Roger, I have two questions though the second is a doozy.
1) What do you think of the Tungsol KT150?
2) What are your top 5 criticisms of the ARC Ref series components (i.e. the Ref 75SE or Ref 150SE amp and the Ref 6 preamp)?
I ask because I own and am proud to own the Ref 150SE and Ref 6 and more importantly, they deliver untempered joy and because while you said some negative things about Bill Johnson, you passed over the fact that Ward Fiebiger was the mind behind the latest designs.
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Hears what JA had to say in Stereophile.. The Audio Research Reference 75 measures well for a classic tube amplifier design with a single pair of output tubes for each channel and a modest degree of loop negative feedback. Its output transformers are also of good quality, the only proviso being that the amplifier should not be used with loudspeakers whose impedance drops significantly below the nominal value of the output transformer tap
Read more at https://www.stereophile.com/content/audio-research-reference-75-power-amplifier-measurements#jbpCd1H...
I lack 99% of your engineering expertise, but I don't read the measurements as being as bad as you seemingly do. It seems to me that JA has a tendency to disagree with his own reviewer's perceptions as to which output tap is best rather than criticizing the design of this amp and it's output tap measurements per se. In some ways, this entire discussion is premised upon design expectations; should the amp designer account for every possibility or to some degree, is the end-user responsible for matching the amp to a suitable loudspeaker? It seems to me that you adopt the former view, which is somewhat quizzical given your avowed distaste for dynamic coned speakers and your view that ESLs/Planars are the only form of speaker that makes musical sense. For better or worse, at Stereophile high-dollar tubed amps seem to be always matched up with various iterations of Wilsons, none of which present graceful impedance curves. I find it curious in general, Roger, that you defend measurements of tube amps as meritorious in a vacuum (pun intended). You seem to imply that the measurements may not tell the complete story, but that just the same any mediocrity in the measurements that are utilized is sure to correlate with deficiencies in sound. In other words, I interpret your posts-not just in this thread but in others too-to be consistent with a person who adopts only the first half of the golden oldie phrase, "not all things that count can be measured and not all things that can be measured count". This may dismay you quite a bit from an engineering standpoint, but I take measurements of tube amps to be very analogous to measurements of DAC's; the best measuring DAC's don't often sound the best. They don't even necessarily render the so-called "musical truth" the best. Is there a known measurement of tubed gear that can predict a tube amp's ability to render the texture of a violin or the blat of a trumpet, the subtlety of David Rawling's plucking of a Martin acoustic, let alone sound stage width or depth? I do agree with you that for the price charged, ARC has no excuse for mounting tube sockets directly onto the PCB. But to my knowledge, that is a reliability issue and not a performance issue. I also agree with you that ARC gear is unnecessarily complex and hard to service. The same could be said for BAT and Lamm and yet they have great reputations. The sheer number of capacitors in both my ARC Ref 150SE and Ref 6 is either alarming or impressive depending upon one's point of view. Again, BAT and Lamm seem to adopt the same approach. Your own decision to go hybrid with your higher powered amp and to go true balanced with your higher powered amp but not your lowered power amp is a head-scratcher. If-as you state-monos are more susceptible to hum than stereo amps, why do you implement RCA-only vs. offering true balanced in the opposite direction? And while a solid state input stage may very well offer better measurements, where is the proof that it sounds better? At the end of the day, isn't it indisputable that it is cheaper to produce and less complicated? You on the one hand have little good to say about Rogue and yet when it comes to hybrid tube amps, I think of Rogue (and Musical Fidelity though I don't count their "tubes" as tubes). |
Preamps are much easier and to me not so interesting as power amps. From the heart, I don't want to tease you out and set you up for some type of audio sparring, a form of website f-erism I despise. I respect you and am willing to do my best to listen/read with an open mind. But that said, you can't possibly mean that preamps are easier in general and I am unaware of any accolades for your preamps (whereas you are lauded for your amps). Obviously you mean that for your tastes and purposes, preamps are easier than amps. Few would argue that the audio world is full of great amps and that there are a dearth of great preamps. I have an opinion that is not subject to proof-that the easier a loudspeaker is to drive (in terms of both impedance curve and sensitivity) the more a great preamp's sonic attributes are appreciated. A great preamp does more than attenuate a signal. It breathes life into music. A great preamp is quietly powerful, while a great amp simply provides grunt. Once again, purely resorting to engineering and lab measurements is a sure way to fail when it comes to preamps. A great preamp needs a great PSU section, preferably outboard. Lab measurements don't explain why a great PSU is so important to the performance of a preamp. |
atmasphere6,745 posts11-27-2018 1:15pmPreamps are much easier and to me not so interesting Roger, IME this statement is false. Many good amplifier designers think that a good preamp is no big deal and then go right ahead and design a poor preamp as a result. This is totally because they really in fact for real don't know what a preamp does! - which is to say, a lot more than just the gain and bandwidth, that sort of thing. If a preamp isn't right, it makes no difference how good the amp or speakers are, the missing information can't be recovered downstream.
