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The New Hypex Fusion Plate amps
The New Hypex Fusion Plate amps
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Old 7th March 2020, 02:58 PM   #2121
Julf is offline Julf  Europe
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Originally Posted by KaffiMann View Post
The noise will not cancel itself, since it's only one signal.

A differential input works on the difference between the inputs. Any noise induced into both wires (the "hot" and "earth" on the source, "+" and "-" on the inputs) gets cancelled as long as the cable is symmetric.
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Old 7th March 2020, 03:16 PM   #2122
TNT is offline TNT  Sweden
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Julf, when you answer like this, I think you should indicated wether you find the thing you comment on correct and only add som further information. This looks like a correction - which is not necessary in this case I believe. Or?

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Old 7th March 2020, 03:19 PM   #2123
Julf is offline Julf  Europe
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Julf, when you answer like this, I think you should indicated wether you find the thing you comment on correct and only add som further information. This looks like a correction - which is not necessary in this case I believe. Or?

Are you referring to my latest comment to KaffiMan?
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Old 7th March 2020, 08:47 PM   #2124
KaffiMann is offline KaffiMann  Norway
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The New Hypex Fusion Plate amps
On a balanced setup you have 3 wires connecting equipment. Hot, cold and ground, IE signal, polarity switched signal and ground.
It almost seems like you are suggesting one should connect gnd to either hot or cold input and the unbalanced signal to the other?
That does not sound like a good solution to me, not with a circuit designed for balanced connection.

If you are talking about using a differential input opamp together with a unbalanced signal only, yes you can do that. But then you are not using the same circuit, and you do not get the same benefits.

You can connect the unbalanced signal to either hot or cold, and gnd to gnd, but not much noise cancelling.
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Last edited by KaffiMann; 7th March 2020 at 08:49 PM.
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Old 7th March 2020, 08:55 PM   #2125
Julf is offline Julf  Europe
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Originally Posted by KaffiMann View Post
On a balanced setup you have 3 wires connecting equipment. Hot, cold and ground, IE signal, polarity switched signal and ground.

Yes and no. You have two wires conducting the signal. Ground can be connected or not, it doesn't matter for the signal. The signal is not referenced to ground.


Quote:
It almost seems like you are suggesting one should connect gnd to either hot or cold input and the unbalanced signal to the other?
Yes, exactly. That is how a differential input works.



I suggest looking at connection #17 in this: Rane Note 110: Sound System Interconnection - AVW


Quote:
If you are talking about using a differential input opamp together with a unbalanced signal only, yes you can do that. But then you are not using the same circuit, and you do not get the same benefits.
You get almost all of the benefits if the cable (connection) is balanced. There will be an impedance unbalance that will make it less than perfect, but still almost as good as with a symmetric source.
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Old 7th March 2020, 09:10 PM   #2126
TNT is offline TNT  Sweden
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Are you referring to my latest comment to KaffiMan?
Yes.

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Old 7th March 2020, 11:11 PM   #2127
KaffiMann is offline KaffiMann  Norway
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There's also this:
Quote:
Other designers, upgrading to balanced interconnections, may have realized that by connecting the shield to signal ground, interfacing to unbalanced equipment is made simpler since signal ground (needed for unbalanced interconnection) will be available on the cable. (This unfortunately allows easy use of 1/4" mono connectors.) This still creates the same problem, signal-grounded balanced shields. Signal-grounded shields on balanced equipment create ground loops in the audio path and modulate the audio signal ground, wreaking havoc with most systems. This practice penalizes those who want to realize the superior performance of balanced interconnections and has given balancing a bad reputation.
RANE Commercial - Knowledge Base

"Balanced and unbalanced systems are not designed to interface together directly."


If you want to quote Rane notes, I advise you to link to the Rane knowledge base instead.
Here's Ranenote 110 again:
RANE Commercial - Knowledge Base

They sum it up like so:
Quote:
Winning the Wiring Wars
- Use balanced connections whenever possible, with the shield bonded to the metal chassis at both ends.
- Transformer isolate all unbalanced connections from balanced connections.
- Use special cable assemblies when unbalanced lines cannot be transformer isolated.
- Any unbalanced cable must be kept under ten feet (three meters) in length. Lengths longer than this will amplify all the nasty side effects of unbalanced circuitry's ground loops.
- When all else fails, digitize everything, use fiber optic cable and enter a whole new realm of problems.
Connecting the wires as you suggest can be done, but it is not recommended in any way.

Edit:
Quote:
Floating unbalanced often works to drive either a balanced or unbalanced input, depending if a TS or TRS standard cable is plugged into it. When it hums, a special cable is required. See drawings #11 and #12, and do not make the cross-coupled modification of tying the ring and sleeve together.
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Last edited by KaffiMann; 7th March 2020 at 11:15 PM.
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Old 8th March 2020, 09:15 AM   #2128
Julf is offline Julf  Europe
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Originally Posted by KaffiMann View Post
If you want to quote Rane notes, I advise you to link to the Rane knowledge base instead.
Here's Ranenote 110 again:
RANE Commercial - Knowledge Base

Indeed. Have a look at connection diagram #17.



A really good explanation is the classic The G Word, or How to Get Your Audio off the Ground by Bruno Putzeys.

Quote:
"The source, they say, produces two signals which are each other’s mirror image. Any source of interference will affect both wires equally and the error is eliminated when the receiver subtracts the two signals. Note how the authors of this type of explanation have difficulty shedding GND-think. If those two signals are neatly symmetrical, about what potential exactly are they symmetrical? The source’s return node? The chassis? Any of those onthe receiving side? And does it even matter? The input should only care about the difference between the two. The whole reason why the input measures the voltage between the two wires is precisely be-cause it’s trying to ignore those irrelevant potentials.

You can cut the amount of circuitry on the transmitting end by half simply by arbitrarily choosing some potential that it has handy anyway and connect one wire there. All it has to do is off-set the potential on the second wire to make the difference between the two the wanted output voltage.

This is just as good as the previous one. There’s no pressing need to drive both wires actively. One will do. On the receiving end it’s only the potential difference that matters. If one wire is connected to whatever node the source calls “my zero volts” the receiver duly subtracts the potentials of the two wires, regardless where its own personal zero volts might be with respect to the source’s. I'm 1.8 m tall when I measure myself standing on the office floor. But this is equally true when I’m standing on a landfill. If you want to know my height, simply subtract the altitude of the refuse horizon from the altitude of my bald patch. There’s no need for me to be dug in halfway.

This is seriously good news. To change an output from single-ended to differential all you need to add is an extra wire to carry the reference potential to the receiver. The burden then falls on the receiver to make the subtraction."



I suggest you fire up your favourite circuit simulator and verify it for yourself.
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Old 8th March 2020, 09:17 AM   #2129
Julf is offline Julf  Europe
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Originally Posted by TNT View Post
Julf, when you answer like this, I think you should indicated wether you find the thing you comment on correct and only add som further information. This looks like a correction - which is not necessary in this case I believe. Or?

Yes, it was a correction.
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Old 8th March 2020, 09:21 AM   #2130
paalj is offline paalj  Norway
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Originally Posted by Julf View Post


I suggest looking at connection #17 in this: Rane Note 110: Sound System Interconnection - AVW
hmm, I have always made my cables according to Hypex: https://www.hypex.nl/img/upload/doc/...1_problems.pdf
chapter 4.5

Connection 17 seems the shield to be floating floating. Or am I missing something?
 

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