Yah, been there done that, but on a 90 foot Grove. Were they using the sliding lock on a cable, or clipping their lanyard to a hardpoint above their D ring?
From what I remember, in the event somebody ends up dangling from a body harness for a half hour or so, the EMT's MUST have training on how to deal with the person after they get them down. Has something to do with return of blood flow to the legs and how the heart deals with it. Apparently there is a small possibility of cardiac arrest.
jn
What useful information is lost through all the 'romp and stomp' that plagues this thread, is why I, at least, strive to keep it going, even though I have to repeat myself.
I am not interested here in ready-made circuits, that amateurs can build from their spare parts. I am interested in sharing what it takes to make a really successful audio product, above and beyond just a good measuring one.
This is where the importance of passive parts quality, power supply design and selection, circuit layout, and exterior shielding all play a part.
However, I have proved, at least to myself, that 'acceptable' designs can now be made with IC's, IF you correctly choose the right IC's for the job. In making the JC-3 phono preamp a success in the audio marketplace, I overcame a personal 'hurdle'. Now, this does NOT mean PERFECT or as good as absolutely possible, but satisfactory for many people who cannot afford super hi end, and cannot build something themselves.
I hope to continually impart what seems to 'work' in making a successful audio product, and it is certainly more than just an interesting circuit topology.
I am not interested here in ready-made circuits, that amateurs can build from their spare parts. I am interested in sharing what it takes to make a really successful audio product, above and beyond just a good measuring one.
This is where the importance of passive parts quality, power supply design and selection, circuit layout, and exterior shielding all play a part.
However, I have proved, at least to myself, that 'acceptable' designs can now be made with IC's, IF you correctly choose the right IC's for the job. In making the JC-3 phono preamp a success in the audio marketplace, I overcame a personal 'hurdle'. Now, this does NOT mean PERFECT or as good as absolutely possible, but satisfactory for many people who cannot afford super hi end, and cannot build something themselves.
I hope to continually impart what seems to 'work' in making a successful audio product, and it is certainly more than just an interesting circuit topology.
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Ha ha. Got a time machine?
THE test: "hey turn that thing off, don't you hear that?"
"...what? hear what? I don't hear anything..."
Believe me, life is simpler without hearing ultrasonics... it's troubling sometimes... can't get anywhere near that now.
Hi-fi becomes easier to get "good". Ha ha.
_-_-bear
How do you know the frequency spectrum of the "thing"? Did you, at least, play around with a calibrated oscillator?Ha ha. Got a time machine?
THE test: "hey turn that thing off, don't you hear that?"
"...what? hear what? I don't hear anything..."
Believe me, life is simpler without hearing ultrasonics... it's troubling sometimes... can't get anywhere near that now.
Hi-fi becomes easier to get "good". Ha ha.
_-_-bear
What's often the case is that the ultrasonics cause lower frequency components from less-than-perfect transducers. That's easy to verify. But still, I have known males near 30 with verified acuity in that range. Male, 40 is not something I've seen demonstrated yet.
Me, no way, even at 30, I was lucky to hit 19k.
And calibration is not an issue these days with digital sources.
Me, no way, even at 30, I was lucky to hit 19k.
And calibration is not an issue these days with digital sources.
I was playing in rock bands so I knocked out those pesky HF's by my early 20's. I did hear a story about Sydney Harman in his mid 80's walking in on some of his engineers doing a listening audition of a new amp design. He exclaimed "that amp is distorting!" Every one else was dumbfounded. Tested the amp more and old Sid was right. Go figure.
At work a good few years ago I was repairing a 600 Watt amplifier for a colleague in another department. No speakers in the lab, so we used a bunch of high powered 50 ohm loads. The amp whistled quite loudly and all of us used some calibrated sources, hand covering dial each time and adjust till whistle could just be heard. I was 36 years old and my personal cut-off was about 21.5Khz to 21.6, some of the others were stopping at sub 20K, but one luck 30 year old was hearing up to about 22K.
the proof was that without seeing the dial each of us would consistently stop at our own limit of hearing. If any of us had been trying to cheat it would have been more variable. It was a bit of fun to see where our ears were compared to each other.
Wrinkle
the proof was that without seeing the dial each of us would consistently stop at our own limit of hearing. If any of us had been trying to cheat it would have been more variable. It was a bit of fun to see where our ears were compared to each other.
Wrinkle
The late Gerald Strang, a pioneering composer of computer music, taught a course at UCLA one year. Class was held in the Electronic Music Studio, a little room in the bowels of the Mathematical Sciences building.
Gerald was fairly far on in years and had significant HF hearing loss. He was fond of demonstrating the equipment (Moog, Buchla) during his lectures. He would sometimes have a loud tone going out of one of the oscillators, and would say Well, we can turn the level down over here (indicating a control) OR simply raise the frequency to beyond audibility! At which point, with a grand gesture and big grin, he would turn the frequency control to where he couldn't hear anything, but unfortunately for the numbers of younger ears in the room, leave a most distressing and quite audible high-frequency signal screaming away out of the AR monitors, often right in someone's ear. Eventually someone would get up and turn the level down.
Gerald was fairly far on in years and had significant HF hearing loss. He was fond of demonstrating the equipment (Moog, Buchla) during his lectures. He would sometimes have a loud tone going out of one of the oscillators, and would say Well, we can turn the level down over here (indicating a control) OR simply raise the frequency to beyond audibility! At which point, with a grand gesture and big grin, he would turn the frequency control to where he couldn't hear anything, but unfortunately for the numbers of younger ears in the room, leave a most distressing and quite audible high-frequency signal screaming away out of the AR monitors, often right in someone's ear. Eventually someone would get up and turn the level down.
