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RVR Transmitters

When you say the "TPO goes down", do you mean the audio modulation level decreases?

You say this several times, and TPO does not change on FM regardless of how you modulate it...unless something is really screwed up.

If it is the audio levels that you are talking about, then that there is your #1 hint...there is an audio processor in the transmitter causing your issues. Bypass that, let the Omnia do its thing, and you'll be much better off.

Do the BNC feed into the MPX input as we are suggesting, and you'll be fine.

-Cornelius Gould
Omnia Audio
 
audiophile. said:
From the RVR manual:
http://www.rvr.it/manuals/manuals.php?d=M1TEX300LCD10EN.pdf

Dip-switch for setting 50 or 75 ms preemphasis. Preemphasis
affects the right and left inputs in stereo mode and the mono
input. MPX inputs are not affected by the preemphasis setting.
Click to expand...

If you going into the correct input those switchs have no effect. You should going into the MPX input (see page 17 of manual).

The configuration you have described is going to be hard to get a consistent peak level (especially with the GE box / SG inline, due to phase shifts, overshoots due to filters, de-emphasis / pre-emphasis, loss of DC coupling, etc.). You have to many variables in the system.

EDIT: The OMB Stereo Generator (its not just a stereo generator) has processing in it. The Omnia and OMB are fighting with one another. I'm 99.99% sure the Omnia straight into RVR will produce better results.

In short, put the Omnia One at transmitter, and reconfigure to FM mode, drive the exciter DIRECTLY from Omnia One!
Click to expand...

Thanks. (and in no way am I trying to sound snotty) I'll consider it (even though you're exactly right). I have my reasons, and if you saw our setup, you'd understand. Our transmitter box is 15 feet in the air, it's improperly grounded, there is no voltage regulator on ANYTHING out there (not my doing), and we don't have the space for the Omnia in there unfortunately. Coupled with the fact that the box is "sealed", but sand and dirt get clogged in all the air vents, and it's really a miracle that our RVR hasn't kicked the bucket yet. Also given the fact that we've owned it for nearly 3 years, for which 2 of them have been spend collecting dust in a closet...Oh yeah, and we haven't had anybody come out to look at it (again not my doing...bureaucracy at its finest). I've been literally trying to get 10 different projects related to audio quality either started or completed in the last few weeks so I'm sorry if I've been a bit scatterbrained when my questions and terminology.... Trust me, I'm not this stupid.

And I've earned myself the idiot of the month award. You can mail my trophy to the school =)

-Robb
 
cgould said:
When you say the "TPO goes down", do you mean the audio modulation level decreases?

You say this several times, and TPO does not change on FM regardless of how you modulate it...unless something is really screwed up.

If it is the audio levels that you are talking about, then that there is your #1 hint...there is an audio processor in the transmitter causing your issues. Bypass that, let the Omnia do its thing, and you'll be much better off.

Do the BNC feed into the MPX input as we are suggesting, and you'll be fine.

-Cornelius Gould
Omnia Audio
Click to expand...

I know what you're saying, but the power output on our transmitter goes down while the modulation level stays the same when small adjustments are made to the bass mixer in the Omnia. Trust me, I've been scratching my head at this one too. Though I'm going to assume it's the OMB not playing nicely with the Omnia... I'm going to see if I can get that damn thing (the OMB) out of the audio chain, because we really don't need it, and I honestly don't know why we bought it in the first place....
 
If there's something in the system which is bandwidth limited, power will vary with modulation. This isn't uncommon to see at all. To isolate it between antenna and transmitter, get a non-reactive dummy load and a good ol' Watt Birdmeter, model 43 is the weapon of choice at that power level, and see if the thing varies with modulation on a good meter into a good load. If it does, try to figure out what inside it is limited in bandwidth. If it doesn't vary into a load, go fix the antenna, or more likely, get one with greater bandwidth. Don't discount power variation with modulation though, it is usually a valid symptom.
 
DJRobbioRobbio said:
I know what you're saying, but the power output on our transmitter goes down while the modulation level stays the same when small adjustments are made to the bass mixer in the Omnia. Trust me, I've been scratching my head at this one too. Though I'm going to assume it's the OMB not playing nicely with the Omnia... I'm going to see if I can get that damn thing (the OMB) out of the audio chain, because we really don't need it, and I honestly don't know why we bought it in the first place....
Click to expand...

wow...OK...

