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BUCKEYEAMPS Hypex NCx500 Amplifier 2channel Review

That is what AP generates.
So Ap generates 5.8 V out, DUT(amps)'s max input voltage is 5.8 V. Last time the value was actually 700W point by my experiment. This time theoretical(by gain) value suggestions from the company.

Points are decreased 150 -> 100, Shorter duration of stress.

Filter past 20 - 20k for all
Filter now 10 - 20k (Almost same to 20 - 20k) for 20 - 5 kHz sweep, 10 - 30k for 10 kHz, 10 - 45k for 15 kHz, 10 - 60k for 20 kHz.

So, 10 kHz to 20 kHz sweep now shows 3rd harmonics and ultrasonic debris.

I'll post new threads about repaired amp, so other details will be there.

A new thread(s) would be good as this one is too way long already!
 
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A new thread(s) is a good as this one is too long already!

I'll post new threads about repaired amp, so other details will be there.
This is a good idea. Let us know when you start the new thread. We can lock this one with a redirect link to the new follow up testing thread. You can either use a call out or drop us a PM. Either method will work. ;)
 
You can see the preview of them.
View attachment 309669
View attachment 309670
View attachment 309683
These are significantly more relaxed test to DUT than in the past. But I still feel quite anxious. Anyway it hasn't been fried yet. Few of test are left.
And I'm sure my wall power is white. I mean she is innocent. Lowest value I've seen was 215 V, It's nicely inside of the standard of our region, 220 V ± 13 V, even in kW drains.
Is the (old,fixed) ballooning we see again at certain freqs normal or some bad connectors came to play again?
 
@thin bLue
As @boXem has pointed out lots of times,the reason for the rising SINAD in upper freqs is unclear sometimes.
Is it distortion,is it noise?
Can we please have a say,10-15-20Khz single measurement with high BW so we can see which is which?
(at least at this amp)

Thanks in advance!
 
As @boXem has pointed out lots of times,the reason for the rising SINAD in upper freqs is unclear sometimes.
Is it distortion,is it noise
Agreed, SINAD is a useful index for equivalence, but high frequency noise and high frequency distortion have different consequences.
 
@thin bLue
As @boXem has pointed out lots of times,the reason for the rising SINAD in upper freqs is unclear sometimes.
Is it distortion,is it noise?
Can we please have a say,10-15-20Khz single measurement with high BW so we can see which is which?
(at least at this amp)

Thanks in advance!

Since the OP is struggling to complete his existing set of tests, thought this might help in the meanwhile. First, let‘s consider conditions. I am using a preproduction build of the same amp and measuring it with my E1DA/E50 combo. From previous experience, I already know noise is more difficult to tame in my test rig, so will measure only the distortion component. Perhaps the OP can reproduce my approach with his AP if he has the time.

Next, some other considerations. First, am going to use a baseline distortion measurement at 1k Hz with a 4 ohm non-inductive dummy load. Second, since you requested a higher frequency, going to use 5k Hz with the same load. Third, since the amp’s output filter attenuates significantly after 20kHz, will focus on THD that is second and third harmonic to help ensure the 2 measurements are being equitably compared.

Here is the comparison…

1693910757144.png


You can see that for most of output of the amp, THD is very comparable with a slight divergence around 240 watts where there is slightly higher distortion for the higher frequency than the lower one. So, whereas in SINAD where noise is included in the metric, there is a more significant divergence at lower power. As is in a more established test environment, see @amirm’s testing of the NCx500 monoblock for reference…

1693913108806.png


So, along with other testing experience, my conclusion is that when you see greater (SINAD) divergence at higher frequencies, it is likely due to higher noise rather rising distortion. I will further condition this based on the test environment being well controlled and baselined. We have all seen what can happen to these very low measurements when contacts are too loose. Am being very careful to ensure solid contact and consistent conditions are being applied with each measurement. If this is not done, then the test rig can skew the measurements and the results cannot be accurately compared.

Hope this helps!
 
