A16Ultra I/O

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Music Manic
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A16Ultra I/O

Post by Music Manic »

I'm using the A16 Ultra as a type of patchbay. The I/O are obviously mono but they are balanced. Would the signal just be using the tip of the jack connector? I have a balanced EQ but also an effect which has unbalanced inputs. Is there any benefit in using balanced cables?

Thanks.
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garyb
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Re: A16Ultra I/O

Post by garyb »

yes, this is a basic in studio engineering and you need to study it further.

basically, a balanced signal has a positive and negative conductor, along with an additional shield(earth ground).
unbalanced connections combine the shield and negative together.

an unbalanced cable has 2 conductors, a balanced cable has 3.

balanced signals generally have less noise and isolating ground between two pieces of gear is easier.

typically, most balanced audio signals are at a level called +4.
most unbalanced audio signals are called -10 or -20.
this is about loudness measured in millivolts, so obviously a +4 signal is much louder. audio loudness is expressed in decibels, dB, and the scale is logarithmic. this is important for understanding why the input level on the A16 might be low when receiving a signal from an unbalanced device or why the signal from the A16 might be hot going into a piece of unbalanced gear. it's not a problem, just something to be aware of. actually, the A16 Ultra has dip switches to change levels for the first 8 channels and also the second 8 channels, so it can have both levels running at the same time, depending on what it is connected to.

for a 1/4" phone cable end, usually balanced is wired tip positive, ring negative and sleeve shield or ground=unbalanced is tip positive and sleeve negative/shield. there is no standard, however. depending on who designed a piece of gear, those arrangements could be totally different. typically, things are as i described.
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garyb
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Re: A16Ultra I/O

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Music Manic
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Re: A16Ultra I/O

Post by Music Manic »

Thanks Gary

I think I've been running my Sherman Filterbank too hot. I'll set the DIP to unbalanced. My crimson EQ 301 is balanced so that's fine. I'm not worried about the unbalanced cable for the Sherman because it's half a foot long. There's no improvement for a pseudo balanced cable is there?

Thanks
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garyb
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Re: A16Ultra I/O

Post by garyb »

might be...
generally, it's not worth worrying about unless there's a ground loop that can't be eliminated.

yes, balanced signals can travel a LONG way, but unbalanced cables should be kept to about 20'.
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Re: A16Ultra I/O

Post by Immanuel »

Music Manic wrote:Thanks Gary

I think I've been running my Sherman Filterbank too hot. I'll set the DIP to unbalanced. My crimson EQ 301 is balanced so that's fine. I'm not worried about the unbalanced cable for the Sherman because it's half a foot long. There's no improvement for a pseudo balanced cable is there?

Thanks
I believe the signal is still balanced, when setting the DIP switch to -10. It is just less loud.

B.t.w. a connection between two devices is only actually balanced, if both the sending device, the receiving device and the cable are balanced.
Information for new readers: A forum member named Braincell is known for spreading lies and malicious information without even knowing the basics of, what he is talking about. If noone responds to him, it is because he is ignored.
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garyb
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Re: A16Ultra I/O

Post by garyb »

that's true, but you can run the shield from the balanced connection only up to the unbalanced end and that is almost as good(floating the shield). it takes a special cable that the engineer needs to wire himself, so most times, it's not worth bothering with. it IS one way to kill a ground loop though.

otherwise, most balanced devices can just short the negative conductor to the shield and run as though unbalanced.
Music Manic
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Re: A16Ultra I/O

Post by Music Manic »

Thanks guys.

I've set half of the I/O to +4 and the other to -10. I find the output of the Sherman filterbank overloads the -10 input, because of the harmonic distortion, so I think I'll send the return to the balanced part of the A16.

It is just relative to voltage when it comes to balanced/unbalanced signals right? The cables either way are tolerant of all voltages aren't they, and impedance won't really matter, will it, if an unbalanced signal feeds a balanced one.
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garyb
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Re: A16Ultra I/O

Post by garyb »

well, it's all line level. there are two main standards for "line level" audio. following is a chart cut from wikipedia. you can google "line level" if you wanna know more.

VRMS VPK VPP
Professional audio +4 dBu 1.228 1.736 3.472
Consumer audio −10 dBV 0.316 0.447 0.894


both are represented by very small voltages. there's no danger to equipment possible from a mismatch other than a blown speaker, if the level was turned up and the system was expecting consumer level and it was pro level instead. neither is really better, except that the balanced lines in most +4 gear allow a little cleaner signal and longer runs without loss of fidelity.

the reason that consumer stuff is unbalanced is because it's simpler, and consumer stuff gets connected to mostly known products made to similar specs.

in a professional environment, there are custom one-offs and strange units from other lands being used together. grounding schemes are not always the same. also, runs tend to be much longer. in a real studio there are hundreds and hundreds of feet of cable. maximum protection from interference is needed on each cable.

not at Music Manic-this is why "i'm a musician not an engineer" is a lame declaration, if you want to own your own studio. there is a lot to know. you can't know it without asking questions and being willing to receive the information.
"the guy who runs the train is the engineer"
Music Manic
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Re: A16Ultra I/O

Post by Music Manic »

Thanks Gary,

Just another question. I want to feed the phono outs of one of my cards to one of those cheap Bluetooth speakers, which has a line input, but probably a low voltage tolerance. What's the max output voltage of the analogue outs of the pulsarII cards.

BTW I'm a musician too but it's great to learn.

Thanks
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garyb
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Re: A16Ultra I/O

Post by garyb »

rca outs are unbalanced -10.

XLR outs are +4 balanced.

nothing will explode if you start with the speakers turned down.
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dante
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Re: A16Ultra I/O

Post by dante »

All good info, so ScopeRised here : https://www.scopeusers.com/ScopeRise/is ... l_mast.htm

A couple more questions :

1) I have a two cables that are stereo jack plug to balanced DIN, so I can plug say a drum machine into my Pulsar Balanced inputs. Although the drum machine doesn't have balanced outs, this is the next best thing in terms of long run humm reduction ?

2) A stereo jack to stereo jack cable can be used as a stereo cable, or a balanced mono - both are the same thing ?
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garyb
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Re: A16Ultra I/O

Post by garyb »

1. it's still unbalanced. that's fine. sometimes you might have an issue with ground, in which case you would disconnect the shield at the unbalanced end.

2. yes, 3 conductor is 3 conductor. there are a lot of different "stereo" cables, however. patch bay cables are 3 conductor balanced trs and were originally used for telephone switchboards. most consumer trs cables are intended to be unbalanced stereo. most studio and professional audio trs are for balanced connections.
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dante
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Re: A16Ultra I/O

Post by dante »

Great thanks !!
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