Barix levels

Gotta watch those Fresnel zones!
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jantonuk
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Barix levels

Post by jantonuk » Sat Jan 14, 2017 4:24 pm

I have some older Barix Instreamer 100's.
I'm using them to build a backup STL.
I have Henry Engineering Matchboxes on either side to handle the +4 dbm conversion to RCA jack -10 dbV that the Barix provides.
I set the first Matchbox to take +4 in (1.23 v), and put -10dbV (315mV) out and plug that into the Instreamer.
The Instreamer gain is set to 0 db.
The Extreamer volume is set to 100%.
I get 210 mV out.
Is this normal?

I want 315 mV into the other Matchbox and then 1.23 v out to feed the Optimod.


John

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Re: Barix levels

Post by RodeoJack » Sat Jan 14, 2017 7:41 pm

The bargraph on the instreamer is a good indicator of how it sees your levels.

If your -10 is hitting the last red dot, you've run out of bits.

Your ideal level into the Barix will depend on whether you have any AGC/limiting before it. If you do, you can go right up to the red, though, given the decent noise specs of the Instreamer, I don't see you gaining much.

I normally keep my boxes in the upper part of the green, maybe hitting yellow on occasion. I don't know exactly how that translates, but it leaves plenty of headroom, especially if you're light on processing.

Out of curiosity, why the combination of equipment? I think your Barix/Henry combos may be around what you would have paid for a pair of Barix 500s, which would have given you balanced IO.

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jantonuk
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Re: Barix levels

Post by jantonuk » Sun Jan 15, 2017 1:51 pm

I already had the Instreamer 100's

What is your experience with the Exstreamer putting out the same level you put in the Instreamer?
John

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Re: Barix levels

Post by KPJL FM » Tue Jan 17, 2017 8:56 am

I'm more concerned about the noise level from the Exstreamer. If it's low, just amplify to the level you need.
Test with steady tone.
Sounds good? Then don't worry about it. Just make sure program level doesn't exceed clipping on peaks.
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jantonuk
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Re: Barix levels

Post by jantonuk » Tue Jan 17, 2017 4:43 pm

I complete understand about the noise floor and headroom issues.
Call me picky but I really want to know why the "comes-outta" is 1/3 lower than the "goes-inta"

John

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Re: Barix levels

Post by BroadcastDoc » Tue Jan 17, 2017 7:53 pm

Unfortunately, it is normal behavior.

They don't design those as reference levels (as you've noticed). There is no correlation between the input level of an Exstreamer and the output level of an Instreamer. My guess is because besides being cheap (but reliable) boxes, the Extreamer can feed all kinds of devices, while the Instreamer can play back audio from all sorts of encoders.

So yeah, you pretty much have to just deal with each side independently.
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Re: Barix levels

Post by Deep Thought » Tue Jan 17, 2017 9:20 pm

BroadcastDoc wrote:
Tue Jan 17, 2017 7:53 pm
cheap (but reliable) boxes
I'm not buying this excuse. If you have to add all sorts of band-aid level converters and adapters to a piece of equipment you're exponentially increasing the potential for failure while increasing the end-cost. I'd much rather buy one properly designed box that presents some sort of standard levels.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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Re: Barix levels

Post by KPJL FM » Wed Jan 18, 2017 8:41 am

Considering the power supply voltage, perhaps the lower output is to keep peaks from causing distortion from clipping.
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Re: Barix levels

Post by BroadcastDoc » Wed Jan 18, 2017 2:34 pm

Deep Thought wrote:
Tue Jan 17, 2017 9:20 pm
BroadcastDoc wrote:
Tue Jan 17, 2017 7:53 pm
cheap (but reliable) boxes
I'm not buying this excuse. If you have to add all sorts of band-aid level converters and adapters to a piece of equipment you're exponentially increasing the potential for failure while increasing the end-cost. I'd much rather buy one properly designed box that presents some sort of standard levels.
Then you can buy their 500 which provides pro in and out. That should do the job without converters. If you're looking for a cheap box, the 100's work fine, but you'll need a converter.

Or, do it right and go with Telos, Comrex, Tieline or the others. But for many people, the 100 does the job just fine.
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Re: Barix levels

Post by jantonuk » Wed Jan 18, 2017 5:53 pm

I've contacted their tech support and after I get it figured out I'll post it.

