Looking at an Inovonics 531 FM Modulation Monitor set on the quickest response time (100 microseconds). Observing an Omnia 11 on one FM, and an Orban 8500 Optimod (version 3.0) on another FM. The Omnia is rock solid with no peaks over 100%. Whenever the 8500 sees a lot of high frequency energy (high hats and cymbals), on the Loud-Punchy preset, I see modulation peaks that sometimes reach 105% - 120%, otherwise it typically hangs around the 100% mark, when the high frequency energy is not there. Is this typical for the 8500, or have FM audio processor's limiter performance come a long way since the 8500? I see the same peaks when I have the Inovonics set on the slowest response time too (1 millisecond).
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Orban Optimod 8500 Overshoots
- Thread starter Brian Bowers
- Start date
All co-located (transmitter, exciter, audio processor, and mod monitor). Using most current GatesAir Flexiva exciter (version with no internal Orban Optimod processor).
...all co-located at the studio site.
Sorry for the confusion. Yes, everything is at one site. No STL's are involved. I bypassed the Voltair, and PPM encoder, and still the overshoots take place. It simply has to be that the 8500 doesn't have the brick wall limiting action like the Omnia 11 FM does. I'm OK with knowing that, I guess I just never realized it before. I'm recommending an Omnia 11 FM to replace it next year.
Have you considered talking to Orban about this? Hard to imagine any modern FM processor without the basic ability to brickwall peaks. That's sort of the point, really.
Meant to call them yesterday. Hopefully this week sometime, although it does have 3.0 version firmware. 98% of the time, peaks are held to 100% (or wherever you obviously have your output set). The other 2% seems to be from program material that has high frequency energy content. That is when I see the overshoots. I guess I've just never really focused on the response times of modulation monitors before, until very recently (over the years, my focus on that comes and goes, as projects redirect my attention). I've recently purchased a Modulation Sciences ModMinder, and if you remember, that device would extend response time out to 10 milliseconds (as of this writing, I don't remember how fast the response time can be set for the ModMinder), in essence, ignoring some quick modulation peaks. This is mainly what nudged my curiosity about modulation monitor response time. The ModMinder is inoperative at this point, so I can't use that as a reference (debating seeing if I can get it repaired, as Modulation Sciences is no more). My Inovonics 531 has 4 choices of response time - between 100 microseconds, and 1 millisecond. I'm finding it interesting that the 8500 sometimes has these overshoots, and the Omnia 11 FM never has any.
My guess is your HF limiting or clipping is set to do no, or very little limiting. Grounded Grid is correct, every Orban processor that I've ever worked with and if set with correct parameters, let's peaks through as you describe.
Are you using one of the Orban presets, or a customized one?
Are you using one of the Orban presets, or a customized one?
Using the Punchy-Loud preset, with no customization. Running composite to the Flexiva FM exciter, although I know for a fact that the same peaks are coming out of the 8500 AES outputs.
I'm sure that these peaks (roughly 2% of the time) are allowed by the FCC, since they typically (from all of the info I read) are looking for the station that is blatantly, and consistently, over-modulating. I just find it interesting, as I guess I've never really put this much thought into it before, even though I've had the Inovonics 531 since 2010. Talking to a Belar Labs guy the other day, he claims that their FMCS-1 modulation monitor has a response time of 1 microsecond. Wow! Really?
Using the Punchy-Loud preset, with no customization. Running composite to the Flexiva FM exciter, although I know for a fact that the same peaks are coming out of the 8500 AES outputs.
Just curious, how would you know the HF peaks over 100% are occurring when you're running analog composite stereo? The reason I was asking about an STL prior, was the common issue when STL's or multiple devices are in the program line after the processing. It isn't uncommon for audio bandwidth or harmonic filters to ring, appearing just as you described. Nothing wrong with the processor, just how devices downstream react to heavily processed audio.
I'm also curious why you would run analog composite out of your audio processor, when you don't even have an STL. All the devices up to and including your exciter, have AES capability. AES has so much better s/n and phase stability than composite. Are you going composite out because you have a composite clipper in the line too?
>>>how would you know the HF peaks over 100% are occurring<<<
...looking at total modulation, while listening to program material. Am I doing something wrong here? 8500 is mounted directly above exciter. No composite clipper. Very short BNC connecting cable. 8500 AES outputs are being used for something else, which I'd rather not elaborate on at this time.
...looking at total modulation, while listening to program material. Am I doing something wrong here? 8500 is mounted directly above exciter. No composite clipper. Very short BNC connecting cable. 8500 AES outputs are being used for something else, which I'd rather not elaborate on at this time.