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Since the OP is struggling just with his existing set of tests, thought this might help in the meanwhile. First, let‘s consider conditions. I am using a preproduction of the same amp and measuring it with my E1DA/E50 combo. From previous experience, I already know noise is more difficult to tame in my test rig, so will measure only the distortion component. Perhaps the OP can reproduce my approach with his AP if he has the time.

Next, some other considerations. First, am going to use a baseline distortion measurement at 1k Hz with a 4 ohm non-inductive dummy load. Second, since you requested a higher frequency, going to use 5k Hz with the same load. Third, since the amp’s output filter attenuates significantly after 20kHz, will focus on THD that is second and third harmonic to help ensure the 2 measurements are being equitably compared.

Here is the comparison…

View attachment 309826

You can see that for most of output of the amp, THD is very comparable with a slight divergence around 240 watts where there is slightly higher distortion for the higher frequency than the lower one. So, whereas in SINAD where noise is included in the metric, there is a more significant divergence at lower power. As is in a more established test environment, see @amirm’s testing of the NCx500 monoblock for reference…

View attachment 309837

So, along with other testing experience, my conclusion is that when you see greater divergence at higher frequencies, it is likely due to higher noise rather rising distortion. I will further condition this based on the test environment being well controlled and baselined. We have all seen what can happen to these very low measurements when contacts are too loose. Am being very careful to ensure solid contact and consistent conditions are being applied with each measurement. If this is not done, then the test rig can skew the measurements and the results cannot be accurately compared.

Hope this helps!
Higher noise with higher power is somewhat intuitive as a lot of things are at play.
But what I asked for is a single measurement with high bandwidth where distortion and noise are separately evident so we see what happens to that debate.
It doesn't have to be at 200 watt,5 watt 15Khz is enough (if you manage to tame noise).
 
Higher noise with higher power is somewhat intuitive as a lot of things are at play.
But what I asked for is a single measurement with high bandwidth where distortion and noise are separately evident so we see what happens to that debate.
It doesn't have to be at 200 watt,5 watt 15Khz is enough (if you manage to tame noise).

Did what I could given I know the limits of my test rig. As I mentioned, a test frequency higher than about 5k Hz is going to be skewed as it‘s harmonics are way above the amp’s output filter and then are not comparable conditions to the 1k Hz baseline. So, not sure what you think can be accomplished with a higher frequency or bandwidth measurements.
 
Since the OP is struggling to complete his existing set of tests, thought this might help in the meanwhile. First, let‘s consider conditions. I am using a preproduction of the same amp and measuring it with my E1DA/E50 combo. From previous experience, I already know noise is more difficult to tame in my test rig, so will measure only the distortion component. Perhaps the OP can reproduce my approach with his AP if he has the time.

Next, some other considerations. First, am going to use a baseline distortion measurement at 1k Hz with a 4 ohm non-inductive dummy load. Second, since you requested a higher frequency, going to use 5k Hz with the same load. Third, since the amp’s output filter attenuates significantly after 20kHz, will focus on THD that is second and third harmonic to help ensure the 2 measurements are being equitably compared.

Here is the comparison…

View attachment 309826

You can see that for most of output of the amp, THD is very comparable with a slight divergence around 240 watts where there is slightly higher distortion for the higher frequency than the lower one. So, whereas in SINAD where noise is included in the metric, there is a more significant divergence at lower power. As is in a more established test environment, see @amirm’s testing of the NCx500 monoblock for reference…

View attachment 309837

So, along with other testing experience, my conclusion is that when you see greater divergence at higher frequencies, it is likely due to higher noise rather rising distortion. I will further condition this based on the test environment being well controlled and baselined. We have all seen what can happen to these very low measurements when contacts are too loose. Am being very careful to ensure solid contact and consistent conditions are being applied with each measurement. If this is not done, then the test rig can skew the measurements and the results cannot be accurately compared.

Hope this helps!

Did you use 45 kHz bandwidth in your test?

Michael
 
Why does it matter?

Because you are comparing to Amir's measurement which is 45 kHz bandwidth. I agree that it is likely an increase in noise that is causing the issues at higher test frequencies but using the same bandwidth would rule out any weird issues with higher harmonics.

