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BS412 LIMITER QUESTION

S

sprostise

Hello my friends.

Greetings first to all on this forum.
I have a question about the BS412 limiter level setting.

Well, I know this is hard to answer this, becouse every country has it's own regulatives.


But, I played a little with this setting ON/OFF and the db setting and the sound on-air is VERY different with various settings.
Well, with the ON and about 3 db there is a lot of noise getting into the exciter. With the setting OFF, the noise is gone.

OK, to make it quick...
Can you post some of your settings and observations about this limiter maybe?

Thank you!

Bostjan
 
You have posted a very general and non-specific question...

Yes, the limiter will very drastically change your sound. It is designed to reduce the RMS energy of the MPX signal and it means a significant drop in loudness and possibly sound texture as well.

Which processor is in question? How is it connected to the transmitter? What is the accepted BS.412 level in your country?

Are you sure there is no noise in the signal otherwise, but it is being masked by the higher RMS energy when the signal is fully modulated (limiter turned off)?


Regards,
Goran Tomas
 
Thanks for the reply.

I know my question is very non-specific...
Well, the processor is an Omnia and I just wanted to know if others use this limiter and which level. The brand of the processor is not important here, becouse almost every better box have this option :)

Let me explain.
If I use a VERY LOUD preset and engage the limiter I get almost the same sound as with the stock preset with the limiter OFF!
So, what is the point to drive the processor as crazy and after engage this limiter?

Regarding the noise. There is no noise when the limiter is OFF between the song pauses.
We have the box driving into a link transmitter and then from the link reciever to the exciter and final trasmitter.

The country regulation is 0 db ???
For now the excepted level is at + 3 db, becouse not everyone is using this regulation :mad:


Thank you and have a nice day.
 
sprostise said:
Thanks for the reply.

I know my question is very non-specific...
Well, the processor is an Omnia and I just wanted to know if others use this limiter and which level. The brand of the processor is not important here, becouse almost every better box have this option :)

Let me explain.
If I use a VERY LOUD preset and engage the limiter I get almost the same sound as with the stock preset with the limiter OFF!
So, what is the point to drive the processor as crazy and after engage this limiter?

Regarding the noise. There is no noise when the limiter is OFF between the song pauses.

We have the box driving into a link transmitter and then from the link reciever to the exciter and final trasmitter.

The country regulation is 0 db ???
For now the excepted level is at + 3 db, becouse not everyone is using this regulation :mad:


Thank you and have a nice day.
Click to expand...

The setting of the BS-412 limiter is generally determined by two issues:

1. If it is required by the broadcast authorities in that Country.
2. If so, what amount of limiting is required. (Generally, most Countries who that require BS-412, what the mix power level to be maintained at 0 dBu.)

What Country are you located? That will help regarding your question.

-Frank Foti
 
In my prior reply, there's a typo. It should read:

2. If so, what amount of limiting is required. (Generally, most Countries that require BS-412, want the mpx power level to be maintained at 0 dBu.

That's what happens when writing a reply before being fully awake. :)

-Frank Foti
 
Well, thanks for the reply Mr. Frank.

I have been in touch with your technical team allready last week.
I was shure it was a fault in Omnia settings with the preset adjustements. But it turned out it was the limiter.

I don't want to be annoying, becouse I know your people have some better things to do, then handle this kind of problems.
So, I turned on this forum for any answers.

The thing is, that when I have the limiter OFF the sound comes ''full'' to the exciter. When it is ON, there is much lower peak level and I have to raise the exciter input level. I guess ,that is why I get so much noise with the adjustement...


Am I right with this one?

Sorry to sound st*pid but I had the original Omnia FM Jr. before this box and had never used this limiter before.

Thank you and respect for the work you and your team is doing!
Bostjan
 
sprostise said:
Well, thanks for the reply Mr. Frank.

I have been in touch with your technical team allready last week.
I was shure it was a fault in Omnia settings with the preset adjustements. But it turned out it was the limiter.

I don't want to be annoying, becouse I know your people have some better things to do, then handle this kind of problems.
So, I turned on this forum for any answers.

The thing is, that when I have the limiter OFF the sound comes ''full'' to the exciter. When it is ON, there is much lower peak level and I have to raise the exciter input level. I guess ,that is why I get so much noise with the adjustement...


