Jim,
I do enjoy too much alcohol (the best amount is none. We previously thought that small amounts of alcohol (eg red wine) conferred some protective benefits in relation to cardiovascular diseases (think stroke and heart attacks) but it turns out those studies were confounded with the Mediterranean diet that the much of the Italian and Greek community enjoy.
Reference:
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2802963
https://www.cdc.gov/alcohol/about-alcohol-use/index.html
https://www.who.int/news-room/fact-sheets/detail/alcohol
I once posed a question to one of the most hyped/publicised previously not for profit but now completely all in on profit and its answer was completely wrong, AND it referenced to something I had written on diyAudio.!!
How can an answer to a question be
based on something I wrote (giving me back what I written?)
That should be reserved for the (best) politicians and CEOs.
Around that time i decided to let the sentient beings decipher my graphs.
But I hear what you aes saying. Resistance isfut… V / I
I do enjoy too much alcohol (the best amount is none. We previously thought that small amounts of alcohol (eg red wine) conferred some protective benefits in relation to cardiovascular diseases (think stroke and heart attacks) but it turns out those studies were confounded with the Mediterranean diet that the much of the Italian and Greek community enjoy.
Reference:
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2802963
https://www.cdc.gov/alcohol/about-alcohol-use/index.html
https://www.who.int/news-room/fact-sheets/detail/alcohol
I once posed a question to one of the most hyped/publicised previously not for profit but now completely all in on profit and its answer was completely wrong, AND it referenced to something I had written on diyAudio.!!
How can an answer to a question be
based on something I wrote (giving me back what I written?)
That should be reserved for the (best) politicians and CEOs.
Around that time i decided to let the sentient beings decipher my graphs.
But I hear what you aes saying. Resistance is
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Like billion of people on the planet, me too, don't feel guilty about that. Red wine is known to be good at low doses, don't trust studies, some centenaries people drink wine regularly.
https://www.bluezones.com/2017/08/longevity-link-how-and-why-wine-helps-you-live-longer/
Some medicals doctors in France don't see that badly, the question is "how many bootle in a week ? Good response is two for the maximun...
Disclaimer to be politicaly correct, water is the best drinking. Too much sugar transform or not in water is toxic.
Of subject but funny...
I agree air is the problem, we don't see it but it has viscoelastic property. How is the contribution of compressed air in distortion ?
This is why I always prefer open baffle for bass reproduction.
.
Air must be compressed A LOT before it occurs in THD - no issue at all for "normal" speaker enclosures. It get's interesting with pressure chambers and maybe compression drivers.
Those studies saying red wine is good are outdated. This is what we learnt in medical school in early C21.
This is now wrong and will filter through medical school in years to come.
We are talking confounding factors.
Eg. People who listen to Linkwitz LX521 and then declare “open baffle bass is better” may be preferring that bass for different reasons
Could it be that he uses one of the best 10” woofer's on the market, in what is effectively a folded DSRI arrangement, and only above ~40Hz.
Hypothesis: very low distortion?
This is now wrong and will filter through medical school in years to come.
We are talking confounding factors.
Eg. People who listen to Linkwitz LX521 and then declare “open baffle bass is better” may be preferring that bass for different reasons
Could it be that he uses one of the best 10” woofer's on the market, in what is effectively a folded DSRI arrangement, and only above ~40Hz.
Hypothesis: very low distortion?
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With respect, I am slightly skeptical of large public health studies like this. I am old enough to remember when similar large population studies concluded that dietary animal fat, particularly beef fat and pork fat, were very harmful. Everyone responded (1970's) by replacing animal fat with vegetable fat, including hydrogenated vegetable oil and various trans fats. We all switched from a fat which humans have been consuming for 100,000 years to some new industrial-produced fats which were never a part of anyone's diet before 1950, and which we were not evolutionary prepared to eat. Later, another study concluded that all dietary fat in general was harmful, and it should be reduced to a minimum. People again responded (1990's) by consuming a lot more fat-free foods, which contained a lot of sugar and highly processed ingredients. We are now just discovering how bad all that crap is. I am still waiting for an apology from all those scientists for getting it, not just wrong, but monumentally wrong. All of those studies should have been carefully caveated so that people would understand that conclusions were just informed guesses, not definitive irrefutable facts.
