VTV Hypex NC1200 Tear Down and Recommendation

[C. Cook]

Power dissipation and therefore heat will go up with increasing load / power output

Correct, but there's only so loud I can play anything in this house. Also, I could be mistaken, but this class d design probably doesn't have a purely linear relationship between power dissipation and heat generated by the ncore modules. I'd have to check into that, but it's certainly not as pronounced as class a and class ab amps I've had.

 

[C. Cook]

It's in the nc1200 manual. it's not mandatory but advisable considering they can kick out 40 amps. anyway the loose crimping is a bigger concern.

Appollon are in a different league in terms of quality compared to vtv.

What brand/vendor did you go with after you got rid of the VTV? Apollon definitely has better cases for the money.

 

[C. Cook]

Power dissipation and therefore heat will go up with increasing load / power output

Also, FWIW, it doesn't look like the Apollon case is any better at heat sinking. I don't see any of the standard slats/fins that good high power class a and b amps have. I have asked Ghent for the heat dissipation specifications on his cases and will post whatever he provides.

 

[mrmojo2022]

Correct, but there's only so loud I can play anything in this house. Also, I could be mistaken, but this class d design probably doesn't have a purely linear relationship between power dissipation and heat generated by the ncore modules. I'd have to check into that, but it's certainly not as pronounced as class a and class ab amps I've had.

From the smps darasheet.

There isn't a plot in the nc1200 datasheet so here is the nc500. your amp would be more than double the numbers here.

So if running onto 4 ohms the case will need to dissipate probably over 200 watts in heat. Far more if pushed to 2 ohms.

So if you are hitting 150 deg F at idle or low power outputs then that's really concerning.

 

[mrmojo2022]

Also, FWIW, it doesn't look like the Apollon case is any better at heat sinking. I don't see any of the standard slats/fins that good high power class a and b amps have. I have asked Ghent for the heat dissipation specifications on his cases and will post whatever he provides.

I doubt you will get anything useful out of Ghent. anywY we already know from the info you provided the case thermal dissipation characteristics are grossly inadequate.

 

[mrmojo2022]

What brand/vendor did you go with after you got rid of the VTV? Apollon definitely has better cases for the money.

I haven't replaced it yet, but I will probably go purifi with one of the quality OEM's, several to choose from. it will be more expensive but worth it over this VTV crap.

 

[kiwifi]

I haven't replaced it yet, but I will probably go purifi with one of the quality OEM's, several to choose from. it will be more expensive but worth it over this VTV crap.

It is unfair to refer to VTV amps as "crap"! They can be an absolute bargain if you are reasonably handy and know how to us a soldering iron.

Here is my amp as delivered...


I replaced the speaker output wires and soldered rather than crimped the all the spade connectors. Then I replaced the mains wiring from the socket to the PSU and trigger boards.


I also applied heat-sink compound to the modules and the PSU.


I regarded the VTV amp as the starting point for a great DIY build. I could not have sourced the individual components for what I paid for the VTV. The amp worked as delivered but I wanted to make it better where I could. The service from Warren Coleman at VTV was excellent.

 

[C. Cook]

From the smps darasheet.
View attachment 178435
There isn't a plot in the nc1200 datasheet so here is the nc500. your amp would be more than double the numbers here.

View attachment 178436

So if running onto 4 ohms the case will need to dissipate probably over 200 watts in heat. Far more if pushed to 2 ohms.

So if you are hitting 150 deg F at idle or low power outputs then that's really concerning.

Right, but look at any of the other main vendors/resellers of Hypex based amps and you're not going to find much better heat-sinking than what VTV is using...Apollon for one. The way they are screwed to the bottom of an also aluminum case is no different. I've asked Ghent for heat-sinking data and will post when it comes in. IF he sends it.

The first set of plots and text of course refers to the SMPS's heat sinking needs, but that's not where the vast majority of the heat in this VTV amp is coming from. It's the class d modules themselves that are generating it. This is the opposite of what happened in every nc500 build I did. I also have an nc502MP that heats up pretty well and that mfg. didn't do anything for heat sinking except rely on the case as a transfer/dissipation mechanism. So for all the talk about inadequate heat sinking, I have yet to encounter a Hypex reseller that implements anything remotely resembling the standard 'vaned' heat sinks typical on class a and class ab. To wit: You're unlikely to find a better configuration for heat than what VTV is using.

