Right, but damping decrease a little waterfall time in the basses. Give a more "fast" sound ?
When I first started to work for Alembic, who did the PA and recording for the Grateful Dead, in 1970, I saw a DC300 parked in a corner. I was told by my associate that the amp sounded very 'weak' compared to its rated power. This we found was because of the extreme protection circuits that cut in very often. It should be remembered that this amp was originally designed for servos, both AC and DC. Audio was sort of an afterthought.
In 1977, John Meyer and I tested 4 amps for TIM(30) and published the results. The Crown and the new (at the time) solid state Audio research failed the test at 100W out. Two other amps passed.
In 1977, John Meyer and I tested 4 amps for TIM(30) and published the results. The Crown and the new (at the time) solid state Audio research failed the test at 100W out. Two other amps passed.
Yeah, the MacroTech amps were the ones with the grounded bridge output.
Somehow, my last response was lost. Thanks, Nelson Pass for giving me the more 'correct' version of what we measured 36 years ago. We did also measure the Electrocompaniet, (passed) and the Crown (failed) but these were not the amps that the magazine gave us to test. This test was TIM (100) that is the most stringent test that we could devise to include ultrasonic garbage as well. TIM (30) (10us r.t.) is a somewhat easier test, but it can be shown possible to generate its waveform characteristics without added ultrasonic interference or hard clipping from previous stages.
Actually, that is the amount of energy stored in the superconducting magnets. When the interconnect solder joint failed, all that energy deposited in the liquid helium. The resultant pressure wave made the dipole magnets in the tunnel play leapfrog. They have to take a 2 year (estimate) time out to re-do all 10 thousand solder joints before they can try full energy.
How does he account for the self inductance of the resistor and the loop trapped magnetic field caused by the tap wires across the resistance?
What an odd way of measuring the temperature of a coil of copper.
If they zero the shunt inductive pickup, they could see the resistance of the wire as a function of time in the sub millisecond range. Of course, it's only the end terminal resistance and will show only where the current is travelling within the wire..but it's better than nothing...
You will get absolutely no sympathy from me on that.
Because it's FUN!!
Smaller than .7 mil gold TC?? The smallest SiO2 caps I used were a quad set of .25, .5, 1, and 2 pf. They were used for tuning. I unfortunately had to measure them to 5% as part of incoming inspection sampling.
jn
Mr Curl,
apparently it's of no consequence on how many legs you once stood, for the number of fingers you're now showing.
John,
The interesting question about these earlier results of the TIM testing would be why these other amplifiers did so bad in the test? Not that the results were incorrect, but what specifically caused such disastrous results say in the case of the Phase Linear amplifier. I remember the very early Phase Linear amplifiers again in pro-audio. What I remember of them was that they actually sounded good but that we had nothing but problems with the power supplies, at least that is what I remember about them. It could have been the extremely difficult loads being driven at the time and perhaps it was the reactive loads that did them in. How does your own design of the Blowtorch show up in this same testing?
The interesting question about these earlier results of the TIM testing would be why these other amplifiers did so bad in the test? Not that the results were incorrect, but what specifically caused such disastrous results say in the case of the Phase Linear amplifier. I remember the very early Phase Linear amplifiers again in pro-audio. What I remember of them was that they actually sounded good but that we had nothing but problems with the power supplies, at least that is what I remember about them. It could have been the extremely difficult loads being driven at the time and perhaps it was the reactive loads that did them in. How does your own design of the Blowtorch show up in this same testing?
Kindhornman, it is the LOW SLEW RATE of the Phase Linear power amp that made it show distortion. The same for the Audio Research, and while not shown, would be the same for a Crown power amp of the time. The test signal TIM(100) is one of the most stringent test signals ever devised for audio, and in many cases, it might be somewhat more than really needed for many practical situations, but it is still a useful tool to show TIM.
Your question about the Blowtorch shows a complete lack of understanding as to what the CTC Blowtorch is or what would make it distort. It would be the same for the Hirata test. You would not measure anything useful, BECAUSE the Blowtorch is UN-SLEWRATE-ABLE, and you would only get risetime limiting.
I'm sorry guys, but think before you ask.
