Marantz ST551 FM tuner Followup: Marantz ST-54 AM/FM tuner
Marantz ST-54 AM/FM tuner, from October 1989 (Vol.12 No.10):
The Marantz CD-94 CD player has become fairly popular in the best systems. For those interested in FM, there is a stunning, matching ST-54 tuner. Actually, the same basic tuner was reviewed four years ago in Vol.8 No.7 as the ST-74. The surface differences between the two tuners are that the latter has no remote control or timer-event recording provisions. Cosmetics have been enhanced by availability in black or gold at $319, with hand-rubbed rosewood end panels an additional $80. The gold/end-panel combination, in my opinion, makes this tuner top-dog in the appearance camp.
My original evaluation of the ST-74 was "...butter-and-marmalade appearance and AM performance, but dry-toast FM." Retesting indicates the marmalade is slightly sweeter and the toast is moister. In fact, this is one of the most sensitive tuners manufactured, at least in mono, and is as quiet as the $600 Luxman T-117 on the weakest stations (1.7µV/9.81dBf). Usable stereo sensitivity is 10µV/25.2dBf, limited by the muting threshold. 50dB stereo quieting is identical to the original measurement, 30µV/34.74dBfa 15% cut above average. SCA rejection is 48dB, up 10dB, and stereo separation is increased from 48dB to 53dB. All other parameters remained unchanged. AM reception is muddy but sensitive, 200µV/m vs the usual 300µV/m (footnote 1).
Basically, this is a good tuner and value; but there are some qualifications and limitations: FM adjacent-channel selectivity is only 8dB in Narrow mode. This limits the tuner to alternate-channel reception only unless both stations are weak. The tuner includes 10kHz-step fine-tuning (40 to +50kHz) which will aid in separating stations in rare instances. It is more useful for exact-tuning cable FM. This feature can be put into memory along with Wide/Narrow on any of the 16 FM presets. Also on the negative side, there is no blend or other weak stereo signal reduction, although it hasas indicatedgood naked stereo quieting. The ST-54 has only a 300-ohm antenna input, and a matching balun probably will be needed. A professional product, which this claims to be, should have a threaded F-type 75-ohm connector for the US market.
Audio Quality: While on the professional theme, I expect more of the companion tuner of the CD-94 than normal because of its association with a dominant species. The older review gave the Marantz product a "mediocre" sound rating"neither good nor poor." The latest version gets the same rating, but I must qualify this statement: after about three weeks' burn-in, the ST-54 is sounding 10% sweeter and crisper, and it is possible a tweak alignment would further improve audio quality (footnote 2).
Therefore, it is my conclusion that the ST-54 is 100% in looks and 60% of the caliber of the CD-94's sound quality, and will serve well in most systems where a slightly above average tuner is needed. Perhaps this is all that can be expected for the price. I would like to see Marantz build a modern tuner that would put the fabled 10B to shame and be a true companion to the CD-94.Don Scott
Footnote 1: Further improvement can be made by peaking the AM antenna near 1500kHz. The trimmer, designated CA02 and circled in red, is located near the right rear of the main circuit board.
Footnote 2: A perfectly aligned tuner will appear exactly center-tuned on stations not closely spaced without the aid of the fine-tuning control, which can be used to determine this. Also, the tuner will not chatter on weak stereo stations if the detector and muting level are set correctly, and it will sound open and clean in the Wide mode.