Please Read and express your feelings and opinions....
Thanks Al, I didn't know that older VAC amps have variable feedback. My 125 watt Class A/B tube amps also have variable global negative feedback at reportedly 4,6,8 and 10 db. My similarly high efficiency speakers, unlike yours, have a difficult impedance curve with low impedance in the bass (3.2 ohms). I set my feedback to 4 db, or minimum. Until I improved my system with the SR fuses and Total Contact, I used to set it to 6 db for CDs and 4 db for LPs and 78s. Now everything sounds open and tonally firm at 4 db. If I were to replace my amps, I would probably buy the VAC 200IQ. |
To add a data point to Steve’s (Fleschler’s) input, my 300B-based class A biased VAC Renaissance 70/70 MkIII amplifier provides a choice of 6 different feedback settings, ranging from 0 (no feedback) to 7.5 db. All of those choices represent relatively modest amounts of feedback, even for a tube amp (for example ARC amps commonly have feedback in the area of 10 to 14 db or so), but nevertheless I prefer the 0 db setting. I suspect one reason for that is that my speakers (Daedalus Ulysses) have an exceptionally flat impedance curve. Presumably that tends to lessen their sensitivity to differences in amplifier output impedance, which in turn will vary among the different feedback settings, and will be highest at the 0 db setting. I’d imagine that with a lot of other speakers one of the other feedback choices would be preferable, depending on how the impedance of the speaker varies over the frequency range, and also on how much bass damping it requires (damping factor being inversely proportional to output impedance). Regards, -- Al |
Negative feedback is certainly a subject that generated plenty of heated debate. The one thing I don't think anyone can argue about is the importance of optimizing the topoly to behave decently before attempting to correct it's bad behavior. I think that's where the solid state crowd can learn from the tube crowd. Tube guys are obsessed with tuning a circuit to get good behavior from the gain devices because gain in their world is too scarce and too expensive to be throwing away on gobs of feedback. |
I assume the discussion is concerning global negative feedback and not local feedback. My amps as well as several other major brands of tube amps use negative global feedback. VAC, one of my favorite major brands, states that their amps use 6 db of negative global feedback. The finest audio/music system I’ve heard is the VAC/Von Schweikert $1million system. I suppose Kevin could have built the amps with no or less feedback, but his design works great with it. My amps have four variable points of negative feedback which I use the minimum for most recordings (some bad rock CDs need more feedback to make them listenable for my wife). I’ve tried no feedback amps and am dissatisfied with their sound (they were also Class A type). |
"Can't we all just get along?" Anonymity in cyberspace is the breeding ground for all sorts of bad behavior including bullying and brow-beating. Some forums and forum moderators run a tight ship; others not so much. Methinks the governing thought is that we are all adults and should behave accordingly. That doesn't seem to work out so well does it? As someone mentioned, it is the nature of the beast. Whether it is high-end audio, sports, hobbies, automobiles or your favorite food, everyone is entitled to their opinion - but one must understand and recognize that it is "their opinion" --whether it is based in fact or not. We come from different cultural and educational backgrounds. We all have something positive and constructive to contribute. Maybe a few ground rules are in order (as long as they are observed and enforced): It's important to remain civil and respectful. Agree to disagree. Think before responding Stay on point Attack the problem - not the person Educate not intimidate Share. Enlighten. Have an open mind. But most of all, have fun. |
👨🚀 gdhal geoffkait - “No controversial audiophile tweak has ever been proven to be a hoax or a fraud. - old audiophile axiom.” @geoffkait Nor has the impossible ever been proven to be the possible. An old opportunistic axiom. 🤑 Whoa! Are you high? That’s illogical to the extreme. A sufficiently advanced technology is indistinguishable from voodoo. That’s what applies here, obviously. |
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"Each 2150 uses global feedback (proudly: its manufacturer suggests that manufacturers who don't use feedback simply don't know how to do so properly)" About the Boulder 2150 from Stereophile. Different strokes for different folks.That isn't quite true- but it is true that many who **do** use it aren't administering it correctly. The problem (known since the 1950s- see Norman Crowhurst) is that feedback makes distortion of its own thru bifurcation of the signal- and so adds higher ordered harmonics and intermodulations interpreted by the ear as brightness and harshness. And no-one has sorted out yet how to get an amplifier to clip graciously while using it. Here is an excellent article regarding the application of feedback and its pitfalls, several of which don't get addressed in many modern designs (and its not an 'anti-feedback' article): http://www.normankoren.com/Audio/FeedbackFidelity.html I recommend reading all parts. I've got a SIT amplifier right now (and not just a Sony VFET either). It is one of the best solid state amps I've heard. Its too bad this technology got binned before it really was understood. |
@atmasphere "Each 2150 uses global feedback (proudly: its manufacturer suggests that manufacturers who don't use feedback simply don't know how to do so properly)" About the Boulder 2150 from Stereophile. Different strokes for different folks. I've heard noise about SITs coming back a bit on account of them being more efficient at converting and inverting AC and DC back and forth. Who knows. |
