[roscoeiii]

B

Looks like there may be a (subjective) “real improvement” to the basic Hypex amp after all:
 
 
http://www.avrev.com/home-theater-power-amplifiers/stereo-amplifiers/rogue-audio-hydra-hybrid-power-amplifier-review.html
 
 

But note that this Rogue Hybrid does not use the ncore modules. It is the ncore bit that has everybody so excited.

[MrAcoustat]

A small package from the Netherlands arrived yesterday and I spent the evening putting the contents into chassis.

I used some chassis from CoZ Cables, which I have mixed feelings about. They fit together very well, all the holes are the right size and in the right place, there are just too many openings to suit me. Note that I've exchanged some email with Robert Cozart and I believe the next batch are going to be simplified. Robert was kind enough to offer me a new set of back plates but I declined, no reason to cut into his margins.

Anyway, assembling a pair of these as mono blocks is pretty easy. As stated in many other threads, this is not a complicated build. The important things are layout and cable dressing. This is discussed in the data sheets available from Hypex and that ship with the modules.

The only thing I found that causes me concern is not having a safety earth connection. They are designed to be Class 2 safety compliant and the SMPS600 module is supplied with insulated stand offs, though one is metal and meant to bond with the chassis to reduce EMI/RFI. Once I had the amplifiers assembled I decided to measure from line neutral to the chassis. It was 120VAC.

When wiring the PS module I followed the standard color code blue/white = neutral and brown/black = line. This made sense as the line fuse is on the brown wire of the board. Now the voltage I measured may be just leakage with no current but it does bother me. I tried reversing the leads and the neutral to chassis voltage drops to about 1.2VAC. I will almost certainly add a safety earth and hope it still sounds the same; I am exceedingly paranoid about safety.

Not much else to say. All the wiring is tightly twisted, 12GA wire was employed for the speakers with ring terminals on each end. The power wire is 16GA and I found some nice lighted switches at Radio Shack. I will likely build a soft latching power circuit at some point but the current setup works just fine. I connected them up last night and the result was as good as I hoped for.

A few photos.





Mostly built, switch and input not wired yet.





The gap above the IEC is because the cut out was for an IEC with switch module. None of the connectors on the bottom row are connected.

Hi Mike, would it be possible for you to give me the measurements of your chassis, i want to order wooden chassis for a pair of mono blocks and this would be very helpfull. Thank You very much MrAcoustat

PS: Wooden chassis like these, now i have to find WHERE ?????

[HT cOz]

You can find dimensions under Ncore Mono Chassis on my website.

Robert

[Rclark]

oh wow, wooden chassis' there are stunning. Hmmm.

[wafflee]

For the choice of chassis, sonically, will there be a noticeable difference between a single dual mono one vs 2 separate mono chassis for NC400 using balance input?

BTW, both the NC400 and the SMP600 come with one end of the power supply cable, I.e. 12pin connector at one end and loose cable at the other end. So, I simply need to do the matching and solder the two loose ends together? If this is the case, I wonder why they don't simply provide one single complete cable. Or I have made anything wrong?

Thanks.

[wafflee]

Oh, I have overlooked the power cable come with SMP600. It should be a "complete" one... my fault...

[jonbee]

For the choice of chassis, sonically, will there be a noticeable difference between a single dual mono one vs 2 separate mono chassis for NC400 using balance input?

I have had Jason's monoblocks and my dual mono (stereo) amp in my system, and I can't say I can know of any difference base on memory. In an A/B, maybe, but it doesn't seem huge to me. I'm very happy with my amp.

[James Romeyn]

For the choice of chassis, sonically, will there be a noticeable difference between a single dual mono one vs 2 separate mono chassis for NC400 using balance input?

BTW, both the NC400 and the SMP600 come with one end of the power supply cable, I.e. 12pin connector at one end and loose cable at the other end. So, I simply need to do the matching and solder the two loose ends together? If this is the case, I wonder why they don't simply provide one single complete cable. Or I have made anything wrong?

Thanks.

Re. the speaker load: the lower the minimum impedance and greater the magnitude of phase shift, the more audible is the mono block advantage over stereo.   

The more difficult is the speaker load the greater is the effect of speaker cable on overall performance.  The shorter is the speaker cable (there are other variables) the less is the speaker cable's negative impact on performance. 

The shortest speaker cable with mono blocks is the distance between binding posts, amp to speaker, with minimum spacing between the amp and speaker it powers.  The shortest speaker cable with a stereo amp is 1/2 the distance of a straight line between the speakers (the stereo amp must be sited at that point).

My speaker load is difficult, 2.8 Ohm minimum.  Each channel employs two matched monitors, one with 4' speaker cable the other with 2' speaker cable.  I have mono NC400.  IMO the longer cable required with a stereo amp would negatively impact audible performance. 

 

[wilsynet]

My NC400 amplifiers were assembled by someone else who decided they preferred the other amplifier they owned, and sold me their NC400 monoblocks.

I'm not sure if the grounds are hooked up correctly.

• The AC mains come in on the left and the center pin is wired to the chassis.
  
• XLR input is on the right, with PIN 1 wired to the chassis too.
  
• Both wires are screwed onto the chassis at the same location.  In the picture, the location is to the right and a bit lower than where the AC mains are coming in.
  