"Kinetic energy is 1/2 * mass * velocity ^2" is a definitive irrefutable fact. "Animal fat is so bad for us we should replace it with an up-till-recently unknown chemically altered vegetable oil without any studies of its possible harmful effects" is not a definitive irrefutable fact... but it was presented to the general public as if it were.
There was another study in the 1970s that concluded that eating cherries caused cancer. In fact the whole of the 1970's and 80's was filled with an ever expanding list of things which caused cancer. Most of the studies were rubbish.
No scientist gets any recognition (or more grant money) for discovering that an existing bit of knowledge is still valid. But come up with a finding which refutes that long-standing bit of knowledge, and the papers get published and you get to appear on podcasts and give lectures on other continents. Everyone has biases and everyone responds to incentives. It is very tempting, and easy, to parse the data until we find some correlation, imagine some causation, and race off to get published. So yes, when it comes large population studies, call me skeptical.
Yes, good point.
Jim,
You have every right to skeptical about medical science. In fact everything should be treated with a health dose of skepticism. It is at still at its infancy, IMHO. In fact antibiotics were only discovered less than 100 years ago (1928; Fleming). Prior to that people may have died from a simple wound infection that becomes gangrenous. WWI and prior.
Can you imagine that? Before that there were all kinds of strange treatment, like blood letting, or drill holes into people skulls to “let out the pressure” We, as in the human community.
Even today we know that it’s not sugar the problem. How we know? Even sugar free alternatives which has zero calories (artificial sweeteners) cause weight gain.
How is this possible? Isn’t calories the cause of weight gain?
Is there something about tasting sweet that triggers a cascade of chemicals signals in our body to store energy as fat. Perhaps we haven’t evolved enough to to know that we don’t need to store all that energy, like we did 1000 years ago when food was scarce.
And if caffeine is the cause for wakeness, why, if you have a decaf in the afternoon, do you still have problems getting to step?
There’s a lot we still don’t know.
BUT, for now, large scale metanalysis is the best level of evidence we have. It’s called Level 1 evidence. But it doesn’t mean a blanket decision for everyone.
One of the challenges in the modern era and a pushback on science that we are experiencing ie. no to vaccines, germ don’t cause infection.* In fact theirs a whole movement of increasing distrust of institutions of authority eg. University, government, hospitals.
It leads to people to take decisions into their own hands. And of course we do our best to support people being autonomous. On the other hand, sometimes it goes too far. The late Steve Jobs is an example of going too far. He had pancreatic cancer but declined surgery multiple times opting for alternatives. What did he think, that every surgeon was trying to rip him off?
The evidence showed that his type of tumour had a high chance of cure, if operated on early. This is unlike many other pancreatic cancers, which really do have low chance of success, surgery or not.
There was a lot of debate over whether PSA testing function as a screening tool. Based on our best available evidence today, we should be doing PSA testing! But we (human community) didn’t know that 20 years ago. (Prostate cancer was what the late Sigfried Linkwitz died of)
Or FOBT testing from, now from age 45 (not 50, for bowel cancer). This wasn’t the case 20 years ago.
There’s a quote from a former Dean of Harvard Medical School.
"Half of what we are teaching you is wrong. Unfortunately, we don’t know which half."
What he means is that science has an always progressing. It’s true that medicine doesn’t have as strong a scientific base as, say, physics.
But remember, Newton thought gravity was related to massive objects. We now know that it’s more correctly understand as to a curvature in space time.
But let’s not throw out the baby with the bath water.
*only partly correct. It’s better understood as immune response and immune dysregulation commencing from initial trigger eg. Bacterial, viral, fungi, prions, self (auto-immune), ?other causes
You have every right to skeptical about medical science. In fact everything should be treated with a health dose of skepticism. It is at still at its infancy, IMHO. In fact antibiotics were only discovered less than 100 years ago (1928; Fleming). Prior to that people may have died from a simple wound infection that becomes gangrenous. WWI and prior.