Also, I did hear back from Hypex and they said the way that the speaker outs are wired is fine. The only reason to go to the double wires for each is to take advantage of the extremely low output impedance that topology offers. YMMV

 

[C. Cook]

It is unfair to refer to VTV amps as "crap"! They can be an absolute bargain if you are reasonably handy and know how to us a soldering iron.

Here is my amp as delivered...
View attachment 178562

I replaced the speaker output wires and soldered rather than crimped the all the spade connectors. Then I replaced the mains wiring from the socket to the PSU and trigger boards.
View attachment 178563View attachment 178564

I also applied heat-sink compound to the modules and the PSU.
View attachment 178565

I regarded the VTV amp as the starting point for a great DIY build. I could not have sourced the individual components for what I paid for the VTV. The amp worked as delivered but I wanted to make it better where I could. The service from Warren Coleman at VTV was excellent.

Excellent point and I had meant to say similar. For the price I paid when I was DIY'ing - not only for the Hypex modules, SMPS, trigger and especially the case - was well above what I paid for the VTV, and that was nc500s, not nc1200s.

Did you notice much difference in the heat after using the heat sink compound? If it makes transfer more efficient/effective then I'd expect to get even higher temps on the exterior of the case (with of course slightly lower temps for the ambient air inside the case and the modules themselves).

 

[kiwifi]

Did you notice much difference in the heat after using the heat sink compound? If it makes transfer more efficient/effective then I'd expect to get even higher temps on the exterior of the case (with of course slightly lower temps for the ambient air inside the case and the modules themselves).

I didn't run the amps prior to my mods, so I can't compare before and after. But I have two stacked in a rack and they barely get above room temperature.

 

[mrmojo2022]

Sorry but you are both trying to defend the indefensible.

The amps are not sold as "starting points for DIY projects" which you have to modify to make safe and perform correctly.

Ghents info is irrelevant. you have already told us your amp case gets to 150 deg F 65 deg C without being run hard. this will cause skin burns. inside will be hotter and beyond the Hypex recommended operating temp. what do you think Ghent can tell you that will change this? trying to excuse this bad design by saying other manufacturers look similar is specious.

So looking at my experience, yours and that detailed in other threads, I absolutely stand by my statement that VTV products are crap.

Enjoy your amp for how long it lasts. I suggest turning those fans up that you have blowing on it. I'm out.

 

[C. Cook]

Sorry but you are both trying to defend the indefensible.

The amps are not sold as "starting points for DIY projects" which you have to modify to make safe and perform correctly.

Ghents info is irrelevant. you have already told us your amp case gets to 150 deg F 65 deg C without being run hard. this will cause skin burns. inside will be hotter and beyond the Hypex recommended operating temp. what do you think Ghent can tell you that will change this? trying to excuse this bad design by saying other manufacturers look similar is specious.

So looking at my experience, yours and that detailed in other threads, I absolutely stand by my statement that VTV products are crap.

Enjoy your amp for how long it lasts. I suggest turning those fans up that you have blowing on it. I'm out.

We get it; trust me we do. Personally I empathize with you. I think I saw your own post back when you opened up the amp you got (if it wasn't you it was someone else with the same issue, also monoblocks), so I went into this purchase knowing that the build quality could be sub-par and with my DIY background and tools/parts on-hand I would have no problem fixing any minor issues. As it happened, there's nothing inside that I see as immediately in need of modification. Some sloppy soldering and questionably not using the secondary pair for the speaker outputs, but otherwise as the cost added up, there's simply no way I could have sourced the modules, SMPS and case for less than $1500. It would've taken some creativity to get my hands on new nc1200 modules to say the least and even the SMPS could amount to $400+ after conversion to Euros and shipping from the Netherlands is factored in. I know because I've bought SMPS and cables direct from Hypex before.

No, mine does not hit 150F. That was a general range of what I thought it might get to based on the first time I measured with an infrared thermometer. The thinking was that since it was around 130-135, it was likely to get even hotter with longer use. Fortunately that isn't what ended up happening. The temperatures actually get lower and settle in around 115-120F after about an hour of program material at a reasonably high volume. I apologize to anyone else reading if I used sloppy wording in my OP. This amp has not reached skin-burning temperatures and doesn't appear that it's going to. Regardless, as I stated in a different reply, Ghent's case (especially the larger ones for stereo applications) are not fundamentally different from anyone else's in that range. In order for it to be, it would have to be much larger than the standard width/depth audio chassis. Apollon doesn't appear to be doing anything special with heat-sinking, and I've opened up other amps purchased from Hypex and Purifi resellers and never encountered any paste, much less bespoke heat sinks with fins or anything like that. What VTV is doing, so is every other seller within the price range.

