The Yamaha NS-555 floor standing speaker was designed specifically for use as part of a home theater system. Nonetheless, it has a fine musical presence that makes it a good choice for someone who wants a full-range speaker for listening to digital or turntable music. It shares a common heritage with the legendary Yamaha NS-10 and NS-10M which have been recording studio staples for decades. They’re used as reference monitors to judge mix quality as it will be reproduced by a standard set of good quality, neutral sounding consumer stereo speakers. We no longer review stand alone speaker sets, but do have a guide to the best soundbars if you need more audio advice.
The ultimate test for a speaker system is how it sounds. Regrettably, there is no specification that can accurately predict that, but frequency response is a good place to start. It tells us how close a speaker can come to reproducing the full spectrum of human hearing.
The Yamaha NS-555 floor standing speaker comes closer to that full range than the majority of the competition. Deep bass response is rated down to a surprising 30Hz. We can generally consider a speaker to be full-range if it can produce anything lower than about 50Hz.
The lowest frequency that most people can hear is around 20Hz while the lowest musical note, that of the lowest A key on a piano comes in at 27.5Hz. The defining high C note of the soprano voice is created by 1046Hz and small cymbals can produce sounds with frequencies in the neighborhood of 15kHz.
The high end of the sonic range is generally considered to be about 20,000Hz, or 20kHz. The Yamaha’s response up to 35kHz allows them to not only reproduce the highest highs that we can hear, but also to recreate the ultrasonic overtones that we merely perceive. The overtones add to the dramatic and emotional spatial quality that makes music an experience rather than just another sound.
The sensitivity rating of the NS-555 floor standing speaker is 88dB. That’s pretty good compared to many speakers on the market but rather inefficient within the group of speakers that has been assembled for this review site. At 88dB, they’re nearly silent when not being driven by content material, but not quite as quiet as others in the review.
A 3dB reduction in efficiency requires twice the input power to result in the same output. That means that a speaker that has 88dB sensitivity requires double the power to attain the same volume as a speaker with 91dB sensitivity. More importantly, it means that the amplifier or receiver is having to work that much harder to produce the sound. The ultimate result of lower efficiency is that the sound is less clear and precise because audio components produce far better results when they’re not being challenged. We believe that this lower efficiency is, in large measure, responsible for the somewhat thinner bass response that is noted with the Yamahas.
Average recommended input power is rated at 100W while the speakers can handle transients up to 250W.
Bass tones generally seem weaker than would be expected by the impressive 30Hz bass response specification of this floor standing speaker. In addition to the sensitivity issue, noted above, we believe that the woofer size and crossover setting also have something to do with rather weak bass. There are two 6½-inch Polymer-Injected Mica Diaphragm cone woofers within the Yamaha NS-555 enclosure. That’s on the smallish side for a woofer being asked to produce such low bass. Further, the crossover from woofer to mid-range is set at a rather high 1000Hz. Asking a 6½ driver to produce 30Hz to 1000Hz is a pretty tall order so it isn’t too surprising that the bass sounds thin.
Mid-range frequencies are handled by a 5-inch cone driver while treble frequencies of 4kHz and higher are directed to a 1-inch aluminum dome tweeter. Both the mid-range and tweeter are attached to waveguide horns which the manufacturer states provide improved imaging.
Despite some reservations about the overall bass response of the Yamaha NS-555 speaker, we still regard it as a good choice for use as the main left-right speaker in a home theater surround sound system where bass will be augmented by a subwoofer. At its rather modest price, it also represents a good value for use as the standalone speakers for a stereo music system.