Fosi Audio BT20A MAX Bluetooth Speaker Amplifier – Stereo Delight For Everyone
Fosi Audio BT20A MAX is a $279 USD Bluetooth Stereo Amplifier for desktop speakers, 2.1 output and multiple power supply units available, and the star of our review today. Given the price point and design, I would normally try to explore some comparisons, but most amplifiers are so far in performance and features that we will broadly approach how it compares to the market.
Introduction
Fosi Audio used to dominate the entry-level Stereo AMP market because they make really affordable, but efficient AMPs, they have top quality, low price and after talking with everyone who sends emails, I learned that they are almost the most used brand of AMPs for car audio when someone wants a simple but really nice sounding setup. I wish I had the time and skills to install the BT20A MAX on my car, but sadly I simply don’t have the experience working on car audio to do it, so for now we will explore how it powers speakers and a desktop setup.
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Product Link
Amazon – https://amzn.to/4v4Ojdr
Build Quality – Design
At its core, BT20A MAX is a similar unit compared to most Fosi Audio Stereo AMPs in the entry-level price range, but it comes with multiple key improvements over the other variants they make. At the core is the BT part as Fosi used a Qualcomm QCC3095 chipset with Bluetooth 6.0 that has support for aptX, aptX HD, aptX Adaptive, aptX Lossless and LDAC, making BT20A MAX the most versatile AMP with bluetooth that I’ve reviewed so far.
As usual, the max output power is insanely high, at 300W x 2 for a 4 OHM impedance while the RMS output power is 180W x 2 for a 4 OHM impedance. This comes with a SNR of 112 dB and a THD of less than 0.003%, all insane numbers really. With a rather flagship level CS4398 DAC, Fosi took off all brakes when making the BT20A MAX, and it even has 2.1 channel support, including a separate subwoofer output.
In a more technical sense, BT20A MAX uses a TI TPA3255 (have not seen this one before) and a NE5532 (this one is quite popular in the price range), to deliver the sound, and it can take in voltage ranging from DC 32V to DC48V, as you can purchase multiple power converters for it. The BT20 series has a BT20A BT20A PRO and BT20A MAX. From A to PRO, the price increase was just 15 USD, but MAX costs almost 3X the price, yet it offers such a high increase in quality, bluetooth support codec, much higher SNR and lower THD, to the point where it would compete in the stereo market with other AMPS than BT20A PRO.
Subjective Usage
BT20A MAX is a simple to use speaker power amplifier, and it has no other outputs besides the speaker output. It also mainly has the RCA speaker input, no XLR and no USB, although it does have bluetooth input. There are two sets of RCA inputs, they sound equally good, there’s no downside, but the unit itself gets really hot during usage and even if it is amplifying silence.
I have tested especially for noise, and BT20A has zero noise, you can safely turn it to max and use it as a pure amplifier with pre set at max, it will have no noise and no background hissing audible with any speakers, it has no self noise, and the only thing that is a bit concerning is that it feels hot to the touch. This being said, Fosi made special venting holes on the side and top, so it does not have any issues, and the longest I ran it was 12 hours straight at all volume levels, and it still ran just fine.
As you have basically nothing to set on it, the only thing you need to take into account is the tone controls, bass and treble slides, which can be engaged at any point. All potentiometers are smooth with a strong damping, the whole unit is solid and nothing is loose inside, nothing rattles inside if you shake it. I would trust BT20A MAX to survive a long time.
Sound Quality
Pairings – I have used the Fosi Audio BT20A MAX to drive a large collection of both floorstanding and bookshelf speakers including Pylon Jasper Monitor 18, Elipson Heritage XLS7 Speakers, Pylon Diamond 30 MKII Stereo Speakers, Amphion Argon3s, and Pylon Audio Jasper 23 Speakers.
It has plenty of power, will make Jasper 23 move just as well as it can control Audience 1+1, it is plenty strong. Given the price point and resolution, I generally would use it to drive speakers that are in a more entry-level range ideally, but if your main power amplifier is not available, you can surely enjoy BT20A MAX even with flagship speakers.
Overall Signature – BT20A MAX sounds a bit V-Shaped, it has a bit of extra bass and extra treble, extra sharpness, at default. It is not especially neutral and linear / neutral, and instead it is a bit colored in tuning. This being said, it is plenty natural in the midrange and has a wide soundstage with a colorful midrange and vivid voicing. It is basically an ideal case for the price range, has plenty of details and a crisp resolution. It produces a soundstage that is wide and holographic, with a natural instrument separation.