I'm still interested to know if anybody else has run tones through their units and measured the levels.

John

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Re: Barix levels

Post by Shane » Thu Jan 19, 2017 12:22 am

While I haven't done a tone test as you have asked, I am using different flavors of digital encoder/decoder setups for various purposes. (Disclaimer: I had not much in the way of input to the decision on what to use for the STL applications.)

We now have three FM frequencies, two of which are AM translators. The class C0 FM is using Telos zips with AAC encoding. This path mostly sounds good and masks trouble fairly well but has split second dropouts more than I would like...sometimes 1 or 2 an hour.

The AM translators are on Tieline Bridge-Its using their "music" algorithms. They sound awful, IMO, worse on music than speech ironically, and sometimes break into chattering briefly with packet drops. Usually not longer than a syllable or two. I would like to try cramming uncompressed PCM down those and see what happens. Haven't yet.

A local church feeds its live worship service to us over a Barix Instreamer running PCM. Our Barix Exstreamer seems to be able to handle this quite well. So of all the streams we are running, I actually prefer the Barix pair, which exhibit few dropouts if any. But they're only in use an hour a week.

On the first config try, I used some form of mp3 thinking the pipe wouldn't take PCM. The mp3 didn't work at all. Just silence. Tried PCM on a lark, really, not expecting it to work either but it did.

Of all the pipes we are using, I like the sound from the Barix the best. YMMV, of course. I did have to make some level adjustments but as long as the input end wasn't going into distortion and was well above any noise floor I considered that end good and set output level on the receive end to approximately what we got out of a telco circuit that was the forerunner to the Barix pair over IP.

The Barix circuit compares closest to the ISDN-type circuits all these boxes are replacing. That's what my ears tell me.

You can adjust levels on your Barix boxes thru the web server and if you really want tone-out to equal tone-in level you should be able to achieve that with those adjustments. More important that every input sees an output level that it wants rather than trying to achieve unity gain, I think.
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Re: Barix levels

Post by Slab Bulkhead » Thu Jan 19, 2017 9:24 am

Shane wrote:
Thu Jan 19, 2017 12:22 am
The AM translators are on Tieline Bridge-Its using their "music" algorithms. They sound awful, IMO, worse on music than speech ironically, and sometimes break into chattering briefly with packet drops. Usually not longer than a syllable or two. I would like to try cramming uncompressed PCM down those and see what happens. Haven't yet.
For some reason the Tieline products seem to fall into making that BRRRAAPP noise or "robot voice" on packet drops, while the Comrex stuff I've dealt with just mutes the audio. The site where I was complaining about the poor DSL service on another board here is fed by a Bridge-It, so you can imagine how great that sounded with all the packet loss issues we were having.

When it's working, I had it running 96k "music" which wasn't too bad since it's an AM and the co-located FM translator is also running in mono. I would imagine 96k stereo would be pretty rough. I mentioned wanting to try AAC, but they don't have the licenses for it. I was told "AAC didn't work" and the owner wanted the money back. I've basically reached the point where I don't care if the thing sounds like crap since the owner obviously doesn't.

It's sad that the dinky 100 watt LPFM I am involved with has better audio. Probably because it uses an old fashioned 950 MHz STL.

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Re: Barix levels

Post by sallen » Fri Jan 20, 2017 10:14 am

I use a pair of Deva Broadcast B90RX units running PCM on a Ubiquiti WIFI link. The Deva seemed to have better buffering on PCM than a Barix combo. It also has AAC. Levels are alot like the instreamer/extreamer combo and I use a match box on the receive end for level adjustment.

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Re: Barix levels

Post by W2XJ » Tue Feb 28, 2017 1:49 pm

Remember Barix is intended for LAN use, not over a jittery WAN I know some people like them because they are cheap but there are better solutions for only slightly more money. The Worldcast APT Silver Stream comes to mind. It is best suited for use over jittery paths because it sends redundant streams over the same paths. Perfectly suited for basic Internet of unlicensed microwave paths. They are simplex but for STL use, problem.

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Re: Barix levels

Post by Shane » Wed Mar 01, 2017 11:14 pm

Apt-x is the gold standard. Thanks for reminding us. I did not know about it being redundant streams which is really the way to do this. There are other products out that can swap out bad packets from one stream with concurrent good ones from another of up to 4 redundant streams all on near real time.
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