Fosi Audio LC30 Analog VU Meter (Black Version) - bling!

A couple of weeks back, I evaluated the Rotel RSS-900 speaker switch and in that article, I mentioned this device, the Fosi Audio LC30 VU Meter and Amp/Speaker Switcher (less than US$150 street price). Notice that I have the "Black" version (Amazon Canada link, AliExpress) which doesn't look like it's as easily available as the typical "Yellow" meter version and it also has a slightly higher MSRP at least here in Canada. I bought this one from the usual consumer channels on sale.

Let's be honest, unless we're working in the studio on a project, for playback, dancing meters are mostly about adding "bling" to the sound system and I'm totally about having fun with this! 😀 This darker "Black" color scheme in my sound room is not as bright and won't distract from watching movies. At lower brightness levels, is easy to not draw attention to itself when lights are off.

Let's talk about this box, the features, and a little about the performance.

Here it is with the shipped cardboard box and contents: the VU "volume unit" meter/switcher box, a USB-A-to-C cable (about 5'), small multi-lingual pamphlet, and the black plastic remote control.

The VU meter/switcher box is made of matte sand-blasted aluminum except for four rubber footers. It has nice rounded edges, small plastic buttons, rear binding posts (typical plastic + metal) and of course the front VU meter screens. It feel reasonably dense at around 3.5lbs with dimensions of around 9.25" W x 3.25" H x 7" D (including the rear binding posts and front knob poking out), with a reassuringly sturdy feel. It's rated to handle up to 250W/channel, 4Ω.

Each of the VU meter screens measure 3.5" diagonally. Here's a closer look at the front:

It's good that the "Fosi Audio" logo and text are small and low contrast. The large knob in the middle is to change the sensitivity of the meter. Audio Science Review has already measured this device and as discussed there, calibration isn't something one should worry about when it comes to bling like this 😉, seriously guys and gals, this is about having a fun meter in your sound system that dances with the music so just use that sensitivity knob to select how much dancing you want to see.

Even if not calibrated, one can see relative left and right channel levels which can help verify when you notice a channel imbalance - is it the music itself, the source component(s), or amp if there is an issue? I'm guessing that the meter is responding to the voltage differential across the speaker terminals rather than sophisticated enough to measure both voltage and current; something like the much more expensive McIntosh MPM4000 can do, originally made for car audio.

As a 2-in/2-out unit, the lower buttons on the LC30 are to select which of 2 amplifiers you want to use, and which of 2 speakers. You'll hear a relay click when switching. This is obviously useful when you want to run A/B listening between two amps and/or speakers. The central lower small button turns the unit on/off (press and hold) and changes brightness (quick press).

The lack of independent volume controls for the speaker outputs will limit the A/B potential (no easy way to equalize volume from the same source/amp), but the addition of such a knob will almost inevitably deteriorate sound quality by putting another component in the audio path.

The back side consists of all your binding posts, accepting banana plugs and bare wire with a single lower USB-C 5V connector to power the unit. The binding posts look and feel to be of good quality, gold plated.

A simple plastic remote control with rubberized buttons, 2 AAA batteries not included. Controls are intuitive with power button, you can directly switch between amplifier A/B and speaker 1/2 with the directional ring, the "light" button turns on/off the VU backlight, +/- buttons to cycle between 5 brightness levels (100%, 75%, 50%, 25%, off), and the SPK/AMP buttons act as toggles. (If needed, inexpensive replacement available.)

Note that this can only switch between one speaker at a time, you cannot power both speakers 1 & 2.

Given how simple the operation and the fact that there's a single amp/speaker in use at any one time, there's really not much to measure. Let's bring out one of my Sony SS-CS5 (M1) bookshelf speakers along with the Nordost-replica 9' speaker cable for a measure of the speaker impedance through this switch box with a short length of 3' 12AWG speaker cable which I'd potentially use to connect to an actual amplifier. This is similar to the quick measurements I did with the Rotel RSS-900 to show what your amplifier "sees". Let's examine the impedance, phase, and EPDR out to 40kHz:

Note also the impedance attenuation in the bass peaks.