>>>how would you know the HF peaks over 100% are occurring<<<
...looking at total modulation, while listening to program material. Am I doing something wrong here? 8500 is mounted directly above exciter. No composite clipper. Very short BNC connecting cable. 8500 AES outputs are being used for something else, which I'd rather not elaborate on at this time.
There's nothing wrong with using the multiplex output. I would argue that yes...in a lab you might measure a difference but in the real world it makes little difference. I would prefer to use Bob or Frank's stereo genny but, once again, we're talking minute differences in performance. That assumes everything is installed using kosher engineering practices. Most modern exciters have decent audio specs.
If your processor can output digital multiplex then that may be worth exploring. Again...this yields a measurable difference in performance but can anyone really tell the difference in radio land?
BTW...I have both the Omnia 11 and Optimod 8700. I have never noticed any more slippage on the Optimod versus the 11.
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>>>how would you know the HF peaks over 100% are occurring<<<
...looking at total modulation, while listening to program material. Am I doing something wrong here? 8500 is mounted directly above exciter. No composite clipper. Very short BNC connecting cable. 8500 AES outputs are being used for something else, which I'd rather not elaborate on at this time.
Sorry if I wasn't being clear Brian; You made the comment that you saw HF peaks above 100% modulation whether digital or composite analog. My question was if you were only doing analog (composite), how did you confirm the peaks, all the way through the transmitter into the air, was generating those peaks above 100% with an AES output from the audio processor if you didn't run AES?
Regarding the question about whether you're doing something wrong by running composite, with all due respect, I answer, yes you are needlessly taking away performance advantages that are already available.
Each time you do a conversion: A/D, D/A, you introduce noise, artifacts, and potentially distortion. Each dB of noise you generate, is one less dB of audio you want your listener to hear. Going into an analog stereo generator from your audio processor is fine if you only have a legacy composite STL, but a complete waste of performance advantages that you get with as much end-to-end AES program chain. Digital from the processor to analog composite (D/A) conversion, then at the end of that short BNC cable is an A/D conversion at the exciter. Huh?
No offense intended to Wavo, but he's totally practicing 1970's thinking. In modern radio we compete with digital devices for ears. Using excessive audio processing and unnecessary format conversions in the program chain, can cost you listeners, especially TSL.
As I had mentioned in one of my previous posts, I just recently scored a used Modulation Sciences FM ModMinder. Maybe some of you have used one of these, or are still using one. I kind of liked using them at a previous cluster, but that was when they were semi cutting edge at the time (I guess, what, 14 years ago?). So a number of weeks ago, I was hooking it up. This is when I was really staring at my Inovonics 531 (utilizing an RF sample from the transmitter). That is when I noticed the HF peaks. We've been running the 8500 for about 9 or 10 years now, and I'm pretty sure I remember seeing these HF peaks the day we first looked at the Inovonics 531, but I really didn't pay much attention to them, since 98% of the peaks held at 100% modulation. I thought maybe RF in the transmitter building was having an effect on the 531. Paying much more attention now, I can confirm that the overshoots coincide with HF energy program material. Also, the 8500 received 3.0 firmware update back in 2012. I admit, I don't normally stare at my mod monitors (maybe as much as I should, but we always seem to pass our simulated FCC inspections), and as long as I see 98% of my modulation peaks hit 100%, I'm happy.
The setup I've been referring to all along goes like this - studio analog output feeds the Voltair input. The Voltair has inserts for the PPM encoder (in my case, all in analog state). The output of the Voltair feeds the 8500 analog input. The 8500 composite output feeds the GatesAir Flexiva exciter input. That's it for that chain. We're using the internal 8500's stereo generator.
We are also MaxxCasting.
http://geobroadcastsolutions.com/
The Geocasting guys are using both AES outputs of the 8500, at this time. They are utilizing an Audemat Modulation Analyzer for their/our booster transmitters, and tell me that they see the same HF peaks on the AES feeds. I don't remember the exact STL that they are using to feed their boosters, but I believe it is also made by GatesAir. I'm not at the transmitter site right now, otherwise I would look. It's all very current stuff.
Even to my golden ears, the 8500 composite output sounds extremely clean, running through the Flexiva, listening to the air feed, in headphones.
The setup I've been referring to all along goes like this - studio analog output feeds the Voltair input. The Voltair has inserts for the PPM encoder (in my case, all in analog state). The output of the Voltair feeds the 8500 analog input. The 8500 composite output feeds the GatesAir Flexiva exciter input. That's it for that chain. We're using the internal 8500's stereo generator.
We are also MaxxCasting.
http://geobroadcastsolutions.com/
The Geocasting guys are using both AES outputs of the 8500, at this time. They are utilizing an Audemat Modulation Analyzer for their/our booster transmitters, and tell me that they see the same HF peaks on the AES feeds. I don't remember the exact STL that they are using to feed their boosters, but I believe it is also made by GatesAir. I'm not at the transmitter site right now, otherwise I would look. It's all very current stuff.