Am I right with this one?

Sorry to sound st*pid but I had the original Omnia FM Jr. before this box and had never used this limiter before.

Thank you and respect for the work you and your team is doing!
Bostjan
Click to expand...

Bostjan,

The BS-412 limiter will reduce the fullness of the sound, as it must reduce the power of the multiplex signal, as specified by the ITU standard. The reduction in loudness is about 10 ~ 12dB. Now, this only holds true, if your Country requires, and mandates adherence of the ITU BS-412 regulation.

If there is no requirement for you, then I would not use the BS-412 limiter.

What Country are you located?

-Frank Foti
 
Thanks for the reply.

We are a radio station from Slovenia. We have the regulation of 0 db, but the +3 db is in agreement...

So, if the limiter reduces as much as 12 db of level, there is no need or sense to drive the adjustements harder and louder...
Thanks and greetings.

Bostjan
 
sprostise said:
Thanks for the reply.

We are a radio station from Slovenia. We have the regulation of 0 db, but the +3 db is in agreement...

So, if the limiter reduces as much as 12 db of level, there is no need or sense to drive the adjustements harder and louder...
Thanks and greetings.

Bostjan
Click to expand...

The limiter is not a 'limiter' as you might think. The algorithm for it is set to observe the "power of the multiplex," as measured over a one minute rolling average. Not the easiest method to describe, and if you wish to know more about it, you should have a look at the ITU regulations, under ITU BS-412 specification.

Basically, the BS-412 limiter function does not allow the clipper system to be pushed as hard. If the observance in Slovenia is +3dB, then you can set the BS-412 limiter threshold to +3dB, and it will hold the multiplex power level to +3dB, as measured on a test set for the ITU specification.

-Frank Foti
 
Thanks for the reply again.

Well if I understand what it does with the signal...
No metter how ''hard'' the adjustements are, it will keep it under +3 db of power.

So, this comes for me to a conclusion - It's ok to keep the processor with a ''normal'' level and settings, becouse the power is going to be reduced anyway?

Thank you for your time and answers, Mr. Frank.

Bostjan
 
sprostise said:
Thanks for the reply again.

Well if I understand what it does with the signal...
No metter how ''hard'' the adjustements are, it will keep it under +3 db of power.

So, this comes for me to a conclusion - It's ok to keep the processor with a ''normal'' level and settings, becouse the power is going to be reduced anyway?

Thank you for your time and answers, Mr. Frank.

Bostjan
Click to expand...

It will affect the power of the transmitter, but the power 'effect' of the multiplex signal.

Your observation is correct. No matter how hard you drive the processor, the BS-412 limiter will keep the ITU power level at +3dB or less, if you have the threshold set to +3dB.

-Frank Foti
 
Dear Bostjan, dragi Boštjan

Če imas tezave, me poklici in ti z veseljem pomagam

MARKO


Why bother with Omnia? All major radio stations in SLovenia use Orban processors! Lately we swap Omnia with Orban at : Zeleni Val, Aktual, RadioHIT, CAPRIS!!!
You can call them and ask, they are very satisfied with sound, and they didn't have any trouble whatsoever with Mpx power settings. Everything was made by us (dealer & support team)!
And Bostjan EVERYONE HAS to be inside of ITU412 in Slovenia! How to deal with it It's every station own problem to solve. Slovenian regulator APEK permits MPX power at +2 dBr, but it tolerates +2,9!!!
Orban 8600 and 8500 V3, with newly imprved mpx power controller Works incedible good! I can prove! Listen to Radio Ognjisce anywhere in SLovenia or Radio Antena 105,2, Radio 1 only in Ljubljana at 88,4 & 107,9!!

