This is a review and detailed measurements of Douk Audio Nobsound NS-02E vacuum tube headphone amplifier. It is on kind loan from a member and costs US $60 on Amazon including Prime shipping.
NS-02E is a cute little thing:
Volume knob is a bit hard to turn due to detents in it but is livable. There is not much else to the unit than 3.5 mmm input and output jacks and a switching power supply:
OK, there is a stupid blue LED that lights up the tube but that is common these days. I can't read the faded writing on the tube so can't tell who has made it. Maybe the owner can advise later.
Nobsound NS-02E Measurements
As usual we start with our dashboard of feeding the unit 2 volts and adjusting the volume control to get 2 volts out:
One channel has much more distortion than the other, bringing the average down even more than one wants to see:
Noise floor is actually better than distortion:
Frequency response rolls off in the bass indicating capacitor coupling:
Tube stages tend to do well with high impedance loads as far as power and this is no exception:
My threshold is 100 milliwatts for this test and the NS-02E sails past that if you allow plenty of distortion before clipping.
Conversely, they don't like low impedance loads:
I was pleasantly surprised by the low output impedance though.
Channel matching is not great:
Nobsound NS-02E Listening Test
I started with my usual 25 ohm Ether CX and found what I expected: the sound gets distorted badly from medium level on up. With 300 ohm Sennheiser HD650 though, the NS-02E woke up and delivered early rattling levels with seemingly low audible distortion. Listening was enjoyable across wide range of content.
Conclusions
Objectively the results are horrible other than available power into high impedance load. With plenty of power before getting to severe distortion, the NS-02E delivers a good subjective experience into high impedance headphones. If you have an itch for "tube sound" and have a high impedance headphone, the Nobsound NS-02E is low cost way to experience that. Otherwise it is a strong pass.
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As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
NS-02E is a cute little thing:
Volume knob is a bit hard to turn due to detents in it but is livable. There is not much else to the unit than 3.5 mmm input and output jacks and a switching power supply:
OK, there is a stupid blue LED that lights up the tube but that is common these days. I can't read the faded writing on the tube so can't tell who has made it. Maybe the owner can advise later.
Nobsound NS-02E Measurements
As usual we start with our dashboard of feeding the unit 2 volts and adjusting the volume control to get 2 volts out:
One channel has much more distortion than the other, bringing the average down even more than one wants to see:
Noise floor is actually better than distortion:
Frequency response rolls off in the bass indicating capacitor coupling:
Tube stages tend to do well with high impedance loads as far as power and this is no exception:
My threshold is 100 milliwatts for this test and the NS-02E sails past that if you allow plenty of distortion before clipping.
Conversely, they don't like low impedance loads:
I was pleasantly surprised by the low output impedance though.
Channel matching is not great:
Nobsound NS-02E Listening Test
I started with my usual 25 ohm Ether CX and found what I expected: the sound gets distorted badly from medium level on up. With 300 ohm Sennheiser HD650 though, the NS-02E woke up and delivered early rattling levels with seemingly low audible distortion. Listening was enjoyable across wide range of content.
Conclusions
Objectively the results are horrible other than available power into high impedance load. With plenty of power before getting to severe distortion, the NS-02E delivers a good subjective experience into high impedance headphones. If you have an itch for "tube sound" and have a high impedance headphone, the Nobsound NS-02E is low cost way to experience that. Otherwise it is a strong pass.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/