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Old 24th May 2013, 02:31 PM   #6881
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Quote:
Originally Posted by rondr View Post
Very unexpected fees here as well in USA. Ordered 2 ncore + SMPSs. Upon arrival before driver would release he needed $80. Total surprise.
i think hypex usually uses ups, so it should be normal, mainly because hypex also declares full customs value, a lot of sellers would claim lower customs value to help out customers, but i don't think hypex wants to touch that.
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Old 24th May 2013, 08:09 PM   #6882
Henkjan is offline Henkjan  Netherlands
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Quote:
Originally Posted by ufokillerz View Post
i think hypex usually uses ups, so it should be normal, mainly because hypex also declares full customs value, a lot of sellers would claim lower customs value to help out customers, but i don't think hypex wants to touch that.
the value of the goods should not have an effect on the fee UPS charges... only tax and duties depend on the value afaik
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Old 24th May 2013, 09:04 PM   #6883
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Originally Posted by Henkjan View Post
the value of the goods should not have an effect on the fee UPS charges... only tax and duties depend on the value afaik
sorry if was not being clear, i was talking about declared customs value in that it does affect tax and duties

ups fees do not change unless there is insurance purchased.
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Old 24th May 2013, 11:37 PM   #6884
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Default Legato 3 and nC 400

Who knows why the ~9V of common mode DC at the output of the Twisted Pear Audio Legato 3 does not play nice with the nC 400 modules? The signal in the nC 400 input stages is actually ground referenced in a way?
Seems like two possible solutions: add coupling caps, or transformer couple the amps' input… Opinions?
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Old 25th May 2013, 04:31 AM   #6885
Julf is offline Julf  Europe
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Originally Posted by barrows View Post
Who knows why the ~9V of common mode DC at the output of the Twisted Pear Audio Legato 3 does not play nice with the nC 400 modules?
Because the nc400 is DC coupled, and amplifies the DC as well as any signal.

If a device puts a significant DC voltage at the output I would consider it a design error (or artificially improving your measurement results by leaving out the series capacitor that should have been there).

Quote:
The signal in the nC 400 input stages is actually ground referenced in a way?
No, not really, the common mode rejection ratio is pretty high.

Quote:
Seems like two possible solutions: add coupling caps, or transformer couple the amps' input… Opinions?
With that much DC, you will offset bias a transformer pretty badly, so a coupling cap is the way to go.
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Old 25th May 2013, 05:08 AM   #6886
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Default Julf...

Thanks for the response. I think you may misunderstand though.

The Legato 3 has around 9 VDC from + to G, and from - to ground. That is, the differential output is centered 9 V away from G. This is not technically DC offset of the differential signal. The signal from +/- can be easily trimmed to a stable offset of an insignificant 0.1 mV or so. Many people have success using this output stage with true differential input amplifiers where the signal is not ground referenced even with an amplifier which is DC coupled. There is nothing wrong with the design of the Legato 3, these qualities are well known, it is a design choice. We are only considering the balanced output here, for the single ended output (which sums the differential stage via an IC opamp) all DC is eliminated.

With a transformer, one can connect only the differential output of the Legato 3 (plus and minus output), and take the ground on the transformer's output from the centertap of the transformer-there is no need to connect the input side of the transformer to the ground of the Legato 3, so there will be no DC to bother the transformer.

I am curious as to the nature of the nCore input stage now. Apparently the input stage is ground referenced via the shield connection of the input connector?
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Old 25th May 2013, 05:33 AM   #6887
miero is offline miero  Czech Republic
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barrows: voltage range on nCore inputs might be limited by power supply voltage ... e.g. from -12V+1.6V to +12V-1.6V and because the Legato is at 9V offset it might be too high when 1V AC is at the output.
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Old 25th May 2013, 05:38 AM   #6888
Julf is offline Julf  Europe
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Quote:
Originally Posted by barrows View Post
The Legato 3 has around 9 VDC from + to G, and from - to ground. That is, the differential output is centered 9 V away from G. This is not technically DC offset of the differential signal. The signal from +/- can be easily trimmed to a stable offset of an insignificant 0.1 mV or so.
OK - thanks for setting me right. Yes, in that case a transformer is OK.

Quote:
I am curious as to the nature of the nCore input stage now. Apparently the input stage is ground referenced via the shield connection of the input connector?
Common mode rejection ratio is 55 dB.
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Old 31st May 2013, 07:07 AM   #6889
Djioul is offline Djioul  France
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Hello all,

I'd like to pur my fingers in the NCore at least for a test.
In order to save money in a first step, would a test be worth the try with a SMPS 300 watts, or is it definitively too low for a nc400?
Output voltage is 48 volts.
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Old 31st May 2013, 07:50 AM   #6890
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Hello, i'm new on this forum. But after reading a lot about the hypex NC400 i'm interested of listening to a pair of those amps. Is someone willing to bring me a visit with a set of NC400 amps? I want to hear them on a set of ATC SCM 20's

I live in Meppel, the Netherlands, maybe someone near Meppel with a set of these amps?

Regards Frans
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