Even to my golden ears, the 8500 composite output sounds extremely clean, running through the Flexiva, listening to the air feed, in headphones.
Sorry if I wasn't being clear Brian; You made the comment that you saw HF peaks above 100% modulation whether digital or composite analog. My question was if you were only doing analog (composite), how did you confirm the peaks, all the way through the transmitter into the air, was generating those peaks above 100% with an AES output from the audio processor if you didn't run AES?
Regarding the question about whether you're doing something wrong by running composite, with all due respect, I answer, yes you are needlessly taking away performance advantages that are already available.
Each time you do a conversion: A/D, D/A, you introduce noise, artifacts, and potentially distortion. Each dB of noise you generate, is one less dB of audio you want your listener to hear. Going into an analog stereo generator from your audio processor is fine if you only have a legacy composite STL, but a complete waste of performance advantages that you get with as much end-to-end AES program chain. Digital from the processor to analog composite (D/A) conversion, then at the end of that short BNC cable is an A/D conversion at the exciter. Huh?
No offense intended to Wavo, but he's totally practicing 1970's thinking. In modern radio we compete with digital devices for ears. Using excessive audio processing and unnecessary format conversions in the program chain, can cost you listeners, especially TSL.
My audio chain is digital AES from the Zetta sound card to the 8700/Omnia11. I totally agree that noise/distortion are additive and that D to A and A to D conversions should be as few as possible.
My thinking is not "1970s thinking." I'm being pragmatic. The listener, in a correctly engineered plant, can NOT tell the difference. IF your equipment allows a digital multiplex connection then it could be argued THAT would be the best interface but most folks do NOT have an exciter/audio processor that can pull that off.
Brain: If you find yourself agreeing with Kelly (he does make some good points) then simply buy a passive AES splitter and feed BOTH sources.
As I had mentioned in one of my previous posts, I just recently scored a used Modulation Sciences FM ModMinder. Maybe some of you have used one of these, or are still using one. I kind of liked using them at a previous cluster, but that was when they were semi cutting edge at the time (I guess, what, 14 years ago?). So a number of weeks ago, I was hooking it up. This is when I was really staring at my Inovonics 531 (utilizing an RF sample from the transmitter). That is when I noticed the HF peaks. We've been running the 8500 for about 9 or 10 years now, and I'm pretty sure I remember seeing these HF peaks the day we first looked at the Inovonics 531, but I really didn't pay much attention to them, since 98% of the peaks held at 100% modulation. I thought maybe RF in the transmitter building was having an effect on the 531. Paying much more attention now, I can confirm that the overshoots coincide with HF energy program material. Also, the 8500 received 3.0 firmware update back in 2012. I admit, I don't normally stare at my mod monitors (maybe as much as I should, but we always seem to pass our simulated FCC inspections), and as long as I see 98% of my modulation peaks hit 100%, I'm happy.
The setup I've been referring to all along goes like this - studio analog output feeds the Voltair input. The Voltair has inserts for the PPM encoder (in my case, all in analog state). The output of the Voltair feeds the 8500 analog input. The 8500 composite output feeds the GatesAir Flexiva exciter input. That's it for that chain. We're using the internal 8500's stereo generator.
We are also MaxxCasting.
http://geobroadcastsolutions.com/
The Geocasting guys are using both AES outputs of the 8500, at this time. They are utilizing an Audemat Modulation Analyzer for their/our booster transmitters, and tell me that they see the same HF peaks on the AES feeds. I don't remember the exact STL that they are using to feed their boosters, but I believe it is also made by GatesAir. I'm not at the transmitter site right now, otherwise I would look. It's all very current stuff.
Even to my golden ears, the 8500 composite output sounds extremely clean, running through the Flexiva, listening to the air feed, in headphones.
Tell us more about the Maxcast and Zonecast Systems these guys market. You're actually running one on air? Please explain your setup and give your impressions. Thanks- maybe this should be another thread...
Just learned from the Geocasting guys that we are in fact using the 8500 AES output for the main exciter input. The composite is only connected for emergency switch-over purposes. Stereo pilot is being utilized in the Flexiva exciter, not in the 8500.
I probably couldn't explain everything there is to know about Maxxcasting, or Zonecasting, as I am, believe it or not, still in the dark on some of what is going on with that system. I think Geocasting's website could possibly explain it better than I could.
I probably couldn't explain everything there is to know about Maxxcasting, or Zonecasting, as I am, believe it or not, still in the dark on some of what is going on with that system. I think Geocasting's website could possibly explain it better than I could.
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