I love being vindicated. I have personally never encountered a manufacturer who seems as neutral and knowledgeable as Ralph. Roger, you may not think that this is a technical question, but why don't you believe that preamps do more than regulate gain and provide ample bandwidth and select sources? What is your scientific engineering basis for making such a claim? Do you feel that volume controls are a simple design choice? Are off the shelf rotary pots good enough for you? You tried to put me down that I must be "new to audio" (I am not, been at it for 43 years since age 16) and yet I bet 99% of us who have similar time in this hobby are not familiar with your preamps. Heck, your amps are miles under the radar as well. Frankly, and here is a technical question for you too, your designs, particularly your RM100 appears awfully similar to those of Don Sachs. His amps are less money. What sets yours apart from his (other than is being far more widely known by word of mouth).I can't help but note that you keep insisting that this thread is for technical questions and yet on multiple occasions you have pitched your products. You in fact asked me why I did not consider your RM200 rather than my ARC Ref 150SE. The answer is one I think I answered previously; I believe as does Ralph evidently that it does no good to have a great preamp and a mediocre preamp. Shite flows downstream. I picked my ARC Ref 6 first and then picked the ARC Ref 150SE because I could count on it mating well with my pre. In addition to my question above, I have another one. And this is not meant to be a challenge despite your likely impression that it is. What is your scientific engineering basis for concluding that damping factor, adequate power, and low distortion are the most important performance criteria for an amp (reliability and serviceability not falling within performance criteria)? You keep beating the dead horse of a single Cary amp as if it that one amp represents all that is wrong with most every competitor's design! It is my impression that damping factor being a non-issue with the great majority of competently designed amps, your design philosophy boils down to your preference for the better dynamic range afforded by the high voltage of tubes combined with low distortion. I accept the former premise-greater dynamic range from higher voltage afforded by tubes-but I reject your fixation on low distortion. Note that I used the word "fixation". Sure low distortion is critical but low distortion can be obtained and yet the amp can sound terrible. An amp can sound great and provide accurate renditions of the recording and yet be on the higher side of accepted distortion levels. My point being that there is a hell of a lot more that goes into a great amp than low distortion. You admit that you eschew premium parts because they allegedly don't afford better sound and because the price increase magnifies 5 fold to the consumer (and I agree on the effect of higher priced parts). Where is your scientific engineering proof that premium parts and wire don't make a beneficial difference? You imply (no, you outright state) that my ARC amp is overpriced compared to your RM200 "at half the price" and yet you disregard that both my preamp and amp are chock-full of expensive parts. There were warnings that this thread could go south if it did not remain Q and A. I appreciate that. I promise not to respond in any way in this thread again. But let me leave with these words; I believe that most who read through this thread with an open and unbiased mind will see a lot of very useful and candid information combined with some highly biased viewpoints by Mr. Modjeski and a fair amount of self-promotion and shilling mixed in. |
Although we disagree on many things I do appreciate your Gentlemanly approach, unlike that other fellow who left us.
Thanks - let's hope he stays away. His approach produces so much noise, its impossible to have an actual conversation, not to mention his creation of an entirely new wing of physics (or at least alternate meanings to words to which no-one was previously aware)...
Well, I lied. I have to respond. Ralph-I can't believe that you said that about me after I have done nothing on this Board (in multiple threads) but praise you and after you agreed that preamps are not easier to design (well) than amps. Yes, there were a couple typos in my last post due to being busy and typing in haste, but my points should have been clear. I could easily recite ten typos and misspellings in the various posts of Mr. Modjeski, were I to feel the need to resort to that. It is also shocking to me that Mr. Modjeski criticized the hell out of your M-60's biasing circuit and claimed your RIAA curve in your preamp is not up to snuff and you are doing nothing but kissing his arse. |
Thanks Ralph. That means all the world to me. I know this sounds cheap and tawdry, but when I replace my Ref 150SE, I will be absolutely slanted toward an Atma-Sphere.
