Because I have fixed many of these problems! Bad cables in sound systems are perhaps the #1 real problem. (#1 with a bullet is mis-use!)
Condenser mics in my world run on 48 volt "phantom" supplies and there is always enough voltage to clear any fault!
We really do not share many common points of view! I thought these were clear every day audio issues. I did not try to bring up arcane or obscure examples.
That is one of the reasons that we created a 'SEMI-SEALED environment in the CTC Blowtorch. It was not hermetically sealed, but only a very few unavoidable air (vents) are present. Also keeping the unit on 24 hours per day, keeps the unit from (breathing) in new contaminants. We also cleaned everything with FREON, deliberately removing any contaminants from the soldering process at several stages, including final assembly. Having repaired 2 units that were out in the field, one from Singapore, the other operating in Great Britain and Hamburg, Germany, the interiors of both were pristine, even over several years of operation, as expected.
Still, we did find that EXERCISING the switches and the pots is a good thing and often brings it 'back to more lifelike'. Sometimes it might even be necessary to clean the TKD pots with a pencil eraser, but this is rare.
Still, we did find that EXERCISING the switches and the pots is a good thing and often brings it 'back to more lifelike'. Sometimes it might even be necessary to clean the TKD pots with a pencil eraser, but this is rare.
Thanks.
I have a chance to get an scp 1 and I was thinking it would be near scp 2 performance but I guess not ........ Would you suggest I go with the new parasound JC 3 over the scp 1?
My experience with bad contacts says that it would also occur at tens of volts, IF the mic or micamp would output that level.The reason it is at 10's of mV is because that happens to be the signal level of that type of equipment.
jan didden
I thought the reference to ultra-modern fly-by-wire aircraft was a nice touch 😉
jan didden
One hopes that they are at least cryotreated.
A nice WS2-loaded grease does wonders for the feel and the contact reliability. I use them (or equivalent from Cinema Engineering) in most of my gear.
Yes, you make extraordinary claims. There is no physics to support < mV breakdown gaps. Your feelings of what should be or makes sense on the surface is what you follow.
😀
Well, it's just with the stock springs, the Shallco's go "Clunk! Clunk! Clunk! Clunk!
But you can get lighter springs from them so they go "Click, click, click, click.." instead.
That's why I was wondering if Charles was using the stock springs.
se
The JC-3 is at least, a complete phono preamp. It is not at the same level of design sophistication as the VR SCP-1 and SCP-2, but it will work well, and many find it 'exceptional' at the price.
However, if you were really 'radical' you could put the JC-1 in front of a vacuum tube phono stage that was designed for moving magnet operation, mainly, and get 90% or so of the JC-2.
However, if you were really 'radical' you could put the JC-1 in front of a vacuum tube phono stage that was designed for moving magnet operation, mainly, and get 90% or so of the JC-2.
It would be great if you guys could just focus on the original topic of this thread. The OT stuff is just a distraction.Gee, I thought I showed some interesting actual experiments and their results, my interpretation of the results does not show any violation of the laws of physics.
But more on topic, let's talk about VU meters the real kind! You know the ones that have 300ms ballistics and read 1.23 volts AC at 1K is 0 or .123 Volts is -20?
What kind of load reducing network is included with a proper VU meter?
What is the actual minimum voltage it responds to?
How did they do this in the 1930's?
Oh Wikipedia is quite light on the actual cool details.
Is there a reason why preamps don't have meters? Is that an important feature that is missing?
One of the posts on this thread I found most interesting but unfortunately got little response was Scott Wurcer's on that most amazing picovoltmeter. It took me some time to look at the site of EM EM Electronics range of miniature amplifier modules for high resolution temperature measurement and calorimetry. Resolve micro degrees with Thermocouples., responsible from this otherworldy piece of electronics, and think some necessary thoughts. The first one was: it's the Brittish again, good to see they are still in the race. The second is that, like with the CT-scanner, the Brits will most likely never make any serious money with it. But those thoughts are definitively OT, so I will suppress them for what is relevant to this thread:
Lesson 1: the picovoltmeter uses ordinary copper for its input terminals. I am sure if silver were any better, or gold for that matter, they would have used that. But they did not. So, from now on, I will for ever continue to use whatever copper cabling I have used for decades, but with even less lingering doubt that something more expensive might be better.
