This is a review and measurements of the Sch-remote EVOR04-slim LCD based audio VU/Spectrum/Visualization module. It was sent to me by the company and costs US $78 ($72 in volume).
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This is a two-board sandwich with the display in the front as you see. On the right there is a USB jack for power or a standard barrel connector for the same. Two analog stereo 3.5mm jacks are provided which you can select from the menu. Screen is touch sensitive. I think it is resistive though as it requires some pressure and has a delay before it detects your touch. To the extent you don't need to touch it often, it is fine.
The unit is hugely configurable through the menu system allowing you to set such things as sensitivity, etc. Here is a shot of the back where the guts are:
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The display in person looks very good. There is a bit of dancing/sequencing pixel going on at times which I suspect is due to refresh rate. There are not only stereo and mono graphs but also differential (X-Y) displays as well. I like the simulated VU meter of which there are 4 or 5:
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This one has peak detection. Here is a shot of it with my mobile phone:
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Company also sent me a compact black plastic case for the unit to make it freestanding.
EVORO4-Slim Measurements
All the VU meters we have tested in the back have had poor front-ends, loading the input down causing severe distortion. So that was the first test I went for by first measuring my Audio Precision analyzer by itself:
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I set the output voltage to 250 millivolts as by default the VU meter is setup for 20 dB gain. I then plugged the EVOR04 in parallel to the signal connection above:
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As you see the impact is basically non-existent indicating a nice buffer in the front-end of the meter.
Not that it matters a ton but I wanted to see how flat the frequency response of the meter was. I used its own display to show the dB value while I selected four different frequencies (calibrated to 1 KHz):
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As you see, there is a bit of drooping at both ends of the spectrum, dropping by 1 dB at 20 Hz and 1.4 dB at 20 kHz.
Last bit was frequency resolution when using the spectrum analyzer:
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The meter was fed a pure sine wave at 100 Hz which should just create a vertical bar. It does that at higher frequencies but as you go down, it widens as you see. It would have been nicer to make this much narrower. Unfortunately that sharply increases the computational requirement (and slows down the response some). Not sure if there are spare CPU cycles to throw at it.
Finally, I connected the meter to my DAC and enjoyed beautiful dancing bar graphs with low latency:
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What I wished the device had was IR remote. Then you could cycle through the visualizations in non-desktop applications.
Conclusions
I got into hi-fi in 1970s when VU meters and spectrum analyzers were often sign of status of the audio device. The larger the VU meter, the more high-end the unit was! Our sources were spinning devices whether we were talking cassette tapes, LP or reel to reel. Today, we have lost all of that with digital. Yes, software visualizations exist but they are too far removed from where the audio samples come out so they don't seem very connected to the music. And at any rate, they are not where they should be -- in our audio rack. I really like to see audio companies innovate in this domain and bring back attractive front panels sporting informative and beautiful displays. Modules like EVOR04 enable this as they seem to be built for OEMs to include in their audio devices.
I was pleasantly surprised how capable and flexible this meter is. I did not remotely do justice to its level of programmability in this write up. It does everything you wish and then some. I mean it even has two stereo audio inputs! And two ways of powering it.
On technical performance, there is no impact on your audio fidelity which is as it should be. The accuracy of the meter itself is not perfect but certainly good enough for fun.
I would like to see a more premium version of it with a stepped up display quality, remote control and better frequency resolution. As it is, what we have is quite compelling.
I am going to put the Sch-remote EVOR04 on my recommended list.
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