MIX 2S and MIX 2M as ADD dsp modules in SDK limit the output

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musurgio
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MIX 2S and MIX 2M as ADD dsp modules in SDK limit the output

Post by musurgio »

Hi,
After exhausting tests the nice MIX2 mdls the free ones we have are limiting the output of the sound.
Also in SDK the dsp modules add(x) do the same as I suppose that MIX2 has been made using those dsps.
The assuming is for the build of the device and not the actual dsp atoms which certainly limit the sound.
What does this mean ?
OK no matter how hard you up the volume at the input of the above mentioned mdl and dsps the output remains constant acting as a limiter !!
I certainly do not want that kind of reaction so I will reconfigure once again my devices in my projects...
The same behaviour I have tested some years ago with the direct outputs of STM24 and 48 scope mixers or was it the 1632 ?
Well I will test that again but I am 100% certain that a main scope mixer acts this way !!
Regards,
Dimitrios
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astroman
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Post by astroman »

I hope it does... :D
your options are: take care of all the levels yourself, accept clipping, ... or use a limiter

cheers, Tom
musurgio
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limiting

Post by musurgio »

Well that is something that I don't like being done wityhout me doing it...
First of all raising the volume before the outputs gets into clipping as a limiting effect when there is enouph headroom left...
Secondly there are limiters out there sold at high prices just because they do a better job than others, so I don't want a "clever" scope module do this instead...
The concept of the adder modules is to just add the signals and not lower around 6 db each adding device and then just limit the mixed output.
It could lower the input by 6 db of each input but after that leave the output alone maybe into clipping if the summing is too much.
This is VERY IMPORTANT !
Regards,
Dimitrios
Immanuel
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Post by Immanuel »

There is no limiting going on. It just turns down the signals before summing. If it didn't do this, and you fed it with 2 signals of more than -6dB ... it would clip. This is pure logic.

This saves you from having to calculate how far you can push each channel. If you feed it with 2 channels of 0dB, then the summed output would be ... 0dB.

It is clipping protection - not limiting.
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astroman
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Re: limiting

Post by astroman »

musurgio wrote:...Secondly there are limiters out there sold at high prices just because they do a better job than others, so I don't want a "clever" scope module do this instead...
sorry, can't resist - but that is plain nonsense
the boxes you refer to are expensive because they are 'famous' and (usually) hand-crafted in small amounts, not because they do something in a specific way.

A digital 'limiter' in the sense of those modules just prevents the signal to take an 'impossible' state (because of finite resolution), it doesn't try to fake the non-linear response (frequency and distortion) of the analog gear. Unless sold as an 'emulation of...'
not to forget that 'better' is in the ear of the beholder ;)

cheers, Tom
musurgio
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limiter

Post by musurgio »

Hi,
I am sure you did not quite understand as what this modules do.
Here is a simple example.
If you open a mixer and if you add two audio channels then by lowering the gain for 6 db for each you can emulate what mix2s does regarding the inputs only right ?
Now the mixer lets the output "float" without having any brickwall limiting !
If there is gonna be distortion its gonna be !
Now why these mix2s devices do not let the signal mix to whatever level they get as the normal scope mixers ?
I know this mix2s device is based on scope atoms add2, add4, etc...
As I posted one scope mixer does the same on its direct outputs "limiting" the out signal without letting it "NORMALLY" distort if it has tom as other scope mixers do.
So don't say that ther are some impossible things here...
I hope you understand what I try to say...
Regards,
Dimitrios
musurgio
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limiting

Post by musurgio »

Hi,
To make my point clearer if you use one or more of these mix2s devices and feed just the input one because input 2 is not used at that specific time the output signal cannot reach 0 digital !
Its always -6 because this headroom is reserved for the input channel 2
I hope you understand my pouint of view better now.
Regards,
Dimitrios
Immanuel
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Post by Immanuel »

As far as I recall, there also are some SDK modules which do not turn down the volume.
voidar
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Post by voidar »

Yes, these devices are normalized as said by the compiler himself.

Your best bet now is the switch-it device.
musurgio
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mix device

Post by musurgio »

Yes but I need the mixing capabilities.
I was avoiding the scope mixers cause I wanted simple mixing phase locked like the mix2s device so switching is either the one or the other.
Can someone build a simple sdk device like mix2s but without output decrease per channel ?
Regards,
Dimitrios
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Shroomz~>
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Post by Shroomz~> »

done :wink:

Hope it's what you're after & sorry about the lack of text labels, I'm quite busy & made it quickly as a break from what I'm doing.

http://www.planetz.com/phpBB2/viewtopic ... 037#175037
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