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Yes, the wide voltage AC 110-240V for power input can be used inany country. You only need to match the power cord adapter of the corresponding country. The operation of the relay commute, between audio and Bluetooth inputs is silent and effective. The useful Bluetooth range is more than 5 meters. The quality of the Bluetooth 4,2 audio is adequate for a second input.
The BT20A Pro has two volume knob options: carrot orange or dark gray. It’s a little thing, but given that I have such a preference for the gray over the orange my review unit was equipped with, it’s obvious that little aesthetic things like this matter. You can think of Fosi Audio BT20A as of a modification of its sibling in the previous entry. The main difference is that BT20A doesn’t have a subwoofer output, but provides twice as much power per each channel, 100 watts each. Same small size, but with a slightly different design with all three knobs of the same size and style, which makes it look somewhat cool. The BT20A can receive audio via either its RCA Line in or Bluetooth. The Bluetooth receiver is limited to SBC and AAC codecs but testing with my iPhone the audio quality was more than acceptable. SoundAs an aside, the company has been a joy to work with. They were exceptionally polite, cordial and patient as I went through my testing and evaluation. They tell me they have internal R&D team and it shows. Common feature of Class D power amplifiers is that they can cause serious noise when used with a radio, so we do not recommend using the BT20A with a radio or too close to it.
The BT20A Pro includes a Bluetooth 5.0 inputin addition to one pair of single-ended RCA inputs. The Bluetooth input has a memory for the last BT source but can be easily reprogrammed for a new Bluetooth source. I tried the amplifier with two purposely built studio speakers and reproducing acoustic recordings manly of serious music, with power outputs lower than 20 W RMS. The overall harmonic distortion was lower than 0,5 % as claimed by Fosi, which enabled a pleasant reproduction of the stringed instruments. The intermodulation distortion (IMD), which confuses the sound of multiple sources, was more noticeable, especially with ensembles of chords or human voice choruses and this was to be expected since the class D amplifier chops the audio signal. Actually the IMD is present in most of the commercial speakers which do not have treated surfaces inside, making it more difficult to distinguish the amount attributable to the amplifier from that produced by the speaker. It feels solidly built and has an anodized matte surface. Weighing in at only700g, it’s super easy to position or move around. The finish is surprisingly good for a budget amp; the BT20A has rounded edges and clean aesthetics. The BT20A Pro draws only 2.5 Watts of power during idle.Also, it barely gets warm even when driving speakers for long periods of time. The best modern electronics are far more energy efficient that amps from the past. This Fosi sips power, which is nice. While the included 32-volt supply works well, given the small upcharge I would recommend going with the larger 48-volt supply.Wow, this little box can pump out some serious watts, albeit in the short term testing! Switching to 32 volts cuts this down even though 4 ohm is mostly current limited:
A more sophisticated amplifier with added features and better Bluetooth connectivity with a range of 50 ft. It has a built-in speaker protection circuit, the TPA3116D2 Chip for hi-fi sound, as well as bass and treble control. This amp was much cleaner over bluetooth than the A07 Pro (or other similar bluetooth implementations I have tried in the past) - my not very scientific approach is to play something totally quiet and listen in the near field to any noise coming out speakers - this amp was the same over bluetooth and RCA as far as that subjective test was concerned. The A07 Pro was not. Hopefully there will be more definitive measurements release here soon. Its a much smaller box than the A07 Pro - so heat might be a problem if played loud for a long time - I imagine if op-amps are swap maybe some extra vents would be drilled into case Yamaha is the name that has been on the amplifier/receiver market for decades, if not to say, for ages. Some may smile in nostalgia, some may even scoff. But the fact is Yamaha is a samurai that faithfully follows its path no matter what. Yamaha A-S301BL shows its predecessors’ style – brave and not shy to be big and bold, definitely not trying to hide itself from view. As a true samurai this Yamaha amp is able to find balance between following new trends in home theatre niche and staying a true protector of true audiophile values. With a set of standard RCA inputs Yamaha A-S301BL supports the digit with a coaxial and an optical inputs. So your TV and Blu-ray player are covered. With the optional YBA-11 wireless adapter A-S301BL can be wirelessly connected to a Bluetooth capable audio source, like a phone or a PC. Additionally, the capabilities of the amp include an option to connect two different set of speakers and easily switch between them. Nice thing to have if you want to power up two rooms. Seeing how you have tone controls anyway, you could tailor any peaking with adjustment of the treble control. Won't be exact but should be good enough.Ensure that there is no interference from other electronic equipment between the BT20A and the audio source. Take a moment to tweak the treble and bass controls once you’ve fired up some music. I found that right in the middle on both the treble and bass works best for me but it will depend on your speakers and your individual preference. The signal to noise ratio of about 70 dB is a value we would like to recommend the manufacturer to work on. The TI TPA3255 seems to be a capable platform when paired with a good implementation which is what we have in BT20A Pro. You get a sense of that in company marketing material which includes Audio Precision measurements. Usability is excellent with high quality case and controls especially with respect to ability to set the tone controls to flat.
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