Lesson 2: they use brass, much reviled in audiophile circles, in some connectors. Look at EM's opamp. A little bandwith limited for audio, but otherwise a nice piece of gear. Haven't seen specs like that ever. So, brass in small signal paths, no problem.
Lesson 3: they use switches. If there were an effect of nanovolt level discontinuities in switches, or the possibility thereof, they might not have chosen to do so.
Perhaps many on this site, like me, are breaking their heads over the same question that made Scott look forward to the next milestone on the Mayan calendar: how on earth did EM do it? A charge pump as suggested? Not likely, because how would you chop a pV size signal? Interesting is, that the noise characteristics they show for their best opamp, is 2 orders of magnitude worse than those for the picovoltmeter. Supposedly, they would use one of those for their input stage. But, how can you reliably read a signal that is 40dB under the noise floor? They must have found a way of counting individual electrons, that's the only thing I can think of. In the beginning of a measurement, input impedance is 30K, meaning about 1800 electrons per second, but that rises to over 10M. If I am correct, that would allow only 1 electron every 6 seconds to enter the device. Measuring 1 highly energetic electron is a trick I can understand. Measuring 1 sloughing electron being pushed ahead by a 5pV differential is quite something else.
Anyways, if guys who can do this, use switches and copper and brass screw-on terminals, that settles some of the disputes in this thread for me.
vac
Lesson 1: the picovoltmeter uses ordinary copper for its input terminals. I am sure if silver were any better, or gold for that matter, they would have used that. But they did not. So, from now on, I will for ever continue to use whatever copper cabling I have used for decades, but with even less lingering doubt that something more expensive might be better.
Lesson 2: they use brass, much reviled in audiophile circles, in some connectors. Look at EM's opamp. A little bandwith limited for audio, but otherwise a nice piece of gear. Haven't seen specs like that ever. So, brass in small signal paths, no problem.
Lesson 3: they use switches. If there were an effect of nanovolt level discontinuities in switches, or the possibility thereof, they might not have chosen to do so.
Perhaps many on this site, like me, are breaking their heads over the same question that made Scott look forward to the next milestone on the Mayan calendar: how on earth did EM do it? A charge pump as suggested? Not likely, because how would you chop a pV size signal? Interesting is, that the noise characteristics they show for their best opamp, is 2 orders of magnitude worse than those for the picovoltmeter. Supposedly, they would use one of those for their input stage. But, how can you reliably read a signal that is 40dB under the noise floor? They must have found a way of counting individual electrons, that's the only thing I can think of. In the beginning of a measurement, input impedance is 30K, meaning about 1800 electrons per second, but that rises to over 10M. If I am correct, that would allow only 1 electron every 6 seconds to enter the device. Measuring 1 highly energetic electron is a trick I can understand. Measuring 1 sloughing electron being pushed ahead by a 5pV differential is quite something else.
Anyways, if guys who can do this, use switches and copper and brass screw-on terminals, that settles some of the disputes in this thread for me.
vac
I have some Weston mV meters from 1899 that still work.
I'll let the other stuff rest till I have time for some bench work, I feel your interpretation does involve impossible physics.
It is the AC to DC that is to me the most interesting part of the old meters.
As to my interpretation, don't jump to judgement, I ain't published yet.
It may be the bad op-amp just being disconnected from the output was not enough! The noise during it's failure period may have disturbed the other input amps, or the few days of thunder and power outage may also have damaged stuff. I am no longer getting the same readings even on the most basic measurements!
I used to have a Weston 10 ua full scale optical meter, I could measure the leakage current of CMOS inputs and even display a heartbeat without any amplifier!
It does not fit exactly at this point in time but i found an interesting article about audio transformers.
http://www.sowter.co.uk/pdf/GAVS.pdf
http://www.sowter.co.uk/pdf/GAVS.pdf
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