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Review (3): High-Power Audio Amplifier Construction Manual, Slone
Ignoble heir to a proud tradition
The history of serious audio amplification-'serious' meaning a concerted effort to achieve fidelity even when mainstream thought held it superfluous-is unusual because, even more so than in Amateur Radio (hams quit building, except for purposely crude and simplistic QRP equipment,in the late sixties for the most part), it has been largely driven by hardcore, soldering-iron-wielding hobbyists. From concert violinist David Sarser to astronaut Norman Thagard, there's a big tradition of bright people wholly outside their discipline plowing new design ground and publishing their results, along with more conventional engineers and technicians whose published works drove first the do-it-yourself builders and then the industry at large. Lincoln Walsh, D.T.N. and Reg Williamson-two unrelated Englishmen twenty years apart-Hafler and Keroes, and many others founded a tradition carried on well into the solid state era: Bongiorno's Ampzilla was the first real stake in the heart of the tube amp's dominance among the hot iron cognoscenti. The "tube revival"-a misnomer because among really serious audiophiles there never was a time where everyone agreed solid state was superior or even acceptable-was, as a previous reviewer notes, a DIY-spearheaded effort with the indefatiguable Ed Dell's Audio Amateur/Glass Audio/AudioXPress magazines and later hardcore journals such as Sound Practices and Vacuum Tube Valley publishing projects, offering parts and describing the finished homebrews in glowing (no pun intended) terms. By no means was solid state abandoned, but tube amplifiers have always been more popular as homebuilt projects. Many books have been written in the past 50 years on the building of high fidelity equipment. This one isn't the worst, but that's no excuse: it's certainly not very good. It's an unedited, disjointed bunch of facts, half-truths, outright sour grapes, and willfully misleading statements coupled to some projects with PCB artwork but little design explanation. The designs themselves look like they are straight out of Audio Amateur or Practical Wireless (UK) circa 1982. Combined with the author's Howard Cosell-like writing style and total lack of fact checking (he lists the manufacturer of Audio Precision audio test equipment as Thurlby Thandar, a Brit company about as far from Beaverton, Oregon as could be imagined!) he's far more likely to provoke High Enders to chuck the book into a river than to change their mind about anything whatsoever. His later book is a little better, but not a lot. There are better writers working for far better publishers with far more useful things to say for anyone actually wanting to build an amplifier, so my advice is to simply avoid this book in favor of several other titles. In recent years, speakers of Japanese, German, and even French have had more quality titles to choose from than the Anglophone press has produced-Reiner zur Linde and Isamu Asano especially are most talked about-but none the less, Slone is not a preffered choice in any language. |
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#2
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Paul, thanks for writing your personal opinion and including 10 lines
to actually comment on the book itself. some projects with PCB artwork but little design explanation I have read the book from cover to cover and every facet of every project design is described in great detail, although not on a per-project basis. Sure, he has a tendency towards increased complexity to achieve extremely low distortion figures, and presents some power amps which are more suited to PA or instrument amplification, but I found the book to be quite lucid. I won't be building any of his amps for hi-fi purposes, but it was an interesting read. It is mostly in obeyance with the respected work of audio guru Douglas Self. Glenn. Paul wrote: Ignoble heir to a proud tradition The history of serious audio amplification-'serious' meaning a concerted effort to achieve fidelity even when mainstream thought held it superfluous-is unusual because, even more so than in Amateur Radio (hams quit building, except for purposely crude and simplistic QRP equipment,in the late sixties for the most part), it has been largely driven by hardcore, soldering-iron-wielding hobbyists. From concert violinist David Sarser to astronaut Norman Thagard, there's a big tradition of bright people wholly outside their discipline plowing new design ground and publishing their results, along with more conventional engineers and technicians whose published works drove first the do-it-yourself builders and then the industry at large. Lincoln Walsh, D.T.N. and Reg Williamson-two unrelated Englishmen twenty years apart-Hafler and Keroes, and many others founded a tradition carried on well into the solid state era: Bongiorno's Ampzilla was the first real stake in the heart of the tube amp's dominance among the hot iron cognoscenti. The "tube revival"-a misnomer because among really serious audiophiles there never was a time where everyone agreed solid state was superior or even acceptable-was, as a previous reviewer notes, a DIY-spearheaded effort with the indefatiguable Ed Dell's Audio Amateur/Glass Audio/AudioXPress magazines and later hardcore journals such as Sound Practices and Vacuum Tube Valley publishing projects, offering parts and describing the finished homebrews in glowing (no pun intended) terms. By no means was solid state abandoned, but tube amplifiers have always been more popular as homebuilt projects. Many books have been written in the past 50 years on the building of high fidelity equipment. This one isn't the worst, but that's no excuse: it's certainly not very good. It's an unedited, disjointed bunch of facts, half-truths, outright sour grapes, and willfully misleading statements coupled to some projects with PCB artwork but little design explanation. The designs