This is where my good friend Lynn and I disagree:) I have heard my Lampi Pacific in the same system as the May (which Lynn doesn't favor). I have heard various tube based DACs, the Schiit Yggy and a few others for SS, and the Pacific is in a different universe to my ear than any of the others. I have not heard the Bruno Putzey DAC except briefly in the Songer/Whammerdyne room. I liked the sound, but I need to hear things in a known system. That DAC was over $10K though. I will bet money that in a blindfold test I will prefer the Pacific or perhaps the expensive SS DAC over the $1000 Chinese dac du jour on ASR. Of course the rest of the system has to be totally transparent for such differences to be heard. My 2 cents and others will disagree. Of course the law of diminishing returns kicks in very hard somewhere about $1000-2000. The Pacific and others of that class live and breathe in a way that even the May cannot (to my ear).
300b lovers
I have been an owner of Don Sachs gear since he began, and he modified all my HK Citation gear before he came out with his own creations. I bought a Willsenton 300b integrated amp and was smitten with the sound of it, inexpensive as it is. Don told me that he was designing a 300b amp with the legendary Lynn Olson and lo and behold, I got one of his early pair of pre-production mono-blocks recently, driving Spatial Audio M5 Triode Masters.
Now with a week on the amp, I am eager to say that these 300b amps are simply sensational, creating a sound that brings the musicians right into my listening room with a palpable presence. They create the most open vidid presentation to the music -- they are neither warm nor cool, just uncannily true to the source of the music. They replace his excellent Kootai KT88 which I was dubious about being bettered by anything, but these amps are just outstanding. Don is nearing production of a successor to his highly regard DS2 preamp, which also will have a unique circuitry to mate with his 300b monos via XLR connections. Don explained the sonic benefits of this design and it went over my head, but clearly these designs are well though out.. my ears confirm it.
I have been an audiophile for nearly 50 years having had a boatload of electronics during that time, but I personally have never heard such a realistic presentation to my music as I am hearing with these 300b monos in my system. 300b tubes lend themselves to realistic music reproduction as my Willsenton 300b integrated amps informed me, but Don's 300b amps are in a entirely different realm. Of course, 300b amps favor efficient speakers so carefully component matching is paramount.
Don is working out a business arrangement to have his electronics built by an American audio firm so they will soon be more widely available to the public. Don will be attending the Seattle Audio Show in June in the Spatial Audio room where the speakers will be driven by his 300b monos and his preamp, with digital conversion with the outstanding Lampizator Pacific tube DAC. I will be there to hear what I expect to be an outstanding sonic presentation.
To allay any questions about the cost of Don's 300b mono, I do not have an answer.
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It might be because those parts work...
FWIW, we use surface mount parts in the module we designed for our class D amp. We assemble them to the board by hand (no machines). You use different tools for that- a different soldering station, and special reader’s glasses so you can see what you’re doing. You missed one of the more vital measurements: distortion vs frequency. Why this is important is that it can show you if the amp is going to make more distortion (and audible, annoying distortion) than the specs would otherwise show. Zero feedback amplifiers have a ruler flat line across the audio band in this regard. Beyond that the distortion spectra must allow the distortion to be innocuous. That’s why SETs sound they way they do. When the amp has feedback, that’s when you can have troubles with distortion rising with frequency. This happens because the design, whether tube or solid state, has insufficient Gain Bandwidth Product (and also points to poor engineering; feedback is control theory, which is a field that is well understood elsewhere in the electronics industry). For those that do not know this term, GBP is the frequency where the gain of the circuit has fallen to a value of 1 (unity gain) and so is the highest frequency where a sine wave can be relatively undistorted. Obviously an amp with a gain of one is not useful- 25 to 30dB is more useful so a preamp can drive the amp in a conventional manner (SETs don’t need quite so much gain, but since they don’t usually use feedback they aren’t part of this discussion). For example if the amp has a GBP of 1 MHz and we are looking for 30dB of gain (a gain of 1000) out of the design, you divide 1MHz by 1000 and you get 1KHz. That is the frequency where the feedback will fall off on a slope (starting at 6dB/octave, but as frequency is increased, falling off faster)- and the distortion will rise on a converse slope. This is why a simple THD value can hide dirt under the carpet; the fact that distortion will be much higher at 7KHz than it is at 100Hz. Its why most solid state amps can play bass just fine, but sound bright and harsh- you’re getting more of the audible annoying kinds of distortion at higher frequencies than the specs otherwise show! This has been one of the bigger disconnects between the spec sheets and what we hear over the years and has given rise to the myth that there are things we can hear that we can’t measure and explains why amps that ’measure poorly’ can sound so good. It is recently become possible to build solid state amps that have so much GBP (we have 20MHz in our class D) that the distortion vs frequency is a ruler flat line, just like in an SET (but of course, overall much lower distortion, so greater detail is audible since distortion can obscure detail); IOW the feedback employed in such amps is supported across the entire audio band. That is why its now possible to build solid state amps that sound for all the world like the best tube amps. FWIW ASR does on occasion graph distortion vs frequency on their site, but its apparent to me that they don’t understand its significance: the line that exists between that graph and what the amp actually sounds like. If you have all the measurements you can know that! |
