Signal dependent noise
You are of course correct, the interfering signal is always there. In the case of the RF pickup, rarely the actual interference only becomes audible when in-band signal intermodulates against it, creating an in-band product. This type of signal dependent noise is most often found the facilities with co-located RF plants, but I have heard it on some hifi tuners as well. Audibly it reminds me of scrape modulation in magnetic recording.
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill
www.wxyc.org
1st on the Internet
You are of course correct, the interfering signal is always there. In the case of the RF pickup, rarely the actual interference only becomes audible when in-band signal intermodulates against it, creating an in-band product. This type of signal dependent noise is most often found the facilities with co-located RF plants, but I have heard it on some hifi tuners as well. Audibly it reminds me of scrape modulation in magnetic recording.
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill
www.wxyc.org
1st on the Internet
When we went to the Netherlands Antillies we received several warnings that what was ok in Amsterdam was not ok here. I still think I should have dropped a bar of Valrhona Cannabis Chocolate in my carry on and pleaded ignorance.
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Say your circuit is quiet @ 1mA(idle) but @ 5mA(idle) noisy.
With a signal that causes 5mA the circuit does not
differentuate between signal current and idle current.
The emphesis should be on the word might. One factor is that there is no standardization of recordings or of system performance. The expectation that you can somehow filter out the listening room is IMO hopeless. Therefore no recording sounds the same on any two systems and most recordings have one or more serious FR errors on any one system because of the variables inherent from one recording to the next even on the same label.
The technology I have developed requires among other things standardization to work. These variables become magnified and make matters even worse than they already are if they aren't corrected. Standardization of performance, now there's a novel idea in this industry all by itself.
The protocol you describe would seem to some incredibly time consuming even tedious. Trained experts to custom set up your listening space to the way it “is supposed to sound”. I think you have gone back around to the Bose customers except they are peeling a few more C notes off their stash.
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Yeah, even Campo Alegre at Curacao isn't what it used to be in the good old days.
(still, i recall a 2nd engineer of a Nedlloyd ship who, till this very day, will deny to ever have been in close contact with a transformer job in Thailand)
Even Steve seems to have trouble keeping track of the right number.
You have it backwards. A sound system which is adjusted to accomodate itself to the acoustics of the room it is installed in to achieve uniformly predicatable results. A real novelty in this industry. Not only new technology and standardization but a rare innovation. Actual engineering.
Believe it or not standardization does not appeal to all in every endeavor. Call out the Handicapper General.
For everyone else, we made perhaps 45 units, of which 40 were sold to outsiders. We had only 2 major problems: Both overseas. The first major problem was when Bob forgot to put some isolated machine screws that tightly mounted the TO-220 fets. They were held by pressure and thermal grease, however, one of the elbow isolating washers broke lose started rattling around. Bob took a chance with the customer in Singapore, that he had a 'qualified technician' who could put the machine screws in, without the necessity of sending the unit back to the USA. However, the tech FORGOT the isolating elbow washer, and attached one of the power supplies live to the chassis.
I personally had to pay for the airfare (about $1100) to and from Singapore as well as airport costs, each way. The unit came back a second time, this time from input stage damage, probably due to lightning. I paid one way, return, perhaps another $600, the second time, because the guy's wife refused to compensate me. They lost their Warranty over this.
Another customer had this super turn-on transient, which blew up 2 power amps and both channels of the CTC in 3 separate incidents. We had to return the money in full for the two amps ($5,000) and had to add a ZENER protection for the input stages of the CTC. Hopefully he sold it to someone else, as I have not heard from him, recently. He's yours, Joachim in future. '-)
I personally had to pay for the airfare (about $1100) to and from Singapore as well as airport costs, each way. The unit came back a second time, this time from input stage damage, probably due to lightning. I paid one way, return, perhaps another $600, the second time, because the guy's wife refused to compensate me. They lost their Warranty over this.
Another customer had this super turn-on transient, which blew up 2 power amps and both channels of the CTC in 3 separate incidents. We had to return the money in full for the two amps ($5,000) and had to add a ZENER protection for the input stages of the CTC. Hopefully he sold it to someone else, as I have not heard from him, recently. He's yours, Joachim in future. '-)
Please note Joachim, the devices are OBSOLETE. They are NOT made anymore. The selection is the top 10% of the devices. YES, they could be hard to replace, but I have some. Erno probably has some too! I told him that it had to come back to the USA. I did NOT know you, and even YOU would have screwed it up, without my help.
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Sure, but I was talking about noise sources other than the signal. And I'm wondering how those require a signal to manifest themselves.
se
Ok, that makes a bit more sense.
But wouldn't the device first have to have some rather bad in-band IMD for this to happen?
se
Then it would seem in that case the "noise" would have to be the signal itself. But that's not what I was talking about.
se
Why did you have to pay for this rather than the "qualified technician" who forgot the shoulder washers? Or for that matter, Bob since he was the one who left out the screws in the first place. Was this after he'd passed away or something?
Why did you send the amp back without having first been paid for the return shipping?
How was this "super turn-on transient" your fault?
Why didn't it come out of the pocket of the manufacturer of the component that was spitting out this "super turn-on transient"?
And why was all this coming out of your pocket? CTC was a partnership was it not?
se
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