I think it is pretty clearly proven that feedback, properly executed, improves (objective) sound quality. Subjective preferences are another matter.
Yesterday my NCore 400s took what I think to be a pretty good static charge at the inputs. One channel survived but the other didn't. Both NC400 and SMPS600 seem to be not functioning. I checked the fuse and its good, swapped SMPS with known working module and tried the bad module with known working SMPS with same results so its obvious both NC400 and SMPS600 are not working. Both NC400 and SMPS600 are marked V3. Is this still the latest version of this pair? I've had them up and running since 11/2012. Not sure if I should try and repair or just replace.
rondr,
could you explain the circumstances under which this happened?
(I won't be able to help, but since my modules have just arrived today, I'd much appreciate any hints on what NOT to do to them)
I was attempting to make the input connection to the preamp output while the NCore was turned on. Bad mistake.
I have made some measurements of Hypex nc400 output impedance by a current injection method. LP 20kHz (2 x RC) had to be used to suppress 450kHz carrier frequency. You will see description of the method in one of the attached images, plus measurements at 1kHz and 10kHz.
Attachments
According to another measurement made by PMA the NCore NC400 seems to dislike large capacitive load (~1 Ohm at 20kHz) that is common on the electrostatic loudspeakers, e.g. Martin Logan CLS2 - http://www.justrealmusic.com/images/graphs/quadclsimp.jpg
rondr,
mine is v4.
Another question regarding the setup od nc400:
The manual states, under max values, input signal to be max +-15V.
I assume this is the maximal possible signal the module can handle at this point. But, I couldn't find any info about the expected signal.
What input signal would drive NC400 to clipping?
(is NC400 designed to work at line-level input (2Vrms)?)
I don't have speakers that could survive full load of nc400, and am trying to figure out the best source configuration for it...
mine is v4.
Another question regarding the setup od nc400:
The manual states, under max values, input signal to be max +-15V.
I assume this is the maximal possible signal the module can handle at this point. But, I couldn't find any info about the expected signal.
What input signal would drive NC400 to clipping?
(is NC400 designed to work at line-level input (2Vrms)?)
I don't have speakers that could survive full load of nc400, and am trying to figure out the best source configuration for it...
The output voltage at max power output is 40 V into 4 or 8 ohm (slightly lower for 2 ohm). Voltage gain is 26 dB. Thus the input voltage for max output seems to be 2 V.
In that case, you might want to look into removing/changing the resistor that controls the gain (in order to lower the gain).
Julf,
thanks for the info! Is there a non-invasive way to adjust the resistance/gain?
I have seen that there are three adjustable resistors (at least it seems so): R71, R95 and R136. However, I found no information about this adjustment in the manual...
Edit:
Found some infos here:
http://www.audiocircle.com/index.php?topic=105438.msg1087123#msg1087123
Still, a more detailed explanation would be nice
thanks for the info! Is there a non-invasive way to adjust the resistance/gain?
I have seen that there are three adjustable resistors (at least it seems so): R71, R95 and R136. However, I found no information about this adjustment in the manual...
Edit:
Found some infos here:
http://www.audiocircle.com/index.php?topic=105438.msg1087123#msg1087123
Still, a more detailed explanation would be nice
Last edited:
Not on the module - you would have to use external resistors.
They affect DC offset and other stuff that you really don't want to touch unless you have to
Nc400 data sheet section 13 - R141
See also gain application note http://hypex.nl/component/weblinks/weblink/23-application-notes/74-gain.html?task=weblink.go
There are lots of posts on setting gain within this (mega) thread, eg:
http://www.diyaudio.com/forums/vendors-bazaar/190434-hypex-ncore-631.html
See also gain application note http://hypex.nl/component/weblinks/weblink/23-application-notes/74-gain.html?task=weblink.go
There are lots of posts on setting gain within this (mega) thread, eg:
http://www.diyaudio.com/forums/vendors-bazaar/190434-hypex-ncore-631.html
Just a small warning - that modification is somewhat invasive and not to be recommended for people with clumsy hands
ChrisPa, thanks!
I had to think about information theory, and how the relative information content of this thread is damn low, even though there is a bunch of useful information...
So far, the safest way I see is to hook my NC400s to the pre-out of my current amp and enjoy it while figuring out the optimal setup.
Maybe a hint for Hypex, to provide a jumper or a similar user-with-clumsy-hands-friendly way of adjusting the gain... My current amp is a 70wpc Marantz, and I have NEVER listened to it on full volume, even with speakers which are far from "high sensitivity". I bought nc400 for its supposed sonic qualities and power efficiency, not for 400w rated power.
So lowering the gain in a way that clipping occurs at some 110% of my maximal listening level (or just the maximal listening level after a couple of beers ) would be a nice way of going easy on volume controls.
Anyway, that's enough of further reduction in information content of this thread
I had to think about information theory, and how the relative information content of this thread is damn low, even though there is a bunch of useful information...
So far, the safest way I see is to hook my NC400s to the pre-out of my current amp and enjoy it while figuring out the optimal setup.
Maybe a hint for Hypex, to provide a jumper or a similar user-with-clumsy-hands-friendly way of adjusting the gain... My current amp is a 70wpc Marantz, and I have NEVER listened to it on full volume, even with speakers which are far from "high sensitivity". I bought nc400 for its supposed sonic qualities and power efficiency, not for 400w rated power.
So lowering the gain in a way that clipping occurs at some 110% of my maximal listening level (or just the maximal listening level after a couple of beers
) would be a nice way of going easy on volume controls.Anyway, that's enough of further reduction in information content of this thread
My understanding is that the compact layout of the nc400 - small track lengths and circuit loops, and the use of surface mount components is a major part of the reason why it works and songs with the performance it does. Jumpers and through hole components would completely muck up its performance
I think you're getting over worried about its power and gain. Just try it and see. You have control over the volume knob - that's where gain is adjusted.
You could always use an external attenuator of you think it's necessary (and/or if removing r141 doesn't drop the gain enough
I think you're getting over worried about its power and gain. Just try it and see. You have control over the volume knob - that's where gain is adjusted.
You could always use an external attenuator of you think it's necessary (and/or if removing r141 doesn't drop the gain enough
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