themselves look like they are straight out of Audio Amateur or Practical Wireless (UK) circa 1982. Combined with the author's Howard Cosell-like writing style and total lack of fact checking (he lists the manufacturer of Audio Precision audio test equipment as Thurlby Thandar, a Brit company about as far from Beaverton, Oregon as could be imagined!) he's far more likely to provoke High Enders to chuck the book into a river than to change their mind about anything whatsoever. His later book is a little better, but not a lot. There are better writers working for far better publishers with far more useful things to say for anyone actually wanting to build an amplifier, so my advice is to simply avoid this book in favor of several other titles. In recent years, speakers of Japanese, German, and even French have had more quality titles to choose from than the Anglophone press has produced-Reiner zur Linde and Isamu Asano especially are most talked about-but none the less, Slone is not a preffered choice in any language. |
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#4
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Stewart Pinkerton wrote
Paul wrote: The "tube revival"-a misnomer because among really serious audiophiles there never was a time where everyone agreed solid state was superior or even acceptable Hardly a misnomer, since only a tiny minority of 'really serious audiophiles' actually use tube amps. And you can't get 'really serious audiophiles' to agree about *anything*, so that comment is totally irrelevant when applied to *any* audio argument! -- Stewart Pinkerton | Music is Art - Audio is Engineering I sense that some, if not, most serious audiophiles do agree about many things in high-end audio. As an example, some would assent that tube electronics really do sound really, really, really good for the ears. Problem occurs when scournful individual would join into conversation and start spouting bad words all over the thread because they would assert that tube would never sound as good to their equals in SS electronics. May I have your point. |
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#5
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"JBorg" wrote in message
om I sense that some, if not, most serious audiophiles do agree about many things in high-end audio. Exactly. Other than a tiny retrograde luantic fringe, serious audiophiles avoid tubed equipment. |
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#6
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On Tue, 23 Nov 2004 06:31:29 -0500, "Arny Krueger"
wrote: "JBorg" wrote in message . com I sense that some, if not, most serious audiophiles do agree about many things in high-end audio. Exactly. Other than a tiny retrograde luantic fringe, serious audiophiles avoid tubed equipment. Why can't you get your spellchecker to work? Also, if you had said "audio consumers" instead of "serious audiophiles", you might have been correct. However, considering how many tube amps change hands each year, it seems like the percentage of "serious audiophiles" who *don't* avoid tube amps is quite a bit more than "tiny". |
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#8
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Jon Yaeger said:
I have a number of like-minded electronic hobbyist friends who also just happen to enjoy listening to music. A lot. One thing that distinguishes me from my immediate family is the pleasure I derive listening to instrumental works. For example, my wife and daughter have no patience with music that lacks vocals. Heh! I noticed that, too. Vocals bore me. I always thought I was the only one. OTOH, I'm aware of postings on the NGs from people who claim that you, Arny, have a certain predilection to minors for carnal purposes. I don't believe most of the personal attacks appearing in NGs, and I hope that all that is fiction and that you are unfortunately a victim of slander. Nothing could be farther from the truth. But if true, surely you might appreciate the irony that it would make you a member of a "retrograde lunatic fringe," or worse . . . ? Arny's a 'borg. He earned that title with honour. Keeping irony alive, In Arny-speak: "If irony killed...." ;-) -- Sander de Waal " SOA of a KT88? Sufficient. " |
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#9
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in article , George M. Middius at
wrote on 11/23/04 1:38 PM: Jon Yaeger said: What, exactly, is a "serious" audiophile? The 'borg definition is somebody who worships "accuracy" as the sine qua non for "serious" audio equipment. No other critierion has any value because they are all subjective. "Accuracy" can be "measured". Praise God. To me and my lunatic music-o-phile friends, in general, good tube designs sound more open and realistic. Most SS amps, even "good" ones, sound sterile to my ears . . . like pushing music through grains of sand. The problem with this HERESY is that you are a DEVIL WORSHIPPER. Given™ that you can't proove™ you can hear a difference between an "accurate" system and one of your apostasy-promoting tubed systems, you are obviously afraid of science. LOt"S! ;-) You assume that science can explain all things and that the measurements we make of amplifiers can account for perceived, subjective aural differences. In my own experience the connection isn't quite so clear. Maybe my empirical senses are faulty and/or science hasn't yet quantified the stuff that makes an amp sound "good." In these and other matters, I dare say that the Galilean-Cartesian paradigm ignores a whole lot of useful anecdotal data, and it is a functional useful -- but not entirely comprehensive -- model for understanding reality. |
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#10
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On Tue, 23 Nov 2004 15:36:36 -0500, Jon Yaeger
