GPO Retro Manhattan Stereo Bluetooth Portable Speaker, Silver

This GPO Manhattan sounds very good. It may be the best overall sound I've ever experienced with a boombox. I have owned or experienced quite a few since the 80's. The Manhattan looks like many other retro ghetto-blasters. However, internally, there are significant improvements. If you were to open up the Manhattan, inside, you will find a pair of actual wooden speaker enclosures, each measuring 9 1/2 x 9 3/8 x 4 1/2 inches HWD and constructed of 1/4-inch wood panels. These enclosures hold the left and right bass drivers (4 1/2 inch woofers). The woofers are good quality, featuring a rubber roll cone suspension and center solid phase plugs for improved high frequency reproduction. The enclosures are a bass-reflex type, with a 1-inch side firing port and a 4 1/2-inch internal duct. I measured the enclosure cabinet resonance to be about 51 Hz, and the port is tuned to about 41 Hz. In simple terms, this boombox can deliver bass down to 40 Hz, which is quite good for any boombox. The high frequency drivers are actual 1-inch mylar soft domes, very similar to good quality soft dome tweeters found in home component speaker systems. They deliver detailed treble without causing fatigue or exhibiting shrillness. The amplifier section consists of a HT-317 chip, which is a class-D type. This is a Chinese chip with very limited data available. However, this chip is used in several amplifier boards. Those amp boards state a power output of 40 watts per channel (peak) with an 18 VDC power supply. The power supply which comes with this unit is an 18 VDC supply rated at 5 amps. I measured the output of the amp section. I was able to get a power bandwidth reading of about 20 watts/ch continuous into a 4-ohm load from about 60 Hz to 18 Khz within /- 1 dB.. I cannot accurately measure THD, but I believe the THD is below 1%, possibly as low as 0.3%, which is quite good, for a boombox. According to amp boards with the identical chip, S/N Ratio is about 100 dB. One such amp board claimed a freq-resp of 20 Hz to 50 KHz. I tried to measure the overall frequency response of this amplifier. The best I could get was about 35 Hz to 19 KHz within 1/-3 dB. There could be a subsonic filter (?). So, what does all this mean? I play this unit with Bass/Treble flat (0 dB) and it just sounds very musical and full bodied. Bass extension is very good. Midrange is well projected and treble is very clean and concise, without the fuzziness or harsh edge of many boomboxes. Even at loud volumes, the sound is clear and full without noticeable clipping or woofer distortion. At low volumes, this unit still delivers smooth deep bass tones, without the need to boost the bass. I do not like the display. I thought it was a true spectrum analyzer. It is useless, sadly. When turned on, a Chinese voice announcement is annoying. This unit sold for $400 about two years ago. Definitely worth the $95 I paid.