Is this the right way to do this, or should something else be happening instead? 

I ask because while doing some troubleshooting together, the manufacturer of another component I have asked me to use a voltmeter and attach probes to the center prong of the AC line and PIN 1 of the amplifier.  It measured 1.1 ohms, and he said that it looks like circuit ground and chassis ground are the same, and ideally they shouldn't be.

[Rclark]

Oh wow that looks terrible. Here are my Ncore's built by JTWrace with the latest wiring. Quite a difference.

textbook:

[wilsynet]

Sorry, I'm dense, I can't tell by the picture what should be happening instead.

[Rclark]

I think the builder wasn't aware of the correct layout options and might have screwed it up.

[jtwrace]

What issue(s) are trying to solve?

[Speedskater]

Without getting into the above photo.  I'm not good at decoding wiring photos.

In general with balanced analog audio XLR connector's, pin #1 is connected to the chassis at the connector.  Anything much over one inch is too long. (2cm)

[wilsynet]

Jtwrace:  The person I was talking to said there's a safety issue with sharing circuit and chassis ground.  Also, I've been trying to resolve a low level hissing sound and a sensitivity to EMI and noise on the power line.  For example, occasionally when I turn on the microwave, all sorts of funny hum and foghorn like sounds start showing up in the speakers.  Not 100% reproducible.

Speedskater: Thanke for XLR PIN1.  What is usually done with the AC center pin?

[jtwrace]

Jtwrace:  The person I was talking to said there's a safety issue with sharing circuit and chassis ground.  Also, I've been trying to resolve a low level hissing sound and a sensitivity to EMI and noise on the power line.  For example, occasionally when I turn on the microwave, all sorts of funny hum and foghorn like sounds start showing up in the speakers.  Not 100% reproducible.

Speedskater: Thanke for XLR PIN1.  What is usually done with the AC center pin?

I'm pretty sure it was one of your threads that I've read about hum with a new preamp.  Is this correct?  Is it only with the preamp and not direct?

[wilsynet]

Just sent you a PM.  Yes, only with the preamp, although I'm wondering if a grounding issue could contribute to more EMI issues.  Just chasing down each possible contributory factor until all items are fixed.  Having said that, if there really is a safety issue, it would be better to resolve it sooner rather than later.

Preamp did go back to the manufacturer (a very reputable one who has an EE background) and he said he found a bad grounding connection on the preamp, fixed it, went through it top to bottom and nothing else found.  He says he thinks the problem may be elsewhere now.

[Speedskater]

The AC power green Safety Ground (EGC) wire should be securely bonded (that means not soldered or attached in any way that might come loose) to the metal chassis near where the AC power enters the chassis.  The XLR jumper should be attached at the XLR connecter.  The AC power input and the signal inputs should be separated by a reasonable distance.

[wilsynet]

Thanks to all who replied both privately and in public.

Looks like I can no longer reproduce the funny resonant fog horn like sound that would occasionally come on when I operated the microwave or some of the lights.  This was happening pretty consistently before I sent the preamp away for diagnosis, and I thought it presented itself again when the preamp returned, but perhaps I had heard something else unrelated.  That aspect of the sound hasn't returned yet, so perhaps it really is fixed.

I still hear a hiss that isn't present when I connect directly to amps from DAC, a hiss that wasn't present when I first acquired the preamp.  So I think this is something that has gone wrong as opposed to systemic with this line of tube preamps.  Even so, I can't hear it from the listening position, so it isn't the end of the world, music sounds pretty awesome anyway, and there is tube gear out there that manifests a low level tube hiss.

I disconnected the AC mains ground to chassis to see if its related, but no dice.  Over the next few days I'll stop by an electronics supply shop to get some parts so I can ground XLR PIN 1 to a closer location and with a much shorter wire.

Jtwrace thinks the hiss may be tube related.  I'll investigate that next.

[ejn1]

Hello all,

First time poster on this thread but have been reading the wealth of knowledge from all on these builds.   Huge thanks to those who have taken to the time to educate others.   I got a wild itch last week to order the parts to build 2 monoblocks.   I'll be connecting to an Auralic Taurus Pre and Auralic DAC and will use with my desktop KEF LS50's.   

I decided to go with the Ghent Audio Cases which I was shocked how quickly they arrived from China.   Quality is surprisingly high.   I'm going to try to change the speaker connectors to WBT versions but would be happy with the ones Ghent supplied.  My main question is the around the grounding.

A couple of questions remaining that would greatly appreciate some help on....

The NC400 detailed manual from Hypex (page 13 Figure 2.  Preferred Connection).   It shows the blue going Pin 2 on the XLR receptacle and white going to Pin 3.   It does not show any connection from the mogami shield.   It show the black single cable nAMPON going from Pin 1 of the NC400 (not xlr receptacle) to it looks like the chassis ground.  It also shows Pin 1 on the XLR receptacle being tied to chassis ground.   My XLR receptable also has a separate chassis ground connector in addition to Pin 1,2,3.   So assume I connect the XLR receptacle ground to chassis ground but not clear on what to do with Pin 1 on the XLR which i believe is the audio ground.   Not sure if i connect the braided cable on the hypex supplied xlr cable to Pin 1 or leave off.

Appreciate any help on this one.   Will be running fully balanced like in the manual preferred connection.

Thanks!