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

tmtomh

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Does anyone have any reports of thumps or such with Purifi-based amps?
 

Rick Sykora

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I'm not so sure. I think that behavior would drastically alter the sound of all content played on the speaker.

Except if I add that my BG’s are at least 3 dB more sensitive than the other 2 2-ways I tried, it is the only explanation that fits the data currently.
 

Rick Sykora

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In researching some alternative Hypex offerings, I noticed that @March Audio and others appear to implement their power switch differently. This may help explain why we see some differences amongst those using the same base Hypex module. If the power can be switched to the standby SMPS rather than removing power at the mains input, maybe better shutdown power behavior is obtained?

Unless additional circuitry is added, the Hypex behavior would still be the same when mains power is lost, but just thought I'd share.
 
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CDMC

CDMC

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In researching some alternatives Hypex offerings, I noticed that @March Audio and others appear to implement their power switch differently. This may help explain why we see some differences amongst those using the same base Hypex module. If the power can be switched to the standby SMPS rather than removing power at the mains input, maybe better shutdown power is possible?

Unless additional circuitry is added, the Hypex behavior would still be the same when mains power is lost, but just thought I'd share.

Good observation. In one case, the unit is being put in standby, the other, power cut off. Mine is the latter and I attribute the pop to the capacitors in the power supply discharging.
 

hdaudio

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

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. :cool:

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.

@Rick Sykora

Frustrating experience but great to have VTV customer service. I'm also curious why there are some reports of power switching pops through the speakers. I anticipate most Hypex implementations would switch power in the same spot and hence Hypex would have considered this scenario and own responsibility for covering it.

What was the source component driving the NC252MP-based VTV? Describe the power down sequences tried (source first, amp first), was pop sound always present and sounding consistent? How was the amp power turned off (rear power switch, 12V trigger removed, simultaneous with source, other). Any pop sound if speakers connected to amp but no input connected and power is switched? Was the input RCA (single ended) converted to XLR or XLR balanced?

Was the amp in stereo or bridged mode? Upon return was Warren at VTV able to reproduce the issue and inquire with Hypex? Sorry for all the questions but curious as Hypex are top performing amp modules excepting this issue.
 

Rick Sykora

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@Rick Sykora

Frustrating experience but great to have VTV customer service. I'm also curious why there are some reports of power switching pops through the speakers. I anticipate most Hypex implementations would switch power in the same spot and hence Hypex would have considered this scenario and own responsibility for covering it.

What was the source component driving the NC252MP-based VTV? Describe the power down sequences tried (source first, amp first), was pop sound always present and sounding consistent? How was the amp power turned off (rear power switch, 12V trigger removed, simultaneous with source, other). Any pop sound if speakers connected to amp but no input connected and power is switched? Was the input RCA (single ended) converted to XLR or XLR balanced?

Was the amp in stereo or bridged mode? Upon return was Warren at VTV able to reproduce the issue and inquire with Hypex? Sorry for all the questions but curious as Hypex are top performing amp modules excepting this issue.

Welcome to ASR!

Not my first time to the rodeo, but since you chose this for your first post, I will oblige ;)...

This VTV model is stereo and was not bridged. I did not plan to use with any sources that have trigger capability, so unit was supplied without that feature. Was switching the power via the rear panel switch in all cases.

Warren indicated he did not hear anything serious with the unit in his system, but did not detail how he tested. He said he has sold 50 or more units of this model without complaint. He asked about my speaker sensitivity and suggested try shorting the input. I was using Neutrik RCA to XLR adapters, so at this point, saw no point in testing with both speakers, so reduced the connections to a single speaker and shorted the rca input. Turned off the back panel switch and got same nasty pop.

I did try some other speakers with varying results and you can find this earlier in this thread. I will readily admit the speaker in question was the worst case. However, while it overemphasizes high frequency content, it presents a very well-behaved load to an amplifier.

While my inner scientist was curious, under the circumstances, did not plan to keep the amp. Warren did not seem as curious, but know he is busy, and appreciated the opportunity to try out his amp. If I had built the amp and discovered the transient, would have contacted Hypex, but was ready to move on. The OP for this thread had indicated he had experienced a power down noise too, so not sure whether it is a design or a potential manufacturing issue, but there are plenty of good alternatives and so my search continues. :cool:
 
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klipsch

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Are the EMI filters still being used in the VTV design? Wondering if that has any impact on the pop. I believe Hypex recommends not using any EMI filters, but perhaps that was only for the NC modules and not these newer self contained units.

Nord and others (like have been mentioned) use soft start modules. They may also be a difference which could be a factor to the pop.
 

hdaudio

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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
 

hdaudio

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Nord and others (like have been mentioned) use soft start modules. They may also be a difference which could be a factor to the pop.

It appears the optional softstart module is available to mitigate concerns when used with a tube preamplifier.

https://www.hypex.nl/faq/
7 Q: Do UcD amplifiers work well with tube preamps?
A: Fundamentally there is no problem of course. However, most tube preamplifiers are designed alongside tube power amplifiers which are always AC coupled. As a result, many tube preamplifiers lack precautions against turn-on/turnoff transients. Some are liable to produce the full anode voltage at their outputs during turn-on and turn-off. We find that a large proportion of repairs are due to tube preamplifiers discharging their output caps into the UcD’s input circuit. Note that most solid state amps dislike such treatment, not just UcD.

https://www.hypex.nl/product/softstart-module/38
Softstart module
Softstart module to minimize transformer inrush currents and provide for push button control at the same time.
 

klipsch

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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)?

This isn't an issue for many, but I've never been a fan of triggers. I do not want anything to consume standby power and I want a physical disconnect when not in use to protect against surges / lightening strikes.
As such, I use 20amp or 30amp switches - same kind found and used for machine shop equipment - to turn on and off my 5 separate circuits that power the different amps for my configuration

I've experienced pops when cutting the switch with cheaper sub pro amps like the inuke. However, I have no pop (that I an hear) for the Nord nc500 amp I've used or sinbosen amps or d-sonic amps or "more expensive" brands used.
 

somebodyelse

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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)?
UcD180 on LXMini - goes to standby on mains connection, no noticeable noise, possibly drowned out by the noise of inserting a uk mains plug. If I stick my ear within a foot or so of the speaker there's a quiet rising note for a couple of seconds when going from standby to on, but no pop. Power to standby is silent, and unplugging from standby anything there may be is quieter than the UK mains plug again. I haven't pulled the plug while powered up, and I haven't yet checked the original builder's sequencing.

UcD32MP (no longer available) - so far as I remember would pop (but not very loudly) if hard-wired to 'on' and switched with a mains switch, but if sequenced so that it goes through standby it's pretty much silent. I've not used it for a while and I'd have to check the arduino code that looks after it to see what the sequencing was.
 
OP
CDMC

CDMC

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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).

IMG_6984 (Large).JPG
IMG_6985 (Large).JPG
IMG_6986 (Large).JPG
 
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Chobes11

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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

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

CDMC

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@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.
 
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Rick Sykora

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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. :cool:
 

Matias

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

CDMC

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

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. :cool:

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

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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?
 
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