• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Why NCx500 isn't necessarily an upgrade

OP
Bjorn

Bjorn

Major Contributor
Audio Company
Forum Donor
Joined
Feb 22, 2017
Messages
1,358
Likes
2,680
Location
Norway
A 1kHz test is all you need? LOL.

What about low frequencies, intermediate frequencies and high frequencies? 20Hz-20kHz, worst case THD is what I want to see.

And that means an analyzer with a decent bandwidth (~200kHz). Oh, but the NCx needs a filter...

I agree totally, the 1kHz THD+N or SINAD wars are hilariously stupid.
Why the need for a bandwidth that's not audible for humans?

Neverthless, let me know exactly what graphs you want to see.
 

pma

Major Contributor
Joined
Feb 23, 2019
Messages
4,742
Likes
11,058
Location
Prague
Voltage noise density related to input is the parameter of interest.
 

Mnyb

Major Contributor
Forum Donor
Joined
Aug 14, 2019
Messages
2,929
Likes
4,128
Location
Sweden, Västerås
That's suppose to be for DIYers.
How it ended up in shops is probably another story.
I know but Vera is not operating in the most price sensitiv segment of the HiFi market. Module cost may not be the biggest factor in thier design. I like thier thermal management :) not many have this .
 

pma

Major Contributor
Joined
Feb 23, 2019
Messages
4,742
Likes
11,058
Location
Prague
Let's look at a THD+N measurement of our Vera Audio P400/1000 with NC500 modules first. Showing both channels in 4 Ohm:
@amirm measurements differ from yours:



He measures -100dB THD+N at 100mW, which would make 0.001%. Your numbers with NCx500 are several times higher (up to 0.01%).
 

Hayabusa

Addicted to Fun and Learning
Joined
Oct 12, 2019
Messages
867
Likes
619
Location
Abu Dhabi
We are in the age of chasing THD numbers in electronics. And while it's certaintly good with low distortion numbers, let me explain why using NCx500 modules or any other newer class D modules isn't necessarily an upgrade. And also why Vera Audio hasn't considered several of new class D modules that been released or are about to be released.

Let's look at a THD+N measurement of our Vera Audio P400/1000 with NC500 modules first. Showing both channels in 4 Ohm:
View attachment 353984

just for fun:

The 0dB SPL line in this graph for a speaker with 90dB/w sensitivity:
( note that 10w is already playing 100dB then )

1710338820561.png
 
OP
Bjorn

Bjorn

Major Contributor
Audio Company
Forum Donor
Joined
Feb 22, 2017
Messages
1,358
Likes
2,680
Location
Norway
@amirm measurements differ from yours:



He measures -100dB THD+N at 100mW, which would make 0.001%. Your numbers with NCx500 are several times higher (up to 0.01%).
He measured without the internal buffer. From your link:
Note that this board includes a pre-amp (buffer). I am testing per above in unbuffered mode.
 
OP
Bjorn

Bjorn

Major Contributor
Audio Company
Forum Donor
Joined
Feb 22, 2017
Messages
1,358
Likes
2,680
Location
Norway
Here are FFT measurements in differents bandwidths of the Vera Audio P150/600 RS in bridge mode.

20KHz bandwidth:
Vera P150_600 in bridged mode measured with 20kHz bandwith.png


40KHz bandwidth:
Vera P150_600 in bridged mode measured with 40kHz bandwith.png


250KHz bandwidth:
Vera P150_600 in bridged mode measured with 250kHz bandwith.png
 
OP
Bjorn

Bjorn

Major Contributor
Audio Company
Forum Donor
Joined
Feb 22, 2017
Messages
1,358
Likes
2,680
Location
Norway
I would say the difference is not in distortion, but in noise. You cannot distinguish it in THD+N plot. You might like to measure THD (without N) as a function of power, instead. REW software (even the free version) will let you find the difference, should it be either THD or N.

My suspect - the gain is the same in both cases??
Is this the type of measurement you're looking for?

THD Ratio vs Measured Level - 4 Ohm Load.jpg
 
Top Bottom