This is the only official one...Active and Obsolete Parts and Semiconductors - Rochester Electronics
Nah, the car's up in Canuckistan and will be running primarily at Mosport International Raceway. My partner's in Mississauga, just outside Toronto.
se
Thanks. Ultimately it was so my partner could tick off an entry on his bucket list, but it will be good PR for the company so is it's a bit of a win/win.
se
Should we talk about how to measure noise? On true random noise how do you get an RMS value?
If we look at the math to do the mean value we see it is an integral function. So how do we pick the limits of the integral? If we take all time we can include the big bang, but we probably want to look at a shorter time. So for a 15 minute segment of music we perhaps would also use 900 seconds for the limits.
If we wanted to measure this noise using a bolometer to beat the need for math, what frequency response range would it require? 1/1800 Hz to 40,000 Hz? What amount of headroom should we allow in the noise amplifier to prevent clipping? 160 dB (my general goal), 135 dB (reasonable range of hearing, 70dB (around the expected s/n limit)?
Now practically the common method is to use a Fluke model 87 true RMS meter, however you must not use the auto range function. When typical audio pink noise is more than 10% of the meters range it begins to clip and read low. So you have to do a manual range set and this limits you to 3 digit accuracy. (Be sure to power the meter up to 4 1/2 digit reading before manually setting the range.)
Now you will need a low noise amplifier and anyone following this thread knows that means low source impedance. But you also still need headroom. As a practical limit 30-40 dB of that is required to get readings to the 3 digit accuracy level.
So even if we can get a good estimate of the noise (We only live so long...), what does that mean to what we perceive? Fletcher Munson come in here. The stuff around 3000 - 5000 hertz counts the most.
Now for a practical issue I remember one tweaked phono preamp that had a power supply resonance that was nicely activated by record warp.
So signal to noise ratios can be very misleading. There are standard weightings when measuring such and they do help in comparisons. So there just might be personal opinion for any preference. This is perhaps influenced by the actual musical appeal.
As mentioned very few collect old bad records, so that is one bias.
(But of course the mood on this thread is that J.C. is always wrong.)
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ES,
The argument really comes down to those who only want to look at purely objective measurements and those who want to enjoy the music and don't really care how you produce that enjoyment. I don't think that all of us believe John is wrong in his approach, it is the one he has chosen to pursue for most of his adult life. I have a friend who I have watched take old music and spend inordinate amounts of time cleaning up, removing clicks and pops, rebalancing the highs and lows, spending perhaps days on one song, one at a time. Perhaps in his eyes it was worth it to do that, someone else may be just as happy listening to the clicks and pops and technically this would be inferior but it really is up to the individual listener what is important. I have no problem enjoying a vinyl album, nor a great recording on CD, I think the technical pursuit is something that needs to go forward, to improve what we can improve, but when the technical aspect becomes more important than the music the reason for music is just lost.
The argument really comes down to those who only want to look at purely objective measurements and those who want to enjoy the music and don't really care how you produce that enjoyment. I don't think that all of us believe John is wrong in his approach, it is the one he has chosen to pursue for most of his adult life. I have a friend who I have watched take old music and spend inordinate amounts of time cleaning up, removing clicks and pops, rebalancing the highs and lows, spending perhaps days on one song, one at a time. Perhaps in his eyes it was worth it to do that, someone else may be just as happy listening to the clicks and pops and technically this would be inferior but it really is up to the individual listener what is important. I have no problem enjoying a vinyl album, nor a great recording on CD, I think the technical pursuit is something that needs to go forward, to improve what we can improve, but when the technical aspect becomes more important than the music the reason for music is just lost.
A spectrum of the demon at work would suffice. The second law, etc. is not a matter of opinion. If someone has a device that they say destroys charge or does mechanical work at a distance with no source of energy, the burden of proof is on them.
All these wonders of science only useful for audio what a shame.
I have observed this scenario many times.
In most cases, the music was out of the game from the beginning.
George
Sy,
While I understand that perpetual motion is not possible do we because of this give up on ever more efficiency in design? Obviously not, but are any of these results any less important though we know we can never get to no energy loss, an asymptotic point where you can never reach? I would suppose that there were many who would have said that super conductivity was also impossible and the pursuit of this was silly, but look at the work that has been done. Perhaps those who try to invent the perpetual motion machines will find something useful even if they can never meet the ultimate goals of no energy loss. Sometimes things come from those who we all call crazy, something so unbelievable that nobody else would even look there, a new way of looking that make no initial sense at all.
While I understand that perpetual motion is not possible do we because of this give up on ever more efficiency in design? Obviously not, but are any of these results any less important though we know we can never get to no energy loss, an asymptotic point where you can never reach? I would suppose that there were many who would have said that super conductivity was also impossible and the pursuit of this was silly, but look at the work that has been done. Perhaps those who try to invent the perpetual motion machines will find something useful even if they can never meet the ultimate goals of no energy loss. Sometimes things come from those who we all call crazy, something so unbelievable that nobody else would even look there, a new way of looking that make no initial sense at all.
How do you really get an accurate spectrum of noise? I think we aren't communicating.
Superconductivity is impossible.. Impossible, I tell ya..!!
Work?? What work?? It's all play.
jn
It could happen. And Scarlett Johannsen could suddenly turn up at my house demanding sex. Similar probabilities. A complete non-understanding of basic physics pretty much precludes someone from making any significant advance.
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