#hot take, one of the least important measurements is THD. Humans are inherently bad at hearing harmonic distortion don’t take my word for it there’s many blind tests you can do online to see how much distortion it takes before you notice. it tends to be shocking how much distortion there is before you notice it (especially if it’s low order). I’ve always had trouble correlating all things I hear with measurements. Still can’t really find a measurement that tells me how black the background of a component is. It doesn’t seem to be noise floor. I’ve heard many amps that have an incredibly low noise floor that aren’t very black sounding, other amps that have quite a high noise floor and are very black sounding. Multi tone seems to loosely correlate with this but again I’ve heard components with incredibly low and linear multi tone that aren’t very black sounding (Insert class D here). As for component cost I completely agree with Lynn. If a component is cheaper to build, why are you charging me so much?!? I have no issue if a designer thinks a cheaper part sounds superior then a more expensive implementation. But you better not charge me more for that 🤨. This is something I appreciate about Atma-sphere’s class D. Ralph fundamentally believes it sounds better than what he was putting out before but he didn’t go charge an arm and a leg for it because “it sounded better”. To me it’s clear most of us have a slight different preference to the sound we like. The thing that makes the Karna mkII (blackbird) so attractive to me is just how much you can change the sound depending on what tubes you roll into it. Other tube amps I’ve heard do not change nearly as much as the Karna mkII. It is spooky transparent to what’s around it. Don very much likes the Linlai WE300B, but to me they aren’t my sound a little to smoky jazz club vibe sounding. Roll something else in and it’s a completely different presentation. Last night I was rolling the 6v6s and it was shocking the difference. Rolling in the JJ’s it was that classic JJ snap and speed in the midrange with a completely unrefined top end 🤮. Definitely won’t be sticking with that tube. But anyway my point with the Karna mkII is I’m not constrained to what Don and Lynn thinks it should sound like. I get to choose what it sounds like and that’s my favorite thing about it. Thanks, Cloud |
[QUOTE="Helom, post: 32394540, member: 71602"]I suppose if I was specifically seeking a lightweight class D amp then I would probably give the Atmasphere model a try. I suspect most class D manufacturers are more concerned with cost savings and size rather than sound quality.[/QUOTE]
A good number of them are trying to get them to perform and sound as good as is possible.
[QUOTE="Richard Austen, post: 32397198, member: 53502"]I think the mistake you're making here is that as mainly an engineer you are looking at this from an engineer's perspective in that SET will go away because it doesn't measure as well as class D (or in your opinion, SET doesn't sound as good).
...Someone like me will come around to class D simply because I don't really care that much about the technology - I care about what I hear. Gear is not the point - Music reproduction is the point. I just see history illustrating whether it is audio, politics, automobiles, etc that the best doesn't always win. Lastly, I think really good-sounding Class D will also need to come from one of the big boys like Yamaha/Denon/Marantz/Sony to generate a larger foothold.[/QUOTE]
I am saying that tube power is on borrowed time because you can get all the best of the tube sound without the downside, combined without the weaknesses (brightness and harshness) of traditional solid state. So I see your opening comment above as a red herring- its not my assumption nor what I said or think. Class D is already here big time and all the big players are on board. So its foothold is enormous.
[QUOTE="Helom, post: 32397328, member: 71602"]I have yet to encounter a class D amp that doesn’t sound “thin,” regardless of specified power, or whether it’s a hybrid or employs a linear PS. It’s weird.[/QUOTE]
The simple answer here is you've not heard them all. Class D amps vary in sound quite a lot, more than tube amps do. Many of them really did have troubles getting the bass right, because they really didn't understand that the power supply really does have to be robust. The idea that they can skimp on that because the idle current is so low got them in trouble.
[QUOTE="Ampexed, post: 32397584, member: 143818"]The problem is that SET sounds the way it does because of its technical imperfections. No class D amplifier designer is going to deliberately make an amplifier which intentionally distorts the signal to the extent that an SET does (the company I work for makes a whole line of class D amps from mid-high end to very high end). Class D can and does sound just fine, but it cannot sound 'just like an SET' because the two types of amps are playing by radically different playbooks. That difference in sound is going to appeal to people with different priorities.[/QUOTE]
SETs sound the way they do because of their distortion. We didn't make our amps to have the distortion of SETs and they don't. But- like SETs, the distortion our class Ds make is mostly the 2nd and 3rd harmonics, with enough amplitude (also like SETs) to mask the higher ordered harmonics. Where its different is that overall the distortion is way lower than any SET, so it sounds more transparent. But it does so without harshness or brightness of any sort- and very good bass. Also like an SET it has a very good first Watt. How it differs in another way from SETs is the higher ordered harmonics don't show up at slightly higher power levels to cause the amp to sound 'dynamic'; IOW it does not have distortion masquerading as 'dynamics' as all SETs do at higher power levels (anything about about -6dB of full power).
