This is a review and detailed measurements of the Douk / Little Bear VU3 dual analog VU meter and 2-way amplifier/speaker switcher. It is kindly sent to me by testing by a special member. VU3 costs US $140 from Amazon including Prime shipping.
The VU meter are the "paper back" ones which I like from my audiophile youth era:
When you light them up, they turn a nice shade of yellow. The sensitivity control for the meters is poorly done in that it does nothing for a bit and then has massive effect and then not much else. On the other hand, the AB momentary toggle switches have a nice feel followed by a reassuring relay click. A cheap looking remote is provided which I did not use but is appreciated.
Power is provided by a USB-C connection:
I used a stand-alone USB power supply for it. Wish there was some trigger option to turn the thing on and off when the amplifier is powered on.
The binding posts are better than I expected although as usual, they are too close together to turn if you are using bare wires as I was.
Douk VU3 Measurements
To detect if there is an impact on the amplifier performance, I decided to use the Purifi reference design amplifier with it. Here is that amp measured again for this test:
SINAD is the same as what I measured before but third harmonic is worse. Wonder if it is aging or my load box is. Anyway, that is not for this article. Let's now route the output from one channel through the VU3 and see what happens:
We have a pretty sharp rise in second harmonic and a mains hum. I played around with grounding, rotating the AC adapter, etc, and nothing would change the nature of it. I can't figure out how we lost 0.2 watt. The box must have rather low impedance to impact the amp this way.
To see the effect across the full power range, I ran the 4 ohm sweep:
There is definitely an impact here. So not good although you could argue SINAD is still > 100 dB so practical impact is low. Then again you paid so much for this Purifi amp and you dragged it down by some 15 dB.
Conclusions
Both this meter and its sister VU2 version seem to put undue load on the source causing distortion. There needs to be a buffer stage with high impedance that doesn't do this. It is a shame as the rest of the functional with remote controlled AB/amp switching is very good.
I personally would not want to degrade the performance of my system by any amount to have some "bling." So I can't recommend the Douk VU3.
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As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The VU meter are the "paper back" ones which I like from my audiophile youth era:
When you light them up, they turn a nice shade of yellow. The sensitivity control for the meters is poorly done in that it does nothing for a bit and then has massive effect and then not much else. On the other hand, the AB momentary toggle switches have a nice feel followed by a reassuring relay click. A cheap looking remote is provided which I did not use but is appreciated.
Power is provided by a USB-C connection:
I used a stand-alone USB power supply for it. Wish there was some trigger option to turn the thing on and off when the amplifier is powered on.
The binding posts are better than I expected although as usual, they are too close together to turn if you are using bare wires as I was.
Douk VU3 Measurements
To detect if there is an impact on the amplifier performance, I decided to use the Purifi reference design amplifier with it. Here is that amp measured again for this test:
SINAD is the same as what I measured before but third harmonic is worse. Wonder if it is aging or my load box is. Anyway, that is not for this article. Let's now route the output from one channel through the VU3 and see what happens:
We have a pretty sharp rise in second harmonic and a mains hum. I played around with grounding, rotating the AC adapter, etc, and nothing would change the nature of it. I can't figure out how we lost 0.2 watt. The box must have rather low impedance to impact the amp this way.
To see the effect across the full power range, I ran the 4 ohm sweep:
There is definitely an impact here. So not good although you could argue SINAD is still > 100 dB so practical impact is low. Then again you paid so much for this Purifi amp and you dragged it down by some 15 dB.
Conclusions
Both this meter and its sister VU2 version seem to put undue load on the source causing distortion. There needs to be a buffer stage with high impedance that doesn't do this. It is a shame as the rest of the functional with remote controlled AB/amp switching is very good.
I personally would not want to degrade the performance of my system by any amount to have some "bling." So I can't recommend the Douk VU3.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