Well, it sounds like you have a narrow-band Power Amplifier or Antenna (if not BOTH) to deal with! You've got your work cut out for you on this one! What kind of antenna is on this thing? Does the reflected (VSWR) go up when the TPO goes down?

-Cornelius
 
cgould said:
DJRobbioRobbio said:
I know what you're saying, but the power output on our transmitter goes down while the modulation level stays the same when small adjustments are made to the bass mixer in the Omnia. Trust me, I've been scratching my head at this one too. Though I'm going to assume it's the OMB not playing nicely with the Omnia... I'm going to see if I can get that damn thing (the OMB) out of the audio chain, because we really don't need it, and I honestly don't know why we bought it in the first place....
Click to expand...

wow...OK...

Well, it sounds like you have a narrow-band Power Amplifier or Antenna (if not BOTH) to deal with! You've got your work cut out for you on this one! What kind of antenna is on this thing? Does the reflected (VSWR) go up when the TPO goes down?

-Cornelius
Click to expand...

We're using a Dielectric DCR-L , 1 bay. I've gotta check on how much we're reflecting, so I'll get back to you with those numbers.
 
The interest is in how much the reflected (or incident) changes, rather more than its absolute value on dry carrier. The first step is still a comparison load vs antenna.
How old is the antenna? IUf memory serves, those toys were FBOF (Fair, But Only Fair) for bandwidth, but tuned to the carrier they should stand a 100KHz or so modulation swing without too much in the way of histrionics.
Assuming the radio plays properly into a load, take a look at the antenna for damage or loose parts. Notew that it has an exposed feed point and gamma match strap. Moving, bending, or corroding any of these will affect bandwidth. If it came with a fine matcher, and you can borrow a swept analyzer with a tracking generator, you can sweep it and tweek it for best flat bandwidth.
When you're looking at reflected power with modulation, be sure you're not overdoing the modulation. Some of those little transistor radios are capable of swinging a MHz or so if the modulator is overdriven. That much swing will almost certainly produce a high reflected component on that antenna.
Let us know how this plays out. These are fun challenges, particularly when they're in someone else's RF system :):)
 
littlejohn said:
The interest is in how much the reflected (or incident) changes, rather more than its absolute value on dry carrier. The first step is still a comparison load vs antenna.
How old is the antenna? IUf memory serves, those toys were FBOF (Fair, But Only Fair) for bandwidth, but tuned to the carrier they should stand a 100KHz or so modulation swing without too much in the way of histrionics.
Assuming the radio plays properly into a load, take a look at the antenna for damage or loose parts. Notew that it has an exposed feed point and gamma match strap. Moving, bending, or corroding any of these will affect bandwidth. If it came with a fine matcher, and you can borrow a swept analyzer with a tracking generator, you can sweep it and tweek it for best flat bandwidth.
When you're looking at reflected power with modulation, be sure you're not overdoing the modulation. Some of those little transistor radios are capable of swinging a MHz or so if the modulator is overdriven. That much swing will almost certainly produce a high reflected component on that antenna.
Let us know how this plays out. These are fun challenges, particularly when they're in someone else's RF system :):)
Click to expand...

The antenna is just over 4 years old =)

Though the funny part is that I've fixed our little problem by using the pre-emph out of the Omnia and readjusting the mixer settings....But the old problem of the bass sounding hollow and phased hasn't been fixed.

Which brings me to my next point...is anybody here good with fiber systems, or have any recc. about STL's...other than fiber & microwave?
 
Try a FiBox system. We got ours 3 years ago for 1500 total. That includes both ends. It can drive up to a couple of miles of fiber. It's really simple to set up. Connect the fiber, adjust the levels on the sending end, and you are done. The receiver is at unity with the sending unit, so no adjustments need to be made at the receiving end. It's been going 24/7 for over 3 years now. No worries. Our BEXT is going on two years. Although it needs a good cleaning out right now. I schedule that every 6 months.
 
We have a BEXT as a backup to our Continental, and, I swear, it sounds better than the Continental...heresy, I know.
 
