds better or worse based on distortion alone.
So, Kost, what specifically and for which specific amplifier are you claiming a spec is significantly worse??
Thanks Ric, but @ $4K US per, I would need to take a loan out on my house, so I would probably get the GaNs first. However, I might be able to extend my budget for your amp to see how it compares to my Audio Alchemy DPA-1, although I am currently looking for a pair of their monos.
Found these on AC/Nuprime: Here’s one from New Zealand another from Sonic Unity
erik_squires Which measurements, @kosst_amogan for which specific Class D amplifier?
make up your mind your making everyone dizzy. One day you put s**t on anyone that presents measured proof, the next day your quoting or asking for measurements, ya can't have it both ways sunshine.
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