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Old 30th November 2012, 06:49 PM   #5721
bavmike is offline bavmike  Canada
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Quote:
Originally Posted by milezone View Post
Just wanted to follow up from a prior post regarding issues I having with my NCores. I'd been away for a couple weeks and wasn't able to get around repairs until recently. An employee at Hypex suggested a possible issue with my speaker posts not being isolated properly. I believe this is where the issue lied. Another problem may have been bad contact due to the binding posts being annealed. Lastly I purchased one of these Line-R 1200VA Automatic Voltage Regulator suggested by Bavmiike. In one fell swoop made all changes and hooked them up and they work perfectly. Furthermore I believe the apc voltage regulator has improved them to worthwhile degree. I sexond Bavmiike's observations and recommend it for digital components with SMPSs. Thank you for the suggestions and thought and also thanks to the people of Hypex in their ability to isolate the issue from fairly junky iphone pictures.
I'm glad it worked out for you. It was the best $50 I've spent in my system by far.
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Old 30th November 2012, 08:07 PM   #5722
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Quote:
Originally Posted by barrows View Post
Some nCore users have reported excellent improvements in sound quality when coupling a DAC to the nCore via a tranformer of some type. Output transformers in the DAC, TVCs, and input transformers in the amp have been reported to result in sound quality improvements.
I noted that one DAC I tried with the nCore produced a course grainy noise floor (still only audible with an inch from tweeter), and have come to suspect that the nCore is sensitive to RF on its input (as are many class D amplifiers).
So, as Julf is pointing out, there may be additional benefits to reducing the gain of the Mytek DAC via a transformer which would justify the high price. Also, going amp direct, using a transformer to step down the voltage a little increases the current drive vs using a resistor based solution, and I find having higher current availability is a good thing when driving amplifiers directly as well.
My AN DAC kit 4 with (balanced) output transformers combines extremely well with the Ncore's! (in my opinion)
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Old 3rd December 2012, 09:09 PM   #5723
robbbby is offline robbbby  Canada
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Does anyone know how many milliamps of DC current is required to hold the SMPS in sleep/standby when using pins 1&5 on connector J1?
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Old 3rd December 2012, 11:46 PM   #5724
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It's the LED of an opto coupler. 5mA is enough.
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Old 3rd December 2012, 11:54 PM   #5725
robbbby is offline robbbby  Canada
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really, that's it?

I originally installed a 9V battery without giving any thought to how much current it was using. The next day when I came home from work both my amps were powered on because the batteries died, it had not even been 20 hours and very well could have been much less since I was not home to see when they actually died.

Not sure exactly what the mAh is on the 9V I used but i'd say for a typical alkaline it's somewhere between 400-500mAh. At only a 5mAh draw the batteries should have lasted 3-4 days.

I was assuming it would be much higher.
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Old 13th December 2012, 08:40 PM   #5726
igy137 is offline igy137  Hungary
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Default Pops at turning off

Hi All,

My nc400 build is up & running sounding great.
I just have an issue with loud pop when turning off the system.

What makes this a bit more complicated, is that everything is build together into a big single chassis, including the DA converter. There only input is optical link to the dac, and the only output is the amplifier output.

The link between the dac - line stage - amp is all balanced.
The nAMPON connectors are connected to the ground of the line stage output (same as to the shield of the input cable of the nc400).

When turned on everything is ok, there's a very slight pop, but it's not even noticable if one does not look specifically for it.

The DC offset on the line stage output (between cold and hot) is 0.1-0.2mV according to my multimeter, hopefully it does not cheat too much at these levels.
The DC offset on the amp output is varying a bit, but not more than 20-30 mV.

(I'd expect that dc at amp output = amp gain x line stage dc, so around 2-3mV offset at the amp output. Probably a measurement artifact only, or not fully precise trimming of the amp. This is not so bad, I guess, anyway.)

However, when I turn off the entire system with the only switch of the chassis, I get a very loud pop.
I made experiments powering them separately, leaving dac+line stage powered, and in this case there's only a very slight pop when powering down the amps only.

So my problem is, I do not want to separate the dac and the amp, as the goal is keeping it compact, and would like to keep only one switch.

Adding a small microcontroller sequencing the power down, would be a possible solution, but that's still not perfect - one can accidentally turn off at the power distributor, blackout, etc. This is probably paranoid a bit, but I like safe designs..

Do you have any idea how could I manage this?

Thanks,

igy

Last edited by igy137; 13th December 2012 at 08:43 PM.
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Old 13th December 2012, 08:51 PM   #5727
Koifarm is offline Koifarm  Netherlands
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igy, i think that the ncore must first be off before the power goes off. You can try a 230VAC relais coppled to the mains switch with the contact on the amp on/off(J9 pin3)and ground (J9 pin4)of the nCore. When you turn off the mainswitch the relais contact turns the ncore off before the powersupply loses his voltage. Normally then there will be no plop.

Last edited by Koifarm; 13th December 2012 at 09:00 PM.
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Old 13th December 2012, 09:18 PM   #5728
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btw, happy b-day NCORE (one year from release just today).
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Old 14th December 2012, 06:06 PM   #5729
igy137 is offline igy137  Hungary
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Koifarm, thanks for the idea, I give it a try!
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Old 15th December 2012, 11:00 AM   #5730
yetis is offline yetis  United States
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Version control.

I just purchased a third amp/power supply and notice they are version 3 and four respectively. Optically they look the same, except the power supply, where there has been the addition of some hardware on the board. I will use this as the center channel, but wonder if and what difference the hardware changes make.
Thank you
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