It didn't bother me any, and listening to components in an anechoic chamber is just amazing, it lays bare all the system faults.
Scott
Sometimes we communicate sometimes we don't. I have drywall walls and only oriental rugs. A normal bedroom is around 30 dBa. 15 really ain't special, but you do have to hold your breath during measurements.
The local all news public radio station is trying to install a backup generator. The noise survey for the zoning hearing showed a high number. To verify it I went to the site at 5:00 A.M. on a Sunday morning. As I arrived even from across the street it was 52 dBa +! Loudest urban site I have ever seen. Noise source was neighborhood airconditioning. Even louder on the site.
Jan about 20,000 words and a diagram or 30. At the end of the year it will be done or at least as far as I am taking the article on power supplies. But I did start it for Ed Dell.
Yes, but the transformer runs out of steam at the frequencies I'm interested in.
Yes, but Walls worked for the government and could not tell the company names
and exact types. I did.
With 20 averaged op amps I got quite close even without correlation. I have given away
one empty board too much, since my 89441A FFT analyzer can do correlation
Seems I now have to do the 2 channel respin...
< hf downloads >
BTW
It really hurts if you give away boards for free and people let them rot in their drawer forever, then.
Last edited:
I thought I had spelt that out.
BTW, I am in the no NFB camp primarily, so my goals are obvious.
.
Well Brad recommends the book, so that's two votes. Bear in mind my interest in driving something you would take pity on me for (ribbon)
Make that three votes.
.
Yes, but the transformer runs out of steam at the frequencies I'm interested in.
Yes, but Walls worked for the government and could not tell the company names
and exact types. I did.
With 20 averaged op amps I got quite close even without correlation. I have given away
one empty board too much, since my 89441A FFT analyzer can do correlation
Seems I now have to do the 2 channel respin...
< hf downloads >
BTW
It really hurts if you give away boards for free and people let them rot in their drawer forever, then.
Gerhard,
It goes without saying your work is meticulous and impressive, but I'll say it anyway.
You got much better results with batteries than I did. I found age and manufacturer had a bit more effect. Things got noisier as they were charged and discharged. (100 cycle test.) I see you didn't look at lead acid batteries. Some of them have bursts of noise I am told are caused by bubble formations. But the rule still seems to be increase in current capacity results in a decrease in noise.
I take it all the power supplies you looked at were series regulated. I think a comparison between series and shunt regulator noise should be interesting.
But our viewpoints are a bit different. I am looking at all the ways noise can couple into a circuit from a power supply and out from the power supply into the AC line, not just supply line noise. However I am sure for your designs those are not real issues.
Now if you were local I'd offer to make you better looking cases for instruments of your caliber.
regards
ES
Yup. Heard the effects of driving a 1:1 transformer post (4 phases paralleled) Sabre DAC, circa 195R source Z and it just didn't cut it. Needs to be well below that.
.
Last edited:
Alas, when just about anything is free, people tend to believe it is worth about what they have paid for it.
A corollary: in the realm of ideas, it may be better to let people steal them.
Walls (search NIST, time frequency group, 1133.pdf) did get even better results than me
because he could measure even further down into the noise.
I did not measure Pb batteries because the ones I had were sulfated, nearly
perfect isolators, I could not force 1uA into one of them even with 30 volts...
Maybe in winter, when I don't need my motorbike so often, but _now_ is not the time for
disassembling it. I also won't buy new Pb batteries for my frequency standard; that
will be LithiumIronSulfate.
Been on both ends of that. I think people believe they have more free time than actually exists and accept things with good intentions then reality comes to bite.
Guess I'm not prone to that, since even an MRI didn't bother me. An anechoic chamber does seem to cause some kind
of sensation in the ear, from a lack of the usual environmental sound.
Ed you know as well as I that maintaining that level in an average home environment is not normal, so good for you. Frankly I just mis-remembered what you said.
Last edited:
The late composer John Cage has an amusing account of his visit to a very quiet anechoic room. He notes the different sounds he hears and has them explained to him. One is the blood coursing in his veins, and the other is explained as the residual noise in his auditory nervous system.
We all have tinnitus at some level. Mine is not disturbing, but takes on the character of an old and very slow modem at times, a sort of random telegraph signal toggling a mostly-two-frequency oscillator. Only in the left ear however.
I can imagine someone telling me "You'd better have that looked at".
Toole has fairly severe tinnitus and has disqualified himself from listening tests.
That's the one, are they really enjoined from naming the parts? I've seen government sponsored papers with all the parts identified. Come to think of it those might have been university papers done on government grants.
Right ear here, sometimes takes on the cricket chirp. It's due to sonic trauma and it just needs to be tuned out.
It was really a side effect of building a low maintainence house sand being sure it was sealed from stink bugs. Radiant in floor heat fed from a water heater not a furnace, multi zone fractional horsepower pumps and the biggest unexpected benefit thermal windows of 3x2 panes over 3x2.
Yes tinitus shows up in my left ear at those levels.
The acoustic changes I did go for included tearing out a wall and a bit more to increase room volume and low frequency response.
- Status
- Not open for further replies.