VTV Hypex Ncore NC252MP (It's all Amir's fault)

[CDMC]

Probably the last update on my amp. I finally got around to correcting the PIN 1 wiring so it meets the Hypex/AES48 specification. A few notes:

1) I purchased Nutrik B series connectors only to find out when I went to use them they don't fit. The Ghent case uses a larger spacing for the screw holes.
2) Switchcraft makes a connector (Part No. PQG3FST112) that grounds to the case and fits, but requires that you solder a small jumper from PIN1. I used these, which can be found at https://www.mouser.com/ProductDetail/Switchcraft/PQG3FST112?qs=gNS5EA6ck2YCDqtrBAKwig==
3) I attempted to sand the case by hand where the XLR connector grounds to the case with zero success at removing the anodizing. I ended up having to hit it with a small dremel.
4) No laughing at my soldering. I was never the best solderer to start with and complements of my Mom's side of the family have a thing called essential tremors which cause my hands to shake when trying to focus on small tasks (fortunately not bad, but will get worse as I age more: the good news is the sole effect from it is you shake).

 

[Chobes11]

After inquiring here is the straightforward response from Hypex taking responsibility for the power down "pop" noise on MCxxxMP series.

"
Yes, unfortunately modules from the NCxxxMP series can suffer from this pop to some extent, depending on the application and implementation.

This issue should be resolved on the new revision which will become available shortly.

Kind regards,
Jos Wolthuis | Hypex Electronics BV | Technical Support Engineer | www.hypex.nl
"


Next question: can anyone comment on power down noise present or not on any other Hypex series (NCORE family NC1200 / NC2000 (aka NC2K) / NC500 or any of the UcDxxx line)?

https://www.hypex.nl/ncore-family/
https://www.hypex.nl/ucd-family/
https://www.hypex.nl/mains-powered-ncore-family-ncxxxmp/ < Hypex reports known issue to address with a new revision

I have an NC1200 stereo amp and no on/off pops. Just a hum out of my speakers when on which I am trying to figure out. I wonder if I need to separate the grounds like the OP just did

 

[Chobes11]

@CDMC looks good! did you notice any improvements from your changes? Did you have a hum that went away?

 

[CDMC]

@CDMC looks good! did you notice any improvements from your changes? Did you have a hum that went away?

None. Mine was dead silent in my system when I got it. It was more of me just wanting it to be correct.

Correction, it seems to have fixed my turn off thump/pop.

 

[Rick Sykora]

Hypex reports that the new version of the MP series is released. This should help with the power down transient. Warren checked and new NC252NP modules are out until August 20. Decided to do 4 channels as I can use to biamp or bridge to stereo if I need more power.

 

[Matias]

Hypex reports that the new version of the MP series is released. This should help with the power down transient. Warren checked and new NC252NP modules are out until August 20. Decided to do 4 channels as I can use to biamp or bridge to stereo if I need more power.

I just got an NC502MP which should be the latest version. No ticks or pops when turning on and off, only pure silent operation.

 

[CDMC]

Well my first try was a bust and am not entirely sure why.

The VTV amplifier sounded fine from power, imaging and noise perspective, but there was a nasty power down pop. It was worse on my bg radia z7 speakers than some of my others, but it was bad enough that I would have to be concerned over tweeter damage. Warren and I discussed and we tried a couple of things, but did not improve. I decided to return it and Warren promptly refunded me.

As Warren pointed out, the Hypex module is self-contained, so not much he could do. Am not sure if it was characteristic of the Hypex design or possibly a defective module, but I am back to shopping for other options.

Just an interesting data point. After fixing the wiring on my VTV the turn off thump is much quieter. I wouldn't think it would make any difference, but am now wondering if since he is tying the grounding together improperly, there is some offset being introduced.

 

[HionHiFi]

Probably the last update on my amp. I finally got around to correcting the PIN 1 wiring so it meets the Hypex/AES48 specification. A few notes:

1) I purchased Nutrik B series connectors only to find out when I went to use them they don't fit. The Ghent case uses a larger spacing for the screw holes.
2) Switchcraft makes a connector (Part No. PQG3FST112) that grounds to the case and fits, but requires that you solder a small jumper from PIN1. I used these, which can be found at https://www.mouser.com/ProductDetail/Switchcraft/PQG3FST112?qs=gNS5EA6ck2YCDqtrBAKwig==
3) I attempted to sand the case by hand where the XLR connector grounds to the case with zero success at removing the anodizing. I ended up having to hit it with a small dremel.
4) No laughing at my soldering. I was never the best solderer to start with and complements of my Mom's side of the family have a thing called essential tremors which cause my hands to shake when trying to focus on small tasks (fortunately not bad, but will get worse as I age more: the good news is the sole effect from it is you shake).

