Once upon a time, i was comparing an old amp WITH and WITHOUT NFB ... My phone was located near speaker . I know when somebody will be calling as i can hear "tacatac-tacatac- tacatac" just one second BEFORE it will ring . I was surprised as i received a call WITHOUT any preinformation , WHEN NFB network was disconnected . I tried it twice with my wife's phone : same silence 
conclusion : Schottky effects in NFB resistors ...
conclusion : Schottky effects in NFB resistors ...
Once upon a time, i was comparing an old amp WITH and WITHOUT NFB ... My phone was located near speaker . I know when somebody will be calling as i can hear "tacatac-tacatac- tacatac" just one second BEFORE it will ring . I was surprised as i received a call WITHOUT any preinformation , WHEN NFB network was disconnected . I tried it twice with my wife's phone : same silence
conclusion : Schottky effects in NFB resistors ...
Yes of course completely changing the topology had nothing to do with it.
Once upon a time, i was comparing an old amp WITH and WITHOUT NFB ... My phone was located near speaker . I know when somebody will be calling as i can hear "tacatac-tacatac- tacatac" just one second BEFORE it will ring . I was surprised as i received a call WITHOUT any preinformation , WHEN NFB network was disconnected . I tried it twice with my wife's phone : same silence
conclusion : Schottky effects in NFB resistors ...
WOW, wonder how this never got discovered before.....
Of course if you do a lot of analogue layout you will know the critical paths so will lay these out to have the smallest loop area thus minimising any EMC problems on these connections (not something you see a lot on DIY designs)...
So micro diodes in cables, diode effect in resistors.....how do we manage to get AC signals from a to b one wonders.
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Oh dear.coresta said:
A wonderful example of 'the first idea I thought of, not knowing or understanding the full situation, must be the correct explanation even though it requires an effect which nobody else has seen'.
You did ensure that the output and NFB input point saw exactly the same impedances and RF environment when NFB was 'on' and 'off'? Anything acting as an antenna and dumping RF somewhere continued to do this even when disconnected?
You changed something; the circuit behaved differently. Circuits do this. It requires no new alleged behaviour from components for this to happen.
There is a restaurant a block from my house. They offer valet parking and place the cars on the side of the public street by my house when busy.
One day I found a wad of one dollar bills lying right by where the cars were parked.
Does this mean they were paying for the space? Was it raining dollar bills the nigh before? How many explanations can one come up with?
Now it is interesting that the feedback version was picking up low level signaling on the telephone line, but give the guy a break, there exists some slight chance that his explanation might be right. (Although almost probably not, so be kind in trying to expand his knowledge.)
One day I found a wad of one dollar bills lying right by where the cars were parked.
Does this mean they were paying for the space? Was it raining dollar bills the nigh before? How many explanations can one come up with?
Now it is interesting that the feedback version was picking up low level signaling on the telephone line, but give the guy a break, there exists some slight chance that his explanation might be right. (Although almost probably not, so be kind in trying to expand his knowledge.)
I think when he said 'phone' he meant mobile/cellphone. No line, but lots of RF.simon7000 said:
If by "slight" you mean 'infinitesimally small but non-zero' then you are right.simon7000 said:
A much more likely explanation is that the feedback network was dumping RF pickup from the output leads onto the feedback point, which had poor EMC behaviour. Disconnect feedback and, voila, no RF dumped at feedback point.
Hello guys ,
I was not complete ... Well, I spoke about cellular GSM phone (TDMA burst for sure ) Then, i tried different resistor technologies of feedback resistors : the use of carbon layer and wirewound (the best sounding) en lieu et place of metal film made the amp SILENT . My conclusion : the metal film ARE rectifiers . Anyway, try it yourself , especially DF96 who knows everything about anything 
Seasons Greatings
Best wishes of music, health, business, love for 2015 !
Pierre
I was not complete ...
Well, I spoke about cellular GSM phone (TDMA burst for sure ) Then, i tried different resistor technologies of feedback resistors : the use of carbon layer and wirewound (the best sounding) en lieu et place of metal film made the amp SILENT . My conclusion : the metal film ARE rectifiers . Anyway, try it yourself , especially DF96 who knows everything about anything Seasons Greatings
Best wishes of music, health, business, love for 2015 !
Pierre
Start here:Hello guys ,
I was not complete ...
Seasons Greatings
Best wishes of music, health, business, love for 2015 !
Pierre
http://www.amazon.co.uk/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304
The attached txt file has links to EMC compatibility testing and engineering solutions. I would suggest you research it more before making wild claims....
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If you want us to comment on something you have done, then it is helpful if you tell us what you did - not just half of what you did.coresta said:
If a metal film resistor is rectifying then you need to return it under warranty for a refund or replacement. Or learn a better soldering technique.
Thank you for your kind remarks. I wish I was as confident in my abilities as you seem to be.
Hi,
To those who commented on magnetic leads of resistors etc. Is there anyone out there that has actually compared them or is this just another one of those audio myths?
I'm not saying there can't be no audible difference but then I'd also like to see it backed up with at the very least repeatable results.
If you come to think of it, all electron tubes and various other parts contain a number of ferrous pins etc. Maybe that would be a great hint for the next scam too then? Or who knows, audio nirvana after all..........
If something sounds different then it should also show up in measurements somehow. Problem is that most measurements made are only there to sell product not to do research with.
Cheers,
To those who commented on magnetic leads of resistors etc. Is there anyone out there that has actually compared them or is this just another one of those audio myths?
I'm not saying there can't be no audible difference but then I'd also like to see it backed up with at the very least repeatable results.
If you come to think of it, all electron tubes and various other parts contain a number of ferrous pins etc. Maybe that would be a great hint for the next scam too then? Or who knows, audio nirvana after all..........
If something sounds different then it should also show up in measurements somehow. Problem is that most measurements made are only there to sell product not to do research with.
Cheers,
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