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PostPosted: Sun May 29, 2016 8:02 pm 

Joined: Sun May 29, 2016 7:11 pm
Posts: 7
I need to setup an Omnia 7 (FM only - no RDS or HD) at the studio and am exploring the idea of placing ST on a PC at the transmitter site to handle clipping and stereo generation (similar to what the Omnia 9sg does). As I don't see any presets within ST designed for this purpose, I'm wondering if this would prove favorable as far as audio quality is concerned and if so, how to best setup ST for this application. FYI: ST will be getting audio from the 7's 'Pre L/R clip' patch point.

I assume the band-pass filtering would be set to mimic what's going on in the '7 and basic phase rotation and pre-emphasis (75us) would be on, but I'm quite unsure as to how to proceed in configuring the advanced clipper (Pre-limiter, Bass, Highs, CPU, Distortion & Sound) and composite clipping (Strictness, Peak precision, Demodulated peak clipping, Also low freqs & Over sampled pre-clip) panels.

CPU power is not an issue and I would like to set this up with absolute emphasis on audio quality (clean audio) and not CPU power savings or efficiency.

Any help would be greatly appreciated.

Thanks,
Brian

BTW: Not sure that it matters, but using the Rustonium 5B preset in the '7.


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PostPosted: Sun May 29, 2016 10:01 pm 

Joined: Tue Jan 26, 2016 11:34 pm
Posts: 54
Location: Jugoistočna Srbija
Maybe this would be of some help to you: http://thimeoaudio.blogspot.rs/2015/01/ ... audio.html
Quote:
At the studio:

Load an FM preset, turn the FM part off and lower the Advanced Clipper drive to a level where the audio never or almost never hits the clipper (example vaue: 0.50).
Lower the Post Amp slider by a few dB to protect the MP3 decoder from clipping (it needs a few dB of headroom; example value: 0.70).

At the transmitter site:

Load the same preset
Turn all the filters before the clipper off: Declipper, PNR Noise & Hum, Natural Dynamics, Phase Rotation and Phase Delay, Noise Gate, AGC, Multiband Compressor, Stereo Widener, Singleband Compressor, Bandpass filter.
Turn the Delossifier on. This filter detects and removes pre-ringing caused by lossy encoding.
Multiply the values of the Post Amp slider and Advanced Clipper drive at the studio side. With the example values above, 0.70 * 0.50 = 0.35. Divide 1 by this number (1 / 0.35 = 2.86). Set the Pre Amp at the transmitter site to that value. Doing this makes the level going into the Advanced Clipper equal to that in the original preset if you hadn't split it into two parts.


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PostPosted: Mon May 30, 2016 9:55 am 
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Since the clipper in the 9sg is the same as the one in Stereo Tool, this will definitely work and give you a very good audio quality. Setting it up should be pretty simple, in short you can just reset all settings, then enable the FM settings and Advanced Clipper plus Composite Clipper. There are a few sliders that you can use to adjust the sound further, I can give you the details on that later.

You shouldn't need to use Phase Rotation (we haven't put that in the 9sg either, we assume that the processor does this part). I assume that the 7 output will also be bandpass-filtered, but you can check the graphs in Stereo Tool to make sure; in the 9sg we've set the lowpass filter to 16400 Hz if I recall correctly.


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PostPosted: Mon May 30, 2016 4:18 pm 

Joined: Sun May 29, 2016 7:11 pm
Posts: 7
Thank you Hans, this is what I was hoping to hear. I'm going to be setting up a test PC sometime this week. Could you please elaborate further on what sliders I could use to adjust the sound further and any other settings that would help to maximize audio quality - I assume cranking all strictness sliders would help? As previously stated, CPU power is not an issue - maximizing audio quality is our focus here. If possible, I'm looking to sound as good on the air with the split configuration as things would sound were the exciter connected directly to the 7's composite output.


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PostPosted: Mon May 30, 2016 6:40 pm 
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The default settings for Strictness are probably very close to optimal.

Settings you might want to try out (these are the ones that we made available in the 9sg):
- Bass: Frequency and Shape
- Sound: Sparkling Highs, Dirty Voices (called Phat Mids in the 9sg), and the shape where you can draw how much distortion you want to allow (you can make it higher for high frequencies).
- Distortion: Bass start/end freq, bass clipping delay settings.

That's it...


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PostPosted: Mon May 30, 2016 11:09 pm 

Joined: Sun May 29, 2016 7:11 pm
Posts: 7
Thanks Hans, I'll keep this in mind when setting up. Am I correct to assume if a particular setting wasn't mentioned (such as the de-esser or pre-limiter) it should be left at it's default value, or should it be totally disabled? And, do you have any optimal value suggestions for the settings you mentioned (particularly the bass settings) verses the 9sg? Again, I'm looking to duplicate what's going on in the 7's final clipping stages... at the transmitter site. Thanks again!


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PostPosted: Wed Jun 01, 2016 5:48 pm 
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Defaults are fine (and pre-limiter should be disabled!).

For bass clipping we have 80% and 90% as default settings. I would also turn Sparkling Highs on (if it isn't enabled already).


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PostPosted: Sat Jun 11, 2016 7:07 pm 

Joined: Sun May 29, 2016 7:11 pm
Posts: 7
I've got this going on a test rig (not actually on air yet) and can't seem to get the bass sounding right. At times it seems to distort, as in too much bass level. I've tried fiddling with the bass settings and can't seem to get a happy medium. There's either too much bass or not enough. I've got the bass clipping set at 90%/80% as suggested and the bass clipping frequencies at default (clip up to 80hz, drop to no clip at 220hz). Bass shape settings are also at default (Strength: 0, max harmonic freq: 160hz). Also, the delay (punchy bass) is set for 0.000 sec delay and delay clip level is at +0.00 (default).

In the advanced clipper panel, the 'Also low freqs' and 'Oversampled pre-clip' options are enabled (not sure this matters, but seemed to help the sound a bit).

Any thoughts would be appreciated.

Thanks!
Brian


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PostPosted: Sun Jun 12, 2016 8:35 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4230
Just load Advanced Clipper settings from Unveil FM preset. Adjust Advanced clipper level as You wish. Let us know.

_________________
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PostPosted: Mon Jun 13, 2016 5:05 am 

Joined: Sun May 29, 2016 7:11 pm
Posts: 7
Thanks Bojcha! I'll give that a try.


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