John, Stupid question. What are the complimentary JFETs doing in the feedback of the opamp from here? http://www.diyaudio.com/forums/anal...ch-preamplifier-part-ii-2405.html#post3068026
When I worked as a lead engineer of support and development of railway radio and electronics, one engineer had been waked up in the middle of the night and sent to a remote station to repair an equipment. They said, the dispatcher had a crappy voice, so he took spare microphone and microphone preamp, and left the town in the rear cabin of a cargo train. When he returned back he was very angry, because indeed the dispatcher has scratchy voice. He had also a scarf around his neck, and was drinking hot tea with honey and raspberry, to heal his throat...
An observation from the cheap seats is that quite a few interesting posting/observations/statements are quite quickly glossed over and surplanted with detailed discussions of sub 100db artifacts or measurements germain to the optical spectrum... (that's a joke son) .
John asked about quality audio pursuits to no real response a few weeks or more ago, although I trully believe that a large number of the people that struggle through the noise to examine this thread are really in pursuit of. I know that I was.
John Curl's reputation and career have been closely aligned with the pursuit of high performance, quality audio design for many years. To follow a thread based on his statement design and find a hostile environment bent on disproving it's fundamental ability to be cutting edge, sonically, must be quite confusing to the poor soul looking for enlightenment wading through the endless pages presented here.
Richard Marsh has been asking fundamental questions based on the reality that audio quality in the real world sucks, how can we move forward, similar followup... Oh well.
The whole point in my speaking out is that I have noted a few very interesting postings that deserved more attention, and doing so would possibly yield insite for all, that were glossed over and not examined with an open mind and egos in check.
I'll point back to Frank's (FAS42) postings and the follow up by Jan concerning (was it AC/DC) compressed recording (bad) and Franks addition of it to his must listen list as an example (good)... This when thought about, and from my experience, opens up an interesting avenue of discourse of the type worthy of this thread and it's namesake.
I don't have the bandwidth right now to put much time into this but think about how a very complex piece of music would appear in the compression discussion. And then think about what is involved in a piece of electronics that would allow it to keep all of the aspects of that recording sorted out, pure and clean sounding without the more dynamic aspects of the music stepping on the more subtle details... The signal still looks compressed in Jan's snapshots, but one system might allow you to hear a pin drop clearly with all hell breaking loose around it while another would turn it into sonic mush. Which measurement would point this out?
Mike
I appreciate your thoughtful comments, Mike. It has been a struggle to firstly get a system to work that well, and secondly to make people aware that this is a very realistic goal. My experiences have been that no matter how complex a piece of music, or sound making, that a setup refined up to the highest level will allow that level of unravelling to take place, in the ear/brain of the listener.
The key, and therefore the answer to your last question, from my point of view, is that low level, high in the audio spectrum frequency, distortion has to be minimised. Especially when the system is running at high average power levels. As an example, to test the capability of an unknown system I would use that AC/DC track, winding up the volume steadily and focusing on and listening to the image, the tonality of the cymbals only, nothing else, as the sound level increased. That would tell me almost everything significant about the system that I would need to know, to assess it ...
Frank
Frustrating -
Thx -- Two thumbs up to you -- sometimes it seems like the response is the equivalent of a blank stare and then moves to a completely different subject.
Thx -- Two thumbs up to you -- sometimes it seems like the response is the equivalent of a blank stare and then moves to a completely different subject.
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Agree Frank. And would add that power supply break-through (or Power Supply Rejection Ratio for us engineers ) would also play a large role.
But I would think that a regular S/N measurement, which gives us dynamic range, would capture that.
Don't forget that a THD+N measurement not only captures the distortion but also the noise floor (which includes power supply mush as well).
Some sophisticated audio measurement equipment (some dedicated like AP, some PC-based like Spectrum) can test equipment with a multifrequency signal (there is even an ISO standard test signal with 31 different frequencies, mimicking music). Under those circumstances you can see the minimum signal that can be reproduced.
A weak signal in the presence of a large signal will be clearly audible if it is above the noise floor, I would think.
Comments?
jan
) would also play a large role. But I would think that a regular S/N measurement, which gives us dynamic range, would capture that.
Don't forget that a THD+N measurement not only captures the distortion but also the noise floor (which includes power supply mush as well).
Some sophisticated audio measurement equipment (some dedicated like AP, some PC-based like Spectrum) can test equipment with a multifrequency signal (there is even an ISO standard test signal with 31 different frequencies, mimicking music). Under those circumstances you can see the minimum signal that can be reproduced.
A weak signal in the presence of a large signal will be clearly audible if it is above the noise floor, I would think.
Comments?
jan
How about testing with a mix of a constant amplitude low level, higher frequency and a much higher, variable level, low frequency and seeing how the modulation artifacts vary especially in regard to the high frequency component as the power supply is more and more stressed?
Frank
Agree Frank. And would add that power supply break-through (or Power Supply Rejection Ratio for us engineers
A weak signal in the presence of a large signal will be clearly audible if it is above the noise floor, I would think.
Comments?
jan
General rule for DIY'ers: A poor psrr amp can be offset by a really good, low noise, low z regulated power supply. The worse the power supply, the greater the amp needs a higher psrr. Usually with small signals the regulated power supply is common. But in power amps, for example, it isnt as common (rare?) to have low noise, regulated voltage and the need for higher psrr is more important.
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