Since I am still here and jabbering, I still maintain that the OP's stated goal of designing an amp for all men and seasons is IMHO misguided. It makes for good marketing but it's not the real world. It may be inconvenient and expensive to buy a new amp when one chooses new loudspeakers but no one said that pursuit of lovely engaging sound is cheap. Though compared to boating and racing cars, it IS cheap. Safer too.
In this holiday season, I too wish to express best wishes for health and happiness to all who contribute to this Board in good faith. Now with that, I am gone from this thread. Not from this Board, but from this thread.
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I said I was done in this thread and once again, I lied. I swear this question is in good faith and not meant to challenge or make a point. While looking over at Tungsol's website I saw this; Engineers and musicians have long debated the question of tube sound versus transistor sound. Conventional methods of frequency response, distortion, and noise measurement have always assumed linear (clean) operation of the test amplifier and have shown that no significant difference exists. In actual operation most amplifiers are often severely overloaded with signal transients. Under this condition there is a major difference in the harmonic distortion of tube and transistor circuits. http://www.tungsol.com/html/faqs14.html
RM or RK, there has been this overriding premise (by RM) that most of us have more power and overhead in our amps than we really need. What is your response to the premise above (and everything else in the link provided)? I can find the link if you like, but in one of Charley Hansen's last interviews with Stereophile he stated that after thinking throughout most of his engineering career that tube-o-philes' preferences were largely imagined, he had come around to the thinking that it is in fact extremely difficult to engineer a solid state amp that captures the same magic that a tube amp can have (and in the meantime Charley acknowledged that he had come around to believing that there is in fact a certain tube magic) and that he thought his latest amp design had captured that magic. I only bring up Charley's arguably unrelated "epiphany" because it may or may not be related to the premise of Tungsol that most amps are severely overloaded in actual operation. So what do you say about this? I happen to have 150 watts of glorious tube power (actually more) with my ARC 150SE matched to very efficient and easy to drive loudspeakers-DeVore O/93's-and I have no problems with audible hum and I am very happy with how my system sounds. |
This is a golden nugget of wisdom; (In their book "Control Design And Simulation", Jack Golten and Andy Verwer discuss (in chapter two) with regard to applying mathematical models to the real world: "...mathematical models invariably involve simplification. Assumptions concerning operation are made, small effects are neglected and idealized relationships are assumed." Ralph-you should never have entered this thread. You tried to kill the OP with kindness and camaraderie, and he spit on you every chance he got. I think most of us reading through this thread can see the OP for what he is; entrenched in the remote past and bitter. His hubris is out of bounds. I have been around long enough to suspect that there must be something else going on in the OP’s life that is causing him to behave so poorly. |
What causes a designer to choose a certain tube type for an audio circuit? Is the circuit designed around a specific tube, or is the best tube type found for the circuit that’s been/being designed? I know there are different electrical properties (I’m not an EE, so that is my untrained understanding), but does one choose the tube primarily for its electrical ability, sound, reliability, or some combination?
I know you would prefer that RM or RK answer this but I have something I can add. I asked this question of ARC's techs (I don't recall which one I spoke to) about their current penchant for designing power amps around the Tungsol KT150 and before that, the KT120. In ARC's case, I was told that they did the former-designed their amps around these tubes. If you happened to follow the history of the Ref series of amps, this is fairly obvious. The KT120 hit the market and the then-current Ref series of power amps were shipping with KT88's. They were able to handle the increased transformer demands presented by the KT120, but just barely. ARC reacted by beefing up their transformers to accommodate the KT120. Then the KT150 came out and this time, ARC was ahead of the curve rather than behind it-it seems they were got their hands on the KT150 before it was released to the public and were able to come to market with their Ref 75SE and Ref 150SE with KT150's installed. This was true of the GS "Galileo" Series as well. The tech I talked to told me that they felt the KT150 was far more linear and "accurate" than all of the predecessor power tubes, and also more durable. Too bad (for me) they are also significantly more expensive. That said, I used an ARC VS110 for about ten years and went through about six sets of various KT88's, 6550's, and even tried KT120's. I know, without a doubt, that I am getting far superior sound with my present amp, the Ref 150SE. The VS110 had a sweet slightly euphonious sound. Bass was good, but nowhere close to the solid slam I get with the Ref 150SE. The treble is far less grainy with my present amp as well. |
Roger; I have not deleted any of my posts. Not a one.
fsonicsmith., you seem to troll my threads, this is not the first time I have encountered you.
