Tachyon88
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Not if you count yourself mucking up this thread with your pedantic and useless replies.
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BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Review
- Thread starter thin bLue
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Not if you count yourself mucking up this thread with your pedantic and useless replies.
restorer-john
Grand Contributor
What's 'truly impressive' (not) is you quoting a best case distortion figure on a non continuous (about to shutdown) at a frequency (15kHz) where your measurement bandwidth is deliberately not even considering even a single harmonic component. LOL.
Let's talk about continuous rated power from 20Hz-20kHz. That means driving the amplifier up to 20kHz continuously to determine its actual capability. And measuring those harmonics with an adedquate measurement bandwidth.
@thin bLue Please retest the amplifier at elevated powers if and when you receive the replacement power supply. It will likely fail in the same way.
Will add, that the board designer tests Buckeye amps as white box, I test them as black box as a contract tester and Dylan tests operationally. As some here already know, I tested at 4 ohms and 2 ohms and attained the rated Hypex specs without issue. I tested 2 different Buckeye NCx500 amps and still use a stereo one in my reference system. My power tests are set to terminate at 1% THD though and it does not appear the OPs testing does.
As this is not his first destructive test, the OP should look harder at his test settings. For that matter, should try a Power vs THD (rather than THD+N). The amount of wiring for his dummy load (or something else) may be adding noise and could cause an early power test abort. Still would hope that the amp is robust enough to self protect, but amp protections are not designed to prevent every possible situation either.
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Dial back the attitude and snark or you will be removed from the conversation Sir.Well design your own good one...
restorer-john
Grand Contributor
The unit tested shutting down/limiting at 0.4% and from 10kHz and up according to the plots. A long way from 1%.
OK, but did not happen during my testing of comparable Buckeye amps. Amir will test one soon and we will have another data point. Am confident, as in the past, his results will mirror my own. For that matter, Buckeye’s designer has not encountered major issues. This suggests the OP might need to consider how his testing differs.
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restorer-john
Grand Contributor
So, Rick, just to confirm- you have tested these amplifiers at 8/4/2R full advertised rated continuous power into all frequencies up to and including 20kHz with correct calculation of the harmonics, to not exceed 1%THD? I have a few hopefully landing on my bench in the next few weeks, so it will interesting to see how our results compare.
I primarily test at 1k Hz but have added tests at 100 Hz and 5k Hz. I only recently have become capable of 2 ohm testing. Am usually looking to verify that an amp performs reasonably close to manufacturers specs. I leave more comprehensive testing to Amir. Do not have near the test automation that an AP provides, so just do selective testing. As have mainly tested Buckeye amps, as you know, am testing an amp built from preassembled and tested modules.
I readily admit, that my measurement gear is not on par with Amir’s, yours or the OPs, but try to be a disciplined tester and (hopefully) do it well enough to be of service and help to others.
p.s. should emphasize that am not out to do destructive testing and am guessing that the OP is not either. Will not get much equipment to review if every product ends up being scrapped or needing repair. Otoh, testing needs to be robust enough to avoid simply rubber stamping every product. The OP blew up his friend‘s Class AB AVR too, so would hope he is introspective enough to consider that his testing or test rig may need some modification.
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Sokel
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I think that one of the key questions is how long every of this test lasts.
SMPS's .pdf clearly states that it's PEAK power (1200 watt) is only for 10 seconds and that it's continuous power is 325 watt:
Would it be fair to ask an output of 1200 watt for longer than that?No.
Is it also fair to advertise specs based on that without mentioning this condition?Also no.
Should the mentioned PSU shut down long before according to it's advertised specs about it's protections?It certainly should.
Maybe we should not blame the messenger for exposing the obvious.More than that,we should embrace such efforts and thank both the reviewer and the owner who accepted to take that risk.
SMPS's .pdf clearly states that it's PEAK power (1200 watt) is only for 10 seconds and that it's continuous power is 325 watt:
Would it be fair to ask an output of 1200 watt for longer than that?No.
Is it also fair to advertise specs based on that without mentioning this condition?Also no.
Should the mentioned PSU shut down long before according to it's advertised specs about it's protections?It certainly should.
Maybe we should not blame the messenger for exposing the obvious.More than that,we should embrace such efforts and thank both the reviewer and the owner who accepted to take that risk.
The old FTC spec in US tried to deal with this issue but went overboard the other way. To me it looks these Purfi modules are designed to be Hi-Fi music amps... not PA amps or sine wave amps and certainly not designed for the old FTC test. However for playing music they seem perfectly fine with exceptional performance. Is there really any point to 700 watts @ 20 Khz for playing music? None that I can think of.
tmtomh
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What has always puzzled me about these specs is that the "real" specs - the continuous power ratings - are pretty darned good as-is. In addition to being misleading, the top-line specs also seem unnecessary for making the case that these are good modules and PSUs.