My opinion on the "failings" of yester-decade's gear is if those characteristics were desirable, why isn't anybody listening to wax cylinders on hand cranked phonographs? After all, the motorized, tube amplified, voice coil driven sound of the 30's was an evolution of that. While that is true, its a simple fact that no-one is listening to 30's technology around here. The list of improvements is much to long to list here- and I'm sure you are aware of them. ...The hardest thing I've had to do is learn to listen for what distortion is. That has brought me into strong agreement with the belief that dynamics are closely associated with distortion. +1 IMO/IME, about 95% of the time when audiophiles use the word 'dynamics' they are really talking about distortion and that word can be safely substituted into the conversation without changing its meaning. The reason this is so is because the ear uses the higher ordered harmonics to sense sound pressure (GE demonstrated this in the 1960s but little was done with that research). This is probably due to the fact that pure sine wave tones don't exist in nature. Its right at this point that our philosophies about how to get good sound probably differ; I am of the opinion that since our ears are so sensitive to these harmonics that its not a good idea to do anything design-wise to generate them and so specifically avoid doing that in our designs. This means that I don't use feedback because feedback, while suppressing distortion, also adds some of its own, and all of higher ordered harmonics which can be easily heard. So if I can do a design that does not make those harmonics, it will be smoother and not sound 'loud'. I've been accused of using 'antiquated' technology in this regard and that is true, but SITs were a short-lived technology in the 1970s and there were no small signal and driver devices that were SITs- only outputs. Regular transistors just don't have the linearity **and** soft clipping to do the job. That is why tubes are still around BTW; if really inferior (and not just antiquated) they would have been gone long ago. |
@kosst_amojan Excellent points... I am learning amp design very slowly. My old buddy is designing a couple of Pure Class A amps now, and he is no different.... He actually forms complete circuit layout in his head before he lays it down on paper... Then he builds, then he listens, then he changes, then he listens. When he gets it right, he'll etch his own boards. These days he is convinced that micro circuitry will sound best. Unfortunate for me, this is over my head. I can follow a schematic, but I don't have the knowledge to lay one out. The most that I can do is to make a few parts changes when finished understanding that one cap or resistor sounds differently than another. |
@geoffkait There mere fact that these snake oil tweaks get nothing but gloating adoration and no criticism for the results by those who try them strongly suggests that it's a psychological phenomenon, not an objective phenomenon. Since you're so fond of wrongly citing rational arguments as "logical fallacy", I'll point out your very real logical fallacy. |
My opinion on the "failings" of yester-decade's gear is if those characteristics were desirable, why isn't anybody listening to wax cylinders on hand cranked phonographs? After all, the motorized, tube amplified, voice coil driven sound of the 30's was an evolution of that.
@timlub Nobody is building class A amps without measuring some voltage and current at the very least. I'm not designing circuits over here. Most of the heavy measuring has already been done. If I get my voltages and currents somewhere on the range of where the circuit has been measured at, there's good reason to believe that I'm achieving results consistent with those measurements. The hardest thing I've had to do is learn to listen for what distortion is. That has brought me into strong agreement with the belief that dynamics are closely associated with distortion. It took me a while to figure out I should just put the damn meter down and listen, twist pots, listen more, twist more pots, and just get it right. I'm very eager to measure what I'm listening to. I feel I've achieved good results trying to tune two channels by ear and I'm curious to see what those numbers really look like. Not that I'd change it. The sound is smooth, articulate, wide, tall, deep, and well centered. It's the best amp I've ever heard. |
almarg “... Which serves to illustrate, IMO, that when it comes to many of the more controversial things in audio the truth is usually a good deal more nuanced than viewpoints that tend to be expressed by those at or near both extremes of the belief spectrum, and usually lies somewhere in between.” >>>Oh, my, what’s this, a compromise! An olive branch? Why would anyone call these things controversial? Except for an extremely small percentage, the results of these“controversial” tweaks are all positive. Calling them controversial appears to be nothing more than a ploy or wishful thinking on the part of long term deniers - the most vociferous most of whom never even tried the device under scrutiny. Give me a break! Are they trying perhaps to justify all the backslapping and cutting & pasting of their wild “scientific” theories they’ve been circulating for years trying to get some traction? Do the math. No controversial audiophile tweak has ever been proven to be a hoax or a fraud. - old audiophile axiom |