It sounds to me that since your experience was so bad - and likely compounded by it being a non-US order with exchange rates and shipping factored in thus being more expensive as well as poor customer service - you were and are justifiably pissed off at VTV and never going to buy from them again. That said, if it was your thread I was thinking of, you got a lot of support from the community without anyone taking such a personally motivated stance against you. It's fine if some of us have tempered expectations and DIY ability to correct any flaws in the 'design' or implementation, rather and it's fine that you're disgusted by your experience with VTV. I would be too if I were you. But I only decided to post this thread in the first place because I was expecting it to be so much worse inside than it was - and again especially for the price I paid.

That said, I'm going to do as I mentioned and push it very hard as often as I can without using the fans during the first two years and see if it fails. There's a warranty if so and I'll take a replacement and sell it on if that happens, then either build one of my own or go with another mfg. (Nord, perhaps). Speaking of Nord, I'm going to take apart their integrated Purifi based amp and post another thread of the teardown. In fact I'm gonna do that right now...(decided against creating a new thread and glommed my Nord Three teardown onto this one by user Maty from 2019: https://www.audiosciencereview.com/...a-dual-mono-teardown.10010/page-2#post-271428

Mine's the integrated version.

 

[C. Cook]

EDIT TO OP

Since I couldn't edit the OP anymore, I wanted to rectify something I said. I never actually measured temperatures of 150F, but rather extrapolated that they would likely reach that point with some long-term high-volume listening. In fact the temperature levels off around 125F (still admittedly quite hot) which isn't enough to burn flesh. I'm still going to keep measuring without using the fans I bought to see if it ever goes higher than 130-135F during use.

 

[C. Cook]

To the thread in general:

Now that I've had a chance to do 'extended' listening and heating tests, I thought I'd chime back in to provide an update. As it happens, the heating is worst when playing program material (TV or music) at a low volume for long periods of time. It hasn't again reached anywhere near how hot it was the first day I measured, but it does get somewhat hot to the touch after about an hour of just low level TV or soft music.

Somewhat paradoxically, or maybe the way these modules actually work, it gets *cooler* when playing loud music for a long period of time. So for soft music/program material the curve with time as the X axis and the Y axis being heat would look like a straight line with a positive slope of maybe a 20 degrees and then leveling off to a plateau at about 115-125F. When playing loud (-ish - can't upset the wife or dog) music for an extended period of time, the graph on the same set of axes would start off as a parabolic curve with an initial positive slope of about 20 degrees, then quickly peaking at 110F and dropping off quite precipitously to a steady level of about 90F (and lower depending on location) on the outside bottom of the case.

I'm not sure if this has been discussed here before, but the high volume behavior mimics my nc500 projects as well as my super easy DIY IcePower AS1200 based stereo amp. It's the extended use at low to very low volumes where the heating seems disproportionate to the actual work the amplifier is doing. Which leaves me with a big ¯\_(ツ)_/¯ but ultimately happy with the amp's performance characteristics in the way that I use it most often.

Hence, so long as the build quality continues to steadily improve and is kept that way (again noting that your amp was no doubt super amateur hour) and the prices remain low, I still recommend VTV amplifiers based on my own personal criteria. Just be sure to open the case, inspect it and be prepared to do a little minor DIY work or ask for a refund/rebuild. YMMV I'm done with my temperature measurements unless something changes in its behavior but will post photos of my infrared thermometer measurements when I have a chance to curate and clean them up.

 

[mrmojo2022]

I think your making apologies to justify your purchase. It's pretty clear that VTV design, build quality and quality control aren't improving.

I'm afraid that it's not possible for the amp to get cooler with increasing power output. You are mistaken, see the data from Hypex above. Also, why would it be hot on day one but not since? 50 to 60 deg C is not just "hot to the touch", it can cause burns.

The case thermal resistance is way too high for this amp design. its a bad design. if VTV did any product testing they obviously ignored the fact the cooling is totally inadequate. Hypex are quite clear that this will reduce component life. I'm not sure why you want to praise it.

