nBarrows, nampon gets low in my case by a short connection in the 4 pole connector, sitting in the nCore unit, tied to what has a earth symbol. This should be OK acc to Hypex person I corresponded with.
So pin 3 and 4 in J9 are permanently connected in my amps.This is also what is hooked up to XLR pin 1
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So pin 3 and 4 in J9 are permanently connected in my amps.This is also what is hooked up to XLR pin 1
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OK
understood. I do not understand why you do not just connect a source (anything, preamp, CD player, etc) for test purposes... and make sure the source has no DC as well. Then allow the set up to warm up, and then measure DC at speaker terminals.
If you then have significant DC, contact Hypex for help.
understood. I do not understand why you do not just connect a source (anything, preamp, CD player, etc) for test purposes... and make sure the source has no DC as well. Then allow the set up to warm up, and then measure DC at speaker terminals.
If you then have significant DC, contact Hypex for help.
The problem arises at friends place. I dont have any issues. Just trying to understand.. I can however reproduce the "stand alone situation"... so I will contact Hypex as this to get their view of the "issue"...
Thanks for helping!
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Thanks for helping!
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Well...
So perhaps your friend's source component has some DC on its output; the nCore is direct coupled, so any DC at the input will be amplfied on the output. Without measuring for DC on your friends source component there is no way to know what is going on.
So perhaps your friend's source component has some DC on its output; the nCore is direct coupled, so any DC at the input will be amplfied on the output. Without measuring for DC on your friends source component there is no way to know what is going on.
Barrows, the DC occurred/occurs with *NO* source connected.
Anyways, I mailed Hypex. I'll get back with any answers 🙂
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Anyways, I mailed Hypex. I'll get back with any answers 🙂
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Good
So no worries then...
I have 20mV on speaker terminals in my system.
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So no worries then...
Currents in the shield (nor anywhere else for that matter) don't drain to ground. They return to their voltage source.Yes, I should have more accurately said that at some point you need to make sure that currents in the shield are drained to ground.
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Currents in the shield (nor anywhere else for that matter) don't drain to ground. They return to their voltage source.
I believe I understand what you're saying, but don't currents drain (flow) to what they're connected to dependent upon the voltage that's driving them there? No connection, no drain (current flow)
And an induced current (in a shield) will drain (flow) to wherever that conductor is connected?
For the most part, those currents are trying to get back to that big power company transformer outside your window. They have little interest in dirt.
An induced current in a wire is trying to get back to something that it has no connection or reference to?
An induced current in the secondary of a transformer is trying to get back to the primary?
An induced current in the secondary of a transformer is trying to get back to the primary?
An induced current in a wire is trying to get back to something that it has no connection or reference to?
An induced current in the secondary of a transformer is trying to get back to the primary?
No, they are just trying to avoid the fine for breaking Kirchhoff's laws 🙂
The current that left one terminal of the secondary is trying to get back to the other secondary terminal.An induced current in the secondary of a transformer is trying to get back to the primary?
Maybe we can look at it as the secondary of an air core transformer. So where is the other secondary terminal?An induced current in a wire is trying to get back to something that it has no connection or reference to?
Or then maybe the current is leaking through an unintended capacitor.
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So reason and resolution for my DC out problem:
"It looks like the 118 mV on the input in amplified 20x causing 2,3 V on the output.
This appears to be caused by a too large common mode offset on the input. We had a small batch of NC400 modules which were adjusted incorrectly due to an error in the testing procedure. This is normally only a problem for unbalanced applications.
You can adjust the common mode voltage as follows:
Measure the voltage between XLR pin 1 and pins 2 or 3 (no other pins shorted). Then adjust potentiometer R95 (VCM) until the meter reads about 0 mV. Do this when the module is at working temperature. At cold temperature the VCM may be set to -300 mV, this will rise to about 0 V when the module warms up.
If the VCM is adjusted correctly and the XLR pins 1 and 3 are shorted, there should be only a few mV DC on the output."
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"It looks like the 118 mV on the input in amplified 20x causing 2,3 V on the output.
This appears to be caused by a too large common mode offset on the input. We had a small batch of NC400 modules which were adjusted incorrectly due to an error in the testing procedure. This is normally only a problem for unbalanced applications.
You can adjust the common mode voltage as follows:
Measure the voltage between XLR pin 1 and pins 2 or 3 (no other pins shorted). Then adjust potentiometer R95 (VCM) until the meter reads about 0 mV. Do this when the module is at working temperature. At cold temperature the VCM may be set to -300 mV, this will rise to about 0 V when the module warms up.
If the VCM is adjusted correctly and the XLR pins 1 and 3 are shorted, there should be only a few mV DC on the output."
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So reason and resolution for my DC out problem:
"It looks like the 118 mV on the input in amplified 20x causing 2,3 V on the output.
This appears to be caused by a too large common mode offset on the input. We had a small batch of NC400 modules which were adjusted incorrectly due to an error in the testing procedure. This is normally only a problem for unbalanced applications.
Glad to hear it was resolved - and I guess the comforting thing is you can verify (by measuring) that it actually solved the problem.
But now as I have started to do the adjustments, I measure 2,4V on INPUTs (nothing shorted..) Oh, my poor Lundahls on my DAC output!?
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But now as I have started to do the adjustments, I measure 2,4V on INPUTs (nothing shorted..) Oh, my poor Lundahls on my DAC output!?
Yikes! So why don't you use an isolating capacitor? And why do you use a transformer? A transformer always adds colouring, so you only use one where other benefits outweigh the downsides....
Caps are evil.
Non-electrolytic caps are much less evil than transformers. Just count how many caps (and how many transformers) the nc400's have.
Illustrating the difference between designer and engineer. What is your rationale for preferring transformers over capacitors?These are my design choices.
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