NVX VADM2 Review (Car Amplifier)

[amirm]

This is a review and detailed measurements of the NVX VADM2 stereo car audio amplifier. It is on kind loan and is selling for $US 173 on Amazon.

Form factor is typical although quality here is a step above average:

I liked the very large power terminals allowing easy termination of my heavy battery cables. Speaker connection is through phoenix connector which increases the risk of shorts due to closeness of the terminals. RCA inputs are provided through a pigtail on the opposite side.

NVX VADM2 Measurements
I warmed up the unit with 5 watts into each channel showing quick stability:

I then ran our dashboard:

We now have enough data to start ranking car audio products based on SINAD (distortion+noise):

This is about average for home audio amplifiers and above average for car audio. So not bad.

Signal to noise ratio is not bad either for the category:

Multitone shows rising distortion at low frequencies:

Frequency response shows high dependency on load (speaker impedance):

Crosstalk is OK:

Power vs distortion is again decent for the class

Max and peak power are essentially the same:

Naturally we lose power at 8 ohm:

Conclusions
The picture here is mixed. Noise and distortion at 1 kHz is above average. But we have load dependency and rising distortion at low frequencies. Until I test more car audio amplifiers, I am not sure how harsh I should be at this point. I am going to give the unit the benefit of the doubt and give the NXV VADM2 a marginal recommendation.

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[Jdunk54nl]

Thanks for measuring it!
It was running my subwoofer (bridged to 4ohms) on my Rzr for a while.

Nvx’s claim of 150w x2 @ 4ohms I’m guessing is for 1% distortion and it seems to do that. Good for them on an honest power rating.

 

[GWolfman]

Thanks for measuring it!
It was running my subwoofer (bridged to 4ohms) on my Rzr for a while.

Nvx’s claim of 150w x2 @ 4ohms I’m guessing is for 1% distortion and it seems to do that. Good for them on an honest power rating.

What's 1% THD in terms of dB (i.e., equivalent)?

 

[Rivet Head]

What's 1% THD in terms of dB (i.e., equivalent)?

1% THD = -40dB

THD to dB - convert percent % to decibels dB percentage voltage % vs per cent converter THD+N total harmonic distortions calculation signal distortion factor attenuation in dB to distortion factor k in percent decibel damping - sengpielaudio Sengpiel

Calculate THD and distortions decibels dB to percentage % per cent percent voltage % vs converter and dB signal distortion THD+N total harmonic distortions factor attenuation damping - Eberhard Sengpiel sengpielaudio

www.sengpielaudio.com

 

[Philipp Paul Klose]

What's 1% THD in terms of dB (i.e., equivalent)?

That is -40 dB below the fundamental.

 

[noel_fs]

i mean, could be worse

 

[AudioSceptic]

That is -40 dB below the fundamental.

I find this simple sequence easy to remember:
1% = -40 dB
0.1% = -60 dB
0.01% = -80 dB
0.001% = -100 dB
0.0001% = -120 dB

 

[NiagaraPete]

Seems pretty good to me for the price.

 

[3125b]

Well the price seems fair, this is about what you could expect from a regular mains powered amp at that price point (disregarding the odd better/cheaper exeption).
Many of these car amps are just way overpriced it seems.

And frankly I think performance beyond what this thing offers is all but irrelevant in the context of car audio. It's an utterly unsitable environment for critical listening anyway.

 

[AudioSceptic]

I find this simple sequence easy to remember:
1% = -40 dB
0.1% = -60 dB
0.01% = -80 dB
0.001% = -100 dB
0.0001% = -120 dB

We could also add:
100% = 0 dB
10% = -20 dB