Author: Rob Scholtes
Omnia.9sg review by Rob Scholtes (Technical Manager FunX)
The Omnia.9sg is available for some time now, but is sparingly used in the Netherlands. Which is unfair, because according to Omnia sound the new FM-stereo generator cleaner and louder than conventional stereo generators and enables a better FM-reception. Does the Omnia.9sg meet up the expectations?
The Omnia.9sg is designed by Leif Cleassen, whom we all know from the Omnia.9, and Hans van Zutphen, the man behind Stereo Tool. Omnia started a collaboration with both gentleman and this resulted in the extraordinary Omnia.9sg. You get the same Omnia.9-interface with all the measurement tools for the audio signal and modulation, thereby the clipper and stereo generator are equipped with some special features.
Omnia says they deliver with the Omnia.9sg ‘1dB extra loudness for free’. In a conventional stereo generator is 100% modulation around 90% stereo audio and 10% pilot-tone. In the stereo generator of the Omnia.9sg the pilot-tone is ‘masked’ inside the audio signal and the full 100% can be modulated. Because its already compressed, you get 1 dB extra loudness, without violating the restrictions of the Radio communications Agency.
The Radio communications Agency uses the old Stokkemask (ITU-R SM.1268 standard) to approve transmitters. The Omnia.9sg is interesting for the Netherlands because it uses an algorithm that keeps the spectrum nicely within the limits of the Stokkemask. Other stereo generators need to hold back the audio level. With the Omnia.9sg is this not the case, in fact the audio level can be louder.
To achieve this the Omnia.9sg uses an algorithm that actively adjusts the clipper. It has a built-in virtual FM-exciter that simulates the MPX-signal and a spectrum analyzer that preforms measurements. The result is a FM-spectrum, when configured correct that never exceeds the limits of the Stokkemask. The side-bands of the spectrum don’t get to wide, which results in better reception quality.
By the use of a sharp filter, the pilot-tune and RDS-carrier wave are protected till 100dB. This enables the possibility to enhance the audio bandwidth to 16,5kHz instead of the common used 15kHz. The psychoacoustic controlled algorithm of the clipper is used in the composite signal to mask distortion to an inaudible level. It also creates 3dB extra space for high frequencies and and 3dB extra left/right modulation within the maximum modulation.
The last but not least novelty is the SBB-mode of the stereo signal. Opinions are divided, but is should reduce multipath distortion a lot. Usually is L-R modulated symmetrical around 38kHz, by cutting of the top half there should be less multipath distortion. The disadvantage of this is that some radios can’t cope with this and switch to mono mode. Omnia found the best of both worlds and cuts off the top half only partially and in to different ways. This gives you the advantage of less multipath distortion, and the radios display a nice stereo image.
Measurement is the key to knowledge
We all know the ability to listen to a audio stream in the remote software NfRemote from the Omnia.9, that’s also possible in the Omnia.9sg. Anytime and anywhere, you’re able to switch between different points in the internal audio chain and listen to the stream. This comes in handy when tweaking your final sound.
The Omnia.9sg has its own measurement equipment built in, for example a oscilloscope, real time analyzer, loudness meter, spectrum analyzer and power / modulation meters. Add to that a build in speaker calibration tool and you can calibrate your speakers to create neutral reference monitors needed when tweaking the sound processing.
The two MPX inputs can be used as source for the internal measuring instruments. So you can use the MPX output of an receiver, connect is to a MPX input and measure what’s really going on On-Air. The MPX input can also be used to connect a back-up stereo generator. In case of a drop-out of the Omnia.9sg it’s possible to switch directly to the transmitter, manual switching for maintenance reasons is also possible.
The Omnia.9sg is equipped with ‘MPX-over-AES’ or ‘Omnia Direct’. This is used when an external digital FM exciter is connected, when fed with the MPX signal you get the best quality. If you have a 192kHz AES connection towards your transmitter you don’t need to place the Omnia.9sg near the transmitter site. Unfortunately the Omnia.9sg isn’t equipped with an 10MHz GPS input, used to sync SNF networks.
It does have a built-in silence detector with audio player and simple multiband processor. The music and audio design are uploaded using FTP and your able to alter the playout in random, 1 track/1 jingle or 2 tracks/1 jingle.
The optional RDS encoder is complaint to the UECP standard and thus compatible with all RDS software. All Omnia equipment is equipped with Livewire+ and is complaint to AES76, so audio can be connected using Audio-over-IP. The Omnia.9sg has a double power connection, not unimportant if you really want to be redundant at the transmitter site.
But most important, the Omnia.9sg is meant to be a stereo generator with build-in clipper. The supplied audio signal from the audio processor needs to be ‘clean’, so without clipping. Omnia states it’s possible to connect the Omnia.9sg directly to a HD processor, so without pre-emphasis-limiter. That pre-emphasis is done entirely by the Omnia.9sg. This could save you the investment of an separate FM processor.
The clipper itself has a ton of configuration possibilities, much more then we were used to until now. It features the well-known ‘Bass Clip Threshold” but Omnia gives you the ability to alter the attack of both clippers and the frequency response of the harmonics. The Omnia.9sg doesn’t have a composite clipper, but with the features ‘Sparkeling High’ and ‘Phat Mids’ you can emulate the effects of a composite clipper, it’s a matter of taste, but you are able to get that extra edge. All together the Omnia.9sg gives you the possibility to create a sound that is truly distinguishable from other audio processors.
The build-in tone generator can generate a 400Hz tone to configure the FM transmitter for maximum swing. For the Omnia.9sg that’s 72kHz to stay inside the Stokkemask. Simple as that, and you never have to worry about it.
When we listen, the first thing that stands out is the stereo image of the Omnia. It has much more depth than any conventional stereo generator. The next thing that stands out is the audio signal that sound much cleaner, voices are much more defined and the higher frequencies get more space. The eventual sound and loudness is created by yourself and the Omnia.9sg gives you this ability.
Because of the sharp low pass filter the audio bandwidth can be tuned to 16,5 kHz and that’s audible in the higher frequencies. Next to that the phase-purity is so big that the stereo image is of a unknown depth, like never heard before on FM.
The Omnia has less multipath-distortion, therefore the FM transmitters range is bigger. The audio signal is better near the edge, without the well-known distortion and drop-outs so you are able to listen longer at the edge of the transmitters range. The Omnia.9sg enlarges the range significant without extra power.
Listening tests learn that the Omnia9.sg indeed sounds clearer and cleaner, while it stays loud. Especially the clearer sound ensures radio programs are better audible at lower volumes. Add to that the better stereo image of the Omnia.9sg, which is better than ever on FM.
The extra 1dB auto modulation can be used for cleaner highs or for extra loudness, the choice is yours. The Omnia.9sg delivers a nicer high frequency response and stays within the limits of the Stokkemask, while audio is modulated louder.
Combined with the high frequency character and controls you are able to create a cleaner and louder FM transmission, while reception quality improves. The multipath distortion is noticeably less. Not only loudness is important in FM transmission but also a clean and un-distorted sound, the Omnia.9sg can be the difference.
Products in the review: Omnia.9sg Stereo Generator