I think you are mistaken. I don't recall ever entering into any debate of any kind let alone some type of trolling-skirmish with you. IMO, you are once again confused. Let me ask you this Roger; other than one of Ralph's amps, which modern era top-tier tube amps have you actually sat down and listened to with not just your own planar speakers, but also modern coned speakers across a decent spectrum? I ask because as I have said previously in this thread, you keep referencing ancient amplifiers of the remote past which you conveniently choose to piss all over. Others have asked you this same question too and you have not responded. Are you living in a cave? I re-entered because I could not resist. I saw that your irascible behavior has continued and not just towards me, so I felt better about re-entering. I do respect you and your knowledge base, but it also pays to be a gentleman. Towards the end of his life, Charley Hansen (you misspelled his name a few posts ago-shame on you) was very vocal about MQA and his debate with JA on another forum became quite heated. Throughout that give and take, both managed to remain polite and civil. You could take a lesson from them. I brought up Charley Hansen's interview towards the end of his life about his latest iteration of amps finally-in his opinion-capturing the sound of the best modern tube amps. Have you sat down to listen to any of his amps? Have you analyzed why they might sound as they do from an engineering standpoint? I am into vinyl, thank you. I am the proud owner of a Manley Steelhead, which I bought new. I love it and love Manley. I wish the aesthetics of their amps suited me more. I acknowledge that letting aesthetics get in the way of a purchase decision seems silly. I also acknowledge that Ralph's views on cartridge loading differ from my own. But as you quoted me (accurately), I have 1% of your engineering knowledge and his too. But I have years and years of empirical experience and based upon that, I have chosen to disregard Ralph's views on cartridge loading as simply not applicable to my particular system and experience. |
Well, it turns out that it was my friend Ralph (we have never met, I simply call him my friend) who misspelled Charley's name.
It is in no way an excuse for bad specs- and in fact our amps have some pretty good specs (if proper measurement technique is used, which means **don’t ground a speaker terminal during testing**, which is the mistake that almost everyone except Charles Hanson made/makes). I suspect you didn’t read the paper at the link very carefully, since you claimed that you read it, yet still with the remonstrations!
Sorry. Now back to my sorely missed idol, the great Charles Hansen. He gave an interview to S'Phile back in October 2016 (or at least, published in that issue) and said this;
I didn't really understand it for a long time. When I first made the Ayre MX-R amps and KX-R preamp, I thought, Okay we've done it. We've made stuff that is so good it's as good as tubes—why would you bother with tubes? But I would still get customers and manufacturers who would say, "Yeah, that's nice, but I'm still sticking with my tube piece, because you haven't got there yet." And one of my weaknesses, for better or worse, is that I have such a big ego, I don't have to listen to other kit. I just listen to my own designs. If I had, I would have known what they were talking about. When we made the KX-R Twenty, we took all our ideas we had been working on for 20 years, and getting feedback from people who were able to teach me how to listen better, and what to listen for—20 years of hard work. And then I hooked up the KX-R Twenty and I went, "Holy cow! This is what they were talking about. No wonder they didn't want to listen to solid-state—this is what they wanted to hear." It just hit me: This is what all those tube nuts were talking about. I would send stuff off to these dyed-in-the-wool tube guys, and they would say, "Nope, it's gotta have a tube in it or it's never going to work right. No, it's just sand. How can it sound right?"
Read more at https://www.stereophile.com/content/charley-hansen-wizard-boulder#1xppIjoxr0TfgdJG.99
My point being that here we have this great engineer who thought he had engineered a product that tested well and sounded great and then he had an epiphany of sorts that something better was indeed out there and attainable. I continue to believe that old maxim that we're all tired of reciting let alone hearing; not all things that matter are amenable to testing. In a separate post your "intake guy" Clio-something really gave me the business about being a troll and not having anything technical to add. He's kind of right and kind of wrong IMHO. I may not have technical expertise but I will never believe that JA's measurements trump listening impressions. Roger-the Roger that I have metaphysically shaken hands with-enthusiastically too-you have endorsed JA's measurement techniques again and again and yet the fact of the matter is that JA has never given any tubed amp an enthusiastic endorsement from the standpoint of measurements. If your amp is an exception, than fine, that would be one instance of my "never" being incorrect. He may have given that monster hybrid integrated by Musical Fidelity-a known S'Phile darling-a thumbs up from a measurement perspective as well. So that would be two exceptions. Btw, go back to the full link of Charley Hansen's interview and see what he said about finding a power cord laying against the carpet at a show and finding that one wood block cured his perceived dissonance. What do you have to say about that? That it was in his mind? |
