Da5id4Vz said:
Just make sure you use a good quality interconnect cable. PLEASE don't use the "emergency cable" that comes with most consumer electronics products these days. Try something like Canare GS-6 w/ F-09 or F-10 connectors, or something of similar quality. You should be quite happy with the results.
Cheers,
Zach
Re: Welcome back
Ideally it wouldn't be. But in order for that to be the case, the common-mode noise would need to be kept common-mode.
With respect to your 0 volt reference, typically, "ground."
Dunno. Never measured it. But I suspect it'd be quite high.
Typically, yes.
Typically, yes.
But this context is with respect to driving the speaker with a balanced source such as a pair of bridged amplifier channels or an amplifier with an output transformer.
I mean that it responds to the difference between the two lines.
In an ideal world, yes. But as I said previously, the common-mode signal needs to remain common-mode and not get converted to differential mode.
I didn't say the driver would cause mode conversion. I said an asymmetrical crossover would. Please read what I wrote:
Asymmetrical crossovers do, yes. Stick an inductor or capcitor on just one line. That line will no longer have the same impedance with respect to ground as the other line. That will unbalance the line and result in mode conversion from common-mode to differential, reducing common-mode rejection.
Whatever unbalances the system. Whether an asymmetrical crossover or simple differences in DC resistance of the two wires, etc.
They'd be induced as voltages with whatever resultant current depending on the nature of the system.
See above.
se
Fred Dieckmann said:
Ideally it wouldn't be. But in order for that to be the case, the common-mode noise would need to be kept common-mode.
With respect to your 0 volt reference, typically, "ground."
Dunno. Never measured it. But I suspect it'd be quite high.
Typically, yes.
Typically, yes.
But this context is with respect to driving the speaker with a balanced source such as a pair of bridged amplifier channels or an amplifier with an output transformer.
I mean that it responds to the difference between the two lines.
In an ideal world, yes. But as I said previously, the common-mode signal needs to remain common-mode and not get converted to differential mode.
I didn't say the driver would cause mode conversion. I said an asymmetrical crossover would. Please read what I wrote:
Asymmetrical crossovers do, yes. Stick an inductor or capcitor on just one line. That line will no longer have the same impedance with respect to ground as the other line. That will unbalance the line and result in mode conversion from common-mode to differential, reducing common-mode rejection.
Whatever unbalances the system. Whether an asymmetrical crossover or simple differences in DC resistance of the two wires, etc.
They'd be induced as voltages with whatever resultant current depending on the nature of the system.
See above.
se
The key point missing from this discussion is exactly what quality is balanced. The missing word here is "impedance" balanced. A symetrical signal can be unbalanced in which case it will result in lousy CMMR.
Conversely an impedance balanced output does not need to be symetrically driven. A perfectly servicable balanced output can be a simple as an op-amp driving the plus wire through a series resistor and the negative wire connected to ground via a resistor of the same value. This scheme also has the advantage of being equally able to drive balanced or unbalanced inputs.
Impedance balanced inputs are a different story and are much more difficult to do well electronically. The higher the input impedance the less sensitive the input is to imbalances in the source. A transformer gives very high input impedance which makes balanced inputs a trivial task, plus it adds galvanic isolation. The only problem with this solution is that good transformers are expensive and cheap transformers sound awful.
By the way, for short (less than 25 feet) cable runs this is mostly a moot point. If you have hum in a system with cables this short you have other problem to sort out and balanced interconnects are not likely to help. Transformer isolation would eliminate ground loops which are one of the most likely problems though.
Phil
Conversely an impedance balanced output does not need to be symetrically driven. A perfectly servicable balanced output can be a simple as an op-amp driving the plus wire through a series resistor and the negative wire connected to ground via a resistor of the same value. This scheme also has the advantage of being equally able to drive balanced or unbalanced inputs.
Impedance balanced inputs are a different story and are much more difficult to do well electronically. The higher the input impedance the less sensitive the input is to imbalances in the source. A transformer gives very high input impedance which makes balanced inputs a trivial task, plus it adds galvanic isolation. The only problem with this solution is that good transformers are expensive and cheap transformers sound awful.
By the way, for short (less than 25 feet) cable runs this is mostly a moot point. If you have hum in a system with cables this short you have other problem to sort out and balanced interconnects are not likely to help. Transformer isolation would eliminate ground loops which are one of the most likely problems though.
Phil
haldor said:
Not sure I follow you here. What has the signal symmetry to do with the quality of any common-mode rejection? Or am I reading you wrong?
