I want to say balanced puts out hotter audio but I'm not entirely sure.
Thanks for sharing the results.
Why don’t you use the Main 2 RCA outs on your VMX1000? Then you could simply use a RCA from the mixer into the EQ. Then from the EQ use a custom cable that drives shield and – on the processor from the shield on the RCA and drives + on the processor from the center on the RCA plug.
Balanced audio into a balanced input will be 3dB hotter than unbalanced audio into a balanced input. Pro and consumer gear uses different voltages for “line level” signals. Tying the – from a balanced output to shield is equivalent to shorting signal to ground, I would not do that, that may be hurting the op-amp on the output killing the level on the + side; leave – floating or use a transformer to convert the balanced signal to unbalanced.
Had a long thing typed out and hit a key and lost it all...grrrr!
I'll try later to respond, I have a cat that sits on my desk, in my way and this keyboard sometimes types what I did not say. LOL!
Bruce.
stvcmty my original reply was focused on your last post.
One thing I have noticed with blanced XLR set ups is when the COLD and SHILED are tied together, the audio's frequency response is like night and day, to where I notice a serious decline in audio quality.
Quickly I want to mention this device from Behringer mostly because it has XLR connectors for both the input and outputs, it is pretty impressive looking and has a lot of features.
It is the Behringer FBQ6200 31 band Ultragraph Pro EQ.
I might purchase this new for about $175.99 off of ebay and keep the audio cables as balanced audio carriers.
The Behringer owner's manuals tell you to tie both COLD and SHIELD together when you hook it up to standard audio equipment that uses RCA jacks for input and outputs, I formerly had my older system hooked up like this HOT to Audio +(positive), COLD to Audio - (Negative ground) and SHIELD to Chassis ground (SHIELD attached to a screw on FM transmitter's metal casing) and the audio seemed pretty good hooked up this way.
When I changed it according to the manual's recommendation of tieing COLD and SHIELD I noticed the audio quailty changed to a much lesser quality!
Now getting back to the mixing board, the mixing board does have MAIN OUT 2, that uses RCA jacks. I utilize that output to send audio to a secondary computer which I use to record my physical media for use on the automated playout computer, that runs Zara Radio Automation software. I record on one computer and then move to the other computer's music library for on-line streaming when the studio is un-manned by a live on-air DJ.
I legally own physical copies of all the music I play on my on-line radio stream, either as vinyl, cassette tape, CD, 8 track tape or reel to reel versions. I do not download MP3s from MP3 websites! Only unless it is from a royalty free website where artists offer their creations (music) for free use.
I use the same computer to run Zara radio as the play out sound card and I also use the same computer with a secondary sound card as the recording device that captures the audio from the DSP9024 and plays it out through that famous BUTT software to my stream host.
What I have here is basically the DSP9024 feeding two different sources on the same cable, splt to feed the FM transmitter and the secondary sound card of the on-line stream.
I have been told that spltting the output of the DSP9024 by simply adding a spliced in female RCA jack pigtails into the audio cable feeding the transmitter is NOT the right way to do this, because I am splitting the audio output to two active devices at the same time and could possibly be depriving one or both devices (computer sound card and FM transmitter) the full line voltage needed for best results. I have those pigtails soldered on the output XLR connectors at the HOT pin and the pigtail's SHIELD tied to both COLD and SHIELD.
Now, I have been told to use MAIN OUT 2 for the streaming and the XLR MAIN OUT 1 for the transmitter. The thing is I am using MAIN OUT 2 to send audio to a computer I use for recording my station I.D.s and the recording of my music as MP3s for the automated play out on computer number two.
The mixer strangely has RCA jacks labeled TAPE OUT, I have tried hooking my automated computer's audio to those jacks and the music played out fine, but there was one major issue here, the audio from the mixer's microphone did not play out over TAPE OUT!
That is important, because unlike a lot of on-line streaming radio stations, we do LIVE broadcasts where music is played off of vinyl records, not a computer's hard drive and it is important that the on-line stream carry the announcer's voice during the naming of played songs and weather forecasts, for some reason, my voice did not appear on the TAPE OUT for some reason.
That Behringer FBQ6200 is an expensive device and it will cut into my monthly allowance of record purchases off of ebay, but I think besides having the DSP9024 compressor/limiter, I still need a bit more control over the individual frequencies themselves.
The DSP9024 is a 6 band audio processor, but even still, each band has a frequency spread and often one frequency or two, in that spread could cause issues with the FM stereo carrier.
At 75us pre-emphasis, often the area around 1KHz to 10KHz can cause the stereopilot light on el-cheapo FM stereo systems to blink.
I mentioned an RCA 5 Cd disc changer stereo earlier, believe or not, there are two licensed stations WBMW 106.5 and WWRX 107.7 that make the pilot blink as well, but itis mostly the BASS thumps that make it blink. WWRX is Hip-Hip music, WBMW is soft rock and good ole' Deliah Loves songs after dark LOL!
I have several Pioneer home stereo systems and car tape decks that don't blink at all.
Time to proof read this mess and correct my typos, my keyboard sometimes creates a character I never typed, but, then again, I have BIG finger tips!
