Transmission line behavior

John Larkin wrote in news: snipped-for-privacy@4ax.com:

When I was a 20-something, I could hear this very loud high pitched note from some crazy intrusion alarm system inside the local grocery store. It was painful if I got too close to the feedhorn of it. I think the store was a Kroger but I can't be certain. It was in Sumter, SC, and I taught electronics at Sumter Area Technical College at the time.

Few patrons showed they could hear it, though.....few complained.

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

Must be why us old farts don't think AM sounds much different from FM any more....(c;]

Are those the doctor's charges at the bottom for the audiometry?...hee hee

John Larkin wrote in news: snipped-for-privacy@4ax.com:

Amen!

I never figured out how they got 400 watts per channel out of a power supply with a 1A line fuse. Those filter caps were in microfarads, not megafarads!

Teaching electronics to young audiofools was always very rewarding. The look on their faces when, faced with learned reality that their 400 watt per channel stereo was, infact, at BEST, 8W per channel was PRICELESS.... (c;]

I had some "must spend" funds left over that had to be spent or lose them next year at the college. One of the toys I bought was the Sencore Stereo Analyzer, which had a nice audio wattmeter and dummy load in it. The teens were so frustrated trying to get their favorite stereo to raise those meters anywhere close to 20% of the advertised power output of the Sansui 9000000 they cherished...hee hee.

Many output transistors suffered and died heating up the dummy load. Stereos aren't rated for 100% duty cycle, you know.....(c;]

That's kinda the thing... I haven't seen any data where they give you, e.g., the standard deviation for hearing statistics. I wouldn't be surprised if, for 16-year-olds, the average guy could hear, say, 20kHz but the standard deviation was, say, 4kHz... you'd still have 1 in ~6 guys able to hear beyond

24kHz...

There's actually a lot of good science out there when it comes to hearing, sound reproduction/reenforcement, etc. but unfortuntaely most of it gets lost under the marketing campaigns of places like Monster Cable who'll try to convince you that you need 8 ga. pure-gold speaker wire to hook up your car's speakers.

You should point them to, e.g., Vladimir's sight as well, to demonstrate what people who know what they're doing can create as well. (E.g.,

. Of course, his 10,000 amp there also costs... $10,000...! -- $1/watt is enough that you'd like to

*think* the manufacturer isn't cutting any corners!

The better ones are... or at least they tell you what their rated DC is...

"Joel Koltner"

** The * threshold shift" graphs you posted are irrelevant to the question of audible or not.

My comments were are based on actual testing - using a sine wave source, a tweeter and real people.

The audibility criteria was " can you hear the tone going on and off " - which has nothing to do with " threshold shift " that audiologists are so obsessed with.

..... Phil

Put this this way, at the end of a 250' run, I would say not much above 3k was making it to end of the wire with out exerting excessive load on the amp. They were using 2 leads of #10 that was part of a 4 other wire polyrad cable rated for 600V.

We make a variety of polyrads, all designed for DC or 60hz operation.

I don't think the compound engineers really took much care into formulating it for audio use.

Jamie

Yep, for the two aids :-( ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
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      Remember: Once you go over the hill, you pick up speed

One of the guys I worked with in college could hear well in excess of 30kHz. The best I could do was about 18kHz and he was a half dozen years older (having done a stint in the Navy instead of getting drafted).

Yeah, morons of the world unite.

Fred expounded in news:Xns9E7EAAC3DDDABnobodyhomecom@74.209.131.13:

Audio is overrated-- at least until dinner is called!

Warren

Jamie wrote in news:EIH1p.6574$ snipped-for-privacy@newsfe11.iad:

I had an audio speaker run in a large auditorium to hide with really LONG cables.

Noone made line transformers that big, so I used two identical filament transformers donated by a friend to "try it", the old fashioned way.

The transformers are still mounted to Bud boxes in the auditorium 20 years later and work just fine.

Shh....don't tell anyone who has commented to me how wonderful it sounds after all these years.....please?

22kHz,

Several years (hmm decade) ago I had a female college intern come to me and complain about the noise from her monitor. I went over and I could hear it too (much closer than where she noticed it). I called it and told support they needed to fix it. They said that all monitors made some noise. I pointed out that if a fifty something male could hear it it must be excruciating to a twenty something female and I could bring in a hammer if they needed it to be non functional to fix. They sent over a guy in his thirties who got within a couple of feet of the monitor and said "we have to fix this".

Audio is overrated -- until payday.

Not when it comes to hearing aids. Seems technology has a long way to go. I know an 85 year old who complains he can't find anything that works well and has tried many brands. He complains the sound is loud enough, just not intelligible. But he can hear fairly well without the aid if the volume is high.

Who makes the best hearing aids?

-Bill

Actually I always hated that about TV. Now I'm over 30 I don't hear it so loud.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

I'd say nearer 20kHz. Many have already damaged their hearing by then with excessively loud walkman/iPod music on the tiny earpod speakers. By

25 most people can't hear 19kHz stereo carrier tone.

These numbers do depend a lot on how many TYA or other heavy rock concerts people have attended. But ability to hear 20kHz in youngsters is not at all uncommon. The mosquito devices to stop teenagers hanging around certain locations utilise the difference in hearing.

That uses 17kHz to target teenagers.

The whine from analogue TV flyback transformers could be particularly annoying if there was any slack in the coil so that it could move.

Most youngsters should be able to hear sine waves to at least 19kHz. I'd say a lot of adults at least in my audience last time I tried this had trouble hearing anything much above 12kHz but some of them could. My own hearing only goes up to about 15kHz these days but I can still hear pipestrelle bat calls due to some sideband nonlinearity or other.

Regards, Martin Brown

Jim Thompson schrieb:

Last test, 46-year-old-hearing...

I still hear my old tube tv-set whistling at 15.625 kHz...

30 Years ago i had add external pilot-tone traps to my FM-tuner because the leaking 19kHz's were a real pain in the neck. OK, that was a el cheapo FM-Rx that time, my Revox B760 in today's use but also way over 30 years old, don't need that.. (70dB rejection built in), but it was way beyond my financial resources at that time)...

Jorgen

That's stupid. To get rid of teenagers, put opera on the Muzak. (although that might drive away some legitimate customers! ;-) )

Cheers! Rich