 

[C. Cook]

I think your making apologies to justify your purchase. It's pretty clear that VTV design, build quality and quality control aren't improving.

I'm afraid that it's not possible for the amp to get cooler with increasing power output. You are mistaken, see the data from Hypex above. Also, why would it be hot on day one but not since? 50 to 60 deg C is not just "hot to the touch", it can cause burns.

The case thermal resistance is way too high for this amp design. its a bad design. if VTV did any product testing they obviously ignored the fact the cooling is totally inadequate. Hypex are quite clear that this will reduce component life. I'm not sure why you want to praise it.

And now you're just accusing me of lying. For this reason I'm going to expedite the video or photo shoot where I take pics of temperature measurements over the span of an hour or two at increasing volume levels. I'll check back in when I've done it.

Why would it be very hot the FIRST day I used it with low volume music but less so as time goes on? Who knows? Metal parts settling and making better contact with the case to aid in heat sinking? The fact that they are more efficient at medium to high volumes than they are at zero volume? The slope for the 8ohm heat curve on the nc500 graph is very shallow. You acknowledge that there's no such graph provided for the nc1200 but you go on to say that it must by nature of it being more powerful, somehow heat up double what the nc500 does. That's flawed reasoning. In fact, the nc1200 might have an even shallower function of heat to wattage output with the plateau behavior I've noticed.

The quality of build in the unit I got is much higher than the one you got. Admittedly yours was just unacceptable. But I'm seeing improvement and mine, while not perfect, is about as good as anyone was going to get for the money. Heck, from what I can tell looking around the gray market at nc1200 modules, VTV may not be making very much profit at all.

 

[mrmojo2022]

Please calm down, I said you were mistaken. I did not accuse you of lying.

Unless you have reinvented the laws of physics it's not possible for the amp to get cooler with increasing power output. the Hypex data above shows very clearly the expected heat output verses electrical power output for both the smps and the nc500. for them to get cooler with increasing power output the lines would be going down. they go up.

The reason I said double the heat power for your amp is that there are TWO nc1200 modules. The graph shows ONE nc500. The nc1200 is not fundamentally more efficient than the nc500 but it can deliver far more current and therefore power. it will therefore get hotter.

Let's read the graphs. make an assumption that you are driving the amp to 10 watts per channel power output into 4 ohms
Smps heat output=25 watts
Nc500 heat output=8 watts therefore 2x nc1200 at least = 16 watts.
Total heat power generated = 41 watts

At 100 watts per channel into 4 ohms
Smps = 35 watts
2x nc1200=28 watts
Total=63watts

At 500watts per channel into 4 ohms
Smps=75 watts
2x nc1200=72 watts
Total=150 watts

with a heatsink that has a thermal coefficient of 1.3 degC / watt you would see temperatures of
53.3 degC
81.9 degC
195 degC

It is true to say that music does not have high rms power, maybe 1/3 peak so in the real world the amp is unlikely to be driven beyond 300 watts average, but that would still be 100 watts heat dissipation and 130 deg C with that heatsink.

So what is the thermal resistance of your case? it's construction is in two shell halves with little contact area between the two. therefore it's the bottom half which does most of the dissipation. the top will of course get hot from the trapped hot internal air. It's size is approx 33x33cm= 190cm2. The heatsink is flat and horizontal so heat transfer to air is further compromised.

Modelled below. flat heatsink with 2 fins (the 2 sides of the case)

With no forced air flow (fan) your case is about 1.1 deg C / watt. no wonder you had to add 4 fans to keep it cool.

It's clear VTV haven't performed even a basic thermal design check.

Re your comments about VTV profitability, I have noted this too. I don't think they will be around much longer. selling at cost price is a great way to fail a business.

 

[C. Cook]

Please calm down, I said you were mistaken. I did not accuse you of lying.

Unless you have reinvented the laws of physics it's not possible for the amp to get cooler with increasing power output. the Hypex data above shows very clearly the expected heat output verses electrical power output for both the smps and the nc500. for them to get cooler with increasing power output the lines would be going down. they go up.

The reason I said double the heat power for your amp is that there are TWO nc1200 modules. The graph shows ONE nc500. The nc1200 is not fundamentally more efficient than the nc500 but it can deliver far more current and therefore power. it will therefore get hotter.