Bruce.
stvcmty said in
Reply #17
Balanced audio into a balanced input will be 3dB hotter than unbalanced audio into a balanced input. Pro and consumer gear uses different voltages for “line level” signals. Tying the – from a balanced output to shield is equivalent to shorting signal to ground, I would not do that, that may be hurting the op-amp on the output killing the level on the + side; leave – floating or use a transformer to convert the balanced signal to unbalanced.
MrBruce Said:
stvcmty you said what you said in the paragraph above, which does make sense, however in your first paragraph you stated:
"Why don’t you use the Main 2 RCA outs on your VMX1000? Then you could simply use a RCA from the mixer into the EQ. Then from the EQ use a custom cable that drives shield and – on the processor from the shield on the RCA and drives + on the processor from the center on the RCA plug".
MrBruce Said.
If I understood you correctly, in that paragraph above, you're saying to short the COLD and SHIELD together at the processor, when in the other paragraph you said not to.
I will totally agree that for some reason the audio quality was 100 better when the cables were wired for balanced audio!
I am switching the connectors back to XLR again and removing the EQ7153 from service, it adds too many audio issues to have to deal with making my job tougher then it was.
My observations are this, I have studied a copy of a VERY hard to follow schematic diagram of the VMX1000's circuitry, it's hard to follow because basically it has the circuits cut up into mini circuits with most circuits ending with the letter A and a horizontal line, perhaps meaning either EARTH GROUND or CIRCUIT BOARD GROUND, very confusing to follow it. At any rate, I am trying to see what would happen if the HOT was used as AUDIO POSITIVE POLARITY, the COLD used as AUDIO NEGATIVE POLARITY and SHIELD as CHASSIS GROUND, in otherwords this SHIELD wire interconnects the chassis of the various conventional audio components together to EARTH GROUND when a NON-BALANCED COMPONENT IS USED such as an FM transmitter.
Thoughts?
To clarify, any device in my audio chain that has XLR connectors would still be wired for balanced audio, by
PIN 1 being GROUND SHIELD
PIN 2 being HOT (+ve)
PIN 3 being COLD (-ve)
The wire from PIN 1 could be used as a chassis ground when attached to UN-BALANCED components (such as a transmitter with RCA jacks), but NOT tied to PIN 3 like the manual says to do.
If I am not mistaken pin #3 COLD is audio negative anyways right?
Bruce.
The links you provide to the articles on processing are articles on STUDIO processing, not on-air processing. Two different animals.
In a recording studio, generally the equalization is done after the compression. Of course, then professional recordings are mastered -- part of that process being further compression and limiting.
In a pro (FCC licensed) broadcast setup, if an equalizer is used, it is always followed by at least one audio processor. It must be, to control modulation levels and to provide optimum loudness.
A balanced source into an unbalanced input is different than an unbalanced source into a balanced input.
In general, balanced source does not want to see the - signal shorted to ground; it will heavily load the op-amp and may hurt the audio quality.
In general, a balanced input does not care if - is shorted to ground, the inverted sum of 0 added to the + audio will just add up to the + audio.
There are different types of balanced inputs and outputs; some will tolerate things that others will not.
This is a pretty good guide to making cables to connect equipment with different types of inputs and outputs. http://www.rane.com/note110.html
I would not buy a new EQ just for balanced inputs and outputs. If you really want to drive things balanced, use some audio isolation transformers to fake balanced inputs and outputs on the EQ you have. Monoprice 6909 could be used for example. If that sounds interesting, I can make a diagram of how to do it.
stvcmty regarding post #22.
Interesting reading in the link you posted above.
Before I had even looked at that page, I had fired up my soldering iron and removed the RCA jacks off of the main audio cable and put the male XLR connectors back on it.
I removed the EQ from service and now I have only the DSP9024 in between the mixing board and transmitter.
I also changed the other cable that feeds the DSP9024 into the transmitter.
Now here is what I did even before reading the information you linked to above, the connector at the DSP29024's output is wired HOT, COLD & SHIELD, however, at the other end, the RCA male plug is wired this way, HOT to RCA AUDIO (+) and COLD wired to RCA AUDIO (-) the SHILED wire was pulled back out of the outer cable jacket, just beyond the RCA plug's casing. This was done to both cables and both LEFT and RIGHT cable's SHIELD wire is joined together with a piece of wire about 2 inches long, this wire mates with the transmitters outer casing via a chassis screw. I do NOT have the COLD and SHIELD tied together anywhere in the audio chain!
Now once I had that done, I hooked everything back up again, then I finally logged in here and read your reply and what was at the link you provided above and read with interest what it had to offer.
I had originally wired everything the way it is suggested in that article, however, I was told NOT to wire it this way and changed it, I removed the exposed shield wire and resoldered it to pin 1 and jumpered pins 1 and 3 together (Shield and Cold) I instantly noticed I had to increase the volume levels on each of the mixer's 5 channel sliders and also the main output of the mixing board, due to lower audio levels. Seems like I lost 3 or 4 dB gain once those two wires were tied together on the XLR connectors.