Similarly, others see the pops and ticks, rapid wear, uneven high frequency performance, limited dynamic range, increased distortion, wow, and flutter associated with ancient vinyl technology as "more authentic".Pops and ticks are often a sign of an unstable phono stage with poor overload margins and in that regard, price has nothing to do with it. People often confuse ticks and pops with the media. But when an LP is produced, the producer has to sign off on the test pressing, and one of the things they sign off on is the noise floor of the LP including ticks and pops. I have plenty of LPs at home that play the entire side without a problem- and I played some of those at the recent AXPONA show as a demo of how important phono preamp stability is. Speed variation is really a thing of the past- no machine made today or anytime in the last 30 years has audible wow and flutter unless malfunctioning. I run a studio and an LP mastering facility; LPs are usually uncompressed with regard to the digital release files (this is because the industry expects the latter to be played in cars). We usually have to request the files in a form untreated by DSP other than normalization. Our cutter head is indeed ancient, being a Westerex 3D; the 1700 mastering amplifiers are cut off at 42KHz, which is the practical upper FR of almost any LP- not that there is anything up there, but most people don't realize that the LP has that sort of bandwidth (and has since the late 1950s). As far as distortion goes- that mostly occurs in playback, not record and in that regard is highly variable according to the ability of the arm to actually track the cartridge correctly, and how stable the phono section actually is. That distortion is often much lower than cited by those with a myopic digital viewpoint. It should be telling that Technics has chosen to jump back into the LP market with 3 'table entries- all of which were seen at the recent AXPONA. LP titles are far easier to find now and sales are still on the rise; the market seems to like them despite their being somehow 'inferior'. Usually when a succeeding art replaces the prior art, the latter is usually consigned to the dust bins of history and the occasional collector. But the LP isn't doing that- all the pressing houses in the US are busy and often backed up 6 months. 1992, 26 years ago, was the year of least vinyl production. |
Atmasphere 4-19-2018... Which serves to illustrate, IMO, that when it comes to many of the more controversial things in audio the truth is usually a good deal more nuanced than viewpoints that tend to be expressed by those at or near both extremes of the belief spectrum, and usually lies somewhere in between. Thanks, Ralph. Best regards, -- Al |
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Yep... Those pesky measurements! And the guys who invent the stuff this hobby is made of. Shame on them for actually achieving results! Quite unlike you and your magic rocks and silly spots. - kosst_amojan For some people, "results" means using antiquated 80 year old technology that is highly vulnerable to changes in performance depending on what it's connected to. And for some folks, the lack of bass and exaggerated highs, coupled with increased harmonic distortion when using this ancient "technology" is "pleasing" or "desirable". Similarly, others see the pops and ticks, rapid wear, uneven high frequency performance, limited dynamic range, increased distortion, wow, and flutter associated with ancient vinyl technology as "more authentic". Unfortunately, we can't confine such individuals who promote and buy this junk to padded cells. We pretty much have to create invisible "padded cells" that effectively allow ourselves to ignore them. Magic resistors, magic vacuum tubes, magic cable suspenders, magic tonearms, magic cartridges, magic isolation blocks, magic "liquid" cables, magic fuses - all roped and cordoned off in those imaginary padded cells. It boils down to ignorance and acceptance. We don't have to "fix" or accept their ignorance - just ignore it and them. |
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I don't understand why some people are allergic to numbers and measurements. You can't construct much of anything without taking some measurements somewhere. This allergy to measurements is about as anti-intellectual and counterproductive as you can get.+1 If it doesn't measure well, I keep working on the circuit. I've been able to measure effects of fuses and power cords, which has often put me at odds with some that make apocryphal claims about them, but also those that I usually regard as 'objectivists' that won't take anything seriously without good measurements. In the latter case, they don't seem to want to cause their hand to move and make the measurements, instead proclaiming that a fuse or power cord can't make a difference. Without the measurements, their proclamations seem to me as bad (and for the same reason) as those that make the apocryphal claims. |
@kosst_amojan I can't disagree with measurements vs speculation... In my case, I haven't always had the capability without diving into some real study to grasp all the measurements. I may at some point, so for me maybe I am the village idiot, because I have dove in on a few occasions. I must be lucky because to date, I have blown anything up. The line insinuating that folks on Agon are allergic to measurements seems to be a bit overblown. You are 100 percent correct though that if you want someone to share about circuit design that you are much better over at DIY. |
@timlub I see it as they're just focused on achieving results. You see different sorts gathering around different things for different results. I've been looking over line stage stuff a little because that's my next project, but I've enjoyed the F7 thread and the speculation going on over there. I don't understand why some people are allergic to numbers and measurements. You can't construct much of anything without taking some measurements somewhere. This allergy to measurements is about as anti-intellectual and counterproductive as you can get. |
