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Basic UK pre-emphasis circuit??
Posted: Wed Jan 20, 2016 3:00 pm
by Elopid
Hey necks,
I need the basic UK pre-emphasis circuit with the resistor and caps, does anyone have it please??
Cheers, Elopid.
Re: Basic UK pre-emphasis circuit??
Posted: Wed Jan 20, 2016 5:58 pm
by NOYB
Why not work it out for components you might already have? Break frequency is given by 1/(2Pi*R*C).
50uS time constant is 1/(2*Pi*50exp-6) which calculates to 3183Hz.
So if you had say a 50nF capacitor kicking around you'd need a resistor of 1k.
Or build a spreadsheet....
Re: Basic UK pre-emphasis circuit??
Posted: Wed Jan 20, 2016 7:02 pm
by Shedbuilt
As can be seen from NOYB's maths, for this type of network, the time constant (S) is the product of resistance in Ohms, and Capacitance in F. For time constant in uS, you can use capacitance in uF. What's often forgotten or not accounted for, is the effect of source and load impedance. Both need to be low - in relation to the value of R. If the load / terminating impedance is too high, the RC network will have little or no effect, and therefore little or no rise at high frequencies. Once that's sorted, if the source impedance is too high, the input will fall as the input impedance of the network falls (with falling xC at higher frequencies) - again leading to reduced or no pre-emphasis. Putting some numbers into it. If you use a 33k resistor, in parallel with a 1.5nF capacitor, you need to be terminating into something like around 5k, with source impedance preferably lower than that, to get a reasonably accurate pre-emphasis curve. You can get 50uS from many capacitor / resistor combinations, but the lower the resistor (and respectively larger capacitor), the lower the terminating and source impedance a need to be.....
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 7:11 am
by thewoodstarr
You want 50uS? its a 12k Resistor and a 4n7 Cap in parallel. If you want to be really anal its 5 nF. So it's 4n7 and 300pF ceramic Cap. Put it in on signal out, the red side of your of your audio cable from your mixer/Source to Your TX Job done.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 7:32 am
by thewoodstarr
Elopid wrote:Hey necks,
I need the basic UK pre-emphasis circuit with the resistor and caps, does anyone have it please??
Cheers, Elopid.
You want 50uS? its a 12k Resistor and a 4n7 Cap in parallel. If you want to be really anal its 5 nF. So it's 4n7 and 300pF ceramic Cap. Put it in on signal out, the red side of your of your audio cable from your mixer/Source to Your TX Job done.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 8:01 am
by thewoodstarr
builtinashed wrote:As can be seen from NOYB's maths, for this type of network, the time constant (S) is the product of resistance in Ohms, and Capacitance in F. For time constant in uS, you can use capacitance in uF. What's often forgotten or not accounted for, is the effect of source and load impedance. Both need to be low - in relation to the value of R. If the load / terminating impedance is too high, the RC network will have little or no effect, and therefore little or no rise at high frequencies. Once that's sorted, if the source impedance is too high, the input will fall as the input impedance of the network falls (with falling xC at higher frequencies) - again leading to reduced or no pre-emphasis. Putting some numbers into it. If you use a 33k resistor, in parallel with a 1.5nF capacitor, you need to be terminating into something like around 5k, with source impedance preferably lower than that, to get a reasonably accurate pre-emphasis curve. You can get 50uS from many capacitor / resistor combinations, but the lower the resistor (and respectively larger capacitor), the lower the terminating and source impedance a need to be.....
Mate what a load of crap. This poor guy wants simple a passive Pre-Emp Circuit. I answered his question anyway.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 8:07 am
by thewoodstarr
Elopid wrote:Hey necks,
I need the basic UK pre-emphasis circuit with the resistor and caps, does anyone have it please??
Cheers, Elopid.
You want 50uS? its a 12k Resistor and a 4n7 Cap in parallel. If you want to be really anal its 5 nF. So it's 4n7 and 300pF ceramic Cap. Put it in on signal out, the red side of your of your audio cable from your mixer/Source to Your TX Job done.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 8:12 am
by thewoodstarr
thewoodstarr wrote:builtinashed wrote:As can be seen from NOYB's maths, for this type of network, the time constant (S) is the product of resistance in Ohms, and Capacitance in F. For time constant in uS, you can use capacitance in uF. What's often forgotten or not accounted for, is the effect of source and load impedance. Both need to be low - in relation to the value of R. If the load / terminating impedance is too high, the RC network will have little or no effect, and therefore little or no rise at high frequencies. Once that's sorted, if the source impedance is too high, the input will fall as the input impedance of the network falls (with falling xC at higher frequencies) - again leading to reduced or no pre-emphasis. Putting some numbers into it. If you use a 33k resistor, in parallel with a 1.5nF capacitor, you need to be terminating into something like around 5k, with source impedance preferably lower than that, to get a reasonably accurate pre-emphasis curve. You can get 50uS from many capacitor / resistor combinations, but the lower the resistor (and respectively larger capacitor), the lower the terminating and source impedance a need to be.....
