Sony MZ-G750
A portable MiniDisc recorder with an AM/FM radio added. It weighs 118 grams, and it let you record off the air without a separate tuner in the bag.
Overview
The MZ-G750 is the radio-equipped member of Sony's 2001 portable MiniDisc family. It shares its mechanism with the MZ-R700 and adds an AM/FM tuner to the same pocketable chassis. Sony's own service documentation lists it at approximately 81 × 74.4 × 28.1 mm and 118 grams for the recorder alone. Sony kept the weight within a couple of grams of the non-radio R700. The supplied accessories are an AC adaptor, a wired headphone/earphone remote, an optical cable, an NC-WMAA nickel-cadmium rechargeable battery, a rechargeable battery carrying case, and a carrying pouch or case with a belt clip (the pouch is omitted on the U.S. model). This was a grab-and-go recorder, not a desktop deck.
The recording and playback engine is standard Sony MiniDisc of the period. It uses ATRAC coding with ATRAC3-LP2 and ATRAC3-LP4 long-play modes, a 44.1 kHz sampling frequency, and a sampling rate converter that accepts 32 kHz, 44.1 kHz, and 48 kHz inputs. A digital source recorded off a CD player or a DAT machine gets converted on the way in. Frequency response is quoted at 20 to 20,000 Hz ± 3 dB, and wow and flutter is listed as below measurable limit. That's the usual MiniDisc party trick: the buffer and error correction do the work a transport can't. Error correction is ACIRC (Advanced Cross Interleave Reed Solomon Code), the modulation system is EFM, and the laser is a GaAlAs MQW diode at λ = 790 nm with continuous emission and output under 44.6 µW measured at 200 mm from the lens. Spindle speed runs 350 rpm to 2,800 rpm in CLV.
With an MDW-80 disc, Sony rates recording and playback time at a maximum of 160 minutes in monaural and 320 minutes in stereo. The LP4 mode does the heavy lifting. The service manual's battery tables are the more useful numbers for anyone actually carrying one. On the supplied NC-WMAA nickel-cadmium pack, Sony's EIAJ figures are roughly 4 hours recording in stereo, 6 in LP2, and 7.5 in LP4. Playback runs about 11.5, 14, and 16 hours respectively. With an LR6 (SG) "STAMINA" alkaline, the numbers jump to around 9, 13, and 16 hours recording, and 36, 42, and 48 hours playing back. Radio listening is quoted at about 9.5 hours on the NiCd and 28.5 hours on alkaline. These are lab numbers measured to the EIAJ standard, and Sony itself notes battery life may be shorter depending on operating conditions and temperature.
The radio section covers AM from 531 to 1,602 kHz and FM from 87.5 to 108.0 MHz, which are the European and most export tuning ranges. Output is a stereo mini-jack rated at 5 mW + 5 mW into a 16-ohm load. That is headphone level and nothing more. Power comes in at the DC IN 3 V jack from the supplied Sony AC adaptor, with regional variants covering 100-240 V, 230 V, and 230-240 V mains depending on the market, plus the NiCd pack or a single AA alkaline.
The G750 is not a NetMD machine, and it is not one of the later Hi-MD units. It is a 2001-vintage recorder built around the original MiniDisc format with the long-play ATRAC3 modes. The service documentation dates to January 2001, with a later revision noted as April 2002, which brackets the model's support life rather than its retail introduction. The mechanism (MT-MZR700-172) and optical pickup (LCX-4R) are shared with the R700. That's good news for parts availability, and bad news for anyone hoping the radio model has a distinct, rarer mechanism. The tuner is the differentiator, and it's the reason the G750 still has a small following among people who want to timeshift radio to MiniDisc without carrying two devices.
The NiCd packs of this era are almost certainly dead or close to it, so a buyer should expect to run on AA alkalines or source a replacement pack. The AC adaptor is the safe way to test one before committing. The optical mini-jack and the headphone remote jack are the two connectors most likely to have been stressed over two decades of pocket carry. The radio is the whole reason to choose a G750 over an R700, so it is the first thing to verify on a used example. A silent tuner turns a G750 into a heavier R700.
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