I agree that DIY is more focused on the technical aspect. Audiogon is more focused on the sound quality. With that said, I also believe that DIY has posted some killer amp designs that sound fabulous. DIY audio has helped me graduate to just above a "Village Idiot" in amp design... I have now built my own amps and modified a few. There are folks that are willing to help here on Agon, but in DIY, these are more the daily topics of discussion. |
kosst_amojan I’d say if your desire is learning, there are better resources. Mr. Carlson’s Lab on YouTube. Diyaudio.com. Passdiy.com. The Burning Amp lectures. Just to name a few. Reading people discussing the finer points of gain device characteristics is a much more fascinating endeavor than reading amatures rattling on about exotic fuses. >>>>It appears there are a great many folks who are extremely “circuit-focused” and who refuse to even consider there’s anything else to this hobby other than measurements and circuits of gain devices. That group, as manifested over on DIYAudio (and elsewhere), comprises some of THE most closed-minded and dismissive people I’ve ever seen. Any topic or concept that’s more than 1 Sigma away from the group and the moderator there is quickly attacked and deep six’d. The Blowtorch thread over on DIYAudio, where John Curl holds forth (at least John himself is not nearly so hyper focused) is up to what, 3 million posts? Including his disciples, the ones with glistening eyes. 😳 That’s 3 Million posts, people, not views. Can you say Hyper focused? He-loo! Knowledge can be defined as what’s left after you subtract everything you forgot from school. The education system has been broken for like forever anyway, have a nice day 😃 |
There are quite a few people on this forum that come to learn. Yes, often they are misguided while learning because they don't have a complete grasp or understanding of the original subject matter. Several people have gained a real education here. Probably not village idiots in the beginning, but definitely not as time goes on. |
I'd say if your desire is learning, there are better resources. Mr. Carlson's Lab on YouTube. Diyaudio.com. Passdiy.com. The Burning Amp lectures. Just to name a few. Reading people discussing the finer points of gain device characteristics is a much more fascinating endeavor than reading amatures rattling on about exotic fuses. |
On a positive note, the best way to deal with clueless self proclaimed "experts" that argue incessantly with self aggrandizing, self promotional blather and nonsense is to simply ignore them. Every forum has them and for newbies, it can be a little daunting trying to decipher between those who are legitimate subject matter experts and the village idiots. In general, the village idiots are the ones who never come up with solid information on their own but spend most of their time praising the anointed "experts" while antagonizing any who offer "new" or "different" information. The other form of "village idiot" that constantly antagonizes others while no one ever seems to respond - it's pretty safe to assume that as most everyone has given up communicating with them, it's probably a good idea not to bother trying yourself. Another helpful hint in avoiding needless conflict with village idiots or people who do nothing more than contribute anger, frustration, and argument is to check other similar online forums with similar sounding member handles. A member search on forums like DIY audio, Stereophile, AudioHeritage will often reveal that such village idiots have a long, proven track record of unchecked stupid, aggravating, or otherwise annoying behavior. Armed with these tools, we don't have to always get sucked in to the next stupid argument. As they say, it takes at least two.... |
cj1965 In Audiogon forums, the ratio of the clueless soothing their fragile egos with endless hand waiving nonsense to the knowledgeable citing proven science and mathematical evidence tends to be pretty high ... The fact that most of their contributions have been hand waiving BS intentionally or unintentionally misleading others doesn't seem to matter ... The end result is often persistent ignorance ... with basic fundamental subjects that ... have been settled long ago and are considered trivial. This fiefdom syndrome is made worse when utterly unqualified salesmen are allowed to pitch their products without any deference to science or facts ... there are a significant number of influences that impede technical progress - causing issues to be constantly revisited that should have been settled long ago.This rather reads as though you have appointed yourself judge, jury and executioner. If your conviction is as resolute as you suggest here, I can only ask: Why do you participate in this forum? You've characterized it as an obstacle to the progress you apparently seek. Do you think your protestations will change the forum's content and the way it's moderated? Are you simply here to complain about how audiophiles pursue their hobby? In any event, your assertion that this humble forum has been an impediment to "technical progress" is absurd. Progress inexorably marches on, driven by science and complex factors that dwarf whatever influence this forum and its members have - even in their dreams. |
"
Some Audiogoners (no names) start threads after threads which ask the
same questions, over and over and over again. They usually get
thoughtful responses, but they, the OPs, don’t seem to learn anything or
have the motivation to act on any of the thoughtful responses. At best,
"they" seem confused or maybe have too much time on their idle hands.