Once you know the 'dynamics' of SETs is really just distortion it kind of wrecks it. So our class D is a lot more satisfying in that regard.
[QUOTE="Helom, post: 32400289, member: 71602"]Unfortunately most class D doesn’t work that way. The topology seems to distill the sound to a thin/lean presentation regardless of what’s upstream. This is especially true at high playback levels where many class D amps just “fall apart” despite their claimed power output.
It’s most apparent with the IcePower and older Hypex modules. Seems it’s still true with at least some of the GaN Fet designs also. Seems it has something to do with how they perform when asked to drive a real dynamic load as opposed to a simulated load.
[/QUOTE]
This statement is false. The real issue is one I pointed out just above: Class D power supplies must be really robust; if not, they will have troubles with bass and might sound dry. This is one area where many class D amp producers skimp out. Its not a problem with the technology as it is the intention of the producer- are they trying to make a buck or are they trying to make a nice amp? The two are vastly different!
[QUOTE="Ampexed, post: 32400846, member: 143818"]Low bass is actually the Achilles heel of class D. They cannot take sustained periods of supplying close to DC levels of current, which is why they are typically rolled off before they have to pass the infasonic region of bass. If they used large heatsinks that would be less of an issue, but then the size, weight and cost advantage of class D would largely go away.[/QUOTE]
This statement is also false. If the amp is designed properly they can sustain current no worries. For example, our amp is rated 200 Watts into 4 Ohms. You can drive it with a sine wave at any bass frequency into that impedance and the amp will sit there and do it all day long- as long as you want with no worries whatsoever. Heatsink design is critical but its not a size thing as best I can make out. Our heatsink is also the mounting method of our module and so isn't any larger than the module itself. Yet the amp has no problem making current up to the limit of the supply itself. So it makes bass as good as any amp I've heard.
This isn't rocket science. What isn't understood well in high end audio is that its driven by intention rather than price. This means good sounding products can be inexpensive, but it also means that you can do what is needed to make a circuit work the way its supposed to. Again, in a class D, the most common sin I've seen amp producers do is they skimp on the power supply. That results in everything you said. But that's not a weakness of the tech, its a failing of the person that's trying to save a buck. It results in failure.
@cloudsessions1 Just so you know, this statement is false. Most self-oscillating class D amps, such as the Purifi, do not have rising distortion with frequency. Where ever you got that your source is wrong. Regarding this comment:
This test is probably not done with attention paid to distortion rising with frequency- and in that context your statement is correct. Most of the online stuff I've seen does not have that built-in to the software. So its not the same thing. When distortion rises with frequency, it puts emphasis on higher ordered harmonics. This is at the root of why solid state has had a reputation for being harsh and bright, and also why feedback has gotten a bad rap in high end audio (because it can mess with a tube amp in a similar fashion). I've already described how Gain Bandwidth Product causes the rise in distortion with frequency. What I've not mentioned in this thread so far is how feedback is usually applied in amplifiers so that the feedback signal itself gets distorted before it can do its job mixing with the incoming audio signal. As a result higher ordered harmonics and intermodulations are created because the feedback node is not linear. Norman Crowhurst (a well known audio guru of the late 1950s and 1960s) wrote about this over 60 years ago, but almost nobody really did anything about it. You can apply feedback without distorting it. That is done the way opamps do it, by mixing the feedback with the audio signal using a resistor network at the input of the amplifier, rather than inside the amplifier. Resistors are far more linear than any tube or transistor! We've employed that technique in our smaller OTLs for decades now. |
@atmasphere you can see the purifi’s distortion vs frequency here: https://audioxpress.com/article/fresh-from-the-bench-a-tale-of-two-class-d-amplifiers-orchard-audio-bosc-and-purifi-audio-eigentakt-eval1 here: https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-purifi-1et400a-amplifier.7984/ and here: https://www.stereophile.com/content/nad-c-298-power-amplifier-measurements
Now the Purifi is a good sounding amp with excellent employed feedback. But it does not rival the best tube gear I’ve heard let alone my $5k Valhalla. As for THD+frequency. Agree to disagree. I have not heard any properly designed SS that isn’t good in the treble whether it has a rising distortion plot or not. to me that was a problem in the 80’s and 90’s. Designers have long known the impacts of high order distortion and taken steps to reduce it in the last two decades. The Pass labs XA60.8 has some of the best treble I’ve heard. It’s sweet, articulate and smooth and it’s distortion rises over 1/2 a percent at 20k. |
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