Can you imagine that? Before that there were all kinds of strange treatment, like blood letting, or drill holes into people skulls to “let out the pressure” We, as in the human community.
Even today we know that it’s not sugar the problem. How we know? Even sugar free alternatives which has zero calories (artificial sweeteners) cause weight gain.
How is this possible? Isn’t calories the cause of weight gain?
Is there something about tasting sweet that triggers a cascade of chemicals signals in our body to store energy as fat. Perhaps we haven’t evolved enough to to know that we don’t need to store all that energy, like we did 1000 years ago when food was scarce.
And if caffeine is the cause for wakeness, why, if you have a decaf in the afternoon, do you still have problems getting to step?
There’s a lot we still don’t know.
BUT, for now, large scale metanalysis is the best level of evidence we have. It’s called Level 1 evidence. But it doesn’t mean a blanket decision for everyone.
One of the challenges in the modern era and a pushback on science that we are experiencing ie. no to vaccines, germ don’t cause infection.* In fact theirs a whole movement of increasing distrust of institutions of authority eg. University, government, hospitals.
It leads to people to take decisions into their own hands. And of course we do our best to support people being autonomous. On the other hand, sometimes it goes too far. The late Steve Jobs is an example of going too far. He had pancreatic cancer but declined surgery multiple times opting for alternatives. What did he think, that every surgeon was trying to rip him off?
The evidence showed that his type of tumour had a high chance of cure, if operated on early. This is unlike many other pancreatic cancers, which really do have low chance of success, surgery or not.
There was a lot of debate over whether PSA testing function as a screening tool. Based on our best available evidence today, we should be doing PSA testing! But we (human community) didn’t know that 20 years ago. (Prostate cancer was what the late Sigfried Linkwitz died of)
Or FOBT testing from, now from age 45 (not 50, for bowel cancer). This wasn’t the case 20 years ago.
There’s a quote from a former Dean of Harvard Medical School.
"Half of what we are teaching you is wrong. Unfortunately, we don’t know which half."
What he means is that science has an always progressing. It’s true that medicine doesn’t have as strong a scientific base as, say, physics.
But remember, Newton thought gravity was related to massive objects. We now know that it’s more correctly understand as to a curvature in space time.
But let’s not throw out the baby with the bath water.
*only partly correct. It’s better understood as immune response and immune dysregulation commencing from initial trigger eg. Bacterial, viral, fungi, prions, self (auto-immune), ?other causes
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At least that would still be done in the case of subdural haemorrhage, but perhaps with a little more elegance. 😎
@tktran303 I'm like @hifijim very skeptical about some people doing medical science , not really (medical) science. Too much conflict of interest, depend on who paid the studies. The distrust comes from that, medical world is becoming industrial and should be craftmanship....
In France we are lucky to have Didier Raoult and I'm very happy to watch its podcast, very interesting the sharing of its experience. And he say the same thing, science/knowledge is progressing !
@IamJF Air is not very linear, have a mass, elasticity and damping ...
In France we are lucky to have Didier Raoult and I'm very happy to watch its podcast, very interesting the sharing of its experience. And he say the same thing, science/knowledge is progressing !
@IamJF Air is not very linear, have a mass, elasticity and damping ...
jerome69,
The shift in science was driven by the removal of lower-alcohol red wine from the school cafeteria. If I recall correctly, red wine sales were cut in half during the 1980s.
Here's some nostalgia:
The shift in science was driven by the removal of lower-alcohol red wine from the school cafeteria. If I recall correctly, red wine sales were cut in half during the 1980s.
Here's some nostalgia:
I once did a short research during my helmholtz resonator studies.
The pressure variation of usual acoustic events (maybe except for very big explosions or rocket launches) is only very tiny fraction of static atmospheric air pressure.
I don't find anything to disagree with in your entire post. In fact, I mostly agree.
I don't have an issue with the individual physicians and surgeons, dentists, optometrists, pharmacists, etc. They generally follow the rule "first do no harm". In my personal experience, my physicians have been highly competent, caring, and wise. Doctors in the USA are overworked and many suffer from burnout, yet my doctors continue to do their work with great dedication.