Bass – Starting from the low-end, even at default, it has a few dB of extra power above what is absolutely neutral. This being said, you can lower those using the bass potentiometer, which is at default set at 12 o’clock. Absolute neutrality / linearity can be achieved with the bass set at 11 o’clock, but it has enough headroom and control to work up to the bass set at max, although that bass introduces both sub bass and mid-bass adding a bit of boom, thickness and a bit of extra oomph too. Bass character is generally bombastic, a bit slow, a bit sleazy, a bit big, perfect for EDM, watching movies and listening to commercial music. It is not very technical, but this means it is not very fatiguing either.
Midrange – You can expect a slightly recessed voicing at default, with a vivid, natural presentation. Resolution is very good for the price range, comparable with what Burson Funk delivers, it has plenty of separation and a strong layering, with a wide lateral separation, although it does not have a lot of depth. Female voices are slightly more emotional and present than male voices as BT20A MAX has a bit of upper midrange bias. I find it best for EDM, Pop, Rock and metal, and it struggles a bit with the complex dynamics and timbre of acoustic instruments, but it is plenty good for its price range.
Treble – Top end extends up to 16 kHz at default, with a slight extra kick and extra sparkle. Treble has a crisp character, and using the treble slider, you can add up to around 8 dB of extra treble, but this is a wide range adjuster that adds upper midrange too, which makes music sound not just brighter, it adds sharpness for pianos, violins and female voices even. There is no treble above 16 kHz, but it renders more micro details and better extension than the price range.
Dynamics And Textures – BT20A MAX has a better dynamic range, wider and with less compression, if used via RCA line input, compared to the Bluetooth input. Texture character is a bit slow, a bit sleazy and this makes it fatigue-free, not the most technical performer, but a bit musical and bombastic, dynamic sounding rather than technical and dry. It is good for most music.
Loudness Saturation Gradient – You will hear a bit of character change with volume, so Bt20A MAX can become more vivid, more punchy and more dynamic at higher volumes, while it sounds smoother and more relaxed at lower volumes. It is great at low and medium volumes, and while THD does not grow at high volumes, it gets more dynamically compressed and more forward, more aggressive at high volumes.
Soundstage – With a wide and holographic image, BT20AMAX sounds rather impressive and it has a first-time wow effect in its sound, which makes it great for entry-level systems and for keeping sound engaging, but it does not have a lot of depth, instead relying on a strong layering and instrument separation to produce a vivid, realistic and fun sound.
Value – Conclusion
When buying Fosi you are buying extreme value, and this is the case with BT20AMAX too, it has top value, offers bass and treble sliders with no added distortion, costs very little and fights with AMPs for speakers that are twice the price, easily offering a more compelling package, and more wow factor, making it a perfect entry-level stereo purchase.
I find BT20A MAX a top choice for a cheap but effective stereo AMP. It is far better than Fosi’s previous AMPs, it has a really high driving power, has no self noise, has bluetooth and although it runs hot, it also has very good ventilation and never turned off even if running for hours at a high volume.
PROs
- Excellent sound for the price range
- Wide and holographic soundstage
- Can add a lot of bass and sub-bass
- Can add a lot of treble and upper midrange
- Small and convenient
- Lots of ventilation to keep it running well
- Beautiful and sharp looking with an edgy take on design
- RCA input with zero self noise even at max volume
- Overall an excellent package with extra bluetooth
Cons
- Runs and stays quite hot while it is working
- Not a very deep sound
- Even with both potentiometers at default, it has a bit of V-Shaped bias with a bit of extra bass and extra treble above neutral linear
Product Link
Amazon – https://amzn.to/4v4Ojdr
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Full Playlist used for this review
We listened to more songs than those named in this playlist, but those are excellent for identifying a sonic signature. I recommend trying most of the songs from this playlist, especially if you’re searching for new music! The playlists are different for Spotify, Tidal and Youtube, and based on the songs I enjoy and are available on each!
https://www.youtube.com/playlist?list=PL_cjBXGmwSHSdGcwuc_bKbBDGHL4QvYBu
https://open.spotify.com/playlist/5J3oloz8Riy9LxEGenOjQ0?si=979ba4f082414be7
https://tidal.com/browse/playlist/330fd544-8e5b-4839-bd35-676b2edbb3d5
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