Mate what a load of crap. This poor guy wants a simple passive Pre-Emp Circuit. I answered his question anyway.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 10:35 am
by thewisepranker
thewoodstarr wrote:
Mate what a load of crap. This poor guy wants simple a passive Pre-Emp Circuit. I answered his question anyway.
You twat. His response was correct and comprehensive.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 10:49 am
by thewoodstarr
thewisepranker wrote:thewoodstarr wrote:
Mate what a load of crap. This poor guy wants simple a passive Pre-Emp Circuit. I answered his question anyway.
You twat. His response was correct and comprehensive.
Ok really? You keep telling yourself that. Again a 12 K resistor and a 4n7 Cap. That is all guy needed to know. Dick Head.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 11:16 am
by SD-E1102
thewoodstarr
That is not the way we use our forum, if you carry on you will no longer be able to use it.
Play nicely or not at all. 
Radionecks Admin
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 11:19 am
by Analyser
thewisepranker wrote:thewoodstarr wrote:
Mate what a load of crap. This poor guy wants simple a passive Pre-Emp Circuit. I answered his question anyway.
You twat. His response was correct and comprehensive.
LOL. +1
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 12:48 pm
by thewoodstarr
SD-E1102 wrote:thewoodstarr
That is not the way we use our forum, if you carry on you will no longer be able to use it.
Play nicely or not at all.
Radionecks Admin
Fine Sorry mate, it grinds my gears when people who think they know, but really don`t. That poor guy just wanted a simple answer to a simple question. To be fair I answered it.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 12:58 pm
by thewoodstarr
This is total Bollocks:- again the chap asked for a simple pre=emp circuit, and the reply was:- builtinashed wrote:
As can be seen from NOYB's maths, for this type of network, the time constant (S) is the product of resistance in Ohms, and Capacitance in F. For time constant in uS, you can use capacitance in uF. What's often forgotten or not accounted for, is the effect of source and load impedance. Both need to be low - in relation to the value of R. If the load / terminating impedance is too high, the RC network will have little or no effect, and therefore little or no rise at high frequencies. Once that's sorted, if the source impedance is too high, the input will fall as the input impedance of the network falls (with falling xC at higher frequencies) - again leading to reduced or no pre-emphasis. Putting some numbers into it. If you use a 33k resistor, in parallel with a 1.5nF capacitor, you need to be terminating into something like around 5k, with source impedance preferably lower than that, to get a reasonably accurate pre-emphasis curve. You can get 50uS from many capacitor / resistor combinations, but the lower the resistor (and respectively larger capacitor), the lower the terminating and source impedance a need to be.....
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 1:07 pm
by Elopid
Just because it's beyond your intelliegence and you don't understand it does not make it total bollocks.
Thanks everyone for your replies. I have built one with 4700pF cap and it works great.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 1:09 pm
by thewisepranker
As I said, it's correct and necessary for completeness. How can you make such assumptions as to what the source impedance is?
If it's too complicated for you to understand, don't comment and go back to something more aligned with your limited mental capacity like connecting together pre-made modules like lots of other "rig builders" do. Or join the BNP or something.
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 2:40 pm
by thewoodstarr
Elopid wrote:Just because it's beyond your and you don't understand it does not make it total bollocks.
Thanks everyone for your replies. I have built one with 4700pF cap and it works great.
Elopid as you can`t spell intelligence, you probably have none! We all can copy and paste from Wikipedia. I was the person who gave you the correct Values. Doughnut!
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 3:18 pm
by Elopid
It was just a typing error chum, what's your excuse?
Re: Basic UK pre-emphasis circuit??
Posted: Sun Jan 24, 2016 11:25 pm
by Gum
thewoodstarr wrote:I was the person who
Posted the same thing about 20 times in a row? Doh-nut!
Re: Basic UK pre-emphasis circuit??
Posted: Sun Feb 07, 2016 1:27 pm
by Elopid
Wasn't quite the outcome I was expecting from a simple question lol.