Public health experts on the other hand, well I find myself questioning their decisions and actions from time to time. Instead of "first do no harm", they seem to follow the mantra of "doing something is better than doing nothing". And yes, in the face of a polio, measles, or covid-19 epidemic, swift action is called for. But there are many, many minor health issues which they seem to lack a sense of proportion.
It is not the large population metadata studies themselves that are the source of my ire, it is the government or public policy over reaction to the study.
Back to low distortion 12" woofers ! ........ j.
@asshatter Nowadays you cannot watch this thing in our TV in France, it will be a scandal. In school restaurant they stop wine for children below 14 year old in 1956. The second video is funny, the little girl (8 year old) like Pastis with mint (we call this "Le Perroquet" ). Now the problems are different,some are complain about sexuality lessons in the school for children...
Yes the air pressure variation seems not so high in a box. I see a paper on measurement air noise distortion Measurement of Turbulent Air Noise Distortion in Loudspeaker Systems
This technique is used to measure defects . At these low frequency, the measure of distortion can be pollute by the quality of the box, the driver....
e.g. Measurement and Perception of Irregular Loudspeaker Defects
Yes the air pressure variation seems not so high in a box. I see a paper on measurement air noise distortion Measurement of Turbulent Air Noise Distortion in Loudspeaker Systems
This technique is used to measure defects . At these low frequency, the measure of distortion can be pollute by the quality of the box, the driver....
e.g. Measurement and Perception of Irregular Loudspeaker Defects
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I concur! 😉
Now, has anyone seen independent verification of Grimm's Audio claim that their Motion Feed Back and current drive enabled SB1 subwoofer indeed has "30dB less distortion"
It appears to me they are using is a subwoofer R off the Shelf
The combination of current drive and motional feedback seems overkill to me. Might one or both of these not work 100%? Imho motional feedback results in a kind of current drive.
I remember reading a paper many decades ago about low frequency human perception that used "headphones" that had a pair of 12" drivers to achieve low levels of distortion at low frequencies and high levels. It may have been in relation to the updated equal loudness curves, post Fletcher Munson.
If one wanted to repeat these experiments today, headphones using a pair of Purifi PTT10.0X04-NAB-01 drivers would provide ultra low distortion even at 120dB, 20Hz.
Hi, current drive could work for whole bandwidth alone, if driver main resonance is tamed by the box, IOW missing electrical damping is replaced with mechanical damping. This means big box though. Motional feedback could reduce box size to very small by controlling the driver position perfectly at resonance regardless of any damping or box alignment. If I remember correct motional feedback doesn't work much higher than the main resonance due to noise and cone breakup, and likely other reasons I need to go and check.
edit. Plenty of MFB info online. Like this post in thread 'Motional Feedback (MFB)?' https://audiosciencereview.com/forum/index.php?threads/motional-feedback-mfb.27956/post-967653
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We have a dedicated forum here about MFB (legacy of Philips, I guess). And quite some experienced developers. I'm not one of them.
For a sub MFB can make sense, especially when you can't predict behaviour, mainly with large signals/cone amplitudes. Real time info on the whereabouts of the cone is very useful. But in the end the bandwidth of the measurement system is limiting the useful range.
Current steering normally is more useful way above Fc. Current happens to be linearly related to excursion if the driver is in the resistive frequency region and thus it makes sense there. Not so in the resonant frequency region, as the relation between current and cone position is everywhere around the block and hard to catch in a simple linear function.
For a sub MFB can make sense, especially when you can't predict behaviour, mainly with large signals/cone amplitudes. Real time info on the whereabouts of the cone is very useful. But in the end the bandwidth of the measurement system is limiting the useful range.
Current steering normally is more useful way above Fc. Current happens to be linearly related to excursion if the driver is in the resistive frequency region and thus it makes sense there. Not so in the resonant frequency region, as the relation between current and cone position is everywhere around the block and hard to catch in a simple linear function.
Just use a Purifi driver and you already have 20dB less distortion ;-)
I will first use a double bass array and perfect setup in the room before thinking about driver feedback. But for the last step it's an interesting technique.