View attachment 75320View attachment 75321View attachment 75322

I'm interested in buying one of these amplifiers. Is this modification necessary after buying?

 

[marcom22]

I just got an NC252MP from AudioPhonics, it's perfect. No ticks or pops when turning on and off, only pure silent operation. There is only a tick when operating system boot-up and load USB driver to communicate with my Topping Dx7s, but afterall no more. Now that I known, I power-on the AMP after Windows loads the desktop.


@amirm What a wonderful AMP, thanks again.

 

[VTV Amplifier]

No modification is necessary. Take a look at the build photo here https://vtvamplifier.com/product/vtv-stereo-amplifier-based-on-hypex-ncore-nc252mp/ Pin#1 is tied directly to chassis at the XLR and is AES48-19 compliant. Hypex acknowledges that NC252MP can make a transient on turn-off and has resolved this issue. Hypex says that it occurs on very few systems so they do not consider it a defect and I can confirm this from the many of these we sell.

 

[Matias]

Nice, it is always good to show the internals on the official website.

 

[Feanor]

In case of my VTV NC252MP received a few weeks ago, it does NOT look exactly like the picture now on the website There it looks like Pin 1 is connect to the chassis close to the connector; it's hard to make out how module's input cable shield is connected ...
.

My VTV NC252MP has the XLR Pin 1 is connected to the XLR shell and thence to chassis Ground at the IEC ground connection point. The only thing that might be a issue is that the amp module's input cable shielding is also connect a Pin 1, (and thence to Gnd), rather being directly connected to chassis Gnd with its own connection. The latter would be in accord with guru advice.

In practical terms the amp is almost completely silent at power up & down. There is no "thump" or other loud noise on either occasion. On shut down there is a really tiny "tsit" from the speakers you can hear from about three feet away. I'm certainly not going to bother trying to fix the wiring on this account.

 

[CDMC]

No modification is necessary. Take a look at the build photo here https://vtvamplifier.com/product/vtv-stereo-amplifier-based-on-hypex-ncore-nc252mp/ Pin#1 is tied directly to chassis at the XLR and is AES48-19 compliant. Hypex acknowledges that NC252MP can make a transient on turn-off and has resolved this issue. Hypex says that it occurs on very few systems so they do not consider it a defect and I can confirm this from the many of these we sell.

It is nice to see that the wiring has been been corrected in the new amps being shipped. There is still one issue, the case is anodized (anodizing acts as an insulator) and the screws that ground to the case are not threaded into the case, they are smaller than the holes and pass through to the nuts on the other side. As such, the wires are not grounded to the case, unless the anodizing has worn away. A quick hit with a Dremel with a sanding wheel where the wires ground to the case will correct this.

 

[VTV Amplifier]

I do hit the chassis with a dremel around the inside of the XLR mounts to remove the anodizing so solder lugs mounted behind the XLR make solid connection to chassis.

 

[Rick Sykora]

Nice, it is always good to show the internals on the official website.

View attachment 81194

may just be camera angle, but what is black wire that looks like it is shorting the speaker center pin wire?

 

[VTV Amplifier]

I think it must be the camera angle. Nothing is shorted

 

[AndrewDavis]

I think it must be the camera angle. Nothing is shorted

Thank you for the reply @VTV Amplifier


I am really enjoying my VTV Purifi 2ch amp!

 

[CDMC]

I do hit the chassis with a dremel around the inside of the XLR mounts to remove the anodizing so solder lugs mounted behind the XLR make solid connection to chassis.

Thanks for clarifying that.

 

[Rick Sykora]

I just got an NC502MP which should be the latest version. No ticks or pops when turning on and off, only pure silent operation.

Which brand is your Hypex or is it DIY? Am trying to narrow down the power down transient conditions and am stepping up to NC502MP. Thanks!

 

[Matias]

Which brand is your Hypex or is it DIY? Am trying to narrow down the power down transient conditions and am stepping up to NC502MP. Thanks!

https://www.audiosciencereview.com/...n-nc500-vs-nc500mp-or-nc502.15123/post-494190