" - ps In Audiogon forums, the ratio of the clueless soothing their fragile egos with endless hand waiving nonsense to the knowledgeable citing proven science and mathematical evidence tends to be pretty high. This scenario is clearly not restricted to Audiogon alone. A high percentage of forums possess posters who "command respect from followers" simply because they have several thousand posts under their belt. The fact that most of their contributions have been hand waiving BS intentionally or unintentionally misleading others doesn't seem to matter. The "reputation" and "belief system" are all that counts. And when a newcomer or "unknown" hits the scene with "facts from the big bad world outside", he/she is often scorned, ridiculed, challenged for credentials, or in egregious cases - the "followers" implore moderators to ban the newbie if the newbie presents facts that disagree with the "grand proclamations of resident forum experts". The end result is often persistent ignorance, in many cases, this ignorance persists with basic fundamental subjects that "in the big bad world outside", have been settled long ago and are considered trivial. This fiefdom syndrome is made worse when utterly unqualified salesmen are allowed to pitch their products without any deference to science or facts.The mere fact that they've been pitching the same old garbage for 30 years is supposed to be enough for the "followers" and sadly in many cases, it is. So just as it is with other forums, at Audiogon, there are a significant number of influences that impede technical progress - causing issues to be constantly revisited that should have been settled long ago. |
Some Audiogoners (no names) start threads after threads which ask the same questions, over and over and over again. They usually get thoughtful responses, but they, the OPs, don’t seem to learn anything or have the motivation to act on any of the thoughtful responses. At best, "they" seem confused or maybe have too much time on their idle hands. Consequently, they post yet again. And again. Because I visit this website in hopes of learning something useful, and not reading endless echoes, seeing those sorts of posts makes me wonder WTF? So, sometimes I speak up and call it out. I also understand, that I am under no pressure to return to A’gon. :) I also understand that many audiophiles are obsessive and nervous (not yours truly of course) and nothing will temper their insecurities. :) Happy listening, folks! |
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@viridian The vast majority of the concerts I've been to have been outside and powerfully amplified. The few events I've attended in an auditorium without amplification aren't something I'd enjoy hearing in my living room. I wouldn't want a recording that sounded 50 to 75 feet away. Trying to capture that essence is of low to no priority to me. Very little of what I listen to is recorded in a live performance setting. It's mostly studio work. Live recordings really don't have much depth or image specificity, generally, unless they're very artfully recorded to capture that in a venue set up specifically to capture that. I know tone chasers are a different bunch. I don't really understand the more extreme of that crowd. I think I and them are using stereos for very different purposes. |
@geoffkait "That is illogical, Captain. We actually can not (rpt not) measure soundstage height or any other dimension, the sound characteristics of the recording venue, sweetness, warmth, presence, wetness, bass tautness, transparency, glare, things of that nature. As I read your manifesto, the ability to measure anything is pretty much your whole premise.Better luck next time." There it is, you liar. 2 pages back. |
Kosst_ feel free to consider my perspective anything that you care to, however I use mini monitors that image quite well. I just fail to hear that type of imaging in the concert hall. And, of course, my hearing could certainly be suspect. I will say that, years ago, when I used Altec 19s, JBL Apollos and Klipsch Cornwalls that presentational aspect of the sound had greater veracity to the concert hall, however the diversions from tonal correctness were a bit hard to live with. I think that we pick the distortions that we can live with in the end. So in my case it’s not a result of owning speakers that don’t image well, but simply a preference for what I believe is a closer representation of concert hall sound. I would ask do you hear this kind of imaging in the concert hall? If you don’t then it is fair to say that is an artifact of the recording/reproduction process, though, to some, a pleasant one. And I think that it is an intentional misreading of my post to say that I suggest that good soundstage and tonal accuracy are, in some way, mutually exclusive. What I said was the Absolute Sound took the emphasis off of tonal correctness when began to focus, almost solely, on aspects of soundstaging. But you knew that’s what I said. |
@geoffkait Yeah, you did. Anybody can go back and look. @viridian I consider that argument a cannard perpetuated by those who like speakers that simply don't image well. And just as you put it, tonal quality is always juxtaposed against imaging as if they're mutually exclusive properties. I don't agree. |