Michael
 
Because you are comparing to Amir's measurement which is 45 kHz bandwidth. I agree that it is likely an increase in noise that is causing the issues at higher test frequencies but using the same bandwidth would rule out any weird issues with higher harmonics.

Michael

Was not using Amir's measurement for comparison to my own as much as to show SINAD measurements of a comparable NCx500. As I also stated in my post, I intentionally limited my testing to the first few harmonics...

As I already mentioned, the amps output filters are already attenuating many of the higher order harmonics. Should have also mentioned that my test rig includes a Class D low pass filter that also attenuates high order harmonics. In the end, my test intentionally limited the bandwidth needed to be within the harmonics being measured.

At 1k Hz, could easily measure up to the 9th harmonic. Including the higher harmonics makes a really small difference and is mainly at low power levels. Do not want to further bulk up an already robust thread so if we want to discuss further, could start a new one,
 
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Was not using Amir's measurement for comparison to my own as much as to show SINAD measurements of a comparable NCx500. As i also stated in my post, I intentionally limited my testing to the first few harmonics...

As I already mentioned, the amps output filters are already attenuating many of the higher order harmonics. Should have also mentioned that my test rig includes a Class D low pass filter that also attenuates high order harmonics. In the end, my test intentionally limited the bandwidth needed to be higher than the harmonics being measured.

At 1k Hz, could easily measure up to the 9th harmonic. Including the higher harmonics makes a really small difference and is mainly at low power levels. Do not want to further bulk up an already robust thread so if we want to discuss further, could start a new one,
We can do it another way then.
Just measure 1Khz with 20-20.000Hz bandwidth and another with 20-48.000Hz bandwidth.
An example I did with my DAC:

20-20K Bandwidth:

20-20K.PNG

20-48K bandwidth:

20-48K.PNG

It's the exact same measurement,I didn't have to make two,Multitone Analyzer just recalculated with the higher bandwidth.
I can immediately see that the first is 105.1db SINAD and the second just 100.9db SINAD and the most of it is noise as in the first is down to -111.5db and in the second gets an about 4db penalty,almost exactly the degraded SINAD.
 
This is a good idea. Let us know when you start the new thread. We can lock this one with a redirect link to the new follow up testing thread. You can either use a call out or drop us a PM. Either method will work. ;)

Hope the OP is ok. Thought after a 2 week absence, he was ready to post another pass. More than another week has gone by with (EDIT) a brief update. Aside from the fancy AP, the main difference in his testing is the AC line voltage. Am wondering whether I should try it. Have tested this amp enough at this point, that am confident it is reliable with 120 VAC. Any word?
 
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Hope the OP is ok. Thought after a 2 week absence, he was ready to post another pass. More than another week has gone by without an update. Aside from the fancy AP, the main difference in his testing is the AC line voltage. Am wondering whether I should try it. Have tested this amp enough at this point, that am confident it is reliable with 120 VAC. Any word?
He just posted this yesterday...


I believe he'll continue in a new thread.
 
He just posted this yesterday...


I believe he'll continue in a new thread.

Thanks, missed that post. :oops:

Updated mine.
 
Well am giving up for now and taking my amp from my test bench and putting it back so I can listen to it.

I hope the OP is ok, but clearly he must have other priorities.:confused:
 
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After 3 months now, still no response from the OP.

Still wish him well, but disappointed by the lack of closure he could have provided for this thread.:(
 
After 3 months now, still no response from the OP.

Still wish him well, but disappointed by the lack of closure he could have provided for this thread.:(

There was a post at some point where OP mentioned having some health problems and mentioned going to the hospital. It doesn’t look like thin blue has logged in since Sept. :(

Sending warm wishes of better health…
 
After 3 months now, still no response from the OP.

Still wish him well, but disappointed by the lack of closure he could have provided for this thread.:(
Hi Rick,

Thank you for updating this review thread. It has been a while and it looks like we were all left hanging as to the final outcome of the failure. The the Amp module fail or did the power supply fail or was there an error in his testing procedure that caused premature failure?

Would you be so kind as to summarize where this test stands please?
 
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