Got a 30 watt Bext Box for backup,just to cover city,in case we lose the main.I agree with sgeirk,Unit sounds great.i was amazed at the quality. Sounds as good as the BE, maybe better.DJ, you might want to check out the new Barix 1000 and get a pair of ethernet radios for STL .the 1000 should be out the 3rd quarter of the year.STL could be done for around 2 grand.
 
DudeFan said:
Try a FiBox system. We got ours 3 years ago for 1500 total. That includes both ends. It can drive up to a couple of miles of fiber. It's really simple to set up. Connect the fiber, adjust the levels on the sending end, and you are done. The receiver is at unity with the sending unit, so no adjustments need to be made at the receiving end. It's been going 24/7 for over 3 years now. No worries. Our BEXT is going on two years. Although it needs a good cleaning out right now. I schedule that every 6 months.
Click to expand...

I've looked at that...But I'm trying to move away from fiber and microwave based studio links partially because with the fiber link...a) I'm starting to think that the line we have was installed improperly, and one of the channels is out of phase/ phasing going on within that channel, b) the station itself doesn't control the fiber link to our transmitter, IT at the school does, and they don't even maintain the line...a third party company that they have no idea about does (amazing, isn't it). Secondly, we can't do microwave, because the "Aesthetics Manager" at the school is completely against having any kind of microwave antenna on top of the student center (the building our studio is in).
 
you definitely have a full plate,it appears.do you have broadband internet or dsl?The Barix will work with several platforms.check out comrex.com and their access units.They run around 5200.00 a pair,last quote i got.
 
menotti1 said:
you definitely have a full plate,it appears.do you have broadband internet or dsl?The Barix will work with several platforms.check out comrex.com and their access units.They run around 5200.00 a pair,last quote i got.
Click to expand...

=) Luckily enough bandwidth ISN'T an issue for us at the school, I'll look into that
 
I can't imagine there would be a phasing problem due to the fiber channel. It sounds like you've got a failing fiber transmitter or receiver. It's all ones and zeros on the fiber, so that if there were an issue of fiber continuity, it would either work or not work.

We've got a Bext XL300 and a PT100. The XL sounds really good. But the PT is amazing!
 
DudeFan said:
I can't imagine there would be a phasing problem due to the fiber channel. It sounds like you've got a failing fiber transmitter or receiver. It's all ones and zeros on the fiber, so that if there were an issue of fiber continuity, it would either work or not work.

We've got a Bext XL300 and a PT100. The XL sounds really good. But the PT is amazing!
Click to expand...

Well by fiber channel I'm referring to the line as a whole, because it's not a straight line for us....Our fiber line runs through 2 different buildings, with 2 different sets of signal boosters...ugh...There are just way too many variables in our audio chain.
 
menotti1 said:
on the armstrong stl we use to run,when you did comp in,it defeated the pre-emph in the xmtr.does it not do that on the RVR?
Click to expand...

Well no, the fiber line doesn't add anything....That's basically garbage in/ garbage out....Umm...the RVR (thank you audiophile btw), through the BNC MPX connections...the pre-emp on the transmitter doesn't apply to that input, it's actually stated in the manual. How I missed that I have no clue.

So all the pre-emph is coming from the Omina, which is fine, and the audio sounds a lot better now, but the bass is still a bit funky with CHR stuff that has a lot of bass energy....
 
So,

It sounds to me like the fiber link is running the COMPOSITE output of the Omnia One through it, and across campus. Am I correct, or is it the discrete left / right out through the fiber?

-C
 
cgould said:
So,

It sounds to me like the fiber link is running the COMPOSITE output of the Omnia One through it, and across campus. Am I correct, or is it the discrete left / right out through the fiber?

-C
Click to expand...

It's running L/R from those XLR outs from the Omnia, then into an EAS decoder, then out to our fiber boxes/ fiber line

-Robb
 
OK...

I see.

I bet you're getting a fair amount of overshoot from that setup, which is probably overmodulating on the high frequencies. Especially if the sample rate is 44.1 kHz or lower. That explains a lot about the issues you're hearing. Any DC coupling in any of the Fiber units will also compromise bass performance as well. Especially the deep lows. You can EASILY end up with a bass tilting problem, causing overmodulation on deep bass, even though it doesn't *sound* like there is much bass there.

-C
 
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