EDIT: @levimax makes essentially the same point, albeit in a different way, just above. Agree.
Agree. It’s easy to talk about peak power with Class D amps just like you used to be able to quote PMPO instead of RMS. But since there isn’t an ISO standard that I know of, maybe we need to decide what is reasonable to advertise and what isn’t.
Short term transients are quick, and that’s where the headroom of class D is great.
In the other hand, the real question I have is why the NC500 is explicit about 100W continuous while the NCx500 isn’t.
Can the T of heatsink stay at 95C with “normal” sized heatsinks or are we talking about something massive or something requiring active cooling? Thermal throttling is pretty common with CPUs, no matter how good your passive heatsink is.
Maybe in the next generation the HypeX modules should implement thermal throttling? I also wonder if McIntosh’s HypeX implementations use any additional protection circuitry the way that Marantz does.
I can run at the speed of light as t decreases to the time step that my body is moving one Planck distance. That is, if distance and time is quantized there is some point where I wasn’t moving and then when I did move move that distance, since I wasn’t moving in a smaller step than a Planck distance there is some snapshot in time where I was moving at the maximum possible speed, right?
That is, if I am running at 5 km/h, am I running at 5 km/h or am I moving a Planck distance every x time, and am I really just moving at the speed of light, waiting a good amount of time and then moving the next quantized distance?
There is no point to driving 100 mph in the U.S. on public roads, but if a car says it can do 100 mph on a closed track, I would be pretty upset if it could only do 65 mph and the engine blew at 90 mph.
There isn’t a tweeter that can handle the power output by the NCx500 but it doesn’t mean that you should advertise that it can…
Is there a point of going for better than 0.1% THD for playing music? The readership certainly votes down the gear that doesn’t hit this spec…
Personally think it's bullshit as to application particularly. Nothing special about "hifi" outside of spec really, so sufficient spec is sufficient spec no matter how you use it. I have same issues when someone says gear is suited to "music" over all other audio requirements (even if they include music, such as movie soundtracks). A sub might be a good application to know what output details are for 20hz at various impedance loads, etc....
The flip side of that is if you have an amp that can produce 700 watts @ 20 Hz and "only" 325 watts @ 20 KHz is it reasonable to call it a 325 watt amp? These amps are designed to play music which has much higher power requirments at lower frequencies than high frequencies. The technology has gotten ahead of the marketing.
Sounds like a much more useful amp to me than the other way around
The old FTC spec is BS if you are trying to see how well an amp can actually play music. When I say Hi-Fi I mean it is desgined to play back recorded music not pass an arbitrary "test" which requires the same power produced at 20 Hz has to be produced at 20 Khz. I could argue making an amp that does this is a "bad" design. Why spend engineering effort and money on "solving" a problem that has nothing to do with playing back music?
Exactly, Oddly people seems to embrace that kind of rating with a lot passion, I don't know why. It seems to me that usually the ratings of class D are very optimistic with peak power ratings and sometimes 10% THD ratings, personally I go with the ''knee"... That said I'm not very trendy so I might be out of touch on this day and age.
No need for insults. An amp that can produce more LF power than HF power would be rated by its HF power according to the FTC test. An amp like this will indeed play music better than an amp with the same FTC power rating that plays LF and HF with the same amount power.
tmtomh
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Yes - it seems to me that you are identifying a key part of what would be a more useful way to rate amp power, as is @levimax .
Take for example an amp that could produce 500 watts into a 4 ohm load at 1kHz with 1% THD. But the amp is a low-distortion amp so when it reaches 1% THD it's already passed the "knee" that Hipocrates refers to - it's already clipping. Before it starts to clip - before the "knee" - it reaches 485 watts and its pre-clipping THD happens to be 0.004%. And let's say that when you test the amp with 10kHz, 15kHz, and 20khz signals, it can't provide the full 500 watts at those frequencies - it clips or shuts down at 275 watts.
In this scenario, the "Hypex" power rating is 500 watts per channel into 4 ohms.
The "FTC as our guide" power rating is 275 watts per channel into 4 ohms.
If I want the safer, more ethical choice, it's clearly the latter.
But it seems to me that the most useful power rating would be "485 watts per channel, 20Hz to 10kHz, 275 watts per channel, 10kHz to 20khz, into 4 ohms at 0.004% THD." That would tell you the actual max power prior to clipping or shut-down that you could get from the amp.
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