wrote: You assume that science can explain all things and that the measurements we make of amplifiers can account for perceived, subjective aural differences. Yup, and that assumption has proved to be absolutely correct in all properly controlled listening tests. In my own experience the connection isn't quite so clear. Maybe my empirical senses are faulty and/or science hasn't yet quantified the stuff that makes an amp sound "good." Correct, your empirical senses are faulty, just like the rest of us. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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#11
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Among people who buy expensive commercially built "High End" stereo
equipment, roughly a third to a half-very roughly-buy some tube equipment and about a fifth buy nothing else. A tenth , very roughly again, listen only to analog (or 'analogue'), i.e. phono records and very many of these (though not all) have equipment with no semiconductors at all or not in the signal path. These are rough and unscientific figures but I'd bet they are pretty close: three dealers I've asked pretty much concur. Some people buy old equipment primarily or exclusively. Some just to look at, many because they listen to it and among these it's almost all tube. Some people build their own amps, preamps, et al-I've heard of building turntables but no amateur has scratchbuilt a CD transport AFAIK-and among these more people build tube than solid state although many build both and not that many build purely solid state although some do. I would say that the big spurt in DIY amp building was when the single ended thing caught on and while it has petered out somewhat, the people who started with WE 91 clones have usually stuck with tubes in general. So Arny is simply wrong, certainly, when he says the tube thing is "tiny". It's small potatoes compared to Wal-Mart and Best Buy type stuff, but compared to expensive pro recording equipment sales and high end home equipment sales in each category it's a significant chunk. When you buy a Manley mic pre, you're competing with GML, but not Peavey: similarly a Audio Research or c-j tube amp competes with Rowland or Levinson, not whatever Circuit City is peddling. And there's no evidence it's shrinking. It appears to be growing. The two latter groups don't interact with High End dealers much or at all so dealers are unable to comment thereon. |
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#12
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Arny Krueger wrote
JBorg wrote I sense that some, if not, most serious audiophiles do agree about many things in high-end audio. Exactly. Other than a Lol ! -- Now about your certain other predilection... |
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#13
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Stewart Pinkerton wrote
Jon Yaeger wrote: You assume that science can explain all things and that the measurements we make of amplifiers can account for perceived, subjective aural differences. Yup, and that assumption has proved to be absolutely correct in all properly controlled listening tests. In my own experience the connection isn't quite so clear. Maybe my empirical senses are faulty and/or science hasn't yet quantified the stuff that makes an amp sound "good." Correct, your empirical senses are faulty, just like the rest of us. If our empirical senses are faulty, what would be an example of a properly controlled listening "test" which would circumvent this problem ? -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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On Wed, 24 Nov 2004 15:26:18 GMT, "JBorg"
wrote: Stewart Pinkerton wrote Jon Yaeger wrote: You assume that science can explain all things and that the measurements we make of amplifiers can account for perceived, subjective aural differences. Yup, and that assumption has proved to be absolutely correct in all properly controlled listening tests. In my own experience the connection isn't quite so clear. Maybe my empirical senses are faulty and/or science hasn't yet quantified the stuff that makes an amp sound "good." Correct, your empirical senses are faulty, just like the rest of us. If our empirical senses are faulty, what would be an example of a properly controlled listening "test" which would circumvent this problem ? A level-matched double-blind ABX test. And there's no 'if' about it. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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Stewart Pinkerton wrote
JBorg wrote: Stewart Pinkerton wrote Jon Yaeger wrote: You assume that science can explain all things and that the measurements we make of amplifiers can account for perceived, subjective aural differences. Yup, and that assumption has proved to be absolutely correct in all properly controlled listening tests. In my own experience the connection isn't quite so clear. Maybe my empirical senses are faulty and/or science hasn't yet quantified the stuff that makes an amp sound "good." Correct, your empirical senses are faulty, just like the rest of us. If our empirical senses are faulty, what would be an example of a properly controlled listening "test" which would circumvent this problem ? A level-matched double-blind ABX test. And there's no 'if' about it. For some reason, I thought that you could be referring to something other than the above. You certainly are so infatuated with it. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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#16
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"The Devil" wrote in message news:a3ccq01vc8vp4m3sagkgbugld7daeg0apo@rdmzrnewst xt.nz... www.devil-****ing-whores-cam.com Didn't work. Maybe its .orgy |
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#17
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Paul said:
"The Devil" emitted : Er, er, I also wish he hadn't drunk all my ****ing Lagavulin. Anyone on their way to Shropshire? I'll meet you at your designated chippy, as long as you have five bottles. Cutting back? Has the price been steadily climbing over there? Two years ago I was able to get it for just $40 a bottle, an absolute friggin' bargain. The next bottle I bought, about six months later, cost $56. The next one was over $70. Then, this last July, I paid $89 for a bottle in Colorado. I think Lagavulin is becoming more and more popular in the US, and the distributors are cashing in. Boon |