Top graph is the Sony SS-CS5M2+Nordost-replica cable only, bottom graph going through the Fosi LC30 with an extra 3' length of 12AWG copper speaker cable. Looks great, basically identical with an insignificant -0.1Ω resistance/impedance change going through the LC30. There's ~250Ω resistance from the amp terminals with no load connected. I tested all the speaker and amp outputs to make sure there was nothing unusual and saw no significant change through any of those speaker/amp outs/inputs combinations (<0.1Ω variation), clean switching and consistency.

One more thing, what does impedance look like when the speaker output is shorted?

As expected, basically a direct output with less then 0.4Ω of resistance going through the 3' 12AWG wire, through the box, across shorted binding posts with a 3" 12AWG wire. No low impedance protection like the "Indirect" Rotel RSS-900 speaker switch outputs.

It's nice that Audio Science Review already checked the distortion and crosstalk which saves me the trouble. In that test, using the Purifi 1ET500A amplifier, the Fosi LC30 is capable of passing along a signal better than -100dB THD+N from 1W up to 150W into 8Ω; this should be plenty transparent for hi-fi listening. There was an increase in crosstalk but still better than -70dB up to 15kHz which again is plenty.

So how does it sound in my system/room?

Let's make some short 20" 12AWG oxygen-free copper cables to go from my Integra DRX-8.4 receiver front L/R output to the VU meter. And have a listen!

KnuKonceptz Kord 12AWG OFC wire (measured), locking gold plated banana plugs. Just 20" length is all I need. No need for quantum this or that cables of course. 😉

Notice I have my old Raspberry Pi 3 'Touch' sitting in the middle audio shelf displaying the Roon playback showing the current album cover (Melody Gardot's My One and Only Thrill). Since the Integra receiver has a USB-A port at the back, I can conveniently plug the LC30 into that and have it power up when the receiver turns on.

Totally great sound.

The point of adding this is not about the sound - so long as it doesn't audibly distort, it's fine. What we want is the dancing VU meters with a classy, vintage look. As noted above, forget "wattage" accuracy of the meters as there's no real calibration potential here (externally at least, internally can consider this) other than just the sensitivity knob. The remote control is convenient and works well. Power utilization is low, just 0.01A with backlight turned off, 0.04A at lowest 25% brightness, up to 0.11A at 100%. The box does not get warm with prolonged use.

I'm enjoying the bling from this Fosi Audio LC30 VU Meter. One criticism about the "Black" model is that the dark red needle's low contrast to the black background might not be as visually noticeable as much as you might like at a distance; I think this color scheme looks great though when closer on a desktop for example. YMMV.

At some point, I'm sure to use the A/B switch function to try out different speakers and amps.

If you're looking around for this kind of device, there's also the Douk Audio VU3 Pro available around the same price which adds a few more 'bling' features like changing screen colors, can handle higher power ratings (up to 350W/channel), simple mono-microphone pick-up mode, and maybe a little more calibration potential with gain and sensitivity knobs. Given the same kind of feature set, I would not be surprised if the Douk and NEOHIPO ET30 VU meter which was surprisingly transparent are using the same OEM design. Measurements of the previous Douk Audio VU3 (non-Pro) suggests maybe a little less transparency compared to the Fosi Audio model.

I might pick up the Douk VU3 Pro to compare for fun if on sale.

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To end, I want to thank readers for music suggestions in the comments over the years! For example, in the post last week, Mike5959 suggested checking out John Scofield and Dave Holland's Memories of Home (2025, DR9). Nice recording, relaxing jazz with guitar and bass for those interested in this genre.

Here's a taste:

As you can hear, this is a variant based on Simon & Garfunkel's "Scarborough Fair/Canticle".

Have a wonderful last days of November, dear audiophiles! We're down to the last month of 2025 and Christmas holidays ahead - my favorite time of the year! ☃︎🎅🎄❄️☃️🎁🦌

Hope you're enjoying the music.