I know for a sad fact that my Dell computer's sound cards are a poor quality choice, plus running Windows XP is another setback. I know by listening to the audio feed on the mixer's monitor (PFL) channel, the audio is not what it should be. I have to cave in and get an upgraded computer system that has better chipset and better audio quality, or the ability to add in expansion sound cards.
The results with everything hooked up the way it is, if the audio quality from the play out computer was better, I would perhaps have the perfect beast here, but the computer that contains the music library is limited because of the chipset limitations.
Bruce.
Now to be honest here, I think I have damaged some of my audio equipment.
Last time I had my Behringer DSP1424P hooked up I rememeber having an AC hum in it, I need to hook it back up again to see if it is still there, but when it was in the audio chain and active, I remember having an AC synewave on the output.
I have spent many hours reading and reading about the proper way to wire balanced audio cables, it is a 3 sided subject, but it makes me wonder, if in some cases, wiring pin 1 to pin 3 at all can damage the equipment involved.
I checked all my equipment's 3 prong power plugs, of course the 3rd prong is and was Earth ground and the L and N were wired correctly to their power supplies. No issues there.
All the power recepticles are properly wired and grounded.
Sadly, I do not have any equipment, such as an oscilloscope on hand to check things out, I guess it's time I invested in one.
But I sense something is not right and I have to try and track down the culprit or culprits. Sigh!
Bruce.
Another article worth reading regarding SHIELDING.
http://www.coreaudiotechnology.com/audio-system-grounding-and-misconceptions/
Have a read, every bit helps...right?
Just wanted to add to my topic, that in my case all my audio processing equipment from the turntables, tape decks, mixer, DSP9024 and transmitter are all on the same outlet and power brick, it states the outlet's polarity and Earth ground are correct.
Bruce.
True, though similar enough to get you in the ballpark of what you need to do. I think one of the sites even recommended further processing after the EQ, which makes sense. My whole beef, which appears to have been ill advised, was that placing an EQ infront of a compressor could cause unwanted effects.
I still have my reservations on adding any EQ infront of a broadcast processor, I'd still recommend placing it after with an added peak limiter at the end or possibly some very light compression.
Though thanks to your knowledgable insight it seems one can safely place the EQ in front without much issue, which is great for those of us on a budget.
Is your dell computer a laptop? If it is a laptop, does the power supply wall plug have 2 or 3 pins?
Running live sound dell laptops using 3 pin bricks were horrible. Fortunately the fix was simple, dell has power bricks that have 2 pin wall plugs.
You said it is a windows XP computer. Back when XP was current, there were nice USB sound cards I had good luck with. They are no longer supported so they can be found for cheap. As a bonus they have balanced inputs and outputs. Search, ebay for example, for m-audio Quattro.
The Dell computer is a desktop variety.
Off the path, I have been reading a lot of white papers on balanced audio 3 conductor cables versus 2 conductor unbalanced cables. It makes no sense to add a different topic to one related to EQ placement, so I will gather my thoughts together and create a separate topic in the proper forum and discuss what I have learned. It has a lot to do with pin #1 and BUZZ or HUM issues.
One thing I hate about my utility company is the numorous brown-outs that have taken place while my equipment was running. Not sure anyone ever experienced when your MAINS is supplied with 50% or less of the 240/120 Volt supply and your 60 watt light bulbs glow like one in a flashlight with near dead batteries, my DSP9024 was operating erratically, sometimes it takes a few minutes to realize what is happening and shutting the unit down hoping nothing is damaged. Sometimes things will still try to operate at half the mains current. I would personally think a downstep transformer would trip causing the next transformer in line to take the burnt of the load, naturally, there's not enough current for everyone, so the load is 1/2 the result.
I've been reading lately about those computer power surge protector units that are supposed to protect your computer equipment can actually damage it not protect it! Not sure if anyone has any of those in use, I have an old Belkin F5C140 surge protector still in service as my computer's power distribution system. Makes me wonder now, if its best to retire it although it's never sacraficed it's self since 2001.
I will say this, this hobby is more annoying and costly than the CB radio hobby ever thought of being and I bought a lot of hardware for CB back in the day and over the years. At least with CB radio, you were allowed to reach someone down the street!
Bruce.
With respect to your brown out problem, if your equipment has switching power supplies, you could look at the input range it will tolerate. Newer switching power supplies will work on 100-240V, 50-60Hz. If you monitor the power line and get a good feel for what the brown out voltage is you could get a step up transformer to keep the line voltage in the switching power supply range. The problem with that include: it only works with wide range switching power supplies, you will need to be incredibly careful with proper grounding after a transformer, the power supplies will hunt for current at the lower voltages which could cause oscillations as the current draw further pulls down the voltage. If you really wanted to stay on the air and had a very good grasp of what the power company is doing and how switching power supplies work, it can be done. We are all becoming victims of switching power supplies; they put a ton of noise out, they let the power company get sloppy because as long as the voltage is somewhere in range a switching power supply will just work, but when the voltage gets out of range the power supplies do odd things. When in doubt, talk to a certified engineer.