Actually balanced interfaces can help here as well. Noise voltages resulting from interchassis currents will tend to be common-mode in which case they would be rejected by a balanced differential input.
se
Balance vs. Symmetry
Hmmm, I have visions of balance, of symmetry, of harmony, of zen. Both sides locked together in an elemental embrace, with two hearts beating as one, pushing and pulling the elemental forces in perfect synchrony as a natural result of the predetermined patterns of their flow. How could that be done...?
See?
Hmmm, I have visions of balance, of symmetry, of harmony, of zen. Both sides locked together in an elemental embrace, with two hearts beating as one, pushing and pulling the elemental forces in perfect synchrony as a natural result of the predetermined patterns of their flow. How could that be done...?
See?
the common-mode noise would need to be kept common-mode.
When you find yourself in a hole, stop digging. This makes less sense than the last round of techno-babel. You have not answered a single question and layed the same vauge BS and speculation on us yet again. I would call it circular reasoning, if there were even the slightest bit of reasoning involved!
"Dunno. Never measured it. But I suspect it'd be quite high." I am beginning to suspect you are quite high........
You're travelling through another dimension, a dimension not only of sight and sound but of mind; a journey into a wondrous land whose boundaries are that of imagination. That's the signpost up ahead--your next stop, the Twilight Zone!
Steve Eddy said:
When you find yourself in a hole, stop digging. This makes less sense than the last round of techno-babel. You have not answered a single question and layed the same vauge BS and speculation on us yet again. I would call it circular reasoning, if there were even the slightest bit of reasoning involved!
"Dunno. Never measured it. But I suspect it'd be quite high." I am beginning to suspect you are quite high........
You're travelling through another dimension, a dimension not only of sight and sound but of mind; a journey into a wondrous land whose boundaries are that of imagination. That's the signpost up ahead--your next stop, the Twilight Zone!
Attachments
Sorry Fred, although Steve is creating some ambiguity via his terminology usage, after reading through the entire thread I get the gist of what he is saying and it does have some value for this specific issue.
I suspect that you also have something of value to offer to this thread and I, for one, would like to hear what it is. Please ignore your animosity with SE and add your technical insights.
I suspect that you also have something of value to offer to this thread and I, for one, would like to hear what it is. Please ignore your animosity with SE and add your technical insights.
The Emperor has no modes!
If someone else can figure out what he is talking about enlighten us. I have read is post carefully and his reply even more carefully. I honestly can't make heads or tails of it. Can any one else understand him, in terms of engineering or physics and not just moral support?
"Ideally it wouldn't be. But in order for that to be the case, the common-mode noise would need to be kept common-mode."
This would be a good place to start......
What does it mean?
SY said:
If someone else can figure out what he is talking about enlighten us. I have read is post carefully and his reply even more carefully. I honestly can't make heads or tails of it. Can any one else understand him, in terms of engineering or physics and not just moral support?
"Ideally it wouldn't be. But in order for that to be the case, the common-mode noise would need to be kept common-mode."
This would be a good place to start......
What does it mean?
Re: The Emperor has no modes!
It means that a differential input, whether active (i.e. opamp or discrete stage), or passive (i.e. a transformer or a loudspeaker voicecoil), only rejects common-mode noise and that if you do something to unbalance the line (such as using an asymmetrical--or unbalanced if you will--crossover in this context), you'll convert some of what would otherwise be common-mode noise into differential mode noise.
My reply was a response to your asking "I would like to know why a speaker is effected by common mode." I said that ideally it wouldn't be, i.e. that ideally a loudspeaker driver would behave as a perfect differential input and would fully reject any common-mode noise, but that if you have an imbalance which results in mode conversion, that common-mode rejection is for naught.
se
Fred Dieckmann said:
It means that a differential input, whether active (i.e. opamp or discrete stage), or passive (i.e. a transformer or a loudspeaker voicecoil), only rejects common-mode noise and that if you do something to unbalance the line (such as using an asymmetrical--or unbalanced if you will--crossover in this context), you'll convert some of what would otherwise be common-mode noise into differential mode noise.
My reply was a response to your asking "I would like to know why a speaker is effected by common mode." I said that ideally it wouldn't be, i.e. that ideally a loudspeaker driver would behave as a perfect differential input and would fully reject any common-mode noise, but that if you have an imbalance which results in mode conversion, that common-mode rejection is for naught.
se
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