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Mr. Phillips wrote:
Paul said: "The Devil" emitted : Er, er, I also wish he hadn't drunk all my ****ing Lagavulin. Anyone on their way to Shropshire? I'll meet you at your designated chippy, as long as you have five bottles. Cutting back? Has the price been steadily climbing over there? Two years ago I was able to get it for just $40 a bottle, an absolute friggin' bargain. The next bottle I bought, about six months later, cost $56. The next one was over $70. Then, this last July, I paid $89 for a bottle in Colorado. I think Lagavulin is becoming more and more popular in the US, and the distributors are cashing in. Boon Could you recommend a calming, sedating beverage for Mikey? Preferably something with a label containing the letters "XXX" and a skull? Bruce J. Richman |
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Dr. Richman said:
Mr. Phillips wrote: Paul said: "The Devil" emitted : Er, er, I also wish he hadn't drunk all my ****ing Lagavulin. Anyone on their way to Shropshire? I'll meet you at your designated chippy, as long as you have five bottles. Cutting back? Has the price been steadily climbing over there? Two years ago I was able to get it for just $40 a bottle, an absolute friggin' bargain. The next bottle I bought, about six months later, cost $56. The next one was over $70. Then, this last July, I paid $89 for a bottle in Colorado. I think Lagavulin is becoming more and more popular in the US, and the distributors are cashing in. Boon Could you recommend a calming, sedating beverage for Mikey? Preferably something with a label containing the letters "XXX" and a skull? I think a five-gallon jug of Nyquil would do the trick, but only if taken all at once. Boon |
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#20
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Paul said:
"Marc Phillips" emitted : Er, er, I also wish he hadn't drunk all my ****ing Lagavulin. Anyone on their way to Shropshire? I'll meet you at your designated chippy, as long as you have five bottles. Cutting back? Has the price been steadily climbing over there? Two years ago I was able to get it for just $40 a bottle, an absolute friggin' bargain. The next bottle I bought, about six months later, cost $56. The next one was over $70. Then, this last July, I paid $89 for a bottle in Colorado. I think Lagavulin is becoming more and more popular in the US, and the distributors are cashing in. I can't say I've noticed a price hike anything like that. Are you sure they were the same vintage? $40 sounds awful cheap for Lagavulin 16 it's normally about Ł30 over here. Prices seem to remain pretty static (aside from rare malts) but there are substantial promotions during the run up to christmas. Talisker, Oban and Laphraiog are all dirt cheap at my local supermarket right now. The $40 bottle was indeed the regular 16, but it was at Trader Joe's, which is famous for scoring some unbelievable deals. I would have purchased an entire case if I knew that was the cheapest, by far, I was ever going to find. Boon |
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#21
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Mr. Phillips wrote:
Dr. Richman said: Mr. Phillips wrote: Paul said: "The Devil" emitted : Er, er, I also wish he hadn't drunk all my ****ing Lagavulin. Anyone on their way to Shropshire? I'll meet you at your designated chippy, as long as you have five bottles. Cutting back? Has the price been steadily climbing over there? Two years ago I was able to get it for just $40 a bottle, an absolute friggin' bargain. The next bottle I bought, about six months later, cost $56. The next one was over $70. Then, this last July, I paid $89 for a bottle in Colorado. I think Lagavulin is becoming more and more popular in the US, and the distributors are cashing in. Boon Could you recommend a calming, sedating beverage for Mikey? Preferably something with a label containing the letters "XXX" and a skull? I think a five-gallon jug of Nyquil would do the trick, but only if taken all at once. Boon It certainly couldn't hurt. Considering the content of his posts, I'd also recommend a supersize portion of Imodium. Bruce J. Richman |
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From: Jon Yaeger
Date: 11/23/2004 10:14 AM Pacific Standard Time Message-id: in article , Arny Krueger at wrote on 11/23/04 6:31 AM: "JBorg" wrote in message om I sense that some, if not, most serious audiophiles do agree about many things in high-end audio. Exactly. Other than a tiny retrograde luantic fringe, serious audiophiles avoid tubed equipment. **** What, exactly, is a "serious" audiophile? One step away from terminal audiophile. The final step being a walking dead audiophile. Their brand of zombieness doesn't happen all at one time. In some cases it takes years of hard work. |
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#23
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#24
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"Cal Cerise" wrote in message
om Among people who buy expensive commercially built "High End" stereo equipment, roughly a third to a half-very roughly-buy some tube equipment and about a fifth buy nothing else. A tenth , very roughly again, listen only to analog (or 'analogue'), i.e. phono records and very many of these (though not all) have equipment with no semiconductors at all or not in the signal path. These are rough and unscientific figures but I'd bet they are pretty close: three dealers I've asked pretty much concur. Just guessing here, but all 3 dealers probably carried tubed equipment. Just for reference, there are at least 10 stores in my area that are arguably selling high end audio. Only one of them carries tubes and he has the smallest store of the bunch. So Arny is simply wrong, certainly, when he says the tube thing is "tiny". It's small potatoes compared to Wal-Mart and Best Buy... Thanks for contradicting yourself, Cal. Tubed audio, particularly tubed consumer audio is as you say Cal, "small potatoes". Nothing wrong with that, but it is how things are. IME most people who are into consumer tubed audio either do so because bragging about tubes make them feel special; or because they want to roll their own power amps, and rolling one's own SS power amps takes some special tools and skills that many amateurs lack. |
