Stuttering electronic interference

[Dave Plowman (News)]

I'm surprised you haven't heard it in your car - both mine do it while listening to CDs.

[Mike]

Even a Yamaha PM1D ?

[Mortimer]

Could be be something to do with the TETRA radio system I have heard a bit about. A nationwide communication system for the police and emergency services which caused a lot of concern because part of the signal uses modulation at 16 Hertz which is similar to brainwave frequencies. I f the system is being extended maybe you have a new mast or transmiiter gone live recently nearby.

[Dave Plowman (News)]

I've not tried that, since the only studio I've worked in which had one didn't have a radio talkback system for sound. They'll happily zap a colour monitor or portable VTR if close enough, though.

I've also had problems with phone pickup on expensive analogue consoles. If it's in the operator's pocket. :-)

Only one I know which appears totally immune is the old Calrec/AMS assignable - but then all the important low level signal paths are usually in another room.

[bof]

In message , mike ring writes

I can tell when the neighbours are out in the garden making secret phone call on their mobiles, as their hiding place is just the other side of the wall from the kids PC speakers.

[tony sayer]

Yes some female bobbies from the greater Manchester police claimed that the TETRA radios made them preggers;!..

To get that to happen the mast would have to be very close, almost next door, and I suspect that the TV interference that TETRA can cause will be far more of a problem.

You haven't had one put up on a roof nearby that you don't yet know about?...

[Mike]

I was about to suggest AMS. I know they used to pay attention to this 'feature' more than most.

Most innovative approach I saw was on a Midas which provided a *really* tempting and convenient place to put your phone down far away from the mic amps.

[Dave Plowman (News)]

They - or the original Calrec - were certainly built well. Their first assignable is still in use in Studio 2 at Teddington Studios. And must be

20 years old. I can remember some BBC Neves being scrap after 5 years.

Heh heh - a good idea. It would be *very* costly to screen or filter a desk against high level RF.

[tony sayer]

In article , Dave Plowman (News) writes

Its not particularly screening thats the problem, its more semiconductor junction demodulation. Some designers had this in mind more than others;)

Still wasn't thought about in those old days!....

[The Natural Philosopher]

was too. used to put a base emitter cap on the input transistor, and a few ohms in series.

[tony sayer]

Not when I worked at Neve and Audix:)

[Dave Plowman (News)]

Problem is that most these days use the same ICs...

[mike ring]

Well, you've got me there. No mobiles close either side, say 50 yards.

But at least now I know what it is I can try to work it out.

Of course there's a busy road in the front with lots of school run 4WDs, cruisers, builders, Essex girls all phoning while driving like crazy, sorry, phoning like crazy while driving.

mike

[Mike]

semiconductor

AFAIR Rupert Neve's mic amp has serial resistors on the two input transistor bases. He also tends to use NPNs rather than the ubiquitous PNP 737 which I was told was were less prone to rectifying r.f. interference.

[The Natural Philosopher]

Mm. They never offered me enough at the interviews Tony, so I left the business.

Their loss it seems.

[tony sayer]

LOL!,

This was a long time ago now. I left Neve after falling fowl of the "prayer meetings after work" policy that went on there;!. Course they wouldn't get away with that sort of caper nowadays..

Or would they in this PC world?.....

[Mike]

Was that when they were at Melbourne (Cambs, not Aus) ? I think nowadays it's more "work after work" as the business is so cut-throat.

[Mike]

Perhaps we should all set up a new audio company to show how it should be done :-)

[Dave Plowman (News)]

Rupert - or his minions - certainly produced some fine sounding gear. His EQ - and compressor/limiters - haven't IMHO been surpassed yet. Although I've got a couple of really ancient Pye compressors that are even sweeter. I'd love to get hold of a working BBC Lim2 - designed before WW2 - and perhaps the nicest limiter ever, but memories tend to be short, audio wise. One case where valves do rule?

[The Natural Philosopher]

Christ! You are right....Never did figure out how putting your hand in the back of the TV to 'feel the power of Jesus' would result in better equipment...

Moind you, at leats you never worked for the ginger pig. Psomiscuous sex mandatoty in every nook and cranny, and good design frowned on. Only bullshit and s**en seemed to count.