Marko Zupan
Radio Ognjisce

Orban dealer support team
 
markoz said:
Dear Bostjan, dragi Boštjan

Če imas tezave, me poklici in ti z veseljem pomagam

MARKO


Why bother with Omnia? All major radio stations in SLovenia use Orban processors! Lately we swap Omnia with Orban at : Zeleni Val, Aktual, RadioHIT, CAPRIS!!!
You can call them and ask, they are very satisfied with sound, and they didn't have any trouble whatsoever with Mpx power settings. Everything was made by us (dealer & support team)!
And Bostjan EVERYONE HAS to be inside of ITU412 in Slovenia! How to deal with it It's every station own problem to solve. Slovenian regulator APEK permits MPX power at +2 dBr, but it tolerates +2,9!!!
Orban 8600 and 8500 V3, with newly imprved mpx power controller Works incedible good! I can prove! Listen to Radio Ognjisce anywhere in SLovenia or Radio Antena 105,2, Radio 1 only in Ljubljana at 88,4 & 107,9!!

Marko Zupan
Radio Ognjisce

Orban dealer support team
Click to expand...

Above post was written like a true professional
 
LOL! Shouldn't R-I get a check for that commercial? LOL! In all seriousness, it's very cool that Frank, Leif, Corny (and Bob at times) comes in here for direct inforamtion about processing. The previous commercial from afar (making wild claims) isn't exactly what I'd call educational.
 
EBU's BS412 directive simply makes it not worthwhile to clip excessively.
Like they say, "You can always turn the volume back up at the receiver, but you can never turn the distortion down."

As much as I think it is a bit of a sledgehammer (some would say 'nanny state') approach to the problem of clipping, it is effective. Living here in Germany I can attest that, along with their 50µsec pre-emphasis, the reduced clipping makes European stations sound a lot prettier than their American counterparts. However, because their modulation density is reduced (RMS must remain 12 dB below peak), perceived interference-free coverage is also reduced.

Now, if they would just enforce BS412 with record companies' releases...LOL!

Kind Regards,
David
 
Marko, hvala v vsakem primeru se slišiva!

I think it would be polite to continue in english...
So, thanks once again Marko and all the others who respond to my question.

First of all, I know the problem was not in the Omnia!
Well, I got this solved, it was the link reciever with a major error. Got it fixed!

Now, let me respond to your suggestion about switching to Orban...
NO WAY! I know a lot of stations in my town use Orban boxes, but that's almost exactly how I would NOT like to be heard.

Orban and Omnia are the world most known and best DSP's of all.
Maybe I could get a better sound with Orban; or be louder. But, let me explain...

We are a non-typical hit radio. Our program contains only about 5% of Lady Ga Ga, Eminem, *Siddharta* type of music.
This kind of music is not difficult to handle and make it sound good. Try with something older or more ''Slovene'' ;-)

This is where our ''little'' Omnia beats even the ''big'' Orban. (I tested an 8500 FM)
Please, let us finish here.

This is the reason why I didn't write the brand name in my first post, becouse I didn't want to start an argue :p
Anyway, I'm quite happy with the responds I got. My first goal was to know, how do other users handle this limiter and on what setting.

As I said, there is no point to drive the processor harder, if it's going to be reduced on the output...


Thanks to all and have a nice day.
 
Hi sprostise,

I was away for a couple of days, but I'm glad you figured out it was not the processor, but the link. Things typically get blamed on the processor, but usually the problem is elsewhere ;)

You are correct that it doesn't make much sense to use an aggressive preset with the limiter engaged. The limiter is designed to reduce the average level of the MPX signal and will thus compensate any increase in density. It's actually more beneficial to use the imposed BS412 restrictions to your advantage and open up the sound and make the audio "breathe" more. Not only will the BS.412 limiter clamp down your signal less, but your sound will have more depth as well.

You don't want to increase the MPX drive to the STL transmitter or the transmitter itself, once you have engaged the BS.412 limiter. If you do, you would be effectively changing the BS.412 threshold. The correct way to set things up is to turn the BS.412 limiter off and verify that you are (peak) modulating the transmitter fully to 75kHz/100%. If you then engage the BS.412 limiter and set it to 0dB or +3dB, you can be sure that the Omnia will adhere to that BS.412 measurement. Like I said, you don't want to change any signal level after the processor at that point, as that will change the level and you will no longer be complaint.

I have quite a lot of experience with audio processing and happen to work for AVC Zagreb which is a sister company to AVC Ljubljana in Slovenia. If you need any further help with either the processor or the adjustments, please let us know. Slovenia is only a short drive from Zagreb and I have measuring equipment to read exact off-air peak and BS.412 modulation levels.


Regards,
Goran Tomas
 
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