Your question about the Blowtorch shows a complete lack of understanding as to what the CTC Blowtorch is or what would make it distort. It would be the same for the Hirata test. You would not measure anything useful, BECAUSE the Blowtorch is UN-SLEWRATE-ABLE, and you would only get risetime limiting.
I'm sorry guys, but think before you ask.
As I said, it is difficult to get into a really useful discussion here, because we have two sorts of 'critics'. People much more educated than most audio designers, who think that they know 'everything' already and are impatient with people like me, when I try to go back to basics, in order to get people not as familiar with audio design to get some added understanding of some audio problem.
On the other hand, I have a number of 'critics' who are essentially 'roadies' with a lot of practical knowledge with audio equipment, but don't really know how they operate at the design level. Both groups have strong personal opinions: One individual might insist that 2V/us is OK for a preamp, another might insist that 1000V/us is necessary for best sound quality. Why is this discrepancy so large? It appears to be because neither individual fundamentally understands the nature of slew rate limiting. If both of them read the Solomon article that I put forth relatively recently, there would be no 'criticism' especially of what I design. But 'you can bring a horse to water, but you can't make him drink'. And so it goes... '-)
On the other hand, I have a number of 'critics' who are essentially 'roadies' with a lot of practical knowledge with audio equipment, but don't really know how they operate at the design level. Both groups have strong personal opinions: One individual might insist that 2V/us is OK for a preamp, another might insist that 1000V/us is necessary for best sound quality. Why is this discrepancy so large? It appears to be because neither individual fundamentally understands the nature of slew rate limiting. If both of them read the Solomon article that I put forth relatively recently, there would be no 'criticism' especially of what I design. But 'you can bring a horse to water, but you can't make him drink'. And so it goes... '-)
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Kindhornman, let me follow up that I too have used Phase Linear power amps. I know both designers as well. I have heard them in use with the Pink Floyd, in 1972, where Kelsey and Morris (London) had racks of them, and with a California based PA used it for the woofer-midrange amp in their design, with some success. And finally, Mark Levinson, in 1973 had a Phase Linear 700 driving a pair of Dayton-Wright electrostatic speakers, with some success, except that his mother complained that it gave her a headache. Mark had used tubes previously, so she knew the difference. In any case, I pretty much know the 'goods' and the 'bads' of the Phase Linear series, much like you do.
John,
Yes they were the Phase Linear 700 amplifiers. If I remember correctly I think that we were one of the very first to use some of these amplifiers at the time and I don't remember the designer's name but think that he was involved with what we were doing somehow. The same with the Spectra Sonics at the time.
I know that your blowtorch is a preamplifier but am wondering why you would not test a pre for the same types of distortion as a power amplifier? And I do not follow why even a super fast slew rate would make this test a non issue?
Yes they were the Phase Linear 700 amplifiers. If I remember correctly I think that we were one of the very first to use some of these amplifiers at the time and I don't remember the designer's name but think that he was involved with what we were doing somehow. The same with the Spectra Sonics at the time.
I know that your blowtorch is a preamplifier but am wondering why you would not test a pre for the same types of distortion as a power amplifier? And I do not follow why even a super fast slew rate would make this test a non issue?
BS!
It was completely by chance that I saw this message, I don't follow this thread anymore, this (and other threads that could be interesting) is so full of meaningless nonsense that I have given up long ago.
I'll ask Jason to delete my account.
Have fun.
Cheers
Stein
Reputedly, Bob Carver. They're still a cult item, fetch lots of money on resale if you can find one that hasn't blown up.
Sy,
Thank you for that information, it was so long ago. It probably didn't help the type of speakers we were using at the time, Altec, JBL and even some old RCA W-bass bins. Another factor was that many times we were doing shows outdoors and the power to drive the system was sometimes portable generators driving the system! I would supposed we put the equipment under the toughest load requirements and if it was going to fail it was going to be under these types of conditions.
Thank you for that information, it was so long ago. It probably didn't help the type of speakers we were using at the time, Altec, JBL and even some old RCA W-bass bins. Another factor was that many times we were doing shows outdoors and the power to drive the system was sometimes portable generators driving the system! I would supposed we put the equipment under the toughest load requirements and if it was going to fail it was going to be under these types of conditions.
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