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Just guessing here, but all 3 dealers probably carried tubed equipment. Just for reference, there are at least 10 stores in my area that are arguably selling high end audio. Only one of them carries tubes and he has the smallest store of the bunch. Our definitions of High End audio are very different probably. I would define a true High End retailer as one that carries four or five lines that advertise heavily in the magazines like Stereophile or Absolute Sound-whether these are 'any good' being another matter altogether-and in most cases does not sell car audio, TV's, computers, cameras, et al. Usually they keep banker's hours and are in upscale, off-main-throughfare locations. So Arny is simply wrong, certainly, when he says the tube thing is "tiny". It's small potatoes compared to Wal-Mart and Best Buy... Thanks for contradicting yourself, Cal. Tubed audio, particularly tubed consumer audio is as you say Cal, "small potatoes". Nothing wrong with that, but it is how things are. IME most people who are into consumer tubed audio either do so because bragging about tubes make them feel special; or because they want to roll their own power amps, and rolling one's own SS power amps takes some special tools and skills that many amateurs lack. High end audio in and of itself-putting aside the question of whether it is in fact really better than mainstream stuff-is a small market. It's of that small market, and not the bigger audio market which is stuff sold at Best Buy, Circuit City, Fry's, big box retailers and catalog houses, that I'm saying tubes constitute a substantial percentage of. Audio Research, c-j, Manley/VTL, et al, are not huge enterprises but they are similar in size to Krell, Mark Levinson, et al. Then there is the various East European and Asian made budget lines that are cropping up and doing some volume through mail order vendors. It's small compared to any 'mainstream' business but it's a lot bigger in dollar volume than, say, manufacture of high power RF tubes for the broadcast and RF heating industries. One may well argue that high end audio is primarily about "virtual penis size", and perhaps it is. But whatever it's about , I know it when I see it, and most every high end store I've been in in over fifteen cities (I go check them out) has something with tubes in it or can get it. It's tough to find a truly high end store-as opposed to a upscale-mainstream home theater vendor who handles, say, Linn, or McIntosh, two channel as a sideline-that will aggressively deter you from buying tubes. |
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#26
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"Cal Cerise" wrote in message
om Just guessing here, but all 3 dealers probably carried tubed equipment. Just for reference, there are at least 10 stores in my area that are arguably selling high end audio. Only one of them carries tubes and he has the smallest store of the bunch. Our definitions of High End audio are very different probably. Classic response of a high end snob. Basically, its the old "your high end isn't high end enough for me". What Cal no doubt wants to say is that these retailers can't be high end enough for him because they don't carry tubes. IOW, Cal wants to define the criteria so he can't possibly lose the discussion. I've just been here and done this too much. End of discussion on the grounds of Cal's obvious intellectual dishonesty. |
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#27
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Arny said:
"Cal Cerise" wrote in message . com Among people who buy expensive commercially built "High End" stereo equipment, roughly a third to a half-very roughly-buy some tube equipment and about a fifth buy nothing else. A tenth , very roughly again, listen only to analog (or 'analogue'), i.e. phono records and very many of these (though not all) have equipment with no semiconductors at all or not in the signal path. These are rough and unscientific figures but I'd bet they are pretty close: three dealers I've asked pretty much concur. Just guessing here, but all 3 dealers probably carried tubed equipment. Just for reference, there are at least 10 stores in my area that are arguably selling high end audio. Only one of them carries tubes and he has the smallest store of the bunch. Perhaps you would like to pick a city that's a bit more culturally sophisticated than Detroit as an example. Boon |
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#28
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High-Power Audio Amplifier Construction Manual, Slone
From: (Marc Phillips) Date: 11/29/2004 7:24 PM Pacific Standard Time Message-id: Arny said: "Cal Cerise" wrote in message .com Among people who buy expensive commercially built "High End" stereo equipment, roughly a third to a half-very roughly-buy some tube equipment and about a fifth buy nothing else. A tenth , very roughly again, listen only to analog (or 'analogue'), i.e. phono records and very many of these (though not all) have equipment with no semiconductors at all or not in the signal path. These are rough and unscientific figures but I'd bet they are pretty close: three dealers I've asked pretty much concur. Just guessing here, but all 3 dealers probably carried tubed equipment. Just for reference, there are at least 10 stores in my area that are arguably selling high end audio. Only one of them carries tubes and he has the smallest store of the bunch. Perhaps you would like to pick a city that's a bit more culturally sophisticated than Detroit as an example. Boon I think you'd be pretty hard pressed to find a high end store in L.A. That doesn't carry any tube equipment. I can't think of any off the top of my head. OTOH and can name at least eight stores that do carry some tube equipment just off the top of my head. |
