Although Ed Simon's input may seem 'off the wall' it is actually a lot more useful than practical jokes or other 'chit-chat' found all through this thread, and it FORCES a different kind of thinking that is a combination of analog and digital (if I might call it that). I have had to tackle similar problems, even recently. For example, I had to 'analyze' the protection circuit that we have used for the last 20 years with our power amps, and try to understand it. I was so flummoxed at first, I was tempted to 'hire' Ed Simon to figure it out for me. (true story). It is a DIFFERENT way of thinking about circuit design that can certainly 'clean some cobwebs' when done in a serious way. Another example that is similar is being generated for Linear Systems as we speak, by Kirkwood Rough, in the form of a sophisticated jfet matching apparatus. I needed a 'block diagram' before I could figure that one out.
In fact, Ed, why don't you make a block diagram, and put it up, so that the rest of us can more easily follow your design decisions?
In fact, Ed, why don't you make a block diagram, and put it up, so that the rest of us can more easily follow your design decisions?
Thanks for the explanation Simon, very interesting design and idea. Yes, design issues are of value here IMO.
Thanks, for your comment. So I will add a bit more trivia.
The other important issue is hysteresis. When you use a comparator there may be some bounce as you go past the trigger point. That is why there are large capacitors in the feedback loop of the op amps. It gives a smoother input, less noise and minor variations.
I also at first used 5% positive feedback to try and make sure the switching had a bit of dead zone. This did not seem to work as the output of the comparator also drove other loads. As the relay chattered when closing this would have been a real problem. The motor load would have kept arcing across the relay contacts and burned them out in a hurry. So adding a capacitor across the relay coil slowed opening down enough that the relays do a smooth switching action. If the capacitors were too big the relays would open too slowly and again burn out early.
A special tip is that on the top of most sealed relays is a small plastic button. This is there because during handling they want the relay to stay clean, but in use the relay does need to breath to prevent a build up of ionized gas and early arcing. So when you see that button or tab be sure to break it off before use!
Well, what about audio in general? Why do many audio manufacturers go to such lengths to make some audio product, that many could care less about, or would be mistaken for something else, perhaps much less expensive in an ABX double blind test?
Today, I heard on the news channel that someone ran a 'controlled test' of different price wines with generally acknowledged differences in quality. Apparently, there was no statistical difference between the different wines. Do you believe this? Do you believe that this was an 'objective' test? Does this fit with YOUR reality? I suspect that the test was on the 'up and up' and only 'ignorable' factors can be cited.
It is the same with audio reproduction. A test can be set-up, and NO statistically difference will be found. Is this YOUR reality regarding audio reproduction? If so, what are you doing here, reading this thread? '-)
Today, I heard on the news channel that someone ran a 'controlled test' of different price wines with generally acknowledged differences in quality. Apparently, there was no statistical difference between the different wines. Do you believe this? Do you believe that this was an 'objective' test? Does this fit with YOUR reality? I suspect that the test was on the 'up and up' and only 'ignorable' factors can be cited.
It is the same with audio reproduction. A test can be set-up, and NO statistically difference will be found. Is this YOUR reality regarding audio reproduction? If so, what are you doing here, reading this thread? '-)
Robert Parker, acknowledged by many to be the greatest wine critic in the world and by some as the greatest critic of anything in the world claims to be able to know by smell and taste alone over 100,000 wines which he can indentify blind. Many would accept this claims as largely valid. If you ever studied the price of fine wine on the world market and by this I'm referring to auction prices, especially during the period from around the early 1990s to recently, you'd know they largely follow Parker's ratings.
There is not necessarily a correlation between the price of wine and its quality. But reviewers like Parker and Wine Spectator Magazine drive demand while supply of a particular wine from a particular vintage remains fixed initially and then dwindles as it is consumed.
Were the prices of audio equipment driven the same way, I suspect many very expensive products would fall drastically on the resale market. To some extent, I think nostalgia plays a role. Early MacIntosh and Marantz amplifiers and preamplifiers are in this category but even Scotts and Fisher fall in this slot. Name brand recognition and loyalty also play a role. Other than that it's often driven by reviewers whose objectivity is highly questionable. I certainly put no stock in their opinions these days.
