Fosi Audio BT30D Bluetooth 5.0 Stereo Audio Receiver

Music is a huge and daily part of our lives. Because we don’t like to overdrive the living-room system just to also “light up” the kitchen area with sound, I’ve kept a small (homebrew) 18+18W amplifier and Minimus 77 speakers on top of our fridge for years. It was linked to the living-room system via a stereo audio isolation transformer, and a Bluetooth receiver with an audio switch. Unsightly, but it worked well and sounded nice. With a recent remodeling of the kitchen and living-room areas, a better-looking solution was required. With a 12x12 soffit running in an “L” shape above all of the kitchen cabinets, in-wall speakers were the obvious choice. We ordered a set of Dayton Audio ME625W in-wall 2-way units and as I will get into later, eventually added a Dayton Audio DCS165 subwoofer and quasi-matching grille, all via Amazon. (The Pyle and FOSI amplifiers mentioned here were also Amazon purchases.) My first choice for a new small amp to power this was the Pyle PFA540BT unit with built-in FM radio and Bluetooth features. That unit was bought as an open box from Amazon. While plenty loud, it had a subtle but definite grating midrange distortion once warmed up that I did not notice until it was outside of the return window. My bad, these new parts all sat around while we finished the other renovations. We all agreed it was annoying, even my kids. Additionally, the switch-mode power supply for that amp was so noisy (RF-wise) that the radio receiver only would pull in one station, with a local antenna from only a couple of miles away. The rest of the band was utterly swamped out. (No FCC cert logo visible on the PSU, now we know why). My second amp was a FOSI audio unit, the BT30D, which is much better. No radio, but BT and line in. As a plus, it’s a 2.1 system with a dedicated drive channel for a passive sub. It’s rated at 50+50+100w. It’s plenty loud, however be aware it ships with a switching power supply that can deliver only about half of that wattage. (24v x 4A = 96W). Ah, marketing. With the amp issue sorted, I was still disappointed that the in-walls did not have bass that matched the small mini-77’s that we had listened to for 10 years. Given the larger drivers and volume of trapped air behind the in-walls, I was a little surprised. Research on the FOSI website was not able to tell me if the FOSI unit has a fixed High Pass Filter on the L-R outputs or not, so I was not sure if it was the speakers, or the amp limiting the bass. Everything below about 120Hz was absent. The Pyle amp, which has no amplified sub output, sounded similar in the bass, and a third full-range analog amp I connected in also played with little bass. Conclusion is that it’s the speakers or the install environment, most likely the speakers, as the two are separated by a lot of insulation, preventing any phase cancelling behind the wall. As a result, the stout little Dayton Audio 6-1/2" sub driver was ordered and installed with a ¾” split-baffle as support in the corner of the soffit for best loading. Once set up and adjusted, we now have a system with some decent extension into the 50-100 Hz range and more than enough volume to fill the kitchen area while providing a nice stereo listening field for most of the room. I wish we had the space for a larger sub driver, but with the framing behind the 12x12 soffit, an 8” or 10” just wasn’t going to fit. The 6-1/2” sub is respectable but it’s being driven rather hard to make up for it’s lack of piston area. A second identical unit is being considered, to double the cone area and increase the efficiency, but at least for the moment it sounds nice at reasonable levels. (EDIT: a second identical sub went in, same baffle approach, as close as I could get it to the first, which helped a lot - a little more cone area to grab air - and they are not being driven so hard. The system as of March 2023 is still going strong and used daily - DSB) On balance, the FOSI amp has been very good and well-behaved. It runs a little warm, but for its size it’s punching well above its weight and the BT implementation sounds quite good. It must have a decent SBC buffer scheme, as we don’t experience any buffer under-run drop-outs over long term listening with any of the apple, android or Chromebooks attached. Bluetooth range has also been solid throughout the area. This is probably due to the external no-compromise BT antenna. The amp is small enough not to notice on top of the fridge, and looks pretty smart. I’d buy it again. I will be posting this same review on the Sub and In-Wall speakers pages as well, because it's kind of a system-level review of all the bits and pieces.

This little amp works great for what it is. Knowing what it is is the key to beign hapy with it. Like most lower-end audio equipment, the listed power rattings are "Max" vs. RMS. This is the maximum output the amp can generate, not the measure of useable power delivered to the speakers. If I had to guess, I'm working with maybe 10-15 good watts here, which is plenty for the small bookshelf speakers I'm driving. The passive sub output is good as well; I didn't figure it would generate enough umph to drive an 8" passive sub, but it's doing just fine. The sound quality is good; its not great. Not a lot of depth, but some of that is due to using small speakers. The low end of the frequency range is minimal. You will need a small sub to complement the smaller speakers that can be driven by this amp. Highs are represented well, mids are a little muddy. Adding a sub is a must as you won't be able to drive even larger bookshelf speakers. The passive sub support is surprisingly solid. There is no noticeable standing hum or static even at maximum volume which surprised me. I plan to use this setup in my garage to extend the audio range of a TV and for streaming music from my phone; it's perfect for this application. If your intent is to drive large, power hungry, speakers in a sound centric installation then you'll be disapointed. If you are looking for audiophile quality sound form this amp, you'll be disappointed again. I'm using an old set of cheap Kenwood surround speakers with 4" drivers and a passive 8" sub. It drives them all and sounds surprisingly good. The bluetooth support is solid and connects flawlesly and fast. The control pots seem to be nice quality although no detents are present. The speaker connections are of fair quality. They include both banana plug support and screw down nuts. The Aux inputs and Sub pre out (for a powered sub) are standard RCA. All said, nice little rig for what it is. I've only been using it for a day but, unless it smokes, it's a decent value.

Packaged nicely, works well, easy to hook up, exactly as described. I have no regrets about my purchase. Only thing I found off is you need to turn off bluetooth on the device that's paired to disconnect bluetooth and move to the physical input. But because of that it also means you don't need to hit a button to change to bluetooth and can do from across the room on your phone. Haven't noticed any audio issues. I have noticed a slight hiss when volume is turned up high with no input but it is barely noticeable and only if you're paying attention, my computer fans drown the noise out and is no way a turn off from buying it. *EDIT* Took away a star for the noticeable, sudden, volume reduction it does randomly. You turn it up for a good song and suddenly it's quieter and the sub output is way more noticeably reduced along with the "fullness" of it. Still a great buy for the price, I think it's overheating or something and protecting itself, I think I would buy a higher power one if I could do it again but there's nothing with the options this has in a higher output available. But regardless fantastic build quality and it's still holding up.