Let's read the graphs. make an assumption that you are driving the amp to 10 watts per channel power output into 4 ohms
Smps heat output=25 watts
Nc500 heat output=8 watts therefore 2x nc1200 at least = 16 watts.
Total heat power generated = 41 watts

At 100 watts per channel into 4 ohms
Smps = 35 watts
2x nc1200=28 watts
Total=63watts

At 500watts per channel into 4 ohms
Smps=75 watts
2x nc1200=72 watts
Total=150 watts

with a heatsink that has a thermal coefficient of 1.3 degC / watt you would see temperatures of
53.3 degC
81.9 degC
195 degC

It is true to say that music does not have high rms power, maybe 1/3 peak so in the real world the amp is unlikely to be driven beyond 300 watts average, but that would still be 100 watts heat dissipation and 130 deg C with that heatsink.

So what is the thermal resistance of your case? it's construction is in two shell halves with little contact area between the two. therefore it's the bottom half which does most of the dissipation. It's size is approx 33x33cm= 190cm2. The heatsink is flat and horizontal so heat transfer to air is further compromised.

With no forced air flow (fan) your case is about 1.1 deg C / watt. no wonder you had to add 4 fans to keep it cool.

View attachment 179819
It's clear VTV haven't performed even a basic thermal design check.

Perfect timing. I just wrapped up a one + hour test of the thermal characteristics. I'm uploading some photos with this post, and will try to post a video so that it's clear I'm not manipulating the experiment or misleading anyone by placing pictures out of order.

First, do you have any idea how loud 10W into these speakers is? LOL that would probably hit 98dB in the room they're in if not higher.

As I described before, when starting with soft and then transitioning to somewhat loud music, the nc1200s tend to initially heat up to 115F* and then over the following hour, with increasing volume on mostly techno tracks (for constant program material), they settle in at ~107F. See pics taken in order and uploaded in same order.

*In today's experiment it never even got to 113F.

So to start, the temperature of the case was between 70 and 80F. Then while listening to music at the -40dB volume setting, it climbed to ~97F then all the way up to about 113F. I then turned it up (-30dB) and let it play while I took the dog for a walk (wife happens to be out of town) and that took about 45 minutes. When I got back, I measured the temp and it was down to ~107F. All perfectly acceptable.

You're not remembering correctly; I'm not using any fans as I clearly explained I was going to do earlier. Recall the statement I made where I said I'm going to run it with no cooling for two years to see if it fails so I can submit a warranty claim to VTV. Whether or not the Hypex modules are covered by warranty with lack of heat mitigation (they aren't), it will be on VTV to make the replacement.

That's a nice diagram of a heat sink you provided, but if you really want to continue this in a productive fashion, please find me some pictures from other manufacturers (not major names like NAD) who are selling OEM Hypex based amps. I want to see how many of them are using that kind of heat sink - or frankly, ANY heat sinking. I've literally never seen anyone using them or doing anything more than screwing the modules to a chassis and letting the chassis dissipate the heat. Apollon doesn't. Nord doesn't. And none of the Hypex DIY nc400 builds that I've seen do (but there are probably thousands of them and of course some people probably do use heat sinks - I just haven't seen one yet).

 

[C. Cook]

OH, I screwed up. The photo with the file name ending in 303 should be where the one ending with 401 is, just reverse them. I didn't capture an image when it was between 112F and transitioning back down to the 107F at 8:36PM.

Seriously there must be someone here who's an actual electrical engineer (I am a degreed EE but I never worked in audio) who has experience with the heat characteristics of PWM based class d amplifiers. There is clearly something other than a straight line from ambient temp to maximum temp going on here. I'm still at a loss as to why the temperatures were so high on the first day I used it, but they haven't gotten anywhere near that high again. I just walked out there to check it and the temperature is steady at ~106F with Underworld's "Dubnobasswithmyheadman" playing at a loud volume which amounts to about 1.5hrs at that setting.

 

[mrmojo2022]

You are missing the point. you running your amp at very low levels is irrelevant. the amp is sold as delivering 700 watts into 4 ohms. it will be in meltdown at that level.

Now turn the amp over and measure the base temperature and the box internal air temp.

Your data actually confirms my calculations with you using the amp at low power output.

What other manufacturers do is irrelevant. Perhaps they are bad too. also you need to stop assuming this is about having "finned" heatsinks. there's more to it than that, surface area and air flow.

You need to stop making apologies for this deficient design.