I've tasted with Parker. I seriously doubt it's true, but as you said, it helps drive fashion in the high end wine market. However, for actual certifications, one must taste blind and do correct identifications. For qualification as a judge at major competitions, one must demonstrate (again, blind) one's ability to detect faults and distinguish wines. Parker will not do blind tasting in any situation where he could potentially be embarrassed, so is not taken seriously (as a taster, as opposed to a market maker) by most pros.
Audio reviewers just have to be able to blather stuff that supports their industry. No qualifications, no knowledge, just the ability to sound authoritative and feed the machine.
John's grasp on sensory testing is minimal. A third hand news story translated through his agenda is nothing that can be reasonably commented on.
Audio reviewers just have to be able to blather stuff that supports their industry. No qualifications, no knowledge, just the ability to sound authoritative and feed the machine.
John's grasp on sensory testing is minimal. A third hand news story translated through his agenda is nothing that can be reasonably commented on.
Back in the late 1970s I thought I'd lost my taste for wine. Then I found a little book by David Peppercorn on a shelf in a wine store and bought one of his suggestions. That's when I realized I needed professional advice about buying wine. I'd wasted a lot of money on wines I didn't like that I'd have avoided if I had some impartial guidance. I eventually learned that there are those who sell wine and those who sell wine buying advice and never to confuse the two.
During my wine buying and drinking mania days I subscribed to Wine Spectator Magazine and bought some of Parker's books. I'd say on the whole, my preferences coincide more closely with James Suckling and James Laube than with Parker. However, Parker was widely regareded as the number one reviewer and his opinions, not WS's drove the market (that's easy to demonstrate with several instances.) In fact it was Parker who literally invented the wine review market as opposed to the wine selling market. He claims to have received death threats for some of his reviews and recieved some huge prize from the French government for his work. He was the original Ralph Nader/Consumer Reports of wine and explains how he chose that path instead of being a practicing attorney in his books. I've read others like Michael Broadbent, Hugh Johnson, and Jancis Robinson but WS and Parker remain my guides about what to buy and what to avoid. Experience (mistakes) has taught me countless times to ignore any advice from the wine merchants themselves.
QPR is the quality price ratio, that is how good a wine is judged to be compared to its price. It is remarkable how often the numerical ratings of Parker and WS agree or are close although their subjective descriptions sometimes vary so wildly, that is their tasting notes you'd hardly know they were talking about the same wine. I've largely lost interest in wine and I think the prices today for prestigious fine wines are as insane as for high end audio equipment. Fortunatly on both fronts I'm lucky. I've got a cellar full of classified Bordeaux mostly from the 1989 and 1990 vintages and I've engineered my own audio equipment to suit what my hearing tells me is accurate and pleasing. I no longer spend much money on either. When I do buy wine or audio equipment, I look for the highest QPR possible.
Couldn't help it, just had to post this one. He is truly amazing.
He picked 43 out of 50 bottles in a true blind test, the next so called 'expert' managed 4 !
Den otroliga blindprovningen
Yes, it's in Swedish, run Chrome or Google Translate.
He picked 43 out of 50 bottles in a true blind test, the next so called 'expert' managed 4 !
Den otroliga blindprovningen
Yes, it's in Swedish, run Chrome or Google Translate.
That's called politics overhere.
I gathered Mr Parker is on the verge of retirement, the aftermath should be interesting.
Indeed. He's done a fine job of making rich and powerful people richer and more powerful. That gets you medals. There's a reason that many vignerons believe that "Bordeaux" is plural for "bordel." Some of the folks he has hired to take over regions for him are quite good. I'll particularly single out David Schildknecht, who is a truly excellent taster and really understands the ins and outs of wine production. Others, well...
Point is, though, that as fashion-driven as the wine business is, real pros are aware of the biases of sighted evaluation and *universally* use double blind methods to remove those biases. No phony excuses about "pressure" or "testing obscuring differences." You either taste a difference or you don't. Frauds, phonies, and self-proclaimed geniuses just don't cut it.
- Status
- Not open for further replies.