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#29
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Paul wrote: Combined with the author's Howard Cosell-like writing style and total lack of fact checking (he lists the manufacturer of Audio Precision audio test equipment as Thurlby Thandar, a Brit company about as far from Beaverton, Oregon as could be imagined!) Thurlby Thandar is the UK agent for AP. Graham |
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#31
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Arny Krueger wrote JBorg" wrote If our empirical senses are faulty, That's a scientific fact, which is well known. If our senses were not faulty there would be no need for microscopes or telephones. what would be an example of a properly controlled listening "test" which would circumvent this problem ? Please see www.pcabx.com for examples. Please see Dr. Corbett's commentary about pcabx dated 11/27/04, RAO Thread Title: Let's do some "scieenccece" in the Hive http://tinyurl.com/4kkxa ************** I had someone do an experiment for me using PCABX. As soon as I saw the data, I knew something was wrong, as the numbers from PCABX could not possibly be right. It took only a few minutes to find these errors in Arny's code: ... ptable(12, 1) = 1.642 ptable(12, 2) = 0.2 ptable(13, 1) = 2.072 ptable(13, 2) = 0.25 should be 0.15 ptable(14, 1) = 2.706 ^ ptable(14, 2) = 0.2 should be 0.1 ptable(15, 1) = 3.17 ^ ptable(15, 2) = 0.075 ... I sent Arny an e-mail reporting this, but I never got a reply to that e-mail. (He had replied to other e-mail I had sent to that address before that.) Those typos are only part of the problem with PCABX. I've been teaching college and university math classes for over thirty years, so my BS detector is well calibrated. But its meter pegs when I read what Arny says about scientific and technical issues involving mathematics, statistics, and design of experiments. You know the feeling when you are in a store and you overhear the salesman unloading a pile of BS on an unsuspecting customer? It's pretty much the same whether it is Radio Shack, or Best Buy, or Lafayette Radio, or an audiophile salon, and Arny brings it to the Internet. When someone follows Arny's advice on statistical design or analysis, you know it is a double blind experiment---it's a case of the blind leading the blind. (1) What Arny calls the "probability you were guessing" is apparently what the rest of the world calls a "p-value". I wrote "apparently" because PCABX cannot even calculate those numbers correctly; even if he had the right numbers, Arny obviously does not understand what they mean. In an ABX experiment, a p-value is calculated under the assumption that the subject is guessing. For instance, if a subject gets 14 correct in 16 trials, we say p = .002 because IF someone is guessing (with 50% chance of a correct answer on each trial) THEN the probability that he will get 14, or 15, or 16 correct in 16 trials is approximately .002. Arny has this bass-ackwards. He claims that IF someone gets 14 correct THEN the probability is .002 that the person was guessing. Of course there is absolutely NO logical or scientific support for that---it is entirely a result of Arny's failure to comprehend what the calculations are about. The fact that Arny refers to a p-value as a probability that the test subject was guessing is a dead giveaway that he has no clue about how statistical science works. (2) There are several reasons why PCABX reports bogus numbers for p-values: One reason is the typos I already mentioned. Another is the fact that Arny based his calculations on part of what David Carlstrom presented as the statistical basis for the original ABX comparator. Carlstrom mentioned two tests---one was based on a binomial distibution and a second was based on a chi-squared distribution. The binomial approach leads to an exact solution for testing H_0: theta = .5 vs H_1: theta .5 where theta is the single-trial probability of a correct answer. Thus theta = .5 means the subject is guessing with the same chance of success as flipping a fair coin, and theta .5 means he is doing better than that. That is an appropriate test if you want to see if a subject is doing *better* than chance would cause him to do. But Carlstrom made an error when he proposed the other test. He described a chi-squared procedure that tests H_0: theta = .5 vs H_1: theta not equal to .5. Now this compares chance behavior to *dfferent-from-chance* performance. Since that includes theta .5 as well as theta .5, the numbers generated this way are off by a factor of two from what would be comparable to the binomial test. This is obvious to anyone with real statistical training, but not to someone who naively copied a formula out of a book and coded it into a computer program. Of course a competent statistician would know how to adapt that chi-squared procedure to the sort of test that Carlstrom described with his binomial plan. Arny's PCABX uses the flawed chi-squared approach, so his calculations are biased; PCABX reports larger p-values (hence less-significant results) than it should. (That error is not quite as far off as a factor of two because there are other errors from approximating a discrete distribution by a continuous one; since they are in the opposite directions, the errors partially cancel.) To see this effect search Google Groups for the Usenet article with Subject: Statistics and PCABX (was weakest Link in the Chain) Newsgroups: rec.audio.high-end Date: 2004-01-13 (3) Yet another issue is that some of the numbers PCABX returns are not calculated by standard procedures at all. Although Arny claims that PCABX follows recognized scientific practice, the fact is that some of the numbers PCABX returns are pure fabrication. Maybe because Arny did not understand what a p-value is, or maybe because he did not realize that he based his calculations on an inappropriate method, PCABX reports p-values of 1 when the observed data show less than half the trials with correct answers. This is NOT a standard calculation based on techniques in any textbook I'm aware of. It also does not agree with the methods described in http://www.pcavtech.com/abx/abx_p9.htm which Arny cited earlier in this thread as an authoritative reference. If Arny has a specific citation of a reference showing how someone with pencil and paper (and perhaps a simple calculator) can duplicate the numbers PCABX comes up with, I'd like to see it. So it's clear that the analysis side of PCABX is broken in many ways. It is also the case that he experimental design part has problems. Although much effort went into refining experimental technique, there appears to be very little awareness of the rest of experimental design. Arny's Ten Commandments^H^H^H^H^H^H^H^H^H^H^H^HRequirements are NOT sufficient to make a good listening experiment. No matter how well you try, the reality is that if a test has only one trial, there is a 50% type I error risk. The ONLY way to reduce that is statistical---you need more trials. Once you do that, there is the issue of how many trials to do, and how many of those are needed to pass the test. PCABX suggests 14 correct in 16 trials, even though that is a really bad choice. If the effect being tested is small, say near threshold, then the 14/16 test will usually (80% of the time) _fail_ to detect a real effect. If the effect is large, then 16 trials is wasteful. A test with far fewer trials may be adequate then. There are plenty of designs that are better than 14/16, but it would be hard to find one that is worse. Once again, Arny gets it bacwards. He starts with 16 trials, then picks 14 (it used to be 12) as a passing score. Of course a rational design might start with specified levels for type I and type II error risks, and then determine a sample size to achieve that performance. For a graduated collection of tests, such as would be the case if the links in the table near the bottom of http://www.pcabx.com/training/index.htm actually worked, we would need only a few trials for the easy samples but many more for the harder ones if we wanted comparable sensitivity of the tests. Using the same number of trials for different levels means that the tests do not have the same power (sensitivity); the result is that subjects will seem to have a threshold-style respnse even if their true response were a linear function of stimulus level. If the true response has a threshold then it is confounded with the test's power function, making interpretation of the results difficult. This is analagous to measuring a decreasing signal with a meter. As the signal level drops, the meter needs to be adjusted to read on a lower range (more sensitive) scale. If that is not done, a naive user may "see" that below some point there is apparently no response when actually there is some response below the current meter range. Using a fixed size of 16 trials over a broad range of stimulus levels will cause that sort of error, yet that is precisely what PCABX says to do. The statistical science in PCABX is Completely Ridiculous & Absolutely Preposterous, which we can abbreviate as CRAP. Lest anyone get the wrong imnpression, I want to be clear that I am in favor of properly-done scientific tests. ABX and similar tests can be properly done, but merely using an ABX data collection plan is no guarantee of a worthwhile experiment. A worthwhile experiment requires competent statistical design and analysis along with good experimental technique. No part is sufficient---all these are necessary. No matter how good the other parts are, if the statistical aspects are bungled, the experiment is ruined. Now I do not claim that good statistical practice is enough to make a successful experiment, but I do argue that failing to get the statistical stuff right is enough to botch the experiment. It is much the same as noting that neither level matching nor time-synchronizing nor blinding alone will make a good experiment, but missing any one can esily ruin on otherwise-okay experiment. ************************************* End report. |
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#32
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"JBorg" wrote in message
. com Arny Krueger wrote JBorg" wrote If our empirical senses are faulty, That's a scientific fact, which is well known. If our senses were not faulty there would be no need for microscopes or telephones. what would be an example of a properly controlled listening "test" which would circumvent this problem ? Please see www.pcabx.com for examples. Please see Dr. Corbett's commentary about pcabx dated 11/27/04, RAO Good idea. It shows what happens if one becomes obsessed with details, and loses the ability to figuratively see the forest for the trees. I see that none of the RAO trolls are bright enough to see the rather gross flaws in Corbett's little study. Let me also recommend the following: http://www.amazon.com/exec/obidos/AS...534735-0115334 |
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#33
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On Mon, 29 Nov 2004 19:59:57 -0500, "Arny Krueger"
wrote: "Cal Cerise" wrote in message . com Just guessing here, but all 3 dealers probably carried tubed equipment. Just for reference, there are at least 10 stores in my area that are arguably selling high end audio. Only one of them carries tubes and he has the smallest store of the bunch. Our definitions of High End audio are very different probably. Classic response of a high end snob. Basically, its the old "your high end isn't high end enough for me". What Cal no doubt wants to say is that these retailers can't be high end enough for him because they don't carry tubes. IOW, Cal wants to define the criteria so he can't possibly lose the discussion. Since *you* attempted to "define the criteria", isn't that *exactly* what you were doing, trying desperately not to "lose the discussion"? |
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On Tue, 30 Nov 2004 10:23:05 -0500, "Arny Krueger"
wrote: "JBorg" wrote in message .com Arny Krueger wrote JBorg" wrote If our empirical senses are faulty, That's a scientific fact, which is well known. If our senses were not faulty there would be no need for microscopes or telephones. what would be an example of a properly controlled listening "test" which would circumvent this problem ? Please see www.pcabx.com for examples. Please see Dr. Corbett's commentary about pcabx dated 11/27/04, RAO Good idea. It shows what happens if one becomes obsessed with details, and loses the ability to figuratively see the forest for the trees. I see that none of the RAO trolls are bright enough to see the rather gross flaws in Corbett's little study. Let me also recommend the following: http://www.amazon.com/exec/obidos/AS...534735-0115334 Thanks for the recommendation. Looks like a great read. BTW, god lies in the details, right? Or are you saying the God is just lying? |
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#35
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"dave weil" wrote in message
On Tue, 30 Nov 2004 10:23:05 -0500, "Arny Krueger" wrote: "JBorg" wrote in message . com Arny Krueger wrote JBorg" wrote If our empirical senses are faulty, That's a scientific fact, which is well known. If our senses were not faulty there would be no need for microscopes or telephones. what would be an example of a properly controlled listening "test" which would circumvent this problem ? Please see www.pcabx.com for examples. Please see Dr. Corbett's commentary about pcabx dated 11/27/04, RAO Good idea. It shows what happens if one becomes obsessed with details, and loses the ability to figuratively see the forest for the trees. I see that none of the RAO trolls are bright enough to see the rather gross flaws in Corbett's little study. Let me also recommend the following: http://www.amazon.com/exec/obidos/AS...534735-0115334 Thanks for the recommendation. Looks like a great read. I admit it, I immediately saw you in its target audience, Weil. Enjoy! |
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#36
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Just for reference, there are at least 10 stores in my area that are arguably selling high end audio. Only one of them carries tubes and he has the smallest store of the bunch. Perhaps you would like to pick a city that's a bit more culturally sophisticated than Detroit as an example. It's interesting to note that the first high-end audio salon in the country was in Detroit--Radio Specialties. It had the first comparison switching arrangement, allowing the customer to listen to a variety of speakers. Norm Strong |
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#37
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"Marc Phillips" wrote in message
Perhaps you would like to pick a city that's a bit more culturally sophisticated than Detroit as an example. Please define cultural sophistication in terms other than the number of audio shops carrying tubed audio gear, if you can. |
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#38
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On Tue, 30 Nov 2004 12:55:04 -0500, "Arny Krueger"
wrote: "Marc Phillips" wrote in message Perhaps you would like to pick a city that's a bit more culturally sophisticated than Detroit as an example. Please define cultural sophistication in terms other than the number of audio shops carrying tubed audio gear, if you can. How about a city that doesn't try to burn itself down once a year. |
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#39
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On Tue, 30 Nov 2004 12:29:22 -0500, "Arny Krueger"
wrote: "dave weil" wrote in message On Tue, 30 Nov 2004 10:23:05 -0500, "Arny Krueger" wrote: "JBorg" wrote in message . com Arny Krueger wrote JBorg" wrote If our empirical senses are faulty, That's a scientific fact, which is well known. If our senses were not faulty there would be no need for microscopes or telephones. what would be an example of a properly controlled listening "test" which would circumvent this problem ? Please see www.pcabx.com for examples. Please see Dr. Corbett's commentary about pcabx dated 11/27/04, RAO Good idea. It shows what happens if one becomes obsessed with details, and loses the ability to figuratively see the forest for the trees. I see that none of the RAO trolls are bright enough to see the rather gross flaws in Corbett's little study. Let me also recommend the following: http://www.amazon.com/exec/obidos/AS...534735-0115334 Thanks for the recommendation. Looks like a great read. I admit it, I immediately saw you in its target audience, Weil. Enjoy! Thanks, I will. Nice deceptive editing, BTW. |
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#40
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"dave weil" wrote in message
On Tue, 30 Nov 2004 12:55:04 -0500, "Arny Krueger" wrote: "Marc Phillips" wrote in message Perhaps you would like to pick a city that's a bit more culturally sophisticated than Detroit as an example. Please define cultural sophistication in terms other than the number of audio shops carrying tubed audio gear, if you can. How about a city that doesn't try to burn itself down once a year. Weil, you didn't even mention the riot at the basketball game! Let me guess, that news hasn't found its way to your burg yet, eh Weil? Inability to distinguish between third-world namesake inner *suburb* and more important and far larger vibrant metro area noted. Ironically